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29 pages, 3815 KB

Open AccessEditor’s ChoiceArticle

Stable Carbon Isotopes of Phytoplankton as a Tool to Monitor Anthropogenic CO₂ Submarine Leakages

by Federica Relitti, Nives Ogrinc, Michele Giani, Federica Cerino, Mirta Smodlaka Tankovic, Ana Baricevic, Lidia Urbini, Bor Krajnc, Paola Del Negro and Cinzia De Vittor

Water 2020, 12(12), 3573; https://doi.org/10.3390/w12123573 - 19 Dec 2020

Cited by 2 | Viewed by 5603

Abstract

This study aims to validate the stable carbon isotopic composition (δ¹³C) of phytoplankton as a tool for detecting submarine leakages of anthropogenic CO_2(g), since it is characterised by δ¹³C values significantly lower than the natural CO [...] Read more.

This study aims to validate the stable carbon isotopic composition (δ¹³C) of phytoplankton as a tool for detecting submarine leakages of anthropogenic CO_2(g), since it is characterised by δ¹³C values significantly lower than the natural CO₂ dissolved in oceans. Three culture experiments were carried out to investigate the changes in δ¹³C of the diatom Thalassiosira rotula during growth in an artificially modified medium (ASW). Three different dissolved inorganic carbon (DIC) concentrations were tested to verify if carbon availability affects phytoplankton δ¹³C. Simultaneously, at each experiment, T. rotula was cultured under natural DIC isotopic composition (δ¹³C_DIC) and carbonate system conditions. The available DIC pool for diatoms grown in ASW was characterised by δ¹³C_DIC values (−44.2 ± 0.9‰) significantly lower than the typical marine range. Through photosynthetic DIC uptake, microalgae δ¹³C rapidly changed, reaching significantly low values (until −43.4‰). Moreover, the different DIC concentrations did not affect the diatom δ¹³C, exhibiting the same trend in δ¹³C values in the three ASW experiments. The experiments prove that phytoplankton isotopic composition quickly responds to changes in the δ¹³C of the medium, making this approach a promising and low-impact tool for detecting CO_2(g) submarine leakages from CO_2(g) deposits. Full article

(This article belongs to the Section Hydrology)

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20 pages, 6782 KB

Open AccessEditor’s ChoiceArticle

Modified Convergent Flow Tracing Method for Evaluating Advective Velocity and Effective Porosity in Fractured Rock Aquifers

by Byung-Woo Kim and Hangbok Lee

Water 2020, 12(12), 3565; https://doi.org/10.3390/w12123565 - 18 Dec 2020

Cited by 1 | Viewed by 3579

Abstract

This study presented the analysis of the modified convergent flow tracing method, which is a modified virtual solute transport approach to retrieve tracer masses from a pulse image (virtual) well to an extraction well. In the convergent flow tracer test, approximate analytical solutions [...] Read more.

This study presented the analysis of the modified convergent flow tracing method, which is a modified virtual solute transport approach to retrieve tracer masses from a pulse image (virtual) well to an extraction well. In the convergent flow tracer test, approximate analytical solutions were extended for the pulse image well using a single-well tracing method. This method transformed the drift-and-pumpback conditions of the single-well tracing method. The method requires a prior information of the effective porosity. Using sodium chloride as a tracer mass, the tracer data sampled through field-scale tests were used to obtain breakthrough curves. This modified method was different from the pre-existing single method because it considers both the ambient groundwater movement (the two classes of drifts) and the constant volumetric flow rate during the pumping phase. The method was applied to the tracer test at underground research tunnel for verifying the theory inductively derived from the single tracing method. Through field tests, the values of velocity and porosity were compared to the results of the drift-and-pumpback equations of the single-well test, and the several different equations related to breakthrough curves of the two-well tests conducted on a field scale. Full article

(This article belongs to the Special Issue Applying Artificial and Environmental Tracing Techniques in Hydrogeology)

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16 pages, 5750 KB

Open AccessEditor’s ChoiceArticle

Modelling of Flood Inundation due to Levee Breaches: Sensitivity of Flood Inundation against Breach Process Parameters

by Yohannis Birhanu Tadesse and Peter Fröhle

Water 2020, 12(12), 3566; https://doi.org/10.3390/w12123566 - 18 Dec 2020

Cited by 10 | Viewed by 4118

Abstract

This paper analyses the sensitivity of flood inundation due to river levee breach against breach process parameters using the 1996 Awash River levee breach case at Wonji, Ethiopia. A parametric levee breach model integrated into the 2D hydrodynamic numerical model Telemac-2D is used [...] Read more.

This paper analyses the sensitivity of flood inundation due to river levee breach against breach process parameters using the 1996 Awash River levee breach case at Wonji, Ethiopia. A parametric levee breach model integrated into the 2D hydrodynamic numerical model Telemac-2D is used to simulate a levee breach flood event at Wonji, Ethiopia. Levee breach process parameters are systemically varied to find out their effect on the flood inundation. The analysis of the model results shows that the flood inundation is sensitive to the final breach dimensions and breach location. However, the parameters describing the levee breach development have negligible influence on the flood inundation. This implies that final breach dimension and breach location in an event of levee breach are the most important and decisive parameters affecting the resulting inundation of the flood plain, and as such should be given due consideration when creating flood inundation maps due to levee breach. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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15 pages, 2351 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of Plasma Activated Water Foliar Application on Selected Growth Parameters of Maize (Zea mays L.)

by Petr Škarpa, Daniel Klofáč, František Krčma, Jana Šimečková and Zdenka Kozáková

Water 2020, 12(12), 3545; https://doi.org/10.3390/w12123545 - 17 Dec 2020

Cited by 44 | Viewed by 5454

Abstract

Utilization of plasma activated water (PAW) for plant growing is mainly connected with the treatment of seeds and subsequent stimulation of their germination. A potential of PAW is its relatively simple and low-cost preparation that calls for studying its wider application in plant [...] Read more.

Utilization of plasma activated water (PAW) for plant growing is mainly connected with the treatment of seeds and subsequent stimulation of their germination. A potential of PAW is its relatively simple and low-cost preparation that calls for studying its wider application in plant production. For this purpose, a pot experiment was realized in order to prove effects of the foliar PAW application on maize growth. The stepped PAW foliar application, carried out in 7-day intervals, led to provable decrease of chlorophyll contents in leaves compared to the distilled water application. The PAW application significantly increased root electrical capacitance, but it had no provable effect on weight of the aboveground biomass. Chlorophyll fluorescence parameters expressing the CO₂ assimilation rate and variable fluorescence of dark-adapted leaves were provably decreased by PAW, but quantum yield of photosystem II electron transport was not influenced. A provably higher amount of nitrogen was detected in dry matter of plants treated by PAW, but contents of other macro- and micro-nutrients in the aboveground biomass of maize were not affected. Results of this pilot verification of the PAW application have shown a potential for plant growth optimization and possibility for its further utilization, especially in combination with liquid fertilizers. Full article

(This article belongs to the Special Issue Applications of Plasma Activated Water and Media in Medicine and Agriculture)

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20 pages, 5820 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Photocatalytic Degradation of Polyamide 66; Evaluating the Feasibility of Photocatalysis as a Microfibre-Targeting Technology

by Jae-Mee Lee, Rosa Busquets, In-Cheol Choi, Sung-Ho Lee, Jong-Kyu Kim and Luiza C. Campos

Water 2020, 12(12), 3551; https://doi.org/10.3390/w12123551 - 17 Dec 2020

Cited by 63 | Viewed by 6611

Abstract

Wastewater treatment plants (WWTPs) have been identified as main contributors to releasing microfibres into the environment, however, WWTPs do not have microfibre-targeting technologies. In this study, photocatalysis is evaluated as a potential technology to treat microfibres in WWTPs by studying the degradation of [...] Read more.

Wastewater treatment plants (WWTPs) have been identified as main contributors to releasing microfibres into the environment, however, WWTPs do not have microfibre-targeting technologies. In this study, photocatalysis is evaluated as a potential technology to treat microfibres in WWTPs by studying the degradation of polyamide 66 (PA66) microfibres using ultraviolet (UV) and titanium dioxide (TiO₂). PA66 microfibres suspended in deionised water were exposed to different combinations of UV and TiO₂. The degradation of the PA66 microfibres was monitored by changes in mass, carbonyl index and morphology using microbalance, infrared spectroscopy, and scanning electron microscopy. The formation of by-products from the degradation of the fibres was evaluated by measuring the chemical oxygen demand (COD) of the treated water. The degradation efficiency was optimised under UVC with a dose of 100 mg TiO₂/L. Under these conditions, the PA66 microfibres presented a 97% mass loss within 48 h. The photocatalytic conditions applied generated a relatively low level of by-products (<10 mg/L of COD). Therefore, photocatalysis with TiO₂ an UVC could potentially be a feasible technology to treat microfibres in WWTPs, although more investigation is required to establish if this treatment leads to the formation of nanofibres. Further work is needed to translate the present optimised conditions to WWTPs. Full article

(This article belongs to the Special Issue Microplastics and Microfibers in Water and Wastewater: A Grand Challenge)

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13 pages, 1371 KB

Open AccessEditor’s ChoiceArticle

Nitrogen and Phosphorus Concentration Thresholds toward Establishing Water Quality Criteria for Pennsylvania, USA

by John W. Clune, J. Kent Crawford and Elizabeth W. Boyer

Water 2020, 12(12), 3550; https://doi.org/10.3390/w12123550 - 17 Dec 2020

Cited by 12 | Viewed by 5720

Abstract

Nutrient enrichment is currently a leading cause of impairment to streams in Pennsylvania. Evaluating the water quality condition and eutrophic status of streams and rivers is a challenge without established thresholds for nutrient concentrations, which can vary depending on climate and landscape characteristics. [...] Read more.

Nutrient enrichment is currently a leading cause of impairment to streams in Pennsylvania. Evaluating the water quality condition and eutrophic status of streams and rivers is a challenge without established thresholds for nutrient concentrations, which can vary depending on climate and landscape characteristics. The US Environmental Protection Agency (USEPA) has published nutrient criteria for nutrient ecoregions nationwide that are used as regional baseline values; and has encouraged states to develop more refined values if better data are available. In this study, we quantified long-term nutrient concentrations observed in streams and rivers across Pennsylvania using a robust water quality dataset compiled from monitoring data collected over the past two decades (2000–2019) by multiple agencies. We estimated nutrient criteria concentration thresholds for each ecoregion using USEPA’s percentile approach. The 25th percentile median concentrations observed in streams and rivers ranged from 0.27 to 2.30 mg/L for total nitrogen (TN), and from 0.010 to 0.053 mg/L for total phosphorus (TP). The percent of sites with available data that exceeded the 25th percentile was 53% for TN and 60% for TP, reflecting longstanding problems with nutrient pollution of rivers and streams in Pennsylvania. The 25th percentile may overestimate background condition levels, as nutrient conditions vary substantially within and among ecoregions. We compared our contemporary concentrations at the threshold values to other published recommended criteria for the region and explored the influence of landscape heterogeneity and seasonality on nutrient concentrations. The spatial and temporal variability of nutrient conditions emphasizes the importance of using percentile analysis as only a guide toward more robust response-based methods, rather than as a method for setting nutrient criteria in Pennsylvania. Our results provide environmental managers with new insights regarding the status of nutrient conditions in streams and rivers across Pennsylvania ecoregions toward further developing numeric nutrient criteria. Full article

(This article belongs to the Special Issue Advances in Aquatic Pollution Assessment and Management)

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13 pages, 2963 KB

Open AccessEditor’s ChoiceArticle

Comparison of Different Anode Materials to Remove Microcystis aeruginosa Cells Using Electro-Coagulation–Flotation Process at Low Current Inputs

by Thenuwara Arachchige Omila Kasun Meetiyagoda and Takeshi Fujino

Water 2020, 12(12), 3528; https://doi.org/10.3390/w12123528 - 16 Dec 2020

Cited by 10 | Viewed by 4706

Abstract

Cyanobacterial blooms are a threat to the drinking water supply owing to their potential toxicity. Microcystins which are the most widespread cyanotoxins, are mainly produced by Microcystis spp. In this study, we cultured Microcystis aeruginosa cells in BG-11 medium at 25 °C to [...] Read more.

