Lake and River Restoration: Method, Evaluation and Management

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Water Quality and Contamination".

Deadline for manuscript submissions: closed (30 November 2019) | Viewed by 62253

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Guest Editor
School of Animal, Rural and Environmental Sciences, Nottingham Trent University, Southwell NG25 0QF, UK
Interests: lake restoration; sediment remediation; algal bloom control; nutrient management
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Institute of Hydrobiology, Chinese Academy of Science, Wuhan, China
Interests: lake ecology; harmful algal blooms; algae biology and algae physiology; cyanobacteria treatment and reutilization

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Guest Editor
Hydraulic Research Institute, Nanjing, China
Interests: lake, river and reservoir management; ecological hydraulics; eutrophication control; lake restoration
School of Animal, Rural and Environmental Sciences, Nottingham Trent University, UK
Interests: lake restoration; wastewater treatment, constructed wetland; emergent pollutants; organic pollutants; bioremediation; environmental chemistry
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Harmful algal blooms (HAB) are one of the most notorious consequences of eutrophication in natural waters, e.g., lakes and rivers, and pose serious threats to water quality, human health, economic development, ecological balance, landscape aesthetics, and social stability. Both external loading of pollutants from anthrophonic discharge and internal loading of pollutants from sediments are expected to further increase HAB occurrence and provide continuous pressure on river and lake ecosystems over the coming decades. Thus, it is urgent to draw the attention of researchers around the world to make great efforts on lake and river restoration to eliminate HAB threats.

Lake and river restoration heavily depends on integrated basin management and technical developments. An integrated water restoration management aims to promote the coordinated development and management of water, land, and related resources in order to maximize economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems. Nutrient recovery, e.g., phosphorous and residue biomass, e.g., algae biomass, are expected to be valuable resources to promote agricultural sustainability and aquatic ecology. Long-term monitoring of water quality and ecological responses, as well as whole water experiments, are necessary for a comprehensive evaluation of innovative restoration methods.

This Special Issue of  Water aims to compile the latest advances in lake and river restoration technology, in terms of advanced materials, applications, evaluation, and management. We foresee that the papers in this Special Issue will significantly contribute to eutrophication control, natural water sustainability, and ecological restoration.

Prof. Gang Pan
Prof. Lirong Song
Prof. Qiuwen Chen
Dr. Tao Lyu
Guest Editors

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Keywords

  • Lake and river restoration: Methods, evaluation, and monitoring
  • Harmful algal blooms: Prediction, prevention, and control
  • Internal loads control and sediment remediation
  • Natural water quality control and management
  • Nutrients recovery for integrated water, energy and food security

Published Papers (13 papers)

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Editorial

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8 pages, 825 KiB  
Editorial
Lake and River Restoration: Method, Evaluation and Management
by Tao Lyu, Lirong Song, Qiuwen Chen and Gang Pan
Water 2020, 12(4), 977; https://doi.org/10.3390/w12040977 - 30 Mar 2020
Cited by 13 | Viewed by 6341
Abstract
Eutrophication has become one of the major environmental issues of global concern due to the adverse effects on water quality, public health and ecosystem sustainability. Fundamental research on the restoration of eutrophic freshwaters, i.e., lakes and rivers, is crucial to support further evidence-based [...] Read more.
Eutrophication has become one of the major environmental issues of global concern due to the adverse effects on water quality, public health and ecosystem sustainability. Fundamental research on the restoration of eutrophic freshwaters, i.e., lakes and rivers, is crucial to support further evidence-based practical implementations. This Special Issue successfully brings together recent research findings from scientists in this field and assembles contributions on lake and river restoration. The 12 published papers can be classified into, and contribute to, three major aspects of this topic. Firstly, a background investigation into the migration of nutrients, and the characteristics of submerged biota, will guide and assist the understanding of the mechanisms of future restoration. Secondly, various restoration strategies, including control of both external and internal nutrients loading, are studied and evaluated. Thirdly, an evaluation of the field sites after restoration treatment is reported in order to support the selection of appropriate restoration approaches. This paper focuses on the current environmental issues related to lake and river restoration and has conducted a comprehensive bibliometric analysis in order to emphasise the fast-growing attention being paid to the research topic. The research questions and main conclusions from all papers are summarised to focus the attention toward how the presented studies aid gains in scientific knowledge, engineering experience and support for policymakers. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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Research

