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Search Results (538)

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Keywords = nutrient discharge

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17 pages, 6690 KiB  
Article
Comparative Assessment of Fractional and Erosion Plot Methods for Quantifying Soil Erosion and Nutrient Loss Under Vetiver Grass Technology on Two Contrasting Slopes in Rainforest Agroecology
by Suarau O. Oshunsanya, Hanqing Yu, Ayodeji M. Odebode, Ini D. Edem, Tunde S. Oluwatuyi, Esther E. Imasuen and Dorcas E. Odeyinka
Agriculture 2025, 15(16), 1762; https://doi.org/10.3390/agriculture15161762 - 16 Aug 2025
Viewed by 249
Abstract
The erosion plot method (EPM) is the most accurate method for measuring total runoff and soil loss in the field, but it is expensive, time-consuming, and tedious to use, thereby limiting the scope of soil erosion research. Alternatively, the fractional method (FM) involves [...] Read more.
The erosion plot method (EPM) is the most accurate method for measuring total runoff and soil loss in the field, but it is expensive, time-consuming, and tedious to use, thereby limiting the scope of soil erosion research. Alternatively, the fractional method (FM) involves measuring a portion of total runoff and soil loss to estimate the total erosion. Although the FM may be easier to use in rainforest agroecology, it has not been evaluated under vetiver grass technology (VGT). Thus, a 2-year field study was conducted to verify the efficacy of the FM under VGT by comparing soil nutrient erosion between the FM and the EPM on two slopes (5% and 10%). Three piped drums (left, central, and right) were used to collect total runoff under the EPM, while only a central piped drum was used under the FM (usual practice). The FM’s runoff and soil loss values were similar to those under the EPM (R2 = 0.98–0.99; p < 0.001). Runoff nutrients (R2 = 0.90; p < 0.001) and eroded nutrients (R2 = 0.97; p < 0.001) from the FM were highly similar to those of the EPM on the 5% slope. Similarly, runoff nutrients (R2 = 0.86; p < 0.001) and eroded nutrients (R2 = 0.95; p < 0.001) from the FM were strongly similar to those of the EPM on a 10% slope. The FM accounted for 92% of the total nutrient erosion measured by the EPM under VGT management. Thus, the FM will make research more efficient, cost-effective, and attractive, particularly in large-scale water erosion studies. Full article
(This article belongs to the Special Issue Assessing Soil Erosion and Associated Nutrient Losses in Agrosystems)
23 pages, 5336 KiB  
Article
Hydrochemistry of Blackwaters in a Shoreline Zone of São Paulo State, Brazil
by Daniel M. Bonotto, Marina Lunardi and Ashantha Goonetilleke
J. Mar. Sci. Eng. 2025, 13(8), 1575; https://doi.org/10.3390/jmse13081575 - 16 Aug 2025
Viewed by 341
Abstract
Blackwater rivers are enriched in humic acids and impoverished in nutrients, sometimes discharging into oceans. Brazil has a coastal zone of about 8700 km, with several blackwater rivers discharging into the Atlantic Ocean, in addition to the Rio Negro of the northern Amazon [...] Read more.