Cyanobacterial blooms are a threat to the drinking water supply owing to their potential toxicity. Microcystins which are the most widespread cyanotoxins, are mainly produced by Microcystis spp. In this study, we cultured Microcystis aeruginosa cells in BG-11 medium at 25 °C to investigate the efficiency of the electro-coagulation–flotation process to remove them. Different anode materials (Fe, Al, Cu, and Zn) along with a graphite cathode were compared separately in the 10–100 mA current range in a 0.025 M Na₂SO₄ electrolyte. Turbidity, optical density at 684 nm (OD₆₈₄), OD₇₃₀, Chl-a concentration, and DOC concentration were analyzed to clarify the mechanism by which M. aeruginosa cells are removed. The Al anode indicated the highest removal efficiencies in terms of turbidity (90%), OD₆₈₄ and OD₇₃₀ (98%), and Chl-a concentration (96%) within 30 min at 4.0 mA/cm² current density and the lowest average electrode consumption of 0.120 ± 0.023 g/L. The energy consumption of the Al electrode was 0.80 Wh/L. From these results, we found that Al was the best among the anode materials evaluated to remove M. aeruginosa cells. However, further studies are required to optimize the Al anode in terms of pH, treatment time, electrode distance, and electrolyte concentration to enhance the removal of M. aeruginosa cells. Full article

(This article belongs to the Section Water and One Health)

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16 pages, 2632 KB

Open AccessEditor’s ChoiceArticle

Effect of Clay Colloid Particles on Formaldehyde Transport in Unsaturated Porous Media

by Theodosia V. Fountouli and Constantinos V. Chrysikopoulos

Water 2020, 12(12), 3541; https://doi.org/10.3390/w12123541 - 16 Dec 2020

Cited by 14 | Viewed by 2869

Abstract

This study examines the effects of two representative colloid-sized clay particles (kaolinite, KGa-1b and montmorillonite, ST_x-1b) on the transport of formaldehyde (FA) in unsaturated porous media. The transport of FA was examined with and without the presence of clay particles under [...] Read more.

This study examines the effects of two representative colloid-sized clay particles (kaolinite, KGa-1b and montmorillonite, ST_x-1b) on the transport of formaldehyde (FA) in unsaturated porous media. The transport of FA was examined with and without the presence of clay particles under various flow rates and various levels of saturation in columns packed with quartz sand, under unsaturated conditions. The experimental results clearly suggested that the presence of clay particles retarded by up to ~23% the transport of FA in unsaturated packed columns. Derjaguin–Landau–Verwey–Overbeek (DLVO) interaction energy calculations demonstrated that permanent retention of clay colloids at air-water interfaces (AWI) and solid-water interfaces (SWI) was negligible, except for the pair (ST_x-1b)–SWI. The experimental results of this study showed that significant clay colloid retention occurred in the unsaturated column, especially at low flow rates. This deviation from DLVO predictions may be explained by the existence of additional non-DLVO forces (hydrophobic and capillary forces) that could be much stronger than van der Waals and double layer forces. The present study shows the important role of colloids, which may act as carriers of contaminants. Full article

(This article belongs to the Section Water Quality and Contamination)

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22 pages, 2567 KB

Open AccessEditor’s ChoiceArticle

Fate of Trace Organic Compounds in Hyporheic Zone Sediments of Contrasting Organic Carbon Content and Impact on the Microbiome

by Cyrus Rutere, Malte Posselt and Marcus A. Horn

Water 2020, 12(12), 3518; https://doi.org/10.3390/w12123518 - 15 Dec 2020

Cited by 11 | Viewed by 3115

Abstract

The organic carbon in streambed sediments drives multiple biogeochemical reactions, including the attenuation of organic micropollutants. An attenuation assay using sediment microcosms differing in the initial total organic carbon (TOC) revealed higher microbiome and sorption associated removal efficiencies of trace organic compounds (TrOCs) [...] Read more.

The organic carbon in streambed sediments drives multiple biogeochemical reactions, including the attenuation of organic micropollutants. An attenuation assay using sediment microcosms differing in the initial total organic carbon (TOC) revealed higher microbiome and sorption associated removal efficiencies of trace organic compounds (TrOCs) in the high-TOC compared to the low-TOC sediments. Overall, the combined microbial and sorption associated removal efficiencies of the micropollutants were generally higher than by sorption alone for all compounds tested except propranolol whose removal efficiency was similar via both mechanisms. Quantitative real-time PCR and time-resolved 16S rRNA gene amplicon sequencing revealed that higher bacterial abundance and diversity in the high-TOC sediments correlated with higher microbial removal efficiencies of most TrOCs. The bacterial community in the high-TOC sediment samples remained relatively stable against the stressor effects of TrOC amendment compared to the low-TOC sediment community that was characterized by a decline in the relative abundance of most phyla except Proteobacteria. Bacterial genera that were significantly more abundant in amended relative to unamended sediment samples and thus associated with biodegradation of the TrOCs included Xanthobacter, Hyphomicrobium, Novosphingobium, Reyranella and Terrimonas. The collective results indicated that the TOC content influences the microbial community dynamics and associated biotransformation of TrOCs as well as the sorption potential of the hyporheic zone sediments. Full article

(This article belongs to the Special Issue Environmental Fate of Contaminants in the Aquatic Environment)

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21 pages, 3431 KB

Open AccessEditor’s ChoiceArticle

Fish Community Responses to Human-Induced Stresses in the Lower Mekong Basin

by Vanna Nuon, Sovan Lek, Peng Bun Ngor, Nam So and Gaël Grenouillet

Water 2020, 12(12), 3522; https://doi.org/10.3390/w12123522 - 15 Dec 2020

Cited by 16 | Viewed by 5549

Abstract

The Mekong River is one of the world’s largest rivers and has an annual captured fish production of about 2.3 million tonnes, equivalent to around 11 billion USD. Although the Mekong provides important ecological and socioeconomic benefits to millions of people, it is [...] Read more.

The Mekong River is one of the world’s largest rivers and has an annual captured fish production of about 2.3 million tonnes, equivalent to around 11 billion USD. Although the Mekong provides important ecological and socioeconomic benefits to millions of people, it is facing intensive change due to anthropogenic stressors. Therefore, it is necessary to understand the changes to the spatiotemporal fish communities to inform sustainable fisheries management. Here, we aimed to characterize patterns of the fish communities and identify the ecological status of each fish community using daily catch data from 2007 to 2018 at 25 monitoring sites in the Lower Mekong Basin (LMB). The collected data were classified by a self-organizing map into four main groups. Group 4 represented the lower Vietnam Mekong Delta (VMD), while groups 1, 2, and 3 were subdivided into subgroups 1a (upper LMB), 1b (upper and middle LMB), 2a (Mekong River below the Khone Falls and Sesan River), 2b (Mekong River below the Khone Falls and Sekong, Sesan and Srepok (3S) Rivers), 3a (Floodplain-Tonle Sap and Songkhram) and 3b (upper VMD). Among the 571 species recorded, 119 were identified as indicator species. Based on the abundance and biomass comparison curves, the fish community of 2b was in a healthier condition with a positive W-statistic value while the rest had a negative W-statistic value. The highest species richness and diversity were observed in 3a and 2b, so these subgroups deserve high management and conservation priority. Likewise, 1a should also be considered as a high priority area since it harbors several endangered and long-distant migratory fishes. It was also noticed that the fish communities of groups 3 and 4, located far from the hydropower dams, remained mostly unchanged compared to those of groups 1 and 2, close to the mainstream and tributary dams in the upper LMB and 3S Rivers. Full article

(This article belongs to the Special Issue Channels for Change: Integrating Multiple Disciplines for New Frontiers in Managing the Mekong River Basin)

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20 pages, 6226 KB

Open AccessEditor’s ChoiceArticle

Evaluation of AnnAGNPS Model for Runoff Simulation on Watersheds from Glaciated Landscape of USA Midwest and Northeast

by Marzia Tamanna, Soni M. Pradhanang, Arthur J. Gold, Kelly Addy, Philippe G. Vidon and Ronald L. Bingner

Water 2020, 12(12), 3525; https://doi.org/10.3390/w12123525 - 15 Dec 2020

Cited by 10 | Viewed by 5076

Abstract

Runoff modeling of glaciated watersheds is required to predict runoff for water supply, aquatic ecosystem management and flood prediction, and to deal with questions concerning the impact of climate and land use change on the hydrological system and watershed export of contaminants of [...] Read more.

Runoff modeling of glaciated watersheds is required to predict runoff for water supply, aquatic ecosystem management and flood prediction, and to deal with questions concerning the impact of climate and land use change on the hydrological system and watershed export of contaminants of glaciated watersheds. A widely used pollutant loading model, Annualized Agricultural Non-Point Source Pollution (AnnAGNPS) was applied to simulate runoff from three watersheds in glaciated geomorphic settings. The objective of this study was to evaluate the suitability of the AnnAGNPS model in glaciated landscapes for the prediction of runoff volume. The study area included Sugar Creek watershed, Indiana; Fall Creek watershed, New York; and Pawcatuck River watershed, Rhode Island, USA. The AnnAGNPS model was developed, calibrated and validated for runoff estimation for these watersheds. The daily and monthly calibration and validation statistics (NSE > 0.50 and RSR < 0.70, and PBIAS ± 25%) of the developed model were satisfactory for runoff simulation for all the studied watersheds. Once AnnAGNPS successfully simulated runoff, a parameter sensitivity analysis was carried out for runoff simulation in all three watersheds. The output from our hydrological models applied to glaciated areas will provide the capacity to couple edge-of-field hydrologic modeling with the examination of riparian or riverine functions and behaviors. Full article

(This article belongs to the Special Issue Hydrological Processes in Small Catchments—Runoff and Sediment Yield in Changing Environment)

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22 pages, 4277 KB

Open AccessEditor’s ChoiceArticle

Quality and Health Risk Assessment Associated with Water Consumption—A Case Study on Karstic Springs

by Ana Moldovan, Maria-Alexandra Hoaghia, Eniko Kovacs, Ionuț Cornel Mirea, Marius Kenesz, Răzvan Adrian Arghir, Alexandru Petculescu, Erika Andrea Levei and Oana Teodora Moldovan

Water 2020, 12(12), 3510; https://doi.org/10.3390/w12123510 - 14 Dec 2020

Cited by 53 | Viewed by 6158

Abstract

In rural areas without centralized water supply systems, inhabitants often use groundwater of unknown quality as drinking water, without understanding the possible negative consequences on their health. Karstic spring waters from Dobrogea region in Romania were assessed for their potential to be used [...] Read more.

In rural areas without centralized water supply systems, inhabitants often use groundwater of unknown quality as drinking water, without understanding the possible negative consequences on their health. Karstic spring waters from Dobrogea region in Romania were assessed for their potential to be used as drinking water source, according to their quality and seasonal variation. The physico-chemical parameters of waters were compared with the guideline values for drinking water established by the World Health Organization and the Directive 98/83/EC. The nitrate and Cr concentrations exceeded the guideline value in the springs from Southern Dobrogea, but met the quality criteria in those from Northern Dobrogea, thus, to be used as drinking water, the karstic springs located in Southern Dobrogea require treatment for nitrates removal. Heavy metals pollution indices showed low to medium cumulative heavy metal pollution in all springs, while the human health risk assessment by oral exposure indicated possible noncarcinogenic risks of nitrates, both for adults and children in springs from South Dobrogea. A rigorous monitoring of the water quality before human consumption is recommended for all four studied water sources. Full article

(This article belongs to the Special Issue Research on Karst Eco-Hydrology and Sediment)

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12 pages, 1207 KB

Open AccessEditor’s ChoiceArticle

Dissolved Organic Matter in Continental Hydro-Geothermal Systems: Insights from Two Hot Springs of the East African Rift Valley

by Andrea Butturini, Stefano Amalfitano, Peter Herzsprung, Oliver J. Lechtenfeld, Stefania Venturi, Lydia A. Olaka, Nic Pacini, David M. Harper, Franco Tassi and Stefano Fazi

Water 2020, 12(12), 3512; https://doi.org/10.3390/w12123512 - 14 Dec 2020

Cited by 6 | Viewed by 3514

Abstract

Little is known about the quantity and quality of dissolved organic matter (DOM) in waters from continental geothermal systems, with only a few reports available from the Yellowstone US National Park. In this study, we explored the chemodiversity of DOM in water samples [...] Read more.

