Total Phosphorus Concentrations Research Articles

Long-term contamination of decabromodiphenyl ether reduces sediment multifunctionality: Insights from nutrient cycling, microbial ecological clusters, and microbial co-occurrence patterns

Despite the widespread detection of polybrominated diphenyl ethers in aquatic ecosystems, their long-term effects on sediment multifunctionality remain unclear. Herein, a 360-day microcosm experiment was conducted to investigate how decabromodiphenyl ether (BDE-209) contamination at different levels (0.2, 2, and 20 mg/kg dry weight) affects sediment multifunctionality, focusing on carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling. Results showed that BDE-209 significantly increased sediment total organic carbon, nitrate, ammonium, available phosphorus, and sulfide concentrations, but decreased sulfate. Additionally, BDE-209 significantly altered key enzyme activities related to nutrient cycling. Bacterial community dissimilarity was positively correlated with nutrient variability. Long-term BDE-209 exposure inhibited C degradation, P transport and regulation, and most N metabolic pathways, but enhanced C fixation, methanogenesis, organic P mineralization, inorganic P solubilization, and dissimilatory sulfate reduction pathways. These changes were mainly regulated by microbial ecological clusters and keystone taxa. Overall, sediment multifunctionality declined under BDE-209 stress, primarily related to microbial co-occurrence network complexity and ecological cluster diversity. Interestingly, sediment C and N cycling had greater impacts on multifunctionality than P and S cycling. This study provides crucial insights into the key factors altering multifunctionality in contaminated sediments, which will aid pollution control and mitigation in aquatic ecosystems.

The Bioaccumulation of Heavy Metals in the Water and Tissues of Invasive Fish Carassius gibelio (Bloch, 1782) and Non-carcinogenic Health Risk Assessment from Meriç Delta Wetland, Türkiye.

Meriç Delta, which has a wide variety of ecosystems, is an A Class Wetland and the most significant natural stagnant freshwater ecosystem located in the south-western of Thrace Region of Türkiye. In this research, heavy metals (Cr, Ni, As, Cd, and Pb) were investigated in the surface water and Carassius gibelio (Bloch, 1782) obtained from Meriç Delta lakes (Gala, Pamuklu, Sığırcı, and Dalyan), which are located on an important migration route of water birds. The heavy metals in surface water samples and fish tissues were determined by ICP-MS. Dissolved oxygen, oxygen saturation (%), pH, electrical conductivity, total dissolved solids, nitrite nitrogen, nitrate nitrogen, and total phosphorus parameters were measured in surface waters. High total phosphorus content was detected in the investigated region. The measured As, Cr, and Ni values in water samples were determined to be higher than Türkiye Regulation Standards criteria. Fish were taken from Gala and Sığırcı Lake. The mean concentrations of measured heavy metals were found to be below permissible values in fish muscle and gill. The target hazard quotient (THQ) and total THQ values (HI) of all heavy metals did not exceed the limit value.

Interplanting potato with grapes improved yield and soil nutrients by optimizing the interactions of soil microorganisms and metabolites.

Interplanting crops is the best method to grow crops synergistically for better utilization of land and agro-resources. Grape (Vitis vinifera) and potato (Solanum tuberosum L.) have highly efficient agricultural planting systems in China, however, how soil physicochemical properties and soil microbial communities and metabolites affect the output of grape-potato interplanting remained unknown. In this study, we employed three planting patterns (CK: grape monocropping; YY: grape interplanted with potato (variety 'Favorita'); LS: grape interplanted with potato (variety 'Longshu7')) at two experimental sites i.e., the Huizhou (2022) site and the Qingyuan site (2023). The grape variety for all planting patterns was 'Sunshine Rose'. Soil samples (top 0-20 cm) at both sites were collected to observe the diversity of bacterial communities and soil metabolites. Our findings revealed that, compared with monocropping, the interplanted systems resulted in higher concentrations of total nitrogen, available phosphorus, and available potassium and enhanced the activities of acid phosphatase, urease, and protease. The potato root exudates also altered the relative abundance of Bacillus, Kaistobacter, and Streptomyces in the rhizosphere. Among the soil metabolites, lipids and organic acids showed the most significant changes. Notably, 13-L-hydroperoxylinoleic acid is the key differentially abundant metabolite involved in the regulation of linoleic acid metabolism pathways. The association analyses of the metabolome, microbiome, and soil physicochemical properties revealed that the interactions of microbes and metabolites resulted in differences in the soil nutrient content, whereas the interactions of 13-L-hydroperoxylinoleic acid and Firmicutes improved the soil nutrient levels and bacterial composition in the interplanting systems. In summary, our findings demonstrated that intercropping grapes with potato 'Favorita' was better with respect to improving soil nutrients, soil enzyme activity, the diversity of soil bacteria, and soil metabolites without causing adverse impacts on grape yield. Overall, this study explained the physiological mechanisms by which soil microorganisms and metabolites promote potato growth in grape interplanting and provided new perspectives for the utilization of soil resources in vineyards.