Blackwater rivers are enriched in humic acids and impoverished in nutrients, sometimes discharging into oceans. Brazil has a coastal zone of about 8700 km, with several blackwater rivers discharging into the Atlantic Ocean, in addition to the Rio Negro of the northern Amazon basin, which is the largest (about 1700 km long) and best-known tropical backwater river. On the other hand, only a few attempts have been made to deal with their hydrochemical composition and how it is related to the hydrochemistry of different water bodies nearby. This paper focuses on a sector of the Atlantic Ocean shore occurring in São Paulo State, enclosing two important Ecological Reserves, i.e., the Restinga State Park of Bertioga and the State Park of Serra do Mar–São Sebastião Nucleus, located at Bertioga and São Sebastião cities, respectively. Physicochemical parameters such as pH and electrical conductivity, as well as the composition of major constituents like sodium, potassium, calcium, magnesium, bicarbonate, chloride, sulfate, nitrate, etc., have been evaluated in two blackwater rivers and one blackwater stream to compare their relative inputs into the Atlantic Ocean. Traditional hydrogeochemical diagrams such as the Piper, Schoeller, Gibbs, van Wirdum, and Wilcox graphs were utilized for investigating the major features of the blackwater’s composition, revealing in some cases that they suffer an accentuated influence of the constituents occurring in the Atlantic Ocean waters, due to backward currents (coastal upwelling or tidal currents). Another highlight of this paper is the measurement of an enhanced concentration of dissolved iron in one blackwater sample analyzed, reaching a value of 1.9 mg/L. Such a finding has also been often reported in the literature for blackwater rivers and streams, as humic and fulvic acids are used to bind Fe3+, keeping it in solution. Nowadays, iron in solution has been considered a very important element acting as a natural fertilizer of the coastal ocean because it is an essential nutrient to marine phytoplankton. Full article
(This article belongs to the Section Chemical Oceanography)
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18 pages, 4602 KiB  
Article
Impact of Kara Sea Shelf Water on Seawater Parameters in Subsurface Layer of Laptev Sea
by Andrey Andreev, Irina Pipko, Svetlana Pugach and Igor Semiletov
J. Mar. Sci. Eng. 2025, 13(8), 1522; https://doi.org/10.3390/jmse13081522 - 8 Aug 2025
Viewed by 259
Abstract
Global climate changes impact the Arctic seas by decreasing the sea ice area and changing the inorganic and organic matter supply via rivers and coastal permafrost thawing. Therefore, climate change may affect biogeochemical processes in the Kara Sea (KS) and Laptev Sea (LS), [...] Read more.
Global climate changes impact the Arctic seas by decreasing the sea ice area and changing the inorganic and organic matter supply via rivers and coastal permafrost thawing. Therefore, climate change may affect biogeochemical processes in the Kara Sea (KS) and Laptev Sea (LS), which form the Arctic Transpolar Drift. This study explores the effect of the KS shelf water supply on seawater parameters in the LS in late summer and early fall 2007, 2008, 2018, 2019, and 2024 using ship-borne (temperature, salinity, dissolved oxygen, nutrients, and pH), satellite-derived (sea surface heights, geostrophic current velocities), and model (current velocities) data. The results demonstrate that an inflow of KS shelf water with salinity of 33.0–34.5, high Apparent Oxygen Utilization values (50–110 µM), and increased concentrations of the dissolved inorganic phosphorus (DIP~ 0.7–1.2 µM), dissolved inorganic nitrogen (DIN~ 4–12 µM) and silicic acid (DSi~ 10–18 µM) enriches the subsurface layer of the LS with nutrients. The distributions of Atlantic—derived water (ADW) and KS shelf water in the LS from August to October depend on water dynamics caused by wind and river discharge. High Lena River discharge and westerly (downwelling favorable) winds promoted the supply of the KS shelf water to the LS through Vilkitsky Strait. In the area of the central trough of the LS, the KS shelf water can be modified by mixing with ADW. Mixing ADW with high DIN/DIP ratios (DIN~ 10 µM at DIP of 0.80 µM) and KS shelf water with low DIN/DIP ratios (DIN~ 8 µM at DIP of 0.80 µM) leads to changes in the DIN vs. DIP ratio in the subsurface layer of the LS. Full article
(This article belongs to the Section Marine Environmental Science)
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17 pages, 2032 KiB  
Article
The Impact of Hydrological Streamflow Drought on Pollutant Concentration and Its Implications for Sustainability in a Small River in Poland
by Leszek Hejduk, Ewa Kaznowska, Michał Wasilewicz and Agnieszka Hejduk
Sustainability 2025, 17(15), 6995; https://doi.org/10.3390/su17156995 - 1 Aug 2025
Viewed by 301
Abstract
The paper presents the results of investigations into the relationship between selected water quality parameters and hydrological streamflow drought in a small river situated in the Mazovian Lowlands in Poland. As hydrological streamflow drought periods become more frequent in Poland, investigations about the [...] Read more.