Little is known about the quantity and quality of dissolved organic matter (DOM) in waters from continental geothermal systems, with only a few reports available from the Yellowstone US National Park. In this study, we explored the chemodiversity of DOM in water samples collected from two geothermal hot springs from the Kenyan East African Rift Valley, a region extremely rich in fumaroles, geysers, and spouting springs, located in close proximity to volcanic lakes. The DOM characterization included in-depth assessments performed by negative electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Reduced, saturated and little aromatic DOM compounds were dominant in the hot spring waters collected from either the Ol Njorowa gorge (ON) or the south shore of the soda-saline Lake Elementaita (ELM). Oxygen-poor and sulfur-bearing DOM molecules prevailed in ON, probably reflecting abiotic sulfurization from sulfide-rich geofluids. Nitrogen-bearing aliphatic and protein-like molecules were abundant in ELM, possibly perfusing through the organic-rich sediments of the adjacent Lake Elementaita. Notably, the heat-altered DOM of ancient autochthonous derivation could represent an overlooked source of aliphatic organic carbon for connected lentic environments, with a potential direct impact on nutrient cycling in lakes that receive geothermal water inputs. Full article

(This article belongs to the Special Issue Dissolved Organic Matter Dynamics in Groundwater, Rivers, and Lakes)

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21 pages, 9458 KB

Open AccessEditor’s ChoiceArticle

Composition of Sedimentary Organic Matter across the Laptev Sea Shelf: Evidences from Rock-Eval Parameters and Molecular Indicators

by Elena Gershelis, Andrey Grinko, Irina Oberemok, Elizaveta Klevantseva, Natalina Poltavskaya, Alexey Ruban, Denis Chernykh, Andrey Leonov, Natalia Guseva and Igor Semiletov

Water 2020, 12(12), 3511; https://doi.org/10.3390/w12123511 - 14 Dec 2020

Cited by 9 | Viewed by 3806

Abstract

Global warming in high latitudes causes destabilization of vulnerable permafrost deposits followed by massive thaw-release of organic carbon. Permafrost-derived carbon may be buried in the nearshore sediments, transported towards the deeper basins or degraded into the greenhouse gases, potentially initiating a positive feedback [...] Read more.

Global warming in high latitudes causes destabilization of vulnerable permafrost deposits followed by massive thaw-release of organic carbon. Permafrost-derived carbon may be buried in the nearshore sediments, transported towards the deeper basins or degraded into the greenhouse gases, potentially initiating a positive feedback to climate change. In the present study, we aim to identify the sources, distribution and degradation state of organic matter (OM) stored in the surface sediments of the Laptev Sea (LS), which receives a large input of terrestrial carbon from both Lena River discharge and intense coastal erosion. We applied a suite of geochemical indicators including the Rock Eval parameters, traditionally used for the matured OM characterization, and terrestrial lipid biomarkers. In addition, we analyzed a comprehensive grain size data in order to assess hydrodynamic sedimentation regime across the LS shelf. Rock-Eval (RE) data characterize LS sedimentary OM with generally low hydrogen index (100–200 mg HC/g TOC) and oxygen index (200 and 300 CO₂/g TOC) both increasing off to the continental slope. According to T_peak values, there is a clear regional distinction between two groups (369–401 °C for the inner and mid shelf; 451–464 °C for the outer shelf). We suggest that permafrost-derived OM is traced across the shallow and mid depths with high T_peak and slightly elevated HI values if compared to other Arctic continental margins. Molecular-based degradation indicators show a trend to more degraded terrestrial OC with increasing distance from the coast corroborating with RE results. However, we observed much less variation of the degradation markers down to the deeper sampling horizons, which supports the notion that the most active OM degradation in LS land-shelf system takes part during the cross-shelf transport, not while getting buried deeper. Full article

(This article belongs to the Special Issue Geochemistry of Water and Sediment)

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26 pages, 6313 KB

Open AccessEditor’s ChoiceArticle

Observations of Nearbed Turbulence over Mobile Bedforms in Combined, Collinear Wave-Current Flows

by Hachem Kassem, Charlotte E. L. Thompson, Carl L. Amos, Ian H. Townend, David Todd, Richard J. S. Whitehouse and Elizabeth Chellew

Water 2020, 12(12), 3515; https://doi.org/10.3390/w12123515 - 14 Dec 2020

Cited by 2 | Viewed by 3246

Abstract

Collinear wave-current shear interactions are often assumed to be the same for currents following or opposing the direction of regular wave propagation; with momentum and mass exchanges restricted to the thin oscillating boundary layer (zero-flux condition) and enhanced but equal wave-averaged bed shear [...] Read more.

Collinear wave-current shear interactions are often assumed to be the same for currents following or opposing the direction of regular wave propagation; with momentum and mass exchanges restricted to the thin oscillating boundary layer (zero-flux condition) and enhanced but equal wave-averaged bed shear stresses. To examine these assumptions, a prototype-scale experiment investigated the nature of turbulent exchanges in flows with currents aligned to, and opposing, wave propagation over a mobile sandy bed. Estimated mean and maximum stresses from measurements above the bed exceeded predictions by models of bed shear stress subscribing to the assumptions above, suggesting the combined boundary layer is larger than predicted by theory. The core flow experiences upward turbulent fluxes in aligned flows, coupled with sediment entrainment by vortex shedding at flow reversal, whilst downward fluxes of eddies generated by the core flow, and strong adverse shear can enhance near-bed mass transport, in opposing currents. Current-aligned coherent structures contribute significantly to the stress and energy dissipation, and display characteristics of wall-attached eddies formed by the pairing of counter-rotating vortices. These preliminary findings suggest a notable difference in wave-following and wave-opposing wave-current interactions, and highlight the need to account for intermittent momentum-exchanges in predicting stress, boundary layer thickness and sediment transport. Full article

(This article belongs to the Special Issue Sediment Transport in Coastal Waters 2.0)

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25 pages, 8769 KB

Open AccessEditor’s ChoiceArticle

Assessment of Hydrology and Sediment Yield in the Mekong River Basin Using SWAT Model

by Ty Sok, Chantha Oeurng, Ilan Ich, Sabine Sauvage and José Miguel Sánchez-Pérez

Water 2020, 12(12), 3503; https://doi.org/10.3390/w12123503 - 13 Dec 2020

Cited by 36 | Viewed by 7541

Abstract

The Mekong River Basin (MRB) in Southeast Asia is among the world’s ten largest rivers, both in terms of its discharge and sediment load. The spatial and temporal resolution to accurately determine the sediment load/yield from tributaries and sub-basin that enters the Mekong [...] Read more.

The Mekong River Basin (MRB) in Southeast Asia is among the world’s ten largest rivers, both in terms of its discharge and sediment load. The spatial and temporal resolution to accurately determine the sediment load/yield from tributaries and sub-basin that enters the Mekong mainstream still lacks from the large-scale model. In this study, the SWAT model was applied to the MRB to assess long-term basin hydrology and to quantify the sediment load and spatial sediment yield in the MRB. The model was calibrated and validated (1985–2016) at a monthly time step. The overall proportions of streamflow in the Mekong River were 34% from surface runoff, 21% from lateral flow, 45% from groundwater contribution. The average annual sediments yield presented 1295 t/km²/year in the upper part of the basin, 218 t/km²/year in the middle, 78 t/km²/year in the intensive agricultural area and 138 t/km²/year in the highland area in the lower part. The annual average sediment yield for the Mekong River was 310 t/km²/year from upper 80% of the total MRB before entering the delta. The derived sediment yield and a spatial soil erosion map can explicitly illustrate the identification and prioritization of the critical soil erosion-prone areas of the MR sub-basins. Full article

(This article belongs to the Special Issue Fluvial Processes and Denudation)

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16 pages, 1224 KB

Open AccessEditor’s ChoiceArticle

Carbon Fixation Trends in Eleven of the World’s Largest Lakes: 2003–2018

by Michael Sayers, Karl Bosse, Gary Fahnenstiel and Robert Shuchman

Water 2020, 12(12), 3500; https://doi.org/10.3390/w12123500 - 12 Dec 2020

Cited by 21 | Viewed by 5810

Abstract

Large freshwater lakes provide immense value to the surrounding populations, yet there is limited understanding of how these lakes will respond to climate change and other factors. This study uses satellite remote sensing to estimate annual, lake-wide primary production in 11 of the [...] Read more.

Large freshwater lakes provide immense value to the surrounding populations, yet there is limited understanding of how these lakes will respond to climate change and other factors. This study uses satellite remote sensing to estimate annual, lake-wide primary production in 11 of the world’s largest lakes from 2003–2018. These lakes include the five Laurentian Great Lakes, the three African Great Lakes, Lake Baikal, and Great Bear and Great Slave Lakes. Mean annual production in these lakes ranged from under 200 mgC/m²/day to over 1100 mgC/m²/day, and the lakes were placed into one of three distinct groups (oligotrophic, mesotrophic, or eutrophic) based on their level of production. The analysis revealed only three lakes with significant production trends over the study period, with increases in Great Bear Lake (24% increase over the study period) and Great Slave Lake (27%) and a decline in Lake Tanganyika (−16%). These changes appear to be related to climate change, including increasing temperatures and solar radiation and decreasing wind speeds. This study is the first to use consistent methodology to study primary production in the world’s largest lakes, allowing for these novel between-lake comparisons and assessment of inter-annual trends. Full article

(This article belongs to the Special Issue The Impact of Environmental Stressors on Carbon Dynamics in the Aquatic System)

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27 pages, 65014 KB

Open AccessEditor’s ChoiceArticle

Trophic Niches, Trophic Positions, and Niche Overlaps between Non-Native and Native Fish Species in a Subalpine Lake

by Davide Cicala, Gianluca Polgar, Jordi René Mor, Roberta Piscia, Stefano Brignone, Silvia Zaupa and Pietro Volta

Water 2020, 12(12), 3475; https://doi.org/10.3390/w12123475 - 10 Dec 2020

Cited by 15 | Viewed by 7036

Abstract

In the last century, Italian freshwater ecosystems have been invaded by several non-native fish species. In the subalpine Lake Mergozzo (northern Italy), several recently introduced non-native species dramatically expanded their populations. We used carbon and nitrogen stable isotopes to describe the isotopic niches [...] Read more.

In the last century, Italian freshwater ecosystems have been invaded by several non-native fish species. In the subalpine Lake Mergozzo (northern Italy), several recently introduced non-native species dramatically expanded their populations. We used carbon and nitrogen stable isotopes to describe the isotopic niches and trophic positions of native and non-native fish species in Lake Mergozzo. We evaluated their trophic niches, trophic diversity, trophic redundancy and trophic evenness utilizing isotopic niche metrics, and estimated asymmetrical niche overlaps. The trophic traits of non-native fish species and Perca fluviatilis clearly define them as trophic generalists, in terms of among-individual variability of their isotopic niches. The historical increase in abundance of fish non-native species in this lake, their dominance by numbers and biomass within the assemblage, and their broad asymmetrical niche overlaps suggest that their higher degree of trophic generalism might have been one of the key factors that have promoted the invasion of the recipient community. Full article

(This article belongs to the Special Issue Biological Invasions in Changing Aquatic Ecosystems: Future Perspectives)

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24 pages, 11060 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Natural and Anthropogenic Groundwater Contamination in a Coastal Volcanic-Sedimentary Aquifer: The Case of the Archaeological Site of Cumae (Phlegraean Fields, Southern Italy)

by Luisa Stellato, Silvio Coda, Michele Arienzo, Pantaleone De Vita, Brunella Di Rienzo, Antonio D’Onofrio, Luciano Ferrara, Fabio Marzaioli, Marco Trifuoggi and Vincenzo Allocca

Water 2020, 12(12), 3463; https://doi.org/10.3390/w12123463 - 9 Dec 2020

Cited by 21 | Viewed by 4874

Abstract

Archeological sites close to coastal volcanic-sedimentary aquifers are threatened by groundwater contaminated by natural and anthropogenic processes. The paper reports on a hydrogeological, chemical (major, minor and trace elements) and isotopic (δD-H₂O, δ¹⁸O-H₂O, δ¹⁵N-NO₃ [...] Read more.