Tempo-spatial Variations in Nitrogen and Phosphorus Loads in Jianli-Hankou Reach of the Middle Yangtze River During the Past 20 Years

Ammonia nitrogen （NH4+-N） and total phosphorus （TP） were the major control pollutants in the Yangtze River Basin. Based on measured data from 2003 to 2020, the temporal and spatial variations in concentrations and fluxes of NH4+-N and TP in the Jianli to Hankou （JL-HK） reach of the Middle Yangtze River were studied, and the impacts of flow-sediment factors, tributary inflows, and others on variations in NH4+-N and TP fluxes were discussed. The results showed that： ① In recent years, NH4+-N and TP concentrations in the mainstream have declined significantly, with annual NH4+-N and TP concentrations at each monitoring station in 2020 averagely decreasing by 41% and 34% compared to those in 2003, respectively. Spatially, NH4+-N and TP concentrations decreased and then increased along the mainstream. NH4+-N and TP concentrations of tributary inflows, which include the Dongting Lake and Han River, were generally lower than that of the mainstream. The multi-year average values of NH4+-N and TP concentrations were both averaged at 0.12 mg·L-1 in the mainstream and were averaged at 0.11 mg·L-1 and 0.09 mg·L-1 in the tributary inflows. ② The flux differences between the upper and lower sections net of tributary confluences showed that NH4+-N and TP fluxes were lost in the Jianli to Luoshan （JL-LS） sub-reach and increased in the Luoshan to Hankou （LS-HK） sub-reach in most years. NH4+-N and TP fluxes decreased in the JL-LS sub-reach, which was related to the lower NH4+-N and TP concentrations in lateral inflows, such as Dongting Lake, and thus lowered the NH4+-N and TP concentrations in the mainstream. The LS-HK sub-reach showed the opposite trends, and the water and sediment loads increased in this sub-reach. Across the whole JL-HK reach, TP flux as well as water and sediment loads were recharged along the reach, whereas NH4+-N flux was reduced greatly, which could be attributed to the pollution abatement conducted in the Yangtze River Basin, which mainly focused on NH4+-N. ③ The correlation analysis results showed that NH4+-N fluxes had the strongest correlation with NH4+-N concentrations but not significantly correlated with discharges and sediment transport rates, indicating that NH4+-N was mainly controlled by point source pollution in the study reach. TP fluxes had higher correlations with discharges and sediment transport rates in high flow level periods, and the correlations between TP fluxes and TP concentrations were better in low flow level periods, reflecting that point source pollution contributed more to TP in dry seasons compared to flood seasons.

Fe3+ augmentation enhancing the nitrogen and phosphorus control in denitrification biofilter based on water supply sludge: Performance and microbial characteristics

The intricate mechanisms of iron (Fe) enhancing the simultaneous nitrogen (N) and phosphorus (P) removal in the denitrification biofilter (DNBF) remain enigmatic and warrant further investigation. Fe2+ and Fe3+ were added to compare the enhancing performances and the dosage concentration was optimized in this study, and the effects of Fe3+ on microbial characteristics were elucidated furtherly. Results demonstrated that the N removal performance with Fe3+ enhancing was better than Fe2+, and the optimal FeCl3 concentration was 0.56 mg/L. The effluent concentrations of total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD) lowed to 0.27, 4.2, and 13.4 mg/L, respectively. Fe3+ promoted microbial richness and diversity, with Proteobacteria, Bacteroidetes and Firmicutes emerging as the advantageous phyla for N and P removal in the DNBF. Microorganisms facilitated Fe3+ reduction to enhance denitrification process, and P was predominantly removed through the precipitation formed by the interaction of Fe and P. Furthermore, Fe3+ was noted to promote functional metabolism, thereby aiding in N removal. This study can reveal the effect of Fe3+ on N removal in the DNBF, and provide a theoretical foundation for advanced N and P removal.