The paper presents the results of investigations into the relationship between selected water quality parameters and hydrological streamflow drought in a small river situated in the Mazovian Lowlands in Poland. As hydrological streamflow drought periods become more frequent in Poland, investigations about the relationship between flow and water quality parameters can be an essential contribution to a better understanding of the impact of low flow on the status of water rivers. Data from a three-year study of a small lowland river along with significant agricultural land management was used to analyze the connection between low flows and specific water quality indicators. The separation of low-flow data from water discharge records was achieved using two criteria: Q90% (the discharge value from a flow duration curve) and a minimum low-flow duration of 10 days. During these periods, the concentration of water quality indicators was determined based on collected water samples. In total, 30 samples were gathered and examined for pH, suspended sediments, dissolved substances, hardness, ammonium, nitrates, nitrites, phosphates, total phosphorus, chloride, sulfate, calcium, magnesium, and water temperature during sampling. The study’s main aim was to describe the relation between hydrological streamflow droughts and chosen water quality parameters. The analysis results demonstrate an inverse statistically significant relationship between concentration and low-flow values for total hardness and sulfate. In contrast, there was a direct relationship between nutrient indicators, suspended sediment concentration, and river hydrological streamflow drought. Statistical tests were applied to compare the datasets between years, revealing statistical differences only for nutrient indicators. Full article
(This article belongs to the Topic Water Management in the Age of Climate Change)
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32 pages, 6657 KiB  
Article
Mechanisms of Ocean Acidification in Massachusetts Bay: Insights from Modeling and Observations
by Lu Wang, Changsheng Chen, Joseph Salisbury, Siqi Li, Robert C. Beardsley and Jackie Motyka
Remote Sens. 2025, 17(15), 2651; https://doi.org/10.3390/rs17152651 - 31 Jul 2025
Viewed by 469
Abstract
Massachusetts Bay in the northeastern United States is highly vulnerable to ocean acidification (OA) due to reduced buffering capacity from significant freshwater inputs. We hypothesize that acidification varies across temporal and spatial scales, with short-term variability driven by seasonal biological respiration, precipitation–evaporation balance, [...] Read more.
Massachusetts Bay in the northeastern United States is highly vulnerable to ocean acidification (OA) due to reduced buffering capacity from significant freshwater inputs. We hypothesize that acidification varies across temporal and spatial scales, with short-term variability driven by seasonal biological respiration, precipitation–evaporation balance, and river discharge, and long-term changes linked to global warming and river flux shifts. These patterns arise from complex nonlinear interactions between physical and biogeochemical processes. To investigate OA variability, we applied the Northeast Biogeochemistry and Ecosystem Model (NeBEM), a fully coupled three-dimensional physical–biogeochemical system, to Massachusetts Bay and Boston Harbor. Numerical simulation was performed for 2016. Assimilating satellite-derived sea surface temperature and sea surface height improved NeBEM’s ability to reproduce observed seasonal and spatial variability in stratification, mixing, and circulation. The model accurately simulated seasonal changes in nutrients, chlorophyll-a, dissolved oxygen, and pH. The model results suggest that nearshore areas were consistently more susceptible to OA, especially during winter and spring. Mechanistic analysis revealed contrasting processes between shallow inner and deeper outer bay waters. In the inner bay, partial pressure of pCO2 (pCO2) and aragonite saturation (Ωa) were influenced by sea temperature, dissolved inorganic carbon (DIC), and total alkalinity (TA). TA variability was driven by nitrification and denitrification, while DIC was shaped by advection and net community production (NCP). In the outer bay, pCO2 was controlled by temperature and DIC, and Ωa was primarily determined by DIC variability. TA changes were linked to NCP and nitrification–denitrification, with DIC also influenced by air–sea gas exchange. Full article
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15 pages, 2232 KiB  
Article
A Multi-Objective Approach for Improving Ecosystem Services and Mitigating Environmental Externalities in Paddy Fields and Its Emergy Analysis
by Naven Ramdat, Hongshuo Zou, Shiwen Sheng, Min Fu, Yingying Huang, Yaonan Cui, Yiru Wang, Rui Ding, Ping Xu and Xuechu Chen
Water 2025, 17(15), 2244; https://doi.org/10.3390/w17152244 - 29 Jul 2025
Viewed by 430
Abstract
Traditional intensive agricultural system impedes ecological functions, such as nutrient cycling and biodiversity conservation, resulting in excessive nitrogen discharge, CH4 emission, and ecosystem service losses. To enhance critical ecosystem services and mitigate environmental externalities in paddy fields, we developed a multi-objective agricultural [...] Read more.