Archeological sites close to coastal volcanic-sedimentary aquifers are threatened by groundwater contaminated by natural and anthropogenic processes. The paper reports on a hydrogeological, chemical (major, minor and trace elements) and isotopic (δD-H₂O, δ¹⁸O-H₂O, δ¹⁵N-NO₃, δ¹⁸O-NO₃, δ¹¹B, ²²²Rn) survey of groundwater at the Cumae archaeological site, which is located in the coastal north-western sector of the volcanic district of Phlegraean Fields (southern Italy), where groundwater flooding phenomena occur. Results show the presence of a complex coastal volcanic-sedimentary aquifer system where groundwater quality is influenced mainly by: (i) aquifer lithology and localized ascent of magmatic fluids along buried volcano-tectonic discontinuities, (ii) mixing of groundwater, deep mineralized fluids and seawater during groundwater pumping, and (iii) nitrate contamination >50 mg/L from non-point agricultural sources. Moreover, δD and δ¹⁸O point toward fast recharge from seasonal precipitations, while the isotopic ratios of N and O in nitrate reveal the contribution of mineral and organic fertilizers as well as leakage from septic tanks. Results can assist the local archaeological authority for the safeguarding and management of the archaeological heritage of the Cumae site. Full article

(This article belongs to the Special Issue Focus on the Salinization Issue in the Mediterranean Area)

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35 pages, 6301 KB

Open AccessEditor’s ChoiceArticle

A Framework for Sustainable Planning and Decision-Making on Resource Recovery from Wastewater: Showcase for São Paulo Megacity

by Mariana C. Chrispim, Fernanda de M. de Souza, Miklas Scholz and Marcelo A. Nolasco

Water 2020, 12(12), 3466; https://doi.org/10.3390/w12123466 - 9 Dec 2020

Cited by 23 | Viewed by 7327

Abstract

Currently, it is important to develop strategic frameworks to support the selection of sustainable resource recovery solutions. This study applies a new framework for planning, implementation, and assessment of resource recovery strategies for a full-scale wastewater treatment plant (WWTP) in São Paulo megacity. [...] Read more.

Currently, it is important to develop strategic frameworks to support the selection of sustainable resource recovery solutions. This study applies a new framework for planning, implementation, and assessment of resource recovery strategies for a full-scale wastewater treatment plant (WWTP) in São Paulo megacity. The framework comprises several steps based on case study-specific data and information from current literature. Data were collected from various sources: a survey with a wastewater treatment utility, national and regional databases, and review of local regulations and international literature. Treatment configuration, wastewater and by-products composition, potential demand (for water, energy, and phosphorus), stakeholder identification, and local legislation were thoroughly discussed regarding decision-making on resource recovery. Scenario analysis was used to explore suitable nutrient and energy recovery measures based on indicators. Biogas recovery and sewage sludge composting showed more favorable conditions due to similar experiences in the area and robust legislation. The proposed framework is a simplified tool, and its application can support managers to get information on resource recovery and how to plan such initiatives in easier ways to facilitate wiser decision-making, and better operation and management. The results on framework use and refinement can guide potential applications in other contexts and stimulate public policy formulation and further research. Full article

(This article belongs to the Special Issue Application of Circular Economy Principles in Water and Wastewater Utilities)

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12 pages, 1660 KB

Open AccessEditor’s ChoiceArticle

Particle Size and Pre-Treatment Effects on Polystyrene Microplastic Settlement in Water: Implications for Environmental Behavior and Ecotoxicological Tests

by Lars Eitzen, Aki Sebastian Ruhl and Martin Jekel

Water 2020, 12(12), 3436; https://doi.org/10.3390/w12123436 - 8 Dec 2020

Cited by 14 | Viewed by 4024

Abstract

Microplastic (MP) particle dispersions used in many recent publications covering adsorption or toxicological studies are not characterized very well. The size distribution of polydisperse dispersions is highly dependent on the agglomeration processes and influences experimental outcomes. Therefore, pre-treatment is a prerequisite for reproducibility. [...] Read more.

Microplastic (MP) particle dispersions used in many recent publications covering adsorption or toxicological studies are not characterized very well. The size distribution of polydisperse dispersions is highly dependent on the agglomeration processes and influences experimental outcomes. Therefore, pre-treatment is a prerequisite for reproducibility. In this study, manual/automated shaking and ultrasonic treatment as different mechanical dispersion techniques were applied for the dispersion of cryomilled polystyrene (PS). Particle numbers and size distribution of dispersions were analyzed by a light extinction particle counter and the dispersion efficiency (E_D) as the ratio between calculated volume and theoretical volume of suspended particles was used to compare techniques. PS dispersions (20 mg/L) treated for 90 min in an ultrasonic bath (120 W, 35 kHz) were evenly dispersed with a particle concentration of 140,000 particles/mL and a high reproducibility (rel. SD = 2.1%, n = 6). Automated horizontal shaking for 754 h (250 rpm) reached similar particle numbers (122,000/mL) but with a lower reproducibility (rel. SD = 9.1%, n = 6). Manual shaking by hand dispersed the lowest number of particles (55,000/mL) and was therefore found to be unsuitable to counteract homo-agglomeration. E_D was calculated as 127%, 104% and 69% for ultrasonic treatment, horizontal shaking and manual shaking, respectively, showing an overestimation of volume assuming spherical shaped particles. Full article

(This article belongs to the Special Issue Analysis and Prevention of Microplastics Pollution in Water: Current Research and Future Directions)

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22 pages, 1514 KB

Open AccessEditor’s ChoiceArticle

Integrated Assessment—How Does It Help Unpack Water Access by Marginalized Farmers?

by Serena H. Hamilton, Wendy S. Merritt, Mahanambrota Das, M. Wakilur Rahman, Sumana S. Bhuiya, Lucy Carter, Michaela Cosijn, Christian H. Roth, Sambhu Singha and Geoffrey J. Syme

Water 2020, 12(12), 3444; https://doi.org/10.3390/w12123444 - 8 Dec 2020

Cited by 4 | Viewed by 3173

Abstract

Water is critical to the lives and livelihoods of rural communities in developing countries; however, access to water can be inequitable within communities. This paper uses a generalized integrated assessment approach to explore the determinants of water access by marginalized farmers in two [...] Read more.

Water is critical to the lives and livelihoods of rural communities in developing countries; however, access to water can be inequitable within communities. This paper uses a generalized integrated assessment approach to explore the determinants of water access by marginalized farmers in two villages in coastal Bangladesh, before and after the setup of local water institutions. The study was part of a broader project aimed at promoting socially inclusive agricultural intensification. An integrative framework was developed in this study to capture and link the diverse range of factors that influence the distribution of water, including the often-overlooked role of social dynamics and governance arrangements. While interventions around improving water resource infrastructure can be critical for freshwater availability, the case studies show that a breakdown of asymmetric power structures may also be needed for water access to all individuals, especially marginalized groups. Establishing a community-based water institution on its own does not necessarily address power issues in a community. It is imperative that the agency and capacities of the marginalized members are developed and that the institutional arrangements foster an enabling environment for marginalized members to influence decision making. Integrated assessment allowed the case studies to be explored from multiple perspectives so as to gain a greater understanding of the barriers and levers to obtaining equitable outcomes from water interventions. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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24 pages, 4527 KB

Open AccessEditor’s ChoiceArticle

Integrating In Situ and Ocean Color Data to Evaluate Ecological Quality under the Water Framework Directive

by Ana C. Brito, Paloma Garrido-Amador, Carla Gameiro, Marta Nogueira, Maria Teresa Moita and Maria Teresa Cabrita

Water 2020, 12(12), 3443; https://doi.org/10.3390/w12123443 - 8 Dec 2020

Cited by 10 | Viewed by 3371

Abstract

The Water Framework Directive (WFD) aims at evaluating the ecological status of European coastal water bodies (CWBs). This is a rather complex task and first requires the use of long-term databases to assess the effect of anthropogenic pressure on biological communities. An in [...] Read more.

The Water Framework Directive (WFD) aims at evaluating the ecological status of European coastal water bodies (CWBs). This is a rather complex task and first requires the use of long-term databases to assess the effect of anthropogenic pressure on biological communities. An in situ dataset was assembled using concomitant biological, i.e., chlorophyll a (Chl a) and environmental data, covering the years from 1995 to 2014, to enable a comprehensive assessment of eutrophication in the Western Iberia Coast (WIC). Given the temporal gaps in the dataset, especially in terms of Chl a, satellite observations were used to complement it. Positive relationships between Chl a 90th percentile and nitrogen concentrations were obtained. The Land-Uses Simplified Index (LUSI), as a pressure indicator, showed no relationship with Chl a, except in Galicia, but it highlighted a higher continental pressure in the Portuguese CWBs in comparison with Galician waters. In general terms, the trophic index (TRIX) showed that none of the CWBs were in degraded conditions. Nevertheless, the relatively high TRIX and LUSI values obtained for the water body in front of Tagus estuary suggest that this area should be subject to continued monitoring. Results highlighted the usefulness of satellite data in water quality assessments and set the background levels for the implementation of operational monitoring based on satellite Chl a. In the future, low uncertainty and harmonized satellite products across countries should be provided. Moreover, the assessment of satellite-based eutrophication indicators should also include metrics on phytoplankton phenology and community structure. Full article

(This article belongs to the Special Issue The WFD 20 Years After—Ecological Status Assessment and Restoration of Aquatic Ecosystems)

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19 pages, 1167 KB

Open AccessEditor’s ChoiceArticle

Evaluation of Environmental Quality of Mediterranean Coastal Lagoons Using Persistent Organic Pollutants and Metals in Thick-Lipped Grey Mullet

by Chiara Leone, Fabrizio Capoccioni, Claude Belpaire, Govindan Malarvannan, Giulia Poma, Adrian Covaci, Lorenzo Tancioni, Michela Contò and Eleonora Ciccotti

Water 2020, 12(12), 3450; https://doi.org/10.3390/w12123450 - 8 Dec 2020

Cited by 7 | Viewed by 3825

Abstract

The evaluation of past and present anthropogenic impacts affecting the ecological quality status of transitional ecosystems is crucial from the perspective of protecting them from further deterioration, and to evaluate remediation and restoration measures. Contamination patterns of thick-lipped grey mullet from two Mediterranean [...] Read more.

The evaluation of past and present anthropogenic impacts affecting the ecological quality status of transitional ecosystems is crucial from the perspective of protecting them from further deterioration, and to evaluate remediation and restoration measures. Contamination patterns of thick-lipped grey mullet from two Mediterranean coastal lagoons within a protected area in Italy were assessed and compared in order to evaluate their overall quality status and to collect information that can provide useful feedback on management choices aimed at enhancing environmental quality and biodiversity conservation. The quality status of the two lagoons was evaluated by an environmental assessment methodology based on indicators of direct and indirect human pressures, while a broad range of analyses were carried out to determine the presence and concentration of persistent organic pollutants (POPs) and metals in fish muscle tissue. A good quality status resulted for both lagoons, and an overall limited anthropogenic impact in the surrounding area. This could account for POPs and metal contamination levels found in mullet, although limited, and relating to their patterns. The overlap of results achieved with the two evaluation approaches can provide support for management choices in Mediterranean lagoon environments, especially for those committed to the protection and conservation of biodiversity. Full article

(This article belongs to the Special Issue Aquatic Ecosafety: Threats, Disturbances, Environmental Monitors and Bioremediation Actions)

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13 pages, 2453 KB

Open AccessEditor’s ChoiceArticle

Comparison of Zooplankton Community Patterns in Relation to Sediment Disturbances by Dredging in the Guemho River, Korea

by Eui-Jeong Ko, Dong-Kyun Kim, Eun-Song Jung, Yu-Ji Heo, Gea-Jae Joo and Hyun-Woo Kim

Water 2020, 12(12), 3434; https://doi.org/10.3390/w12123434 - 7 Dec 2020

Cited by 9 | Viewed by 3343

Abstract

This study aimed to determine whether a swimming-type (planktonic and epiphytic) zooplankton group compared with the taxonomic group is appropriate to indicate the environmental changes caused by dredging. Water sampling in the littoral zone was conducted from 2007 to 2015, including the dredging [...] Read more.

This study aimed to determine whether a swimming-type (planktonic and epiphytic) zooplankton group compared with the taxonomic group is appropriate to indicate the environmental changes caused by dredging. Water sampling in the littoral zone was conducted from 2007 to 2015, including the dredging period from October 2010 to June 2012. The water quality, number of species, population densities, and biotic indices were compared for both dredging period and grouping type. Nine of 11 water quality parameters were changed by the dredging period. The results showed that the rotifer and planktonic groups were consistently dominant. In all groups, population density was the lowest during the dredging period. After dredging, both the number of species and population density increased only in the epiphytic group. The dominant species, including Polyarthra vulgaris, Brachionus calyciflorus, B. rubens, and Bosmina longirostris, were included in the planktonic group for 9 years. Evenness did not differ, but diversity increased after the dredging period. This study showed that zooplankton could be used as a supplemental biological assessment tool for evaluating the impact of river dredging. Full article

(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)

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17 pages, 2819 KB

Open AccessEditor’s ChoiceArticle

Developing Pseudo Continuous Pedotransfer Functions for International Soils Measured with the Evaporation Method and the HYPROP System: I. The Soil Water Retention Curve

by Amninder Singh, Amir Haghverdi, Hasan Sabri Öztürk and Wolfgang Durner

Water 2020, 12(12), 3425; https://doi.org/10.3390/w12123425 - 6 Dec 2020

Cited by 12 | Viewed by 4256

Abstract

Direct measurements of soil hydraulic properties are time-consuming, challenging, and often expensive. Therefore, their indirect estimation via pedotransfer functions (PTFs) based on easily collected properties like soil texture, bulk density, and organic matter content is desirable. This study was carried out to assess [...] Read more.