Soil pathogenic fungal groups and soil nutrient cycling under land use practices in Liupanshan Mountain in China

AbstractDifferent land‐use practices in temperate forests strongly affect soil quality and soil microbial communities, whereas the assembly and interactions of soil functional fungal communities provide positive feedback. Therefore, the effects of forest ecosystem degradation on the composition of functional soil fungal community and soil nutrient cycling are of particular importance. We studied forest ecosystems in the Liupanshan Mountains in the northwestern part of the Loess Plateau and analyzed the relationship of soil fungal community and soil nutrient cycling under different land use practices (natural forest [NF], plantation forest, and farmland [FL]). The results showed that soil pH and electrical conductivity were the highest in FL, whereas the soil carbon cycle index and nitrogen cycle index decreased. The soil total phosphorus content did not change significantly with an increase in available phosphorus content. The change from NF to FL significantly increased the number of operational taxonomic units, diversity, and richness of soil fungal communities. The composition of the soil fungal communities was also strongly influenced by carbon and nitrogen cycle indices. In addition, FL reclamation increased the complexity of the soil microorganism co‐occurrence network, and the interrelationships between soil functional fungal community were enhanced. Pathogenic fungal communities were enriched in FLs, and their relative abundance was significantly regulated by environmental factors such as pH and the ratio of nitrogen to phosphorus. The soil pathogenic fungal community affected carbon and nitrogen cycle indices to varying degrees.

Evaluation of a Greenhouse Ecosystem to Treat Craft Beverage Wastewater

An aerated greenhouse ecosystem, often referred to as a Living Machine®, is a technology for biological wastewater treatment within a greenhouse structure that uses plants with their roots submerged in the wastewater. This system has a small footprint relative to traditional onsite wastewater treatment systems and constructed wetland, can treat high-strength wastewater, and can provide a high level of treatment to allow for reuse for purposes such as irrigation, toilet flushing, and landscape irrigation. Synthetic and actual craft beverage wastewaters (wastewater from wineries, breweries, and cideries) were examined for their treatability in bench-scale greenhouse ecosystems. The tested wastewater was high strength with chemical oxygen demands (COD) concentrations of 1120 to 15,000 mg/L, total nitrogen (TN) concentrations of 3 to 45 mg/L, and total phosphorus (TP) concentrations of 2.3 to 90 mg/L. The COD, TN, and TP concentrations after treatment ranged from below 125 to 560 mg/L, 1.5 to 15 mg/L, and below 0.25 to 7.8 mg/L, respectively. The results confirm the ability of the aerated greenhouse ecosystem to be a viable treatment system for craft beverage wastewater and it is estimated to require 54 and 26% lower hydraulic retention time than an aerobic lagoon and a low temperature, constructed wetland, respectively, the types of systems that would likely be used for this type of wastewater for onsite locations.

Tracing nitrogen and phosphorus pollution in urban runoff: Insights from isotopic tracers and SWMM modeling