Traditional intensive agricultural system impedes ecological functions, such as nutrient cycling and biodiversity conservation, resulting in excessive nitrogen discharge, CH4 emission, and ecosystem service losses. To enhance critical ecosystem services and mitigate environmental externalities in paddy fields, we developed a multi-objective agricultural system (MIA system), which combines two eco-functional units: paddy wetlands and Beitang (irrigation water collection pond). Pilot study results demonstrated that the MIA system enhanced biodiversity and inhibited pest outbreak, with only a marginal reduction in rice production compared with the control. Additionally, the paddy wetland effectively removed nitrogen, with removal rates of total nitrogen and dissolved inorganic nitrogen ranging from 0.06 to 0.65 g N m−2 d−1 and from 0.02 to 0.22 g N m−2 d−1, respectively. Continuous water flow in the paddy wetland reduced the CH4 emission by 84.4% compared with the static water conditions. Furthermore, a simulation experiment indicated that tide flow was more effective in mitigating CH4 emission, with a 68.3% reduction compared with the drying–wetting cycle treatment. The emergy evaluation demonstrated that the MIA system outperformed the ordinary paddy field when considering both critical ecosystem services and environmental externalities. The MIA system exhibited higher emergy self-sufficiency ratio, emergy yield ratio, and emergy sustainable index, along with a lower environmental load ratio. Additionally, the system required minimal transformation, thus a modest investment. By presenting the case of the MIA system, we provide a theoretical foundation for comprehensive management and assessment of agricultural ecosystems, highlighting its significant potential for widespread application. Full article
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23 pages, 10278 KiB  
Article
Natural-Based Solution for Sewage Using Hydroponic Systems with Water Hyacinth
by Lim Yen Yen, Siti Rozaimah Sheikh Abdullah, Muhammad Fauzul Imron and Setyo Budi Kurniawan
Water 2025, 17(14), 2122; https://doi.org/10.3390/w17142122 - 16 Jul 2025
Viewed by 538
Abstract
Domestic wastewater discharge is the major source of pollution in Malaysia. Phytoremediation under hydroponic conditions was initiated to treat domestic wastewater and, at the same time, to resolve the space limitation issue by installing a hydroponic system in vertical space at the site. [...] Read more.
Domestic wastewater discharge is the major source of pollution in Malaysia. Phytoremediation under hydroponic conditions was initiated to treat domestic wastewater and, at the same time, to resolve the space limitation issue by installing a hydroponic system in vertical space at the site. Water hyacinth (WH) was selected in this study to identify its performance of water hyacinth in removing nutrients in raw sewage under batch operation. In the batch experiment, the ratio of CODinitial/plantinitial was identified, and SPSS ANOVA analysis shows that the number of plant size factors was not statistically different in this study. Therefore, four WH, each with an initial weight of 60 ± 20 g, were recommended for this study. Throughout the 10 days of the batch experiment, the average of COD, BOD, TSS, TP, NH4, and color removal was 73%, 73%, 86%, 79%, 77%, and 54%, respectively. The WH biomass weight increased by an average of 78%. The plants have also improved the DO level from 0.24 mg/L to 4.88 mg/L. However, the pH of effluent decreased from pH 7.05 to pH 4.88 below the sewage Standard B discharge limit of pH 9–pH 5.50. Four WH plant groups were recommended for future study, as the COD removal among the other plant groups is not a statistically significant difference (p < 0.05). Furthermore, the lower plant biomass is preferable for the high pollutant removal performance due to the fact that it can reduce the maintenance and operating costs. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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31 pages, 3790 KiB  
Systematic Review
Plants Used in Constructed Wetlands for Aquaculture: A Systematic Review
by Erick Arturo Betanzo-Torres, Gastón Ballut-Dajud, Graciano Aguilar-Cortés, Elizabeth Delfín-Portela and Luis Carlos Sandoval Herazo
Sustainability 2025, 17(14), 6298; https://doi.org/10.3390/su17146298 - 9 Jul 2025
Viewed by 974
Abstract
The latest FAO report indicates that aquaculture accounts for 51% of the global production volume of fish and seafood. However, despite the continuous growth of this activity, there is evidence of the excessive use of groundwater in its production processes, as well as [...] Read more.