Direct measurements of soil hydraulic properties are time-consuming, challenging, and often expensive. Therefore, their indirect estimation via pedotransfer functions (PTFs) based on easily collected properties like soil texture, bulk density, and organic matter content is desirable. This study was carried out to assess the accuracy of the pseudo continuous neural network PTF (PC_NN-PTF) approach for estimating the soil water retention curve of 153 international soils (a total of 12,654 measured water retention pairs) measured via the evaporation method. In addition, an independent data set from Turkey (79 soil samples with 7729 measured data pairs) was used to evaluate the reliability of the PC_NN-PTF. The best PC_NN-PTF showed high accuracy (root mean square error (RMSE) = 0.043 cm³ cm⁻³) and reliability (RMSE = 0.061 cm³ cm⁻³). When Turkish soil samples were incorporated into the training data set, the performance of the PC_NN-PTF was enhanced by 33%. Therefore, to further improve the performance of the PC_NN-PTF for new regions, we recommend the incorporation of local soils, when available, into the international data sets and developing new sets of PC_NN-PTFs. Full article

(This article belongs to the Special Issue Soft Computing for Water and Aquatic Resource Management)

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13 pages, 3233 KB

Open AccessEditor’s ChoiceArticle

Sediment Carbon Variations in the Venice Lagoon and Other Transitional Water Systems of the Northern Adriatic Sea

by Adriano Sfriso, Alessandro Buosi, Yari Tomio, Abdul-Salam Juhmani, Stefania Chiesa, Marta Greco, Chiara Gazzola, Michele Mistri, Cristina Munari and Andrea Augusto Sfriso

Water 2020, 12(12), 3430; https://doi.org/10.3390/w12123430 - 6 Dec 2020

Cited by 5 | Viewed by 3991

Abstract

The concentrations of inorganic, organic and total carbon, and some sedimentary parameters (sediment density, fines, pH, and shell fragments), have been analyzed in surface sediments of the Venice Lagoon since 1987. Environmental scenarios, characterized by different anthropogenic impacts, have been considered, especially in [...] Read more.

The concentrations of inorganic, organic and total carbon, and some sedimentary parameters (sediment density, fines, pH, and shell fragments), have been analyzed in surface sediments of the Venice Lagoon since 1987. Environmental scenarios, characterized by different anthropogenic impacts, have been considered, especially in the central basin where more information is available. Data collected in 2009 in the lagoons and ponds of Po Delta, in Comacchio Valleys and Pialassa della Baiona have been also considered and analyzed together with those recorded in the whole Venice Lagoon in 2011. The results show a strong correlation of the inorganic carbon (Cinorg) with the carbonatic or siliceous origins of the sediments and changes of both Cinorg and organic carbon (Corg) according to different anthropogenic impacts, especially eutrophication and clam-fishing activities. Higher sediment density, grain-size, and pH were associated to good-high ecological conditions and the higher presence of inorganic carbon of biological origin (shell fragments and calcified macroalgal fragments). Conversely, Corg, which is associated to eutrophic conditions, was strongly affected by the sediment disturbance and the presence of high concentrations of bivalves which enhance its consumption. Full article

(This article belongs to the Special Issue Aquatic Ecosafety: Threats, Disturbances, Environmental Monitors and Bioremediation Actions)

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15 pages, 3464 KB

Open AccessEditor’s ChoiceArticle

Small Floodplain Reservoirs in the Face of Climate Change—Sink or Source of Nutrients?

by Joanna Gmitrowicz-Iwan, Sławomir Ligęza, Jacek Pranagal, Halina Smal and Heronim Olenderek

Water 2020, 12(12), 3423; https://doi.org/10.3390/w12123423 - 5 Dec 2020

Cited by 9 | Viewed by 2483

Abstract

Despite various water protection measures, good water quality and reduction of nutrient loads seem very distant goals, largely due to limited knowledge of processes occurring in river valleys. Our study aimed at establishing the role of small floodplain reservoirs in the eutrophication processes, [...] Read more.

Despite various water protection measures, good water quality and reduction of nutrient loads seem very distant goals, largely due to limited knowledge of processes occurring in river valleys. Our study aimed at establishing the role of small floodplain reservoirs in the eutrophication processes, in the face of recent climate changes. The content of phosphorus and nitrogen compounds was determined in sediments and water of small floodplain reservoirs, (the Vistula River Valley, Poland) using spectrophotometric and Kjeldahl’s method. Nutrient loads in sediments were linked to the texture and total organic carbon content. Seasonal changes in water quality were strictly connected to changing weather conditions, flood and drought. The concentrations of PO₄³⁻ and NO₃⁻ were found to rise after summer flooding. Increases in NH₄⁺, total phosphorus (TP) and total nitrogen (TN) were correlated with the surface water area reduction in the reservoirs, which during the year of the study was on average 62%. Therefore, small floodplain reservoirs could be considered simultaneously as sinks and sources of nutrients. On the one hand, they accumulate P and N compounds carried by the river during the flood. On the other hand, climate change cause that small floodplain reservoirs may be responsible for enhanced biomass production. Full article

(This article belongs to the Section Water Quality and Contamination)

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19 pages, 2620 KB

Open AccessEditor’s ChoiceArticle

Impact of Nutrients, Temperatures, and a Heat Wave on Zooplankton Community Structure: An Experimental Approach

by Uğur Işkın, Nur Filiz, Yu Cao, Érika M. Neif, Burak Öğlü, Torben L. Lauridsen, Thomas A. Davidson, Martin Søndergaard, Ülkü Nihan Tavşanoğlu, Meryem Beklioğlu and Erik Jeppesen

Water 2020, 12(12), 3416; https://doi.org/10.3390/w12123416 - 4 Dec 2020

Cited by 29 | Viewed by 6546

Abstract

Shallow lakes are globally the most numerous water bodies and are sensitive to external perturbations, including eutrophication and climate change, which threaten their functioning. Extreme events, such as heat waves (HWs), are expected to become more frequent with global warming. To elucidate the [...] Read more.

Shallow lakes are globally the most numerous water bodies and are sensitive to external perturbations, including eutrophication and climate change, which threaten their functioning. Extreme events, such as heat waves (HWs), are expected to become more frequent with global warming. To elucidate the effects of nutrients, warming, and HWs on zooplankton community structure, we conducted an experiment in 24 flow-through mesocosms (1.9 m in diameter, 1.0 m deep) imitating shallow lakes. The mesocosms have two nutrient levels (high (HN) and low (LN)) crossed with three temperature scenarios based on the Intergovernmental Panel on Climate Change (IPCC) projections of likely warming scenarios (unheated, A2, and A2 + 50%). The mesocosms had been running continuously with these treatments for 11 years prior to the HW simulation, which consisted of an additional 5 °C increase in temperature applied from 1 July to 1 August 2014. The results showed that nutrient effects on the zooplankton community composition and abundance were greater than temperature effects for the period before, during, and after the HW. Before the HW, taxon richness was higher, and functional group diversity and evenness were lower in HN than in LN. We also found a lower biomass of large Cladocera and a lower zooplankton: phytoplankton ratio, indicating higher fish predation in HN than in LN. Concerning the temperature treatment, we found some indication of higher fish predation with warming in LN, but no clear effects in HN. There was a positive nutrient and warming interaction for the biomass of total zooplankton, large and small Copepoda, and the zooplankton: phytoplankton ratio during the HW, which was attributed to recorded HW-induced fish kill. The pattern after the HW largely followed the HW response. Our results suggest a strong nutrient effect on zooplankton, while the effect of temperature treatment and the 5 °C HW was comparatively modest, and the changes likely largely reflected changes in predation. Full article

(This article belongs to the Special Issue Effect of Extreme Climate Events on Lake Ecosystems)

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13 pages, 2450 KB

Open AccessEditor’s ChoiceArticle

Prediction of Water Level and Water Quality Using a CNN-LSTM Combined Deep Learning Approach

by Sang-Soo Baek, Jongcheol Pyo and Jong Ahn Chun

Water 2020, 12(12), 3399; https://doi.org/10.3390/w12123399 - 3 Dec 2020

Cited by 220 | Viewed by 15233

Abstract

A Convolutional Neural Network (CNN)-Long Short-Term Memory (LSTM) combined with a deep learning approach was created by combining CNN and LSTM networks simulated water quality including total nitrogen, total phosphorous, and total organic carbon. Water level and water quality data in the Nakdong [...] Read more.

A Convolutional Neural Network (CNN)-Long Short-Term Memory (LSTM) combined with a deep learning approach was created by combining CNN and LSTM networks simulated water quality including total nitrogen, total phosphorous, and total organic carbon. Water level and water quality data in the Nakdong river basin were collected from the Water Resources Management Information System (WAMIS) and the Real-Time Water Quality Information, respectively. The rainfall radar image and operation information of estuary barrage were also collected from the Korea Meteorological Administration. In this study, CNN was used to simulate the water level and LSTM used for water quality. The entire simulation period was 1 January 2016–16 November 2017 and divided into two parts: (1) calibration (1 January 2016–1 March 2017); and (2) validation (2 March 2017–16 November 2017). This study revealed that the performances of both of the CNN and LSTM models were in the “very good” range with above the Nash–Sutcliffe efficiency value of 0.75 and that those models well represented the temporal variations of the pollutants in Nakdong river basin (NRB). It is concluded that the proposed approach in this study can be useful to accurately simulate the water level and water quality. Full article

(This article belongs to the Special Issue Water-Quality Modeling)

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17 pages, 5676 KB

Open AccessEditor’s ChoiceArticle

Warming of Near-Surface Summer Water Temperatures in Lakes of the Conterminous United States

by Roger W. Bachmann, Daniel E. Canfield, Jr., Sapna Sharma and Vincent Lecours

Water 2020, 12(12), 3381; https://doi.org/10.3390/w12123381 - 2 Dec 2020

Cited by 10 | Viewed by 3202

Abstract

Because warming water temperatures have widespread consequences for freshwater communities, we were interested in estimating the patterns and rates of change of near-surface summer water temperatures in United States lakes. We developed multiple regression models to relate daily surface water temperatures in lakes [...] Read more.

Because warming water temperatures have widespread consequences for freshwater communities, we were interested in estimating the patterns and rates of change of near-surface summer water temperatures in United States lakes. We developed multiple regression models to relate daily surface water temperatures in lakes of the conterminous United States to 8-day average air temperatures, latitude, elevation, and sampling month and year using data from 5723 lake samples in the months of June-September during the period 1981–2018. Our model explained 79% of the variation with a root-mean-square error of 1.69 °C. We predicted monthly average near-surface water temperatures for 1033 lakes for each year from 1981 through 2018. Lakes across the conterminous United States have been warming for the period 1981–2018 at an average heating rate of 0.32 °C per decade for the summer months (June–September). The average summer warming from 1981–2018 would be the equivalent of a lake decreasing 259 m in elevation or moving 233 km south. On the basis of national air temperatures starting in 1895, it was inferred that lake water temperatures are variable from year to year and have been steadily increasing since 1964, but that maximum temperatures in the 1930s were just as warm as those in 2008–2018. Full article

(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)

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12 pages, 1442 KB

Open AccessEditor’s ChoiceArticle

Sustainable Exploitation of Dominant Fishes in the Largest Estuary in Southeastern China

by Linlong Wang, Li Lin, Yuan Li, Yankuo Xing and Bin Kang

Water 2020, 12(12), 3390; https://doi.org/10.3390/w12123390 - 2 Dec 2020

Cited by 12 | Viewed by 2898

Abstract

Globally, marine fisheries have declined under multiple stresses including overfishing, climate change, and habitat degradation. The Min River Estuary, as the largest estuary in southeastern China, has confronted this situation over recent decades. In this study, the dominant species of fish stocks in [...] Read more.