Water contamination in certain rivers during rainfall necessitates the evaluation of pollutant levels within pipelines and the identification of their sources to ensure effective pollution control. In this study, we assess pollutant concentrations during runoff from surfaces, pipelines, and channels, identify pollutant sources within pipelines, and analyze sewage leakage contributions to channel pollution in residential areas in Wuxi City, China. The results showed that the event mean concentrations of total nitrogen (TN), total phosphorus (TP), ammonium (NH4+-N), and nitrate (NO3−-N) in the drainage outlet runoff were 3.4, 1.1, 8.8, and 14.9 times higher than in impervious surface runoff. The predominant forms of nitrogen and phosphorus in runoff shift from organic to inorganic as they move from the surface to pipelines. The pipeline load and contribution were further estimated by combining water quantity calculations from the calibrated and verified Storm Water Management Model (SWMM) with measured nitrogen and phosphorus concentrations in the runoff. TN, NH4+-N, NO3−-N, and PO43--P within the pipelines accounted for 59%, 83%, 90%, and 77% of the discharge loads, respectively. The application of the Stable Isotope Analysis in R (SIAR) package (MixSIAR) revealed that the domestic sewage and soil organic N were the predominant sources of pollutants within drainage pipelines, contributing 23.7% and 32.6% of NO3−-N, respectively. Additionally, the sewage leakage accounted for 33.7% and 66.9% of NO3−-N in drainage runoff and channels, respectively. Unlike existing methods, this study quantitatively highlights the significant impact of pipeline pollutants and sewage leakage on urban river water quality, providing essential insights for developing effective strategies to mitigate non-point source water pollution.

One third of African rivers fail to meet the ’good ambient water quality’ nutrient targets

The ambition of Sustainable Development Goal (SDG) target 6.3 is to improve global water quality by 2030. SDG indicator 6.3.2 monitors progress towards this target by assessing water bodies against ‘good’ ambient water quality criteria, with nutrients (nitrogen and phosphorus) as part of the key metrics. However, large data gaps present a fundamental challenge, especially for Africa on how to assess the progress being made with respect to both the current and desired future situations. Here, a continental water quality model for Africa is presented to simulate river sediment load, Total Nitrogen (TN) and Total Phosphorus (TP) loads and concentrations. Furthermore, critical areas and hotspots of TN and TP pollution are mapped for the period 2017 – 2019, in relation to the United Nations Environment Programme (UNEP) target thresholds used for the assessment of SDG indicator 6.3.2. Utilizing the UNEP’s criteria, which designates a water body as having “good ambient water quality” if 80% or more of its monitored values meet their targets, it is estimated that 44 % and 15 % of African rivers fail to meet the set water quality thresholds for simulated TP and TN, respectively. When synthesizing data for both TP and TN, 34 % of the rivers do not qualify as having “good ambient water quality”. Geographically, the most pronounced nutrient pollution hotspots were in North Africa, Niger River Delta, Nile River basin, Congo River basin and specific zones in Southern Africa. These areas correlate with regions characterized by high inputs of fertilizers, manure and wastewater discharge.

The advantage of afforestation using native tree species to enhance soil quality in degraded forest ecosystems

Different vegetation restoration methods have improved soil quality to varying degrees. This study, focused on the forest–grassland–desert transition zone in the Hebei–Inner Mongolia border region, and employed a systematic grid sampling method to establish fixed monitoring plots in the Saihanba Mechanized Forest Farm and the Ulan Buh Grassland. The differences in soil quality evolution across various vegetation restoration methods under the same climatic and soil historical conditions were analyzed, elucidating the roles of these vegetation restoration methods in degraded forest ecosystems, with the aim of providing a reference for ecological restoration under similar land conditions. This study used a grid method to establish sample points in the forest–grassland–desert transitional zone and assessed five methods of vegetation restoration sites: artificial forest composed of native species of Larix principis-rupprechtii (FL), artificial forest composed of exotic Pinus sylvestris var. mongolica (FP), natural secondary broad-leaved forest (FN), open grassland (GO), and enclosed grassland (GC). The differences in soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkaline hydrolysis nitrogen (AN), rapidly available phosphorus (AP) and rapidly available potassium (AK) among the different vegetation restoration sites were compared via variance analysis, and the soil quality index (SQI) was calculated to assess the soil quality at the sample points. The SOC, TN, and AN contents of forest soil were significantly greater than those of grassland, and the TN, TP, AN, AK, and SOC contents of FL, FN, and GC were significantly greater than those of FP and GO. Among them, the TN, TP, and SOC contents were the highest in the FL, reaching 2.74, 0.39, and 47.27 g kg−1, respectively. In terms of ecological stoichiometric characteristics, the average N:P ratio in the study area was 6.68, indicating a serious lack of N in the study area. Among the different types of restoration sites, the effect was stronger in the FP than in the FL, and the TN and AN contents were only 1.48 g kg−1 and 116.69 mg kg−1, respectively. The SQI in the FL was not significantly different from that in the FN or GC, but it was significantly greater than that in the FP and GO. These findings indicate that native tree species restoration in degraded forest ecosystems significantly improved soil quality, while the introduction of exotic tree species for afforestation had a minimal effect on improving soil quality.