The latest FAO report indicates that aquaculture accounts for 51% of the global production volume of fish and seafood. However, despite the continuous growth of this activity, there is evidence of the excessive use of groundwater in its production processes, as well as pollution caused by nutrient discharges into surface waters due to the water exchange required to maintain water quality in fishponds. Given this context, the objectives of this study were as follows: (1) to review which emergent and floating plant species are used in constructed wetlands (CWs) for the bioremediation of aquaculture wastewater; (2) to identify the aquaculture species whose wastewater has been treated with CW systems; and (3) to examine the integration of CWs with recirculating aquaculture systems (RASs) for water reuse. A systematic literature review was conducted, selecting 70 scientific articles published between 2003 and 2023. The results show that the most used plant species in CW systems were Phragmites australis, Typha latifolia, Canna indica, Eichhornia crassipes, and Arundo donax, out of a total of 43 identified species. These plants treated wastewater generated by 25 aquaculture species, including Oreochromis niloticus, Litopenaeus vannamei, Ictalurus punctatus, Clarias gariepinus, Tachysurus fulvidraco, and Cyprinus carpio, However, only 40% of the reviewed studies addressed aspects related to the incorporation of RAS elements in their designs. In conclusion, the use of plants for wastewater treatment in CW systems is feasible; however, its application remains largely at the experimental scale. Evidence indicates that there are limited real-scale applications and few studies focused on the reuse of treated water for agricultural purposes. This highlights the need for future research aimed at production systems that integrate circular economy principles in this sector, through RAS–CW systems. Additionally, there is a wide variety of plant species that remain unexplored for these purposes. Full article
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18 pages, 2162 KiB  
Article
Simultaneous Decontamination for Ammonia Nitrogen and Phosphate Efficiently by Crystal Morphology MgO-Coated Functional Biochar Derived from Sludge and Sunflower Stalk
by Zhiwei Li, Jingxin Huang, Weizhen Zhang, Hao Yu and Yin Wang
Toxics 2025, 13(7), 577; https://doi.org/10.3390/toxics13070577 - 9 Jul 2025
Viewed by 424
Abstract
Eutrophication driven by nitrogen and phosphorus discharge remains a critical global environmental challenge. This study developed a sustainable strategy for synergistic nutrient removal and recovery by fabricating MgO-coated biochar (Mg-MBC600) through co-pyrolysis of municipal sludge and sunflower stalk (300–700 °C). Systematic investigations revealed [...] Read more.
Eutrophication driven by nitrogen and phosphorus discharge remains a critical global environmental challenge. This study developed a sustainable strategy for synergistic nutrient removal and recovery by fabricating MgO-coated biochar (Mg-MBC600) through co-pyrolysis of municipal sludge and sunflower stalk (300–700 °C). Systematic investigations revealed temperature-dependent adsorption performance, with optimal nutrient removal achieved at 600 °C pyrolysis. The Mg-MBC600 composite exhibited enhanced physicochemical properties, including a specific surface area of 156.08 m2/g and pore volume of 0.1829 cm3/g, attributable to magnesium-induced structural modifications. Advanced characterization confirmed the homogeneous dispersion of MgO nanoparticles (~50 nm) across carbon matrices, forming active sites for chemisorption via electron-sharing interactions. The maximum adsorption capacities of Mg-MBC600 for nitrogen and phosphorus reached 84.92 mg/L and 182.27 mg/L, respectively. Adsorption kinetics adhered to the pseudo-second-order model, indicating rate-limiting chemical bonding mechanisms. Equilibrium studies demonstrated hybrid monolayer–multilayer adsorption. Solution pH exerted dual-phase control: acidic conditions (pH 3–5) favored phosphate removal through Mg3(PO4)2 precipitation, while neutral–alkaline conditions (pH 7–8) promoted NH4+ adsorption via MgNH4PO4 crystallization. XPS analysis verified that MgO-mediated chemical precipitation and surface complexation dominated nutrient immobilization. This approach establishes a circular economy framework by converting waste biomass into multifunctional adsorbents, simultaneously addressing sludge management challenges and enabling eco-friendly wastewater remediation. Full article
(This article belongs to the Special Issue Environmental Study of Waste Management: Life Cycle Assessment)
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21 pages, 2629 KiB  
Article
SDG 6 in Practice: Demonstrating a Scalable Nature-Based Wastewater Treatment System for Pakistan’s Textile Industry
by Kamran Siddique, Aansa Rukya Saleem, Muhammad Arslan and Muhammad Afzal
Sustainability 2025, 17(13), 6226; https://doi.org/10.3390/su17136226 - 7 Jul 2025
Viewed by 481
Abstract
Industrial wastewater management remains a critical barrier to achieving Sustainable Development Goal 6 (SDG 6) in many developing countries, where regulatory frameworks exist but affordable and scalable treatment solutions are lacking. In Pakistan, the textile sector is a leading polluter, with untreated effluents [...] Read more.