Globally, marine fisheries have declined under multiple stresses including overfishing, climate change, and habitat degradation. The Min River Estuary, as the largest estuary in southeastern China, has confronted this situation over recent decades. In this study, the dominant species of fish stocks in the Min River Estuary, including Coilia mystus, Cynoglossus abbreviates, Collichthys lucidus, Amblychaeturichthys hexanema, Polydactylus sextarius, Harpodon nehereus, and Secutor ruconius, were evaluated by the length-based Bayesian biomass estimator method (LBB). Outcomes could be grouped into three categories as healthy, showing the lowest exploitation rate (E: 0.31–0.43) and highest relative biomass (B/B_msy: 1.30–1.90), including S. ruconius, C. mystus, and H. nehereus; overfished, with a medium E (0.50–0.58) and B/B_msy (0.68–0.79), including A. hexanema and C. abbreviates; and collapsed, with the highest E (0.89–0.92) and lowest B/B_msy (0.03–0.21), including C. lucidus and P.sextarius. Corresponding imperative countermeasures such as using larger-sized mesh gears and reducing fishing intensity should be deployed according to the current status of each species for sustainable fishery exploitation and fish conservation. Full article

(This article belongs to the Section Water, Agriculture and Aquaculture)

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21 pages, 3342 KB

Open AccessEditor’s ChoiceArticle

Phytoplankton Community Response to Nutrients, Temperatures, and a Heat Wave in Shallow Lakes: An Experimental Approach

by Nur Filiz, Uğur Işkın, Meryem Beklioğlu, Burak Öğlü, Yu Cao, Thomas A. Davidson, Martin Søndergaard, Torben L. Lauridsen and Erik Jeppesen

Water 2020, 12(12), 3394; https://doi.org/10.3390/w12123394 - 2 Dec 2020

Cited by 36 | Viewed by 6245

Abstract

Phytoplankton usually responds directly and fast to environmental fluctuations, making them useful indicators of lake ecosystem changes caused by various stressors. Here, we examined the phytoplankton community composition before, during, and after a simulated 1-month heat wave in a mesocosm facility in Silkeborg, [...] Read more.

Phytoplankton usually responds directly and fast to environmental fluctuations, making them useful indicators of lake ecosystem changes caused by various stressors. Here, we examined the phytoplankton community composition before, during, and after a simulated 1-month heat wave in a mesocosm facility in Silkeborg, Denmark. The experiment was conducted over three contrasting temperature scenarios (ambient (A0), Intergovernmental Panel on Climate Change A2 scenario (circa +3 °C, A2) and A2+ %50 (circa +4.5 °C, A2+)) crossed with two nutrient levels (low (LN) and high (HN)) with four replicates. The facility includes 24 mesocosms mimicking shallow lakes, which at the time of our experiment had run without interruption for 11 years. The 1-month heat wave effect was simulated by increasing the temperature by 5 °C (1 July to 1 August) in A2 and A2+, while A0 was not additionally heated. Throughout the study, HN treatments were mostly dominated by Cyanobacteria, whereas LN treatments were richer in genera and mostly dominated by Chlorophyta. Linear mixed model analyses revealed that high nutrient conditions were the most important structuring factor, which, regardless of temperature treatments and heat waves, increased total phytoplankton, Chlorophyta, Bacillariophyta, and Cyanobacteria biomasses and decreased genus richness and the grazing pressure of zooplankton. The effect of temperature was, however, modest. The effect of warming on the phytoplankton community was not significant before the heat wave, yet during the heat wave it became significant, especially in LN-A2+, and negative interaction effects between nutrient and A2+ warming were recorded. These warming effects continued after the heat wave, as also evidenced by Co-inertia analyses. In contrast to the prevailing theory stating that more diverse ecosystems would be more stable, HN were less affected by the heat wave disturbance, most likely because the dominant phytoplankton group cyanobacteria is adapted to high nutrient conditions and also benefits from increased temperature. We did not find any significant change in phytoplankton size diversity, but size evenness decreased in HN as a result of an increase in the smallest and largest size classes simultaneously. We conclude that the phytoplankton community was most strongly affected by the nutrient level, but less sensitive to changes in both temperature treatments and the heat wave simulation in these systems, which have been adapted for a long time to different temperatures. Moreover, the temperature and heat wave effects were observed mostly in LN systems, indicating that the sensitivity of phytoplankton community structure to high temperatures is dependent on nutrient availability. Full article

(This article belongs to the Special Issue Effect of Extreme Climate Events on Lake Ecosystems)

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21 pages, 6624 KB

Open AccessEditor’s ChoiceArticle

Trend Analysis of Nitrate Concentration in Rivers in Southern France

by Fayçal Bouraoui and Anna Malagó

Water 2020, 12(12), 3374; https://doi.org/10.3390/w12123374 - 1 Dec 2020

Cited by 5 | Viewed by 3935

Abstract

Excessive nutrients in rivers, lakes and aquifers are still threatening environmental health in Europe. Stringent regulations have led to progress in water quality, however hotspots with high nitrate concentrations still exist in Europe and understanding the impact of management on the nitrate concentrations [...] Read more.

Excessive nutrients in rivers, lakes and aquifers are still threatening environmental health in Europe. Stringent regulations have led to progress in water quality, however hotspots with high nitrate concentrations still exist in Europe and understanding the impact of management on the nitrate concentrations and trends in these critical areas is still challenging. In this paper, we use the Exploration and Graphics for RivEr Trends (EGRET) statistical tool to eliminate the impact of flow variation, both short- and long-term, on nitrate concentration. We apply this tool to the south of France where water quality and quantity monitoring data is readily available. We compare the Mann–Kendall non-parametric approach to estimate trend and a methodology commonly used by Member States of the European Union when they report their progress in implementing the Nitrates Directive (referred to MSD approach hereafter). We showed that using the latter approach for the period 2008–2015 and the Mann–Kendall test leads to similar results in percentage of stations exhibiting trends, however with a significant disagreement on the stations exhibiting these trends. We further showed that when using flow-weighted nitrate concentrations instead of the simple mean nitrate concentration, the MSD approach results in a significant underestimation of the stations with an increasing trend. We also demonstrated that most of nitrate concentration time series are characterized by a bell-shaped curve with an increase of concentration from 1990 to mid-2000 and then a significant decreasing trend due to the implementation of management measures from mid-2000 to 2017. Most of the significant decreasing nitrate concentration trends are localized in Nitrate Vulnerable Zones that correspond to areas where strict nutrient management is required, highlighting the efficiency of the policy in place. Full article

(This article belongs to the Section Water Quality and Contamination)

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30 pages, 17834 KB

Open AccessEditor’s ChoiceArticle

Long-Term Changes of Morphodynamics on Little Ice Age Lateral Moraines and the Resulting Sediment Transfer into Mountain Streams in the Upper Kauner Valley, Austria

by Moritz Altmann, Livia Piermattei, Florian Haas, Tobias Heckmann, Fabian Fleischer, Jakob Rom, Sarah Betz-Nutz, Bettina Knoflach, Svenja Müller, Katharina Ramskogler, Madlene Pfeiffer, Florentin Hofmeister, Camillo Ressl and Michael Becht

Water 2020, 12(12), 3375; https://doi.org/10.3390/w12123375 - 1 Dec 2020

Cited by 15 | Viewed by 4370

Abstract

Since the end of the Little Ice Age (LIA), formerly glaciated areas have undergone considerable changes in their morphodynamics due to external forces and system-internal dynamics. Using multi-temporal high-resolution digital elevation models (DEMs) from different remote sensing techniques such as historical digital aerial [...] Read more.

Since the end of the Little Ice Age (LIA), formerly glaciated areas have undergone considerable changes in their morphodynamics due to external forces and system-internal dynamics. Using multi-temporal high-resolution digital elevation models (DEMs) from different remote sensing techniques such as historical digital aerial images and light detection and ranging (LiDAR), and the resulting DEMs of difference (DoD), spatial erosion and accumulation patterns can be analyzed in proglacial areas over several decades. In this study, several morphological sediment budgets of different test sites on lateral moraines and different long-term periods were determined, covering a total period of 49 years. The test sites show high ongoing morphodynamics, and therefore low vegetation development. A decrease as well as an increase of the mean annual erosion volume could be demonstrated at the different test sites. All test sites show a slope–channel coupling and a decrease in the efficiency of sediment transport from slopes to channels. These developments are generally subject to conditions of increasing temperature, decreasing short-term precipitation patterns and increasing runoff from adjacent mountain streams. Finally, the study shows that sediment is still available on the investigated test sites and the paraglacial adjustment process is still in progress even after several decades of deglaciation (~133 years). Full article

(This article belongs to the Special Issue Transformation of Glacial and Periglacial Environments in Mountain Regions)

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20 pages, 5152 KB

Open AccessEditor’s ChoiceArticle

Time Series Changes in Fish Assemblages and Habitat Structures Caused by Partial Check Dam Removal

by Shigeya Nagayama, Nobuo Ishiyama, Taro Seno, Hideyuki Kawai, Yoichi Kawaguchi, Daisuke Nakano and Futoshi Nakamura

Water 2020, 12(12), 3357; https://doi.org/10.3390/w12123357 - 30 Nov 2020

Cited by 10 | Viewed by 3184

Abstract

Despite a steep increase in dam removal projects, there are few studies on the biophysical responses to dam removal. In this study, we evaluated the short-term (1.5 years) and long-term (5.5 years) effects of partial check dam removal on fish assemblages and their [...] Read more.

Despite a steep increase in dam removal projects, there are few studies on the biophysical responses to dam removal. In this study, we evaluated the short-term (1.5 years) and long-term (5.5 years) effects of partial check dam removal on fish assemblages and their habitats. First, the habitat preferences of fish were examined at a channel unit scale: pools, rapids, and side channels satisfied the seasonal habitat requirements of the fish assemblages. Partial check dam removal increased the abundance of these habitats and diversified the habitat structures owing to the sediment release from the dam; in contrast, the bedrock distinctly decreased 1.5 years after dam removal. However, 5.5 years after dam removal, the bedrock proportion increased, and the habitat structures were simplified again owing to the re-transportation of sediments. Similar temporal changes were also determined through a reach-scale analysis with a change in the bed materials. Anadromous Oncorhynchus masou began to spawn and recolonize in the upstream section of the dam after the dam removal, causing similar assemblage compositions between the downstream and upstream sections. The abundance of Salvelinus malma and Noemacheilus barbatulus toni in the upstream reaches decreased over time after the dam removal. The temporal changes in the biophysical responses suggest that long-term monitoring is indispensable for the reliable evaluation of dam removal effects. Full article

(This article belongs to the Special Issue Endangered Freshwater Ecosystems: Threats and Conservation Needs)

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19 pages, 2311 KB

Open AccessEditor’s ChoiceArticle

The Role of Water Supply Development in the Earth System

by Slobodan P. Simonovic and Patrick A. Breach

Water 2020, 12(12), 3349; https://doi.org/10.3390/w12123349 - 29 Nov 2020

Cited by 15 | Viewed by 3827

Abstract

The ANEMI model is an integrated assessment model of global change that emphasizes the role of water resources. Securing water resources for the future is a key issue of global change and ties into global systems of population growth, climate change carbon cycle, [...] Read more.

The ANEMI model is an integrated assessment model of global change that emphasizes the role of water resources. Securing water resources for the future is a key issue of global change and ties into global systems of population growth, climate change carbon cycle, hydrologic cycle, economy, energy production, land use and pollution generation. The focus of the presented work is on the development of global water supplies necessary to keep pace with a growing population and global economy. With the structure of the ANEMI model, a series of experiments are conducted in order to assess: (i) the current role of water supply in the global Earth system; (ii) the level of water stress that can be expected in the future; and (iii) what are the potential effects of water quality on global surface water supply and the distribution of water supply types. The results of model simulations show that surface water resources were sufficient to meet the water demand and water quality is not shown to be a significant factor for the development of surface water supplies. Due to globally aggregated scale, these impacts are averaged and likely understated. Full article

(This article belongs to the Special Issue Feature Papers of Water Resources Management, Policy and Governance)

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14 pages, 2432 KB

Open AccessEditor’s ChoiceArticle

Distributions of Microplastics in Surface Water, Fish, and Sediment in the Vicinity of a Sewage Treatment Plant

by Tae-Jin Park, Seung-Hyun Lee, Myung-Sung Lee, Jae-Kwan Lee, Ji-Hyoung Park and Kyung-Duk Zoh

Water 2020, 12(12), 3333; https://doi.org/10.3390/w12123333 - 27 Nov 2020

Cited by 80 | Viewed by 9518

Abstract

Microplastics are ubiquitously found in freshwater and marine environments worldwide. In particular, wastewater treatment plants (WWTPs) or sewage treatment plants (STPs) have been recognized as a main source of microplastics in the receiving freshwater. However, only a few studies have been conducted to [...] Read more.