Jump to: Editorial

37 pages, 7241 KiB  
Article
Hyporheic Process Restoration: Design and Performance of an Engineered Streambed
by Paul D. Bakke, Michael Hrachovec and Katherine D. Lynch
Water 2020, 12(2), 425; https://doi.org/10.3390/w12020425 - 5 Feb 2020
Cited by 6 | Viewed by 5168
Abstract
Stream restoration designed specifically to enhance hyporheic processes has seldom been contemplated. To gain experience with hyporheic restoration, an engineered streambed was built using a gravel mixture formulated to mimic natural streambed composition, filling an over-excavated channel to a minimum depth of 90 [...] Read more.
Stream restoration designed specifically to enhance hyporheic processes has seldom been contemplated. To gain experience with hyporheic restoration, an engineered streambed was built using a gravel mixture formulated to mimic natural streambed composition, filling an over-excavated channel to a minimum depth of 90 cm. Specially designed plunge-pool structures, built with subsurface gravel extending down to 2.4 m, promoted greatly enhanced hyporheic circulation, path length, and residence time. Hyporheic process enhancement was verified using intra-gravel temperature mapping to document the distribution and strength of upwelling and downwelling zones, computation of vertical water flux using diurnal streambed temperature patterns, estimation of hyporheic zone cross section using sodium chloride tracer studies, and repeat measurements of streambed sand content to document evolution of the engineered streambed over time. Results showed that vertical water flux in the vicinity of plunge-pool structures was quite large, averaging 89 times the pre-construction rate, and 17 times larger than maximum rates measured in a pristine stream in Idaho. Upwelling and downwelling strengths in the constructed channel were larger and more spatially diverse than in the control. Streambed sand content showed a variety of response over time, indicating that rapid return to an embedded, impermeable state is not occurring. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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9 pages, 986 KiB  
Article
Synergistic Recapturing of External and Internal Phosphorus for In Situ Eutrophication Mitigation
by Minmin Pan, Tao Lyu, Meiyi Zhang, Honggang Zhang, Lei Bi, Lei Wang, Jun Chen, Chongchao Yao, Jafar Ali, Samantha Best, Nicholas Ray and Gang Pan
Water 2020, 12(1), 2; https://doi.org/10.3390/w12010002 - 18 Dec 2019
Cited by 8 | Viewed by 4357
Abstract
In eutrophication management, many phosphorus (P) adsorbents have been developed to capture P at the laboratory scale. Existing P removal practice in freshwaters is limited due to the lack of assessment of the possibility and feasibility of controlling P level towards a very [...] Read more.
In eutrophication management, many phosphorus (P) adsorbents have been developed to capture P at the laboratory scale. Existing P removal practice in freshwaters is limited due to the lack of assessment of the possibility and feasibility of controlling P level towards a very low level (such as 10 μg/L) in order to prevent the harmful algal blooms. In this study, a combined external and internal P control approach was evaluated in a simulated pilot-scale river–lake system. In total, 0.8 m3 of simulated river water was continuously supplied to be initially treated by a P adsorption column filled with a granulated lanthanum/aluminium hydroxide composite (LAH) P adsorbent. At the outlet of the column (i.e., inlet of the receiving tanks), the P concentration decreased from 230 to 20 µg/L at a flow rate of 57 L/day with a hydraulic loading rate of 45 m/day. In the receiving tanks (simulated lake), 90 g of the same adsorbent material was added into 1 m3 water for further in situ treatment, which reduced and maintained the P concentration at 10 µg/L for 5 days. The synergy of external and internal P recapture was demonstrated to be an effective strategy for maintaining the P concentration below 10 µg/L under low levels of P water input. The P removal was not significantly affected by temperature (5–30 °C), and the treatment did not substantially alter the water pH. Along with the superior P adsorption capacity, less usage of LAH could lead to reduced cost for potation eutrophication control compared with other widely used P adsorbents. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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9 pages, 1036 KiB  
Article
Phosphorus Fractions in the Sediments of Yuecheng Reservoir, China