Industrial wastewater management remains a critical barrier to achieving Sustainable Development Goal 6 (SDG 6) in many developing countries, where regulatory frameworks exist but affordable and scalable treatment solutions are lacking. In Pakistan, the textile sector is a leading polluter, with untreated effluents routinely discharged into rivers and agricultural lands despite stringent National Environmental Quality Standards (NEQS). This study presents a pilot-scale case from Faisalabad’s Khurrianwala industrial zone, where a decentralized, nature-based bioreactor was piloted to bridge the gap between policy and practice. The system integrates four treatment stages—anaerobic digestion (AD), floating treatment wetland (FTW), constructed wetland (CW), and sand filtration (SF)—and was further intensified via nutrient amendment, aeration, and bioaugmentation with three locally isolated bacterial strains (Acinetobacter junii NT-15, Pseudomonas indoloxydans NT-38, and Rhodococcus sp. NT-39). The fully intensified configuration achieved substantial reductions in total dissolved solids (TDS) (46%), total suspended solids (TSS) (51%), chemical oxygen demand (COD) (91%), biochemical oxygen demand (BOD) (94%), nutrients, nitrogen (N), and phosphorus (P) (86%), sulfate (26%), and chloride (41%). It also removed 95% iron (Fe), 87% cadmium (Cd), 57% lead (Pb), and 50% copper (Cu) from the effluent. The bacterial inoculants persist in the system and colonize the plant roots, contributing to stable bioremediation. The treated effluent met the national environmental quality standards (NEQS) discharge limits, confirming the system’s regulatory and ecological viability. This case study demonstrates how nature-based systems, when scientifically intensified, can deliver high-performance wastewater treatment in industrial zones with limited infrastructure—offering a replicable model for sustainable, SDG-aligned pollution control in the Global South. Full article
(This article belongs to the Special Issue Progress and Challenges in Realizing SDG-6 in Developing Countries)
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14 pages, 931 KiB  
Article
Using Systems Thinking to Manage Tourist-Based Nutrient Pollution in Belizean Cayes
by Daniel A. Delgado, Martha M. McAlister, W. Alex Webb, Christine Prouty, Sarina J. Ergas and Maya A. Trotz
Systems 2025, 13(7), 544; https://doi.org/10.3390/systems13070544 - 4 Jul 2025
Viewed by 222
Abstract
Tourism offers many economic benefits but can have long-lasting ecological effects when improperly managed. Tourism can cause overwhelming pressure on wastewater treatment systems, as in Belize, where some of the over 400 small islands (cayes) that were once temporary sites for fishermen have [...] Read more.
Tourism offers many economic benefits but can have long-lasting ecological effects when improperly managed. Tourism can cause overwhelming pressure on wastewater treatment systems, as in Belize, where some of the over 400 small islands (cayes) that were once temporary sites for fishermen have become popular tourist destinations. An overabundance of nitrogen, in part as a result of incomplete wastewater treatment, threatens human health and ecosystem services. The tourism industry is a complex and dynamic industry with many sectors and stakeholders with conflicting goals. In this study, a systems thinking approach was adopted to study the dynamic interactions between stakeholders and the environment at Laughing Bird Caye National Park in Belize. The project centered on nutrient discharges from the caye’s onsite wastewater treatment system. An archetype analysis approach was applied to frame potential solutions to nutrient pollution and understand potential behaviors over time. “Out of control” and “Underachievement” were identified as system archetypes; “Shifting the Burden” and ‘‘Limits to Success’’ were used to model specific cases. Based on these results, upgrading of the wastewater treatment system should be performed concurrently with investments in the user experience of the toilets, education on the vulnerability of the treatment system and ecosystem, and controls on the number of daily tourists. Full article
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16 pages, 1415 KiB  
Article
Assessment of Surface Water Quality in the Krynka River Basin Using Fluorescence Spectroscopy Methods
by Sergey Chufitskiy, Sergey Romanchuk, Besarion Meskhi, Anastasiya Olshevskaya, Victoria Shevchenko, Mary Odabashyan, Svetlana Teplyakova, Anna Vershinina and Dmitry Savenkov
Plants 2025, 14(13), 2014; https://doi.org/10.3390/plants14132014 - 1 Jul 2025
Viewed by 343
Abstract
This study presents a biomonitoring study of surface waters in the Krynka River basin, encompassing three major regional reservoirs: Khanzhenkovskoe, Olkhovskoe, and Zuyevskoe. These water bodies face significant anthropogenic pressure from mining effluents, industrial discharges, and domestic wastewater. Key pollutants identified are surfactants [...] Read more.