An Analysis of the Spatiotemporal Variability of Key Water Quality Parameters in China

Intensifying anthropogenic disturbances have caused water pollution in China in recent decades. China has a vast territory with diverse climate conditions, land use types, and human activities, leading to significant water quality variability. However, few studies have investigated nationwide spatiotemporal patterns of key water quality parameters. In this study, we analyze monthly water quality observations from 3647 gauge stations to understand how water quality changes over time and space in China. We group the stations by water resource regions and adopt Python and SPSS to analyze the spatiotemporal variability and intercorrelations of eight water quality parameters. Results indicate that the concentrations of biochemical oxygen demand of 5 days (BOD5), chemical oxygen demand (COD), dissolved oxygen (DO), ammonia nitrogen (NH3-N), total nitrogen (TN), and total phosphorus (TP) show similar spatial patterns, with higher concentrations in the northern parts than the southern regions of China. The concentrations of COD and TP are higher in the rainy season than in the dry season, while DO, NH3-N, and TN show the opposite seasonal patterns. Strong positive correlations were found between BOD and COD, NH3-N and TP. The annual cumulative distribution figures demonstrate that all parameters showed slightly lower concentrations in 2022 and 2023 than in 2021, except for DO and TN. The TN/TP ratios across different water resource regions in China are significantly higher than 16, indicating that phosphorus is the limiting factor of eutrophication. This investigation provides a comprehensive understanding of the spatiotemporal variability of water quality parameters across China. The results of this study are highly valuable for investigating mechanisms regulating water quality across large spatial scales, thus providing valuable implications for improving water quality and mitigating water pollution.

Co-composting of Black Soldier Fly Frass (BSFF) with various organics additives for nutrient enhancement

Black soldier fly frass is the nutrient-rich waste produced by black soldier fly larvae. This study aimed to enhance the frass by co-composting it with fish meal, bone meal, boiler ash, and sawdust. The co-composting process involved blending frass with the selected materials to achieve C:N ratio of 20, 25 and 30. After co-composting, characterization of total carbon, nitrogen, phosphorus and potassium contents and germination test were conducted. Fish meal increased nitrogen from 2.47 % to 3.10 %, bone meal improved phosphorus from 0.024 % to 0.042 %, and boiler ash raised potassium from 0.0023 % to 0.0039 %. Nevertheless, all the NPK source additives are required to balance and enhance all the nutrient level. Additionally, composts BSFF, fish meal, bone meal, and boiler ash, resulted in 100 % seed germination. The study demonstrates that co-composting frass with these materials effectively improves its nutrient content, providing a sustainable alternative for organic waste management and nutrient recycling.

Effect of Nano Urea on Leaf Nutrients and Some Quality Parameters of Tea (Camellia sinensis (L) O. Kuntze)

Some important parameters of tea on mature plants of TV 23 clone were studied after application of Nano-urea as foliar spray at Experimental Garden for Plantation Crops, Assam Agricultural University, Jorhat during the period 2021-2022. The usage of "Nano Urea" (Liquid), a novel product created and patented by Indian Farmers Fertilizer Cooperative Limited (IFFCO), is projected to replace the use of urea granules, one of the most widely used fertilizers in the world. Leaf nutrients i.e., nitrogen, phosphorus, potassium and quality parameters i.e., Caffeine, polyphenol were observed after application of nano urea. Leaf nitrogen, leaf phosphorus and leaf potassium were found to be increased with the application of higher dose of Nano Urea. Leaf nitrogen was observed maximum (4.57%) in the plot where 0.4% Nano-urea applied in three sprays. Total phosphorus content of leaf was found to be the highest in treatment T7(0.423%) the lowest was observed in treatment T0 (0.370%). Total potassium content of leaf was the highest in treatment T7 (2.517%) and lowest K2O content was observed in treatment T0 (2.013%) which was a control. In quality parameters, it was found that application of Nano Urea showed significant impact on the total caffeine content of tea leaf. The highest value of caffeine was found in treatment T7 (3.233%) and lowest was found in treatment T0 (3.10%) (control).