by Chenghua Dang, Ming Lu, Zheng Mu, Yu Li, Chenchen Chen, Fengxia Zhao, Lei Yan and Yao Cheng
Water 2019, 11(12), 2646; https://doi.org/10.3390/w11122646 - 15 Dec 2019
Cited by 3 | Viewed by 2969
Abstract
As a result of the inexorable development of the economy and the ever-increasing population, the demand for water in the urban and rural sectors has increased, and this in turn has caused the water quality and eutrophication of the reservoir to become a [...] Read more.
As a result of the inexorable development of the economy and the ever-increasing population, the demand for water in the urban and rural sectors has increased, and this in turn has caused the water quality and eutrophication of the reservoir to become a legitimate concern in the water environment management of river basins. Phosphorus (P) is one of the limiting nutrients in aquatic ecosystems; P in the sediment is a primary factor for eutrophication. Yuecheng Reservoir is located in one of the most productive and intensively cultivated agricultural regions in North China. Detailed knowledge of the sediment is lacking at this regional reservoir. The first study to look into the different P fractions and its diffusion fluxes at the water sediment interface of the Yuecheng Reservoir makes it possible to learn about the internal P loading. According to the results, the concentrations of total phosphorus (TP) ranged from 1576.3 to 2172.6 mg kg and the P fraction concentration sequence is as follows: P associated with calcium (Ca–Pi) > organic P (Po) > P bound to aluminum (Al), ferrum (Fe) and manganese (Mn) oxides and hydroxides (Fe/Al–Pi). The results demonstrated that, although the construction of a large number of water conservancy projects in the upper reaches of the river resulted in the decrease of inflow runoff, the pollutions from terrestrial plants or materials played a key role in the sediment phosphorus fraction, and they should be emphasized on the water environment management of river basin. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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20 pages, 1791 KiB  
Article
Sorption Properties of the Bottom Sediment of a Lake Restored by Phosphorus Inactivation Method 15 Years after the Termination of Lake Restoration Procedures
by Renata Augustyniak, Jolanta Grochowska, Michał Łopata, Katarzyna Parszuto, Renata Tandyrak and Jacek Tunowski
Water 2019, 11(10), 2175; https://doi.org/10.3390/w11102175 (registering DOI) - 19 Oct 2019
Cited by 15 | Viewed by 3243
Abstract
Artificial mixing and phosphorus inactivation methods using aluminum compounds are among the most popular lake restoration methods. Długie Lake (Olsztyńskie Lakeland, Poland) was restored using these two methods. Primarily, P precipitation and inactivation methods significantly increased the sorption properties of Długie Lake bottom [...] Read more.
Artificial mixing and phosphorus inactivation methods using aluminum compounds are among the most popular lake restoration methods. Długie Lake (Olsztyńskie Lakeland, Poland) was restored using these two methods. Primarily, P precipitation and inactivation methods significantly increased the sorption properties of Długie Lake bottom sediment. Fifteen years after the termination of the restoration procedure, the alum-modified “active” sediment layer still has higher P adsorption abilities, which can limit P internal loading. Relatively low amounts of phosphates in the near-bottom water of Długie Lake, even in anoxia, as well as the fact that the assessed maximum sediment P sorption capacity is still higher than NH4Cl–P (labile P) and BD–P (Fe-bound P) sum (“native exchangeable P”), confirm that hypothesis. Among the tested P adsorption models for the sediment, the double Langmuir model showed the best fit to the experimental data (the highest R2 values). This may indicate that phosphorus adsorption by the tested sediments most likely occurs through phosphate binding at two types of active sorption sites. P adsorption by the studied lake sediment during experiments was significantly connected to aluminum content in sediment. The research into the adsorption properties of sediment can be used as a tool for the evaluation of lake restoration effects. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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15 pages, 3239 KiB  
Article
Reducing the Phytoplankton Biomass to Promote the Growth of Submerged Macrophytes by Introducing Artificial Aquatic Plants in Shallow Eutrophic Waters
by Yue Wu, Licheng Huang, Yalin Wang, Lin Li, Genbao Li, Bangding Xiao and Lirong Song
Water 2019, 11(7), 1370; https://doi.org/10.3390/w11071370 - 2 Jul 2019
Cited by 14 | Viewed by 3555
Abstract
Harmful cyanobacterial blooms frequently occur in shallow eutrophic lakes and usually cause the decline of submerged vegetation. Therefore, artificial aquatic plants (AAPs) were introduced into enclosures in the eutrophic Dianchi Lake to investigate whether or not they could reduce cyanobacterial blooms and promote [...] Read more.
Harmful cyanobacterial blooms frequently occur in shallow eutrophic lakes and usually cause the decline of submerged vegetation. Therefore, artificial aquatic plants (AAPs) were introduced into enclosures in the eutrophic Dianchi Lake to investigate whether or not they could reduce cyanobacterial blooms and promote the growth of submerged macrophytes. On the 60th day after the AAPs were installed, the turbidity, total nitrogen (TN), total phosphorous (TP), and the cell density of phytoplankton (especially cyanobacteria) of the treated enclosures were significantly reduced as compared with the control enclosures. The adsorption and absorption of the subsequently formed periphyton biofilms attached to the AAPs effectively decreased nutrient levels in the water. Moreover, the microbial diversity and structure in the water changed with the development of periphyton biofilms, showing that the dominant planktonic algae shifted from Cyanophyta to Chlorophyta. The biodiversity of both planktonic and attached bacterial communities in the periphyton biofilm also gradually increased with time, and were higher than those of the control enclosures. The transplanted submerged macrophyte (Elodea nuttallii) in treated enclosures recovered effectively and reached 50% coverage in one month while those in the control enclosures failed to grow. The application of AAPs with incubated periphyton presents an environmentally-friendly and effective solution for reducing nutrients and controlling the biomass of phytoplankton, thereby promoting the restoration of submerged macrophytes in shallow eutrophic waters. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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16 pages, 2496 KiB  
Article
Priority Pollutants in Water and Sediments of a River for Control Basing on Benthic Macroinvertebrate Community Structure
by Xiang Liu, Jin Zhang, Wenqing Shi, Min Wang, Kai Chen and Li Wang
Water 2019, 11(6), 1267; https://doi.org/10.3390/w11061267 - 17 Jun 2019
Cited by 13 | Viewed by 3173
Abstract
Understanding the drivers of macroinvertebrate community structure is fundamental for adequately controlling pollutants and managing ecosystems under global change. In this study, the abundance and diversity of benthic macroinvertebrates, as well as their chemical parameters, were investigated quarterly from August 2014 to April [...] Read more.
Understanding the drivers of macroinvertebrate community structure is fundamental for adequately controlling pollutants and managing ecosystems under global change. In this study, the abundance and diversity of benthic macroinvertebrates, as well as their chemical parameters, were investigated quarterly from August 2014 to April 2015 in four reaches of the Huai River basin (HRB). The self-organizing map (SOM) algorithm and canonical correspondence analysis (CCA) were simultaneously applied to identify the main factors structuring the benthic community. The results showed that the benthic community structure was always dominated by gastropoda and insecta over seasons and presented obvious spatial and temporal heterogeneity along different pollution levels. The insects were always the top contributors to number density of the benthic community, except for the summer, and the biomass was mainly characterized by mollusca in all seasons. Statistical analysis indicated that TN and NH3-N in water, as well as Hg, As, Cd, and Zn in sediments, were the dominant factors structuring the community, which determined the importance of sediment heavy metal concentrations in explaining the benthic community composition in comparison with other factors. These major factors should be given priority in the process of river pollutant control, which might be rated as a promising way to scientifically improve river health management and ecological restoration. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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16 pages, 4731 KiB  
Article
Modified Local Soil (MLS) Technology for Harmful Algal Bloom Control, Sediment Remediation, and Ecological Restoration