This study presents a biomonitoring study of surface waters in the Krynka River basin, encompassing three major regional reservoirs: Khanzhenkovskoe, Olkhovskoe, and Zuyevskoe. These water bodies face significant anthropogenic pressure from mining effluents, industrial discharges, and domestic wastewater. Key pollutants identified are surfactants (SAAs), sulfates, phenols, chlorides, and manganese, with chemical oxygen demand (COD) exceeding regulatory limits. The research was conducted in September 2024. Based on the Specific Combinatorial Water Pollution Index, surface waters in the studied objects can be characterized as slightly polluted. To assess the negative impact of the identified pollutants on hydrobionts, the species composition of phytoplankton of the studied water bodies was analyzed. In the Olkhovskoe Reservoir and Olkhovaya River, cyanobacterial blooms (Oscillatoria agardhii G.) were observed, altering biodiversity in the Krynka River and Zuyevskoe Reservoir. Phytoplankton genera Synedra, Amphiprora, and Navicula—established bioindicators of aquatic ecosystem health—were dominant in Khanzhenkovskoe Reservoir, signaling nutrient enrichment and organic pollution. Changes in the species composition and structure of phytoplankton in the Krynka River, its tributaries and reservoirs, indicate a change in the level of saprobic water bodies from β to α-mesosaprobic, which indicates both the general level of surface water pollution and the accumulation of pollutants along the course of the river. The paper presents the results of fluorimetric analysis of photosynthetic activity of natural phytoplankton cells and demonstrates the possibility of using fluorescence induction curves for regular monitoring measurements. Fluorescence parameters indicate a general deterioration of photosynthetic activity of natural phytoplankton. The growth of Oscillatoria agardhii in the waters of the Olkhovskoe Reservoir and of green microalgae in the Zuevskoe Reservoir led to an increase in the fluorescence quantum yield (Fv/Fm) and the total photosynthetic activity index (PI), which makes it possible to use these parameters as indicator parameters reflecting the intensity of “blooming” of various phytoplankton species. Full article
(This article belongs to the Special Issue Biological Responses of Plants to Environmental Pollution)
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19 pages, 3257 KiB  
Article
Total Phosphorus Loadings and Corrective Actions Needed to Restore Water Quality in a Eutrophic Urban Lake in Minnesota, USA: A Case Study
by Neal D. Mundahl and John Howard
Limnol. Rev. 2025, 25(3), 28; https://doi.org/10.3390/limnolrev25030028 - 1 Jul 2025
Viewed by 305
Abstract
Lake Winona, a 129 ha eutrophic urban lake comprised of two interconnected basins, exceeds state water quality standards for total phosphorus. Historical lake nutrient data and traditional watershed modeling for the lake’s two basins highlighted multiple major pathways (e.g., municipal stormwater discharges, watershed [...] Read more.
Lake Winona, a 129 ha eutrophic urban lake comprised of two interconnected basins, exceeds state water quality standards for total phosphorus. Historical lake nutrient data and traditional watershed modeling for the lake’s two basins highlighted multiple major pathways (e.g., municipal stormwater discharges, watershed runoff, internal loading, and wetland discharges) for total phosphorus (P) loading, with >900 kg P/year estimated entering the water columns of each basin. Updated data sources and newer watershed modeling resulted in significantly different (both higher and lower) P loading estimates for the various P sources, especially watershed runoff and internal loading. Overall, basin-specific loading estimates using the updated model were significantly lower (28–40%) than previous estimates: 680 and 546 kg P/year mobilized in the western and eastern basins, respectively. To achieve state water quality standards (<60 ppm P for the western basin, <40 ppm for the eastern basin), watershed and internal P loading each would need to be reduced by approximately 120 kg P/year across the two basins. Reductions could be achieved by a combination of alum treatments to reduce internal loading, removal of common carp (Cyprinus carpio) to prevent interference with alum treatments and nutrient releases via excretion and defecation, and six engineered structures to intercept P before it enters the lake. The different P reduction projects would cost USD 119 to 7920/kg P removed, totaling USD 5.2 million, or USD 40,310/hectare of lake surface area. Full article
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26 pages, 1025 KiB  
Review
A Review of Harmful Algal Blooms: Causes, Effects, Monitoring, and Prevention Methods
by Christina M. Brenckman, Meghana Parameswarappa Jayalakshmamma, William H. Pennock, Fahmidah Ashraf and Ashish D. Borgaonkar
Water 2025, 17(13), 1980; https://doi.org/10.3390/w17131980 - 1 Jul 2025
Cited by 1 | Viewed by 2274
Abstract
Harmful Algal Blooms (HABs) are a growing environmental concern due to their adverse impacts on aquatic ecosystems, human health, and economic activities. These blooms are driven by a combination of factors, including nutrient enrichment, environmental factors, and hydrological conditions, leading to the excessive [...] Read more.