Impact of joint dispatch of reservoir group on water pollution incident in drinking water source area

To reduce the harm of water contamination incidents in drinking water source areas (DWSAs) and explore feasible approaches, the research developed a hydrodynamic water quality model for DWSAs based on two dimensional water quality and quantity equations, Geographic Information System (GIS), and Digital Elevation Model (DEM). The Heshangshan Drinking Water Source Area (HDWSA) in the Three Gorges Reservoir Area (TGRA) was selected as the research area, with total phosphorus (TP) as the representative pollutant in the water. The research investigated the changes in TP content during various hydrological phase under pollution incident, compared the duration and trends of TP concentration exceeding standard value before and after joint reservoir group dispatch. The results showed that the migration speed of TP pollutants varied from slowest to fastest in the following order: dry phase, recession phase, storage phase, and flood phase. Under pollution incident condition, the time demanded for TP content to meet standard value in each water phase was 36 min (dry phase), 33 min (recession phase), 30 min (storage phase), and 27 min (flood phase). The joint dispatch group 1–3 shortened the time required to meet standard value by 6–13 min (dry phase), 5–11 min (recession phase), 4–9 min (storage phase), and 3–7 min (flood phase). The trend of TP concentration before and after joint dispatch showed four stages: significant increase, sharp decrease, rapid decrease, and slow decrease. Joint dispatch of reservoir group can effectively reduced the TP concentration in DWSA under pollution incident.

Phosphorus doped hydrogenated silicon oxycarbide: Film formation, properties and its application on silicon heterojunction solar cell

An ultrathin phosphorus doped hydrogenated microcrystalline silicon oxycarbide (n-μc-SiCO:H) layer deposited by plasma enhanced chemical vapor deposition (PECVD) method can be used as a window layer for silicon heterojunction solar cells. The optical and electrical properties of n-μc-SiCO:H films were controlled by PECVD deposition conditions. The interplay effects of H2, CO2 and PH3 to SiH4 gas ratio on the chemical composition, material structure and properties of n-μc-SiCO:H film were systematically determined. O, H, C and P atoms were observed to incorporate into the silicon network of n-μc-SiCO:H layer, while most of the atoms bond directly to Si atoms. Incorporation of oxygen and carbon atoms into n-μc-SiCO:H film, confirmed by XPS as formation of Si-O and Si-C bonds, enlarged the optical absorption band gap (Eg) value. Both film crystallinity and phosphorus concentration in n-μc-SiCO:H layer were observed to be controlled by the H2, CO2 and PH3 to SiH4 gas ratio. The electric performance of HJT solar cell was depended on the optical and electrical properties of n-μc-SiCO:H layer. An average efficiency (across ∼ 120 cells) of 26.32 % was achieved in cells with optimized deposition parameters for the n-μc-SiCO:H layer. The reaction gas ratio was also the dominant factor in determining the number and size of nanoscale Si crystallites embedded in the n-μc-SiCO:H layer. The conductivity of n-μc-SiCO:H layer was determined by the activated phosphorus concentration but independent of the total phosphorus concentration. It was also found that large concentrations of small Si crystallites of size less than 3 nm improved film conductivity.

Phosphorus prediction in the middle reaches of the Yangtze river based on GRA-CEEMDAN-CNLSTM-DBO

Accurate and rapid prediction of water quality is crucial for the protection of aquatic ecosystems. This study aims to enhance the prediction of total phosphorus (TP) concentrations in the middle reaches of the Yangtze River by integrating advanced modeling techniques. Using operational and discharge data from the Three Gorges Reservoir (TGR), along with water quality parameters from downstream sections, we used Grey Relational Analysis (GRA) to rank the factors contributing to TP concentrations. The analysis identified turbidity, permanganate index (CODMn), total nitrogen (TN), water temperature, chlorophyll a, upstream water level variation, and discharge from the Three Gorges Dam (TGD) as the top contributors. Subsequently, a coupled neural network model was established, incorporating these key contributors, to predict TP concentrations under the dynamic water level control during flood periods in the TGR. The proposed GRA-CEEMDAN-CN1D-LSTM-DBO model was compared with conventional models, including BP, LSTM, and GRU. The results indicated that the GRA-CEEMDAN-CN1D-LSTM-DBO model significantly outperformed the others, achieving a correlation coefficient (R) of 0.784 and a root mean square error (RMSE) of 0.004, compared to 0.58 (R) and 0.007 (RMSE) for the LSTM model, 0.576 (R) and 0.007 (RMSE) for the BP model, and 0.623 (R) and 0.006 (RMSE) for the GRU model. The model's accuracy and applicability further validated in two sections: YC (Yunchi) in Yichang City and LK (Liukou) in Jingzhou City, where it performed satisfactorily in predicting TP in YC (R = 0.776, RMSE = 0.007) and LK (R = 0.718, RMSE = 0.007). Additionally, deep learning analysis revealed that as the distance away from dam increased, prediction accuracy gradually decreased, indicating a reduced impact of TGR operations on downstream TP concentrations. In conclusion, the GRA-CEEMDAN-CN1D-LSTM-DBO model demonstrates superior performance in predicting TP concentration in the middle reaches of the Yangtze River, offering valuable insights for dynamic water level control during flood seasons and contributing of smart to the advancement of water management in the Yangtze River.

Spatiotemporal and vertical variability of water quality in lentic small water bodies: implications of varying rainfall and land use conditions.

Lentic small water bodies (LSWBs) deteriorate owing to anthropogenic activities, such as untreated domestic and agricultural waste disposal. Moreover, different turnover mechanisms occur during different seasons, contributing to nutrient enrichment and consequent degradation of LSWBs. However, understanding their spatial, temporal, and vertical variations during different seasons is understudied. In addition, studies on the variation in water quality under varying rainfall and land-use conditions are limited. Therefore, in this study, three LSWBs located in Northern India were studied during the pre-monsoon and monsoon seasons (December 2022 to October 2023). Total nitrogen (TN), chlorophyll-a (Chl-a), total phosphorus (TP), temperature, pH, dissolved oxygen (DO), total dissolved solids (TDS), chemical oxygen demand (COD),secchi disk depth (SDD), and water level (WL) were measured monthly. Sentinel-2 and CHIRPS pentad data were used for land use, land cover classification, and rainfall analysis. The spatial analysis indicates that the seasonal shift affects the water quality distribution, especially near the inlets and at the edges. The overall concentrations of TN and TP decreased during the monsoon season; however, they increased significantly at the inlets of the LSWBs. On the other hand, the Chl-a concentration shifted towards the edges due to the inflow during the monsoon. Temporal analysis also suggests that the arrival of the monsoon lowers pH, DO, and TDS. However, the concentrations of TN and TP increased because of agricultural runoff. Chl-a and COD show distinct variations due to the individual LSWBs' local conditions. Vertical variability analysis demonstrated pH, temperature, and TN stratification during the pre-monsoon period. However, during the monsoon, stratification is less significant due to intermixing. Redundancy analysis (RDA) showed that land use and rainfall patterns affected the water quality of LSWB 1, 2, and 3 by 53.49%, 81.62%, and 92.64%, respectively. This shows that land use, land cover, and rainfall changes affect the water quality of LSWBs. This study highlights the negative impact of runoff from agricultural land use as the main factor responsible for increased nutrient levels in the LSWBs.

The Potential of Elephantorrhiza goetzei Seed Extract as a Coagulant for Household Drinking Water Treatment

ABSTRACTPoor access to adequate, clean, and safe water is one of the greatest world problems people encounter. There has been considerable attention in recent times toward the use of natural coagulants for water treatment. This study seeks to promote this by investigating the potential of Elephantorrhiza goetzei (E. goetzei) seed extract as natural coagulants for water treatment. This included the determination of key ingredients responsible for the coagulation process and optimal dosages for the removal of turbidity, fluoride, manganese, and iron. The residual content of organic matter in the treated water and the quality of sludge produced were also investigated. The methodology consisted of a proximate analysis procedure to investigate the active ingredient(s) responsible for coagulation and standard jar tests. Standard methods were used for the analyses. Coagulant dosages ranging from 0 to 300 mg/L at a rapid mixing speed of 120 rpm for 1 min, a slow mixing speed of 30 rpm for 15 min, and a settling time of 15 min were used for the jar test. The analysis of variance (ANOVA) using IBM SPSS Version 20 was conducted, and regression models were developed to determine the effect of coagulant dosage on turbidity, pH, total dissolved solids, fluoride, iron, manganese, chemical oxygen demand (COD), nitrogen, and phosphorus. The results obtained from the proximate analysis of E. goetzei seed extract show that values of 5.25%, 21.40%, 8.23%, 32.99%, 2.20%, and 29.93% were obtained for moisture, crude protein, crude fiber, fat, ash, and carbohydrate content, respectively. Moreover, seed extract of E. goetzei achieved removal efficiencies up to 94.8%, 50.1%, 90.0%, and 53.9% for turbidity, fluoride, iron, and manganese in water, respectively. The coagulant has the potential to achieve the desired World Health Organization (WHO) drinking water standards for turbidity, fluoride, iron, and manganese. The COD increased from 55.3 to 419.3 mg/L as the coagulant dosage increased from 0 to 100 mg/L. This could cause an unwanted rise in microbial activities, affecting the microbiological quality of the treated water. The total nitrogen and phosphorus concentrations obtained in the sludge at 100 mg/L were 0.343 and 0.194 µg/kg, respectively, and this compromises its attractiveness for agricultural reuse purposes.

Advancing non-optical water quality monitoring in Lake Tana, Ethiopia: insights from machine learning and remote sensing techniques

Water quality is deteriorating in the world's freshwater bodies, and Lake Tana in Ethiopia is becoming unpleasant to biodiversity. The objective of this study is to retrieve non-optical water quality data, specifically total nitrogen (TN) and total phosphorus (TP) concentrations, in Lake Tana using Machine Learning (ML) techniques applied to Landsat 8 OLI imagery. The ML methods employed include Artificial Neural Networks (ANN), Support Vector Regression (SVR), Random Forest Regression (RF), XGBoost Regression (XGB), AdaBoost Regression (AB), and Gradient Boosting Regression (GB). The XGB algorithm provided the best result for TN retrieval, with determination coefficient (R2), mean absolute error (MARE), relative mean square error (RMSE) and Nash Sutcliff (NS) values of 0.80, 0.043, 0.52, and 0.81 mg/L, respectively. The RF algorithm was most effective for TP retrieval, with R2 of 0.73, MARE of 0.076, RMSE of 0.17 mg/L, and NS index of 0.74. These methods accurately predicted TN and TP spatial concentrations, identifying hotspots along river inlets and northeasters. The temporal patterns of TN, TP, and their ratios were also accurately represented by combining in-situ, RS and ML-based models. Our findings suggest that this approach can significantly improve the accuracy of water quality retrieval in large inland lakes and lead to the development of potential water quality digital services.

Effects of the Water Diversion Project from the Three Gorges Reservoir to the Hanjiang River on diatom blooms in Middle and Lower reaches of the Hanjiang River

ABSTRACT The algal blooms in the Middle and Lower reaches of the Hanjiang River (MLHR) have become a great aquatic eco-environmental problem over recent years. The planned implementation of the Water Diversion Project from the Three Gorges Reservoir to the Hanjiang River (WDP-TH) would influence the growth and propagation of diatoms and the development of algal blooms. In this paper, a dynamic model of diatom growth is developed that considers factors such as light exposure, water temperature, total phosphorus, and flow velocity. The effects of the WDP-TH on algal density and blooms in the MLHR were predicted for a typical median year, a typical dry year, and an extremely dry year. The results showed that following the water recharge in a typical median year, the propagation of diatoms in the MLHR was significantly promoted because of an increase in total phosphorus concentration. However, following the water recharge in typical dry and extremely dry years, increased flow rate and improved hydrodynamic conditions significantly inhibited diatom growth and accelerated the transport process. The results of the hypothetical simulation showed that after the initiation of the WDP-TH, inhibition effects of improved hydrodynamic force on algae were more apparent than promotion effects of increased total phosphorus concentration in the MLHR.