Microplastics are ubiquitously found in freshwater and marine environments worldwide. In particular, wastewater treatment plants (WWTPs) or sewage treatment plants (STPs) have been recognized as a main source of microplastics in the receiving freshwater. However, only a few studies have been conducted to examine the impact of these facilities on receiving waters. In this study, we investigated the distribution of microplastics in surface water, fish, and sediment near a sewage treatment plant (STP) in the Tanchon stream, one of the main tributaries flowing into the Han River, Korea. The concentration of microplastics in water varied spatially and temporarily, ranging between 5.3 and 87.3 particles/m³ (31.4 ± 28.5 particles/m³). In fish, the concentration in upstream and downstream sites was 7.3 ± 7.3 and 12.4 ± 17.9 particles/fish, respectively. Spatially, the downstream site was the most polluted with microplastics in water and fish. The concentration of microplastics was positively correlated with fish body length and weight. In sediment, microplastic concentration in upstream and downstream sites was 493.1 ± 136.0 and 380.0 ± 144.2 particles/kg, respectively. The contribution of upstream to the microplastic load in downstream was 15.8% in dry season (April), which was higher than that of STP effluent and Yangjaechon creek. Meanwhile, the highest load was observed in STP effluent (5.1%) in rainy season (August). Microplastics were more abundant in water in the rainy season (37.4 ± 37.0 particles/m³) than in the dry season (28.2 ± 22.2 particles/m³). Polyethylene (49%) and polypropylene (18%) were the most abundant polymer types in water, fish, and sediment. Regarding shape of microplastics, fragments were dominant (95%) over fiber and film in water, fish, and sediment. Full article

(This article belongs to the Special Issue Microplastics in Aquatic Environments and Wastewater Treatment )

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24 pages, 3514 KB

Open AccessEditor’s ChoiceArticle

Selection of Macroinvertebrate Indices and Metrics for Assessing Sediment Quality in the St. Lawrence River (QC, Canada)

by Mélanie Desrosiers, Bernadette Pinel-Alloul and Charlotte Spilmont

Water 2020, 12(12), 3335; https://doi.org/10.3390/w12123335 - 27 Nov 2020

Cited by 5 | Viewed by 3572

Abstract

This study aims to evaluate the anthropogenic pressure in the St. Lawrence River by assessing the relationships between composition and chemical contamination of sediments and macroinvertebrate community structure using a selection of indices and metrics. The aims of this study are to (i) [...] Read more.

This study aims to evaluate the anthropogenic pressure in the St. Lawrence River by assessing the relationships between composition and chemical contamination of sediments and macroinvertebrate community structure using a selection of indices and metrics. The aims of this study are to (i) determine the composition of macroinvertebrate community in sediments across a gradient of disturbance, (ii) select relevant macroinvertebrate indices and metrics for the assessment of sediment quality, (iii) investigate whether responses of selected indices and metrics differ across habitats and/or sediment quality classes, and finally, (iv) determine the thresholds for critical contaminants related to significant changes in the most relevant indices and metrics. Organic and inorganic contaminants as well as other sediment variables (sediment grain size, total organic carbon, nutrients, etc.) and macroinvertebrate assemblages were determined in 59 sites along the river. Fourteen macroinvertebrate indices and metrics, on the 264 initially selected, were shown to be the most effective to be used in bioassessment for the St. Lawrence River. However, the variation in macroinvertebrate indices and metrics remains strongly explained by habitat characteristics, such as sediment grain size or the level of nutrients. There is also an influence of metals and, to a lesser extent, organic contaminants such as petroleum hydrocarbons. The 14 selected indices and metrics are promising bioassessment tools that are easy to use and interpret in an environmental assessment of sediment quality in the St. Lawrence River. Full article

(This article belongs to the Special Issue Freshwater Macroinvertebrates: Main Gaps and Future Trends)

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25 pages, 3797 KB

Open AccessEditor’s ChoiceArticle

Advancing Collaborative Water Governance: Unravelling Stakeholders’ Relationships and Influences in Contentious River Basins

by Rodrigo Rojas, Gabriella Bennison, Victor Gálvez, Edmundo Claro and Gabriel Castelblanco

Water 2020, 12(12), 3316; https://doi.org/10.3390/w12123316 - 26 Nov 2020

Cited by 42 | Viewed by 7519

Abstract

Collaborative water governance (CWG) has emerged as a promising framework to tackle water management challenges. Simple identification of participants however is not enough to unravel the intricacies of stakeholders’ interlinkages, roles and influences for robust CWG. A clear understanding of the stakeholders’ landscape [...] Read more.

Collaborative water governance (CWG) has emerged as a promising framework to tackle water management challenges. Simple identification of participants however is not enough to unravel the intricacies of stakeholders’ interlinkages, roles and influences for robust CWG. A clear understanding of the stakeholders’ landscape is therefore required to underpin CWG. In this work, we combine stakeholder analysis (SA), social network analysis (SNA) and participatory processes (PP) under a theoretical collaborative governance framework to advance CWG in the contentious Rapel River Basin (RRB), Chile. By combining these techniques, we identified a cohort of leading (and secondary) stakeholders, their relationships and critical roles on basin-wide CWG-enabling networks (collaborative ties, information flows and financial exchanges) and their influence to achieve a shared vision for water planning. The results show members of this cohort perform critical roles (bridging, connecting and gatekeeping) across the networks and in influencing explicit elements of the shared vision. Specific CWG-enabling networks properties indicate a weak adaptive capacity of stakeholders to deal with potential water management challenges and strong prospects for sharing innovative ideas/solutions and achieving long-term water planning goals. A major CWG implementation challenge in the RRB is the lack of a leading organisation. One way forward would be formally organising stakeholders of the identified cohort to advance CWG in the RRB. By implementing the methodological framework, we facilitated social learning, fostered trust among stakeholders and mobilised efforts towards implementing CWG in practice in the contentious RRB. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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20 pages, 4251 KB

Open AccessEditor’s ChoiceArticle

Seasonal Distributions of Phytoplankton and Environmental Factors Generate Algal Blooms in the Taehwa River, South Korea

by Bo-Ram Sim, Hyung-Chul Kim, Chung-Sook Kim, Jin-Ho Kim, Kyung-Woo Park, Weol-Ae Lim and Won-Chan Lee

Water 2020, 12(12), 3329; https://doi.org/10.3390/w12123329 - 26 Nov 2020

Cited by 13 | Viewed by 3709

Abstract

Algal blooms have occurred in the Taehwa River estuary in South Korea despite the improvement of water quality since environmental renewal projects in the 1990s. In this study, we investigated the causes of algal blooms by measuring the water retention time using a [...] Read more.

Algal blooms have occurred in the Taehwa River estuary in South Korea despite the improvement of water quality since environmental renewal projects in the 1990s. In this study, we investigated the causes of algal blooms by measuring the water retention time using a floating buoy, water quality parameters, and phytoplankton distribution data from 2012. An algal bloom did not occur in February because of phosphate limitations in the Taehwa River estuary; however, the concentration of nutrients in the water inflow from the basin triggered a significant algal bloom in the upper estuary in the month of May. In this regard, the phytoplankton population was dominated by nano- and pico-sized flagellates. In August, the freshwater inflow into the estuary greatly increased due to heavy rainfall, resulting in a shorter retention time of the water bodies, which seemed to prevent an algal bloom. In November, a bloom of Cryptophyceae occurred at one of the sites (the U2 site) due to sufficient nutrients in the water and the long retention times of the water bodies. Our results indicate that a decrease in the nutrients (N and P) supplied from the basin is required for a reduction in algal blooms in the Taehwa River estuary. Additional studies are needed to further elucidate the effects of the land-based, nutrient-rich pollutants flowing into the Taehwa River estuary on algal bloom generation considering the fact that the streams have different environmental characteristics. Full article

(This article belongs to the Special Issue The Ecological Assessment of Rivers and Estuaries: Present and Future)

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23 pages, 8535 KB

Open AccessEditor’s ChoiceArticle

Monitoring the Hydrological Balance of a Landslide-Prone Slope Covered by Pyroclastic Deposits over Limestone Fractured Bedrock

by Pasquale Marino, Luca Comegna, Emilia Damiano, Lucio Olivares and Roberto Greco

Water 2020, 12(12), 3309; https://doi.org/10.3390/w12123309 - 25 Nov 2020

Cited by 19 | Viewed by 3420

Abstract

Many mountainous areas in Campania, Southern Italy, are characterized by steep slopes covered by loose unsaturated pyroclastic deposits laying upon fractured limestone bedrock. The soil covers are mainly constituted by layers of ashes and pumices. Large and intense rainfall events trigger shallow landslides, [...] Read more.

Many mountainous areas in Campania, Southern Italy, are characterized by steep slopes covered by loose unsaturated pyroclastic deposits laying upon fractured limestone bedrock. The soil covers are mainly constituted by layers of ashes and pumices. Large and intense rainfall events trigger shallow landslides, often turning into debris flows that cause huge damage and casualties. The slope of Cervinara, around 40 km Northeast of Naples, was involved in a catastrophic flowslide on 16 December 1999, triggered by a rainstorm of 325 mm in 48 h. To capture the main effects of precipitation on the slope stability, hydro-meteorological monitoring activities have been carried out at the slope to assess the water balance for three years (2017–2020). The field monitoring data allowed the identification of the complex hydrological processes involving the unsaturated pyroclastic soil and the shallow groundwater system developing in the limestone bedrock, which control the conditions that potentially predispose the slope to landslide triggering. Specifically, late autumn has been identified as the potentially most critical period, when slope drainage processes are not yet effective, and soil covers already receive large amounts of precipitation. Full article

(This article belongs to the Special Issue Rainfall Infiltration Processes and Their Effects on Landslide Hazard)

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30 pages, 12064 KB

Open AccessEditor’s ChoiceArticle

Modeling of Mass Balance Variability and Its Impact on Water Discharge from the Urumqi Glacier No. 1 Catchment, Tian Shan, China

by Kira Thiel, Anselm Arndt, Puyu Wang, Huilin Li, Zhongqin Li and Christoph Schneider

Water 2020, 12(12), 3297; https://doi.org/10.3390/w12123297 - 24 Nov 2020

Cited by 6 | Viewed by 4476

Abstract

Originating in the Tian Shan mountains, Urumqi River plays a key role in terms of water supply to downstream areas. In its headwaters, Urumqi Glacier No. 1 (UG1) is the largest glacier contributing to water discharge. Assessing its response to the changing climatic [...] Read more.

Originating in the Tian Shan mountains, Urumqi River plays a key role in terms of water supply to downstream areas. In its headwaters, Urumqi Glacier No. 1 (UG1) is the largest glacier contributing to water discharge. Assessing its response to the changing climatic conditions in the area is of major importance to quantify future water availability. We here apply COSIPY, a COupled Snowpack and Ice surface energy and mass balance model in PYthon, to UG1, implementing a new albedo parameterization which integrates site-specific bare-ice albedo values on a pixel-by-pixel basis observed by remote sensing. We assess model performance threefold: quantitatively based on long-term measurement data of (1) surface mass balance (SMB) and (2) water discharge as well as qualitatively (3) comparing simulated snow line altitudes to such imated on the basis of time-lapse photography. Comparison of the modeled SMB with annually-averaged data from ablation stakes reveals that COSIPY including the new albedo parameterization accounts for 57.6% of the variance observed in the measurements. The original albedo parameterization performs only slightly inferior (57.1%). Glacier-wide comparison between modeled and glaciological SMB shows high agreement. In terms of discharge prediction, COSIPY reproduces onset and duration of the discharge season well. Estimated discharge from the whole catchment shows shortcomings in exactly matching the measured times series, but interannual variability is captured. Full article

(This article belongs to the Special Issue Transformation of Glacial and Periglacial Environments in Mountain Regions)

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16 pages, 4724 KB

Open AccessEditor’s ChoiceArticle

Variations in Soil Erosion Resistance of Gully Head Along a 25-Year Revegetation Age on the Loess Plateau

by Zhuoxin Chen, Mingming Guo and Wenlong Wang

Water 2020, 12(12), 3301; https://doi.org/10.3390/w12123301 - 24 Nov 2020

Cited by 22 | Viewed by 2929

Abstract

The effects of vegetation restoration on soil erosion resistance of gully head, along a revegetation age gradient, remain poorly understood. Hence, we collected undisturbed soil samples from a slope farmland and four grasslands with different revegetation ages (3, 10, 18, 25 years) along [...] Read more.