Harmful Algal Blooms (HABs) are a growing environmental concern due to their adverse impacts on aquatic ecosystems, human health, and economic activities. These blooms are driven by a combination of factors, including nutrient enrichment, environmental factors, and hydrological conditions, leading to the excessive growth of algae. HABs produce toxins that threaten aquatic biodiversity, contaminate drinking water, and cause economic losses in fisheries and tourism. The causes of HABs are multifaceted, involving interactions between environmental factors such as temperature, light availability, and nutrient levels. Agricultural runoff, wastewater discharge, and industrial pollution introduce excessive nitrogen and phosphorus into water bodies, fueling bloom formation. Climate change further exacerbates the problem by altering precipitation patterns, increasing water temperatures, and intensifying coastal upwelling events, all of which create favorable conditions for HAB proliferation. This review explores the causes, ecological consequences, and potential mitigation strategies for HABs. Effective monitoring and detection methods, including satellite remote sensing, molecular biotechnology, and artificial intelligence-driven predictive models, offer promising avenues for early intervention. Sustainable management strategies such as nutrient load reductions, bioremediation, and regulatory policies can help mitigate the adverse effects of HABs. Public awareness and community involvement also play a crucial role in preventing and managing HAB events by promoting responsible agricultural practices, reducing waste discharge, and supporting conservation efforts. By examining existing literature and case studies, this study underscores the urgent need for comprehensive and interdisciplinary approaches to regulate HABs. Full article
(This article belongs to the Section Water Quality and Contamination)
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24 pages, 1906 KiB  
Article
Coupling Advanced Oxidation and Anaerobic Treatment for Landfill Leachate: Magnetite-Catalyzed Ozone and USAB Reactor Efficiency
by Dorance Becerra-Moreno, Antonio Zuorro, Fiderman Machuca-Martínez, Luisa F. Ramírez-Rios, Janet B. García-Martínez and Andrés F. Barajas-Solano
Inorganics 2025, 13(7), 218; https://doi.org/10.3390/inorganics13070218 - 30 Jun 2025
Viewed by 890
Abstract
Sanitary landfill leachate treatment was evaluated using magnetite-catalyzed ozone, an upflow anaerobic sludge blanket (UASB) reactor, and microalgae, both individually and in combination, to improve biodegradability and remove organic matter, solids, metals, and nutrients. Leachates were characterized before and after each treatment, and [...] Read more.
Sanitary landfill leachate treatment was evaluated using magnetite-catalyzed ozone, an upflow anaerobic sludge blanket (UASB) reactor, and microalgae, both individually and in combination, to improve biodegradability and remove organic matter, solids, metals, and nutrients. Leachates were characterized before and after each treatment, and their impacts on methanogenic activity, aerobic toxicity, and the BOD5/COD ratio were assessed. Magnetite-catalyzed ozone pretreatment enhanced biodegradability, enabling an optimal coupling point with the UASB at 40 min when the specific methanogenic activity reached 0.22 g CH4-COD/(gVSS·d). The UASB achieved COD removal rates of up to 75%, but high concentrations were maintained in the effluent with low ammoniacal nitrogen and phosphorus removal rates. Microalgae promoted nutrient removal, reducing total nitrogen and phosphorus by up to 65% and 70%, respectively, although with lower efficiency in terms of organic matter removal. Process coupling demonstrated that ozonation followed by UASB application improved anaerobic degradation, whereas the use of microalgae after biological treatment optimized the final effluent quality. Despite the improvements achieved, the final values for some parameters still exceeded the discharge limits, indicating the need for operational adjustments or additional treatments to ensure effective purification. Full article
(This article belongs to the Special Issue Transition Metal Catalysts: Design, Synthesis and Applications)
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