by Gang Pan, Xiaojun Miao, Lei Bi, Honggang Zhang, Lei Wang, Lijing Wang, Zhibin Wang, Jun Chen, Jafar Ali, Minmin Pan, Jing Zhang, Bin Yue and Tao Lyu
Water 2019, 11(6), 1123; https://doi.org/10.3390/w11061123 - 29 May 2019
Cited by 25 | Viewed by 6925
Abstract
Harmful algal blooms (HABs), eutrophication, and internal pollutant sources from sediment, represent serious problems for public health, water quality, and ecological restoration worldwide. Previous studies have indicated that Modified Local Soil (MLS) technology is an efficient and cost-effective method to flocculate the HABs [...] Read more.
Harmful algal blooms (HABs), eutrophication, and internal pollutant sources from sediment, represent serious problems for public health, water quality, and ecological restoration worldwide. Previous studies have indicated that Modified Local Soil (MLS) technology is an efficient and cost-effective method to flocculate the HABs from water and settle them onto sediment. Additionally, MLS capping treatment can reduce the resuspension of algae flocs from the sediment, and convert the algal cells, along with any excessive nutrients in-situ into fertilisers for the restoration of submerged macrophytes in shallow water systems. Furthermore, the capping treatment using oxygen nanobubble-MLS materials can also mitigate sediment anoxia, causing a reduction in the release of internal pollutants, such as nutrients and greenhouse gases. This paper reviews and quantifies the main features of MLS by investigating the effect of MLS treatment in five pilot-scale whole-pond field experiments carried out in Lake Tai, South China, and in Cetian Reservoir in Datong city, North China. Data obtained from field monitoring showed that the algae-dominated waters transform into a macrophyte-dominated state within four months of MLS treatment in shallow water systems. The sediment-water nutrient fluxes were substantially reduced, whilst water quality (TN, TP, and transparency) and biodiversity were significantly improved in the treatment ponds, compared to the control ponds within a duration ranging from one day to three years. The sediment anoxia remediation effect by oxygen nanobubble-MLS treatment may further contribute to deep water hypoxia remediation and eutrophication control. Combined with the integrated management of external loads control, MLS technology can provide an environmentally friendly geo-engineering method to accelerate ecological restoration and control eutrophication. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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22 pages, 3575 KiB  
Article
A Phased Assessment of Restoration Alternatives to Achieve Phosphorus Water Quality Targets for Lake Okeechobee, Florida, USA
by Yogesh Khare, Ghinwa Melodie Naja, G. Andrew Stainback, Christopher J. Martinez, Rajendra Paudel and Thomas Van Lent
Water 2019, 11(2), 327; https://doi.org/10.3390/w11020327 - 14 Feb 2019
Cited by 32 | Viewed by 6844
Abstract
Achieving total phosphorus (TP) total maximum daily loads (TMDL) for Lake Okeechobee (Florida, FL, USA), a large freshwater lake, is a key component of the greater Everglades ecosystem restoration and sustainability of south Florida. This study was aimed at identification of a cost-effective [...] Read more.
Achieving total phosphorus (TP) total maximum daily loads (TMDL) for Lake Okeechobee (Florida, FL, USA), a large freshwater lake, is a key component of the greater Everglades ecosystem restoration and sustainability of south Florida. This study was aimed at identification of a cost-effective restoration alternative using four TP control strategies—Best Management Practices (BMPs), Dispersed Water Management (DWM), Wetland Restoration, and Stormwater Treatment Areas (STAs)—to achieve a flow-weighted mean TP concentration of 40 µg/L at lake inflow points, through a phased scenario analysis approach. The Watershed Assessment Model was used to simulate flow and phosphorus dynamics. The 10-year (1998–2007) ‘Base’ scenario calibration indicated ‘acceptable’ to ‘good’ performance with simulated annual average flows and TP load of 2.64 × 109 m3 and 428.6 metric tons, respectively. Scenario results showed that TP load reduction without STAs would be around 11–40% with respect to Base compared to over 75% reduction requirement to achieve TMDL, indicating STAs as a necessary component to achieve restoration. The most cost-effective alternative to achieve TP target consisted of implementation of nutrient management BMPs, continuation of existing DWM projects, and the construction of ~200 km2 of STAs for a total project cost of US $4.26 billion. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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16 pages, 4825 KiB  
Article
Enhanced Phosphate Removal from Water by Honeycomb-Like Microporous Lanthanum-Chitosan Magnetic Spheres
by Rong Cheng, Liang-Jie Shen, Ying-Ying Zhang, Dan-Yang Dai, Xiang Zheng, Long-Wen Liao, Lei Wang and Lei Shi
Water 2018, 10(11), 1659; https://doi.org/10.3390/w10111659 - 14 Nov 2018
Cited by 14 | Viewed by 3597
Abstract
The removal of phosphate in water is crucial and effective for control of eutrophication, and adsorption is one of the most effective treatment processes. In this study, microporous lanthanum-chitosan magnetic spheres were successfully synthetized and used for the removal of phosphate in water. [...] Read more.
The removal of phosphate in water is crucial and effective for control of eutrophication, and adsorption is one of the most effective treatment processes. In this study, microporous lanthanum-chitosan magnetic spheres were successfully synthetized and used for the removal of phosphate in water. The characterization results show that the dispersion of lanthanum oxide is improved because of the porous properties of the magnetic spheres. Moreover, the contact area and active sites between lanthanum oxide and phosphate were increased due to the presence of many honeycomb channels inside the magnetic spheres. In addition, the maximum adsorption capacity of the Langmuir model was 27.78 mg P·g−1; and the adsorption kinetics were in good agreement with the pseudo-second-order kinetic equation and intra-particle diffusion model. From the results of thermodynamic analysis, the phosphate adsorption process of lanthanum-chitosan magnetic spheres was spontaneous and exothermic in nature. In conditional tests, the optimal ratio of lanthanum/chitosan was 1.0 mmol/g. The adsorption capacity of as-prepared materials increased with the augmentation of the dosage of the adsorbent and the decline of pH value. The co-existing anions, Cl and NO3 had little effect on adsorption capacity to phosphate, while CO32− exhibited an obviously negative influence on the adsorption capacity of this adsorbent. In general, owing to their unique hierarchical porous structures, high-adsorption capacity and low cost, lanthanum-chitosan magnetic spheres are potentially applicable in eutrophic water treatment. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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16 pages, 3427 KiB  
Article
Effects of Dredging Season on Sediment Properties and Nutrient Fluxes across the Sediment–Water Interface in Meiliang Bay of Lake Taihu, China
by Ji-Cheng Zhong, Ju-Hua Yu, Xiao-Lan Zheng, Shuai-Long Wen, De-Hong Liu and Cheng-Xin Fan
Water 2018, 10(11), 1606; https://doi.org/10.3390/w10111606 - 8 Nov 2018
Cited by 21 | Viewed by 4722
Abstract
The influence of dredging season on sediment properties and nutrient fluxes across the sediment–water interface remains unknown. This study collected sediment cores from two sites with different pollution levels in Meiliang Bay, Taihu Lake (China). The samples were used in simulation experiments designed [...] Read more.
The influence of dredging season on sediment properties and nutrient fluxes across the sediment–water interface remains unknown. This study collected sediment cores from two sites with different pollution levels in Meiliang Bay, Taihu Lake (China). The samples were used in simulation experiments designed to elucidated the effects of dredging on internal loading in different seasons. The results showed that dredging the upper 30 cm of sediment could effectively reduce the contents of organic matter, total nitrogen, and total phosphorus in the sediments. Total biological activity in the dredged sediment was weaker (p < 0.05) than in the undredged sediment in all seasons for both the Inner Bay and Outer Bay, but the effect of 30-cm dredging on sediment oxygen demand was negligible. Dredging had a significant controlling effect on phosphorus release in both the Inner Bay and Outer Bay, and soluble reactive phosphorus (SRP) fluxes from the dredged cores were generally lower (p < 0.05) than from the undredged cores. In contrast, NH4+-N fluxes from the dredged cores were significantly higher (p < 0.05) than from the undredged cores in all seasons for both sites, this indicates short-term risk of NH4+-N release after dredging, and this risk is greatest in seasons with higher temperatures, especially for the Inner Bay. Dredging had a limited effect on NO2-N and NO3-N fluxes at both sites. These results suggest that dredging could be a useful approach for decreasing internal loading in Taihu Lake, and that the seasons with low temperature (non-growing season) are suitable for performing dredging projects. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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11 pages, 3046 KiB  
Article
The Optimal Width and Mechanism of Riparian Buffers for Storm Water Nutrient Removal in the Chinese Eutrophic Lake Chaohu Watershed
by Xiuyun Cao, Chunlei Song, Jian Xiao and Yiyong Zhou
Water 2018, 10(10), 1489; https://doi.org/10.3390/w10101489 - 22 Oct 2018
Cited by 24 | Viewed by 5491
Abstract
Riparian buffers play an important role in intercepting nutrients entering lakes from non-point runoffs. In spite of its ecological significance, little is known regarding the underlying mechanisms of riparian buffers or their optimal width. In this study, we examined nutrient removal efficiency, including [...] Read more.
Riparian buffers play an important role in intercepting nutrients entering lakes from non-point runoffs. In spite of its ecological significance, little is known regarding the underlying mechanisms of riparian buffers or their optimal width. In this study, we examined nutrient removal efficiency, including the quantity of nutrients and water quality, in the littoral zone of different types of riparian buffers in the watershed around eutrophic Lake Chaohu (China), and estimated the optimal width for different types of riparian buffers for effective nutrient removal. In general, a weak phosphorus (P) adsorption ability and nitrification-denitrification potential in soil resulted in a far greater riparian buffer demand than before in Lake Chaohu, which may be attributed to the soil degradation and simplification of cover vegetation. In detail, the width was at least 23 m (grass/forest) and 130 m (grass) for total P (TP) and total nitrogen (TN) to reach 50% removal efficiency, respectively, indicating a significantly greater demand for TN removal than that for TP. Additionally, wetland and grass/forest riparian buffers were more effective for TP removal, which was attributed to a high P sorption maximum (Qmax) and a low equilibrium P concentration (EPC0), respectively. The high potential nitrification rate (PNR) and potential denitrification rate (PDR) were responsible for the more effective TN removal efficiencies in grass riparian buffers. The nutrient removal efficiency of different types of riparian buffers was closely related with nutrient level in adjacent littoral zones around Lake Chaohu. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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13 pages, 2077 KiB  
Article
First-Principles Study on the Migration of Heavy Metal Ions in Ice-Water Medium from Ulansuhai Lake
by Chi Sun, Changyou Li, Jianjun Liu, Xiaohong Shi, Shengnan Zhao, Yong Wu and Weidong Tian
Water 2018, 10(9), 1149; https://doi.org/10.3390/w10091149 - 28 Aug 2018
Cited by 13 | Viewed by 3933
Abstract
Energy is a fundamental driver that causes material movement. It is important to discover changes in energy by studying the internal mechanism of pollutant migration between system components during the freezing process. To explore the migration mechanism of heavy metal ions (HMIs) from [...] Read more.
Energy is a fundamental driver that causes material movement. It is important to discover changes in energy by studying the internal mechanism of pollutant migration between system components during the freezing process. To explore the migration mechanism of heavy metal ions (HMIs) from ice to water in a lake, we carried out a laboratory freezing experiment and simulated the distribution and migration of HMIs (Fe, Cu, Mn, Zn, Pb, Cd, and Hg) under different conditions. Then, we analyzed the use of energy by first-principle calculations. The results showed that HMIs are more stable in an aqueous environment than in an ice environment. For the same HMI, the binding energy in water is smaller than that in ice. Hence, the HMIs migrated from ice to water as the lake was freezing. The ability of different kinds of heavy metals to migrate from ice to water is related to their binding energy in ice. The concentrations of HMIs in ice are positively correlated with their binding energies. This study investigated the migration characteristics and mechanisms of HMIs in the process of lake freezing. Full article
(This article belongs to the Special Issue Lake and River Restoration: Method, Evaluation and Management)
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