The effects of vegetation restoration on soil erosion resistance of gully head, along a revegetation age gradient, remain poorly understood. Hence, we collected undisturbed soil samples from a slope farmland and four grasslands with different revegetation ages (3, 10, 18, 25 years) along gully heads. Then, these samples were used to obtain soil detachment rate of gully heads by the hydraulic flume experiment under five unit width flow discharges (2–6 m³ h). The results revealed that soil properties were significantly ameliorated and root density obviously increased in response to restoration age. Compared with farmland, soil detachment rate of revegetated gully heads decreased 35.5% to 66.5%, and the sensitivity of soil erosion of the gully heads to concentrated flow decreased with revegetation age. The soil detachment rate of gully heads was significantly related to the soil bulk density, soil disintegration rate, capillary porosity, saturated soil hydraulic conductivity, organic matter content and water stable aggregate. The roots of 0–0.5 and 0.5–1.0 mm had the highest benefit in reducing soil loss of gully head. After revegetation, soil erodibility of gully heads decreased 31.0% to 78.6%, and critical shear stress was improved by 1.2 to 4.0 times. The soil erodibility and critical shear stress would reach a stable state after an 18-years revegetation age. These results allow us to better evaluate soil vulnerability of gully heads to concentrated flow erosion and the efficiency of revegetation. Full article

(This article belongs to the Special Issue Soil–Water Conservation, Erosion, and Landslide)

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15 pages, 1518 KB

Open AccessEditor’s ChoiceArticle

The Adsorption Selectivity of Short and Long Per- and Polyfluoroalkyl Substances (PFASs) from Surface Water Using Powder-Activated Carbon

by Heejong Son, Taehoon Kim, Hoon-Sik Yoom, Dongye Zhao and Byungryul An

Water 2020, 12(11), 3287; https://doi.org/10.3390/w12113287 - 23 Nov 2020

Cited by 75 | Viewed by 7764

Abstract

Nine per- and polyfluoroalkyl substances (PFASs), including six perfluoroalkyl carboxylic acids (PFCAs) and three perfluoroalkyl sulfonic acids (PFSAs), were tested to find their adsorption selectivity from surface water and the feasibility of the powder activated carbon (PAC) process between the perchlorination and coagulation [...] Read more.

Nine per- and polyfluoroalkyl substances (PFASs), including six perfluoroalkyl carboxylic acids (PFCAs) and three perfluoroalkyl sulfonic acids (PFSAs), were tested to find their adsorption selectivity from surface water and the feasibility of the powder activated carbon (PAC) process between the perchlorination and coagulation processes by operating parameters such as mixing intensity, dosage, contact time, initial pH, and concentration of perchlorination. The removal efficiency of four types of PAC revealed that the coal-based activated carbon was clearly advanced for all of the PFASs, and the thermal regenerated PAC did not exhibit a significant reduction in adsorption capacity. The longer carbon chain or the higher molecular weight (MW) obtained a higher adsorption capacity and the MW exhibited a more proportional relationship with the removal efficiency than the carbon chain number, regardless of the PFCA and PFSA species. Approximately 80% and 90% equilibria were accomplished within 60 and 120 min for the long chain carbon PFAS, respectively, while for the short chain PFAS, 240 min was required to reach 85% equilibrium. The effect of mixing intensity (rpm) was not considered for the removal of the PFAS, although it was relatively influenced in the short PFAS species. Due to the surface charge of the PAC and the properties of protonation of the PFASs, the acid condition increased the PFASs’ adsorption capacity. The prechlorination decreased the removal efficiency, and the reduction rate was more significantly influenced for the short chain PFAS than for the long chain PFAS. Full article

(This article belongs to the Section Wastewater Treatment and Reuse)

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19 pages, 4588 KB

Open AccessEditor’s ChoiceArticle

Assessing Land-Cover Effects on Stream Water Quality in Metropolitan Areas Using the Water Quality Index

by TaeHo Kim, YoungWoo Kim, Jihoon Shin, ByeongGeon Go and YoonKyung Cha

Water 2020, 12(11), 3294; https://doi.org/10.3390/w12113294 - 23 Nov 2020

Cited by 12 | Viewed by 7513

Abstract

This study evaluated the influence of different land-cover types on the overall water quality of streams in urban areas. To ensure national applicability of the results, this study encompassed ten major metropolitan areas in South Korea. Using cluster analysis, watersheds were classified into [...] Read more.

This study evaluated the influence of different land-cover types on the overall water quality of streams in urban areas. To ensure national applicability of the results, this study encompassed ten major metropolitan areas in South Korea. Using cluster analysis, watersheds were classified into three land-cover types: Urban-dominated (URB), agriculture-dominated (AGR), and forest-dominated (FOR). For each land-cover type, factor analysis (FA) was used to ensure simple and feasible parameter selection for developing the minimum water quality index (WQI_min). The chemical oxygen demand, fecal coliform (total coliform for FOR), and total nitrogen (nitrate-nitrogen for URB) were selected as key parameters for all land-cover types. Our results suggest that WQI_min can minimize bias in water quality assessment by reducing redundancy among correlated parameters, resulting in better differentiation of pollution levels. Furthermore, the dominant land-cover type of watersheds, not only affects the level and causes of pollution, but also influences temporal patterns, including the long-term trends and seasonality, of stream water quality in urban areas in South Korea. Full article

(This article belongs to the Special Issue Assessing Water Quality by Statistical Methods)

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18 pages, 6356 KB

Open AccessEditor’s ChoiceArticle

Integrated Taxonomy for Halistemma Species from the Northwest Pacific Ocean

by Nayeon Park, Andrey A. Prudkovsky and Wonchoel Lee

Water 2020, 12(11), 3283; https://doi.org/10.3390/w12113283 - 22 Nov 2020

Cited by 2 | Viewed by 3655

Abstract

During a survey of the siphonophore community in the Kuroshio Extension, Northwest Pacific Ocean, a new Halistemma Huxley, 1859 was described using integrated molecular and morphological approaches. The Halistemma isabu sp. nov. nectophore is most closely related morphologically to H. striata Totton, [...] Read more.

During a survey of the siphonophore community in the Kuroshio Extension, Northwest Pacific Ocean, a new Halistemma Huxley, 1859 was described using integrated molecular and morphological approaches. The Halistemma isabu sp. nov. nectophore is most closely related morphologically to H. striata Totton, 1965 and H. maculatum Pugh and Baxter, 2014. These species can be differentiated by their nectosac shape, thrust block size, ectodermal cell patches and ridge patterns. The new species’ bracts are divided into two distinct types according to the number of teeth. Type A bracts are more closely related to ventral bracts in H. foliacea (Quoy and Gaimard, 1833) while Type B bracts are more similar to H. rubrum (Vogt, 1852). Each type differs, however, from the proximal end shape, distal process and bracteal canal. Both of the new species’ morphological type and phylogenetic position within the genus Halistemma are supported by phylogenetic analysis of concatenated DNA dataset (mtCOI, 16S rRNA and 18S rRNA). Integrated morphological and molecular approaches to the taxonomy of siphonophores showed a clear delimitation of the new species from the congeners. Halistemma isabu sp. nov. is distributed with the congeners H. rubrum, H. cupulifera, H. foliacea and H. striata in the northwestern Pacific Ocean. Full article

(This article belongs to the Special Issue Species Richness and Diversity of Aquatic Ecosystems)

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13 pages, 1286 KB

Open AccessEditor’s ChoiceArticle

Factors Influencing Abundances and Population Size Structure of the Threatened and Endemic Cyprinodont Aphanius iberus in Mediterranean Brackish Ponds

by Serena Sgarzi, Sandra Brucet, Mireia Bartrons, Ignasi Arranz, Lluís Benejam and Anna Badosa

Water 2020, 12(11), 3264; https://doi.org/10.3390/w12113264 - 21 Nov 2020

Cited by 5 | Viewed by 4008

Abstract

Aphanius iberus is an endemic cyprinodontoid fish species of Mediterranean ponds in danger of extinction. In this study, we studied some abiotic and biotic factors that can influence A. iberus’s size structure and density in Mediterranean brackish ponds. We sampled fish using [...] Read more.

Aphanius iberus is an endemic cyprinodontoid fish species of Mediterranean ponds in danger of extinction. In this study, we studied some abiotic and biotic factors that can influence A. iberus’s size structure and density in Mediterranean brackish ponds. We sampled fish using fyke nets in 10 ponds of Empordà (Spain) during the spring season. Our results showed that a better ecological status (according to the Water Quality of Lentic and Shallow Ecosystems (QAELS) index), pond’s depth and pond’s isolation (reflected by an increase in total nitrogen) were related to larger individual sizes and more size-diverse populations. Increasing the salinity is known to help the euryhaline A. iberus acting as a refuge from competitors. Nevertheless, our results showed that higher conductivities had a negative effect on A. iberus’s size structure, leading to a decrease in the mean and maximum size of the fish. Fish abundance (expressed as captures per unit of effort (CPUE)) seemed to increase with increasing the pond’s depth and total nitrogen (the latter reflecting pond isolation). In conclusion, our results suggest that achieving a better pond ecological status may be important for the conservation of endangered A. iberus, because better size-structured populations (i.e., larger mean and average lengths) were found at higher water quality conditions. Full article

(This article belongs to the Special Issue Ecology and Conservation of Freshwater Fishes Biodiversity)

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20 pages, 5200 KB

Open AccessEditor’s ChoiceArticle

Climate Change Impact on Hydropower Resources in Gauged and Ungauged Lithuanian River Catchments

by Darius Jakimavičius, Gintaras Adžgauskas, Diana Šarauskienė and Jūratė Kriaučiūnienė

Water 2020, 12(11), 3265; https://doi.org/10.3390/w12113265 - 21 Nov 2020

Cited by 16 | Viewed by 4156

Abstract

Hydropower (potential and kinetic energy) is one of the most important renewable energy sources in the world. This energy is directly dependent on water resources and the hydrological cycle. Ongoing climate changes are likely to influence the availability/amount of this energy resource. The [...] Read more.

Hydropower (potential and kinetic energy) is one of the most important renewable energy sources in the world. This energy is directly dependent on water resources and the hydrological cycle. Ongoing climate changes are likely to influence the availability/amount of this energy resource. The present study explores the relationship between climate changes and river runoff, projects future runoff in both gauged and ungauged river catchments, and then assesses how these alterations may affect the future hydropower resources in Lithuania. Runoff projections of the gauged rivers were evaluated applying Swedish Department of Climate hydrological model, and runoff of ungauged river catchments were estimated by created isoline maps of specific runoff. According to an ensemble of three climate models and two Representative Concentration Pathway scenarios, runoff and hydroelectric energy projections were evaluated for two future periods (2021–2040, 2081–2100). The results demonstrated a decrease in future river runoff. Especially significant changes are expected according to the most pessimistic RCP8.5 scenario at the end of the century. The projected changes are likely to bring a negative effect on hydropower production in the country. These findings could help understand what kind of benefits and challenges water resource managers may face in the future. Full article

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31 pages, 5407 KB

Open AccessEditor’s ChoiceArticle

The Impacts of Climate Change on Wastewater Treatment Costs: Evidence from the Wastewater Sector in China

by Ami Reznik, Yu Jiang and Ariel Dinar

Water 2020, 12(11), 3272; https://doi.org/10.3390/w12113272 - 21 Nov 2020

Cited by 14 | Viewed by 5951

Abstract

Treatment of wastewater is expected to become a major development issue in the years to come. We investigate the relationship between climate and costs of wastewater treatment with the objective of examining if changes in climate might have an impact on the costs [...] Read more.

Treatment of wastewater is expected to become a major development issue in the years to come. We investigate the relationship between climate and costs of wastewater treatment with the objective of examining if changes in climate might have an impact on the costs of wastewater treatment. For that purpose, we use a cross-section sample of 163 treatment plants from China to estimate the industry’s cost function. The methodology used comprises an econometric estimation procedure of treatment costs of the wastewater sector, and a simulation of changes in these costs predicted with future climate conditions, policy implementation scenarios, population growth and development trends. Our results find evidence of climate change impact on treatment costs. We also simulate potential impact of future policy and climate scenarios on costs of treatment, and we measure the cost impact of all other cost determinants but climate—as these are indirectly affected by accounting for climate in the estimation procedure. This indirect impact predicts total cost changes of different magnitudes across the range of future scenarios investigated. Full article

(This article belongs to the Special Issue Water Management: New Paradigms for Water Treatment and Reuse)

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