Quality Standards For Surface Water Research Articles

Water Quality Analysis for Agriculture: A Case Study of Nong Khon Saen Community Area, Udon Thani, Thailand

This work aims to assess the water quality in the Nong Khon Saen community area in Udon Thani for agriculture purposes and its suitability for direct use in water consumption. The sample was collected annually from January to March during the period 2019–2022. The work was undertaken to investigate two different water resources (Huai Luang River and Nong Khon Saen reservoir) for the parameters of pH, temperature, electrical conductivity (EC), dissolved oxygen (DO), and biochemical oxygen demand (BOD). The results showed that all parameters of Huai Luang River were within the acceptable limits of Type 3 surface water quality standards from the Pollution Control Department (PCD), Thailand. The average pH was 6.59±0.18 (Std. pH 5–9), temperature was 27±0.01 ℃ (Std. Natural), EC was 679±12.11 μS/cm (Std. None), DO was 5.39±0.63 mg/l (Std. > 4.0 mg/L), and BOD was 1.71±0.70 mg/L (BOD Std. < 2.0 mg/l). The acceptable water quality parameters were caused by general flushing of rainfall, river water flow, and runoff from agricultural fields. Moreover, the water quality of the Nong Khon Saen reservoir showed a higher BOD concentration (2.61±0.54 mg/L) beyond acceptable limits. The high concentration of BOD was caused by the water plants and the decomposition of animals in the surface water area. For other parameters, the average pH (7.11±0.42), Temperature (28±0.01 ℃), EC (689.58±24.18 μS/cm) and DO (8.39±1.13 mg/L) were shown within acceptable limits. Therefore, the water quality is a requirement concerned with agricultural activities that are dependent on water resources.

Assessment of Surface Water Quality of Huai Luang River in Udon Thani, Thailand, Using the Water Quality Index

This study aimed to analyze the surface water quality of the Huai Luang River using the water quality index (WQI) method. Five parameters were analyzed to assess the water quality of the Huai Luang River; they were dissolved oxygen (DO), biochemical oxygen demand (BOD), total coliform bacteria (TCB), fecal coliform bacteria (FCB), and ammonia (NH3). The Huai Luang River is the municipality’s primary consumption water source in Udon Thani province, Thailand. WQI classifications were calculated by using the surface water quality standards program of Thailand’s Pollution Control Department (PCD-WQI). The results showed that the water quality in the Huai Luang River was bad status, in the WQI range of 54-60 scores. The major sources of pollutants in the Huai Luang River were wastewater from communities, agriculture, and animal farms are the main contributors to water pollution. Seasonal water quality variations were observed at each monitoring site from March 2022 to February 2023. WQI concentration in the rainy season (March to June) was generally among the highest (57 score) compared with other seasons (56 score in winter and 54 score in summer). While the WQI concentration of the upstream sampling site (domestic wastewater) had the lowest (55 score) compared with the other sites (59 score for midstream and 60 score for downstream). Therefore, this research study presented valuable information on WQI for the Huai Luang River for water quality management by administrators and local community participation.

The spatiotemporal variations characteristic and pollution evaluation of water quality in Qujiang River, China

In order to study the spatiotemporal variations characteristic of water quality and potential pollution sources of Qujiang River, the water quality data of twelve water quality parameters at three monitoring sections (Tuanbaoling, Baita, and Sailong) from 2015 to 2019 were analyzed by using comprehensive pollution index (CPI) and multivariate statistical techniques (MST). The water quality parameters of Qujiang River basically meet the class 3 value of environmental quality standards for surface water (GB3838-2002, China). CPI varies from 0.62 to 1.06 and the water quality is characterized by slight pollution at the three monitoring sections. Cluster analysis (CA) results show that the months can be divided into three groups on the basis of similarities of the water quality characteristics: Group 1 (dry season), which includes January-April and November–December; Group 2 (flood season), that is, July; Group 3 (flat season), which consists of May–June and August–October. Principal component analysis (PCA) results identify four principal components (PCs) for the dry season and flood season, and five PCs for the flat season, thus explaining 58.23%, 82.94%, and 73.23% of the total variance, respectively. The results of the independent sample t-test show significant differences among the pH, Permanganate index (CODMn), Ammonia nitrogen (NH3–N), Total nitrogen (TN), Fecal coliform (F.coli), and (Flow) Q in the three monitoring sections. Moreover, the pollution is more serious in Baita than Tuanbaoling and Sailong Section and the main problem in the Qujiang River is the high water organic and nitrogen nutrient pollutant content. Hence, monitoring and protection need to be strengthened in the Baita section of Qujiang River.

Impacts of high-quality coal mine drainage recycling for replenishment of aquatic ecosystems in arid regions of China: Bacterial community responses

Coal mine water is usually recycled as supplementary water for aquatic ecosystems in arid and semiarid mining regions of China. To ensure ecosystem health, the coal mine water is rigorously treated using several processes, including reverse osmosis, to meet surface water quality standards. However, the potential environmental impacts of this management pattern on the ecological function of receiving water bodies are unclear. In this study, we built several microcosm water ecosystems to simulate the receiving water bodies. High-quality treated coal mine drainage was mixed into the model water bodies at different concentrations, and the sediment bacterial community response and functional changes were systematically investigated. The results showed that the high-quality coal mine drainage could still shape bacterial taxonomic diversity, community composition and structure, with a concentration threshold of approximately 50%. Moreover, both the Mantel test and the structural equation model indicated that the salinity fluctuation caused by the receiving of coal mine drainage was the primary factor shaping the bacterial communities. 10 core taxa in the molecular ecological network influenced by coal mine drainage were identified, with the most critical taxa being patescibacteria and g_Geothermobacter. Furthermore, the pathway of carbohydrate metabolism as well as signaling molecules and interactions was up-regulated, whereas amino acid metabolism showed the opposite trend. All results suggested that the complex physical-chemical and biochemical processes in water ecosystems may be affected by the coal mine drainage. The bacterial community response and underlying functional changes may accelerate internal nutrient cycling, which may have a potential impact on algal bloom outbreaks.

A shallow constructed wetland combining porous filter material and Rotala rotundifolia for advanced treatment of municipal sewage at low HRT.

Water scarcity is a worldwide problem. Recycled municipal wastewater is considered a useful alternative to the conventional types of water resources. In this study, a shallow constructed wetland (SCW) with porous filter material and Rotala rotundifolia was used for advanced municipal sewage treatment. The wetland without plant was set as the control (SCW-C). The pollutant removal performance of the system at different hydraulic retention times (HRTs) was investigated. The diversity of the microbial community was analyzed, and the fate of nutrients, mainly N and P, in the system was discussed. Results showed that SCW was efficient in pollutant removal. Effluent concentrations of chemical oxygen demand (COD), total phosphorus (TP), and ammonium nitrogen (NH4+-N) were 15.0-23.6, 0.19-0.28, and 0.83-1.16mg/L, separately, with average removal efficiencies of 61.2%, 46.3%, and 88.1% at HRT 18h, which met the requirements of type [Formula: see text] water set by the environmental quality standards for surface water in China. The richness and evenness of the bacterial community were significantly higher in the plant-rooted SCW. They increased along with the system. The dominant genera in the system were phosphate-solubilizing bacteria, nitrifying bacteria, and denitrifying bacteria. The P in the influent mainly flowed to the substrate and plant. At the same time, most N was removed by nitrification and denitrification. These findings suggested that the SCW could remove pollutants from the municipal sewage effluent and meet the standard requirement at low HRT.

Integrated treatment of suburb diffuse pollution using large-scale multistage constructed wetlands based on novel solid carbon: Nutrients removal and microbial interactions

In this study, an integrated treatment system was proposed and applied in situ, including detention tank, multistage constructed wetlands (CWs) and wastewater treatment plants (WWTPs), preventing nutrients flowing into Dianchi Lake, in which the treatment performance of multistage CWs were evaluated principally. Results skillfully realized the bypass purification of upstream river at dry reasons, as well as the effective management and treatment of the collected diffuse pollution at rainy reasons. The purified water flowing into water bodies could satisfy the Grade III of environmental quality standards for surface water in China with the average effluent concentrations of COD, NH4+-N, TN and TP decreased to 10 (51.2–72.7%), 0.5 (67.2–83.0%), 1.0 (71.2–79.6%) and 0.15 (72.3–89.4%) mg L−1, respectively. High-throughput sequencing results indicated that the application of poly-3-hydroxybutyrate-cohyroxyvelate-sawdust (PS) blends could enrich norank_f_Anaerolineaceae (7.95%) and Bradyrhizobium (10.2%), which were distinct from the dominant genera of Pleurocapsa (13.0%) in gravel-based CWs. Functional genes and metabolism analysis uncovered that the heterotrophic denitrification was the main pathway of nitrogen removal with the abundance of genes encoding TCA cycle, glycolysis and denitrification process up-regulated. In addition, molecular ecological network (MEN) analysis suggested the denitrification genes were positively correlated with the predominant microbes in PS-based CWs, favorable for denitrifiers to transfer and utilize electron donors during denitrification process. This study proved that the developed PS blends as carbon supplies in CWs and the proposed integrated treatment system are effective methods for watershed management, providing valuable reference to low-pollution wastewater treatment in practical engineering projects.

Impacts of the development of mineral metal resources on surface water quality in the Mongolian Plateau based on meta-analysis

The mining of metal resources is one of the major sources of heavy metals in surface water, but studies on the different characteristics of the impact of the exploitation of mineral metal resources on surface water from a large-scale perspective are lacking. In the present study, we quantified the impacts of mineral metal resource development on As, Cu, Cr, Pb, Zn, Hg, Ni, Cd, Mn, and Fe in the overlying water and sediments of surface water under different scenarios (i.e., different geographic units and different mined metal types) using meta-analysis for the Mongolian Plateau of Mongolia and the Inner Mongolia Autonomous Region of China, which is rich in mineral metal resources and has high exploitation and use intensity. Finally, funnel plots and Egger’s regression analysis were used to test the publication bias of the data. The results show that the order of heavy metal content in the overlying water of the Mongolian Plateau was Fe > Mn > As > Zn > Cu > Pb > Cr > Ni > Cd > Hg, and the order of heavy metal content in the sediment was Fe > Mn > Zn > Cr > Pb > Ni > Cu > As > Cd > Hg. In addition, As, Cr, Zn, Hg, Cd, and Pb in overlying water exceeded the standard to different degrees, among which the contents of As and Pb were 1.4 and 1.3 times higher than the World Health Organization guideline, and the contents of Cr, Pb, Hg, Cd were 1.5, 1.3, 25.4, 2.6 times Chinese environmental quality standards for surface water, and the contents of As, Pb, Zn, Hg were 1.4, 1.3, 4.7, 12.7 times Mongolian water quality standards, respectively. The content of As in sediments was 2.6 times the background value of soil environmental quality in Inner Mongolia. Significant differences existed in the content of heavy metal pollutants in surface water of different countries; the content of heavy metals in the overlying water was significantly higher in Inner Mongolia Autonomous Region of China than in Mongolia. Copper and molybdenum polymetallic mines significantly increased the content of Cd, Cr, Cu, Fe, Hg, Pb, and Zn in the overlying water, while the content of As, Cr, Pb, and Zn in overlying water increased significantly due to lead–zinc mining. However, the mining of gold–silver, lead–zinc, copper–molybdenum, and other polymetallic mines all significantly affected the concentration of As in sediments. The results of the present study can provide data support for environmental protection and the restoration of surface water in metal mining areas of the Mongolian Plateau.

Evaluation of the water quality of a highly polluted stream with water quality indices and health risk assessment methods

The water quality of Çorlu Stream, located in the Thrace region of Türkiye, and exposed to intense industrial pressure, was evaluated by monitoring 10 toxic metals and 13 other water quality variables in the dry and wet seasons of 2021. Seven different water quality indices were applied to determine the pollution level at the sampling stations in the stream. In addition, human health risks from exposure to toxic metals in stream water via ingestion and dermal contact were evaluated. The results showed that the water quality at stations S2 and S3 of Çorlu Stream receiving domestic and industrial discharges are seriously polluted by NH4–N, PO4–P, COD, BOD5 and suspended solids according to surface water quality standards. In addition, these stations were highly polluted and had poor water quality according to the results of the water quality indices. The average Cr level at station S3 exceeded the permissible levels set for the protection of aquatic life due to effluent discharges from the leather factories. Considering the results of the health risk assessment methods, non-carcinogenic risks from ingestion of combined metals in stream water can be expected at station S3 for both children and adults and at station S2 for children. Also, it was estimated that Cr and As at station S3 may cause carcinogenic health risks for residents.

Spatial distribution characteristics and pollution levels of heavy metals in surface water and sediments of the Heihe cascade reservoir system, China

Abstract The operation of cascade reservoir systems has altered river hydrology and sediment distribution patterns. In this study, 31 surface water and sediment samples were collected from the Heihe River from July to August in 2019 and 2020 to investigate the spatial distribution and sources of heavy metals and assess their ecological risks. The results revealed that the concentrations of heavy metals in surface water were much lower than the quality standards for surface water in China, and there were no significant differences in the natural reaches, center and tail of the reservoir. Cd in surface sediments was at a heavy contamination and high risk level, and the heavy metal pollution levels in the main streams and tributaries differed greatly, especially in the graded reservoirs with a gradual accumulation trend. This may be related to the fact that there were many fine-grained sediments in the reservoir center near the dam. Factor analysis-multiple linear regression (FA-MLR) revealed that heavy metals mainly come from natural factors and anthropogenic input, with anthropogenic inputs mainly coming from mining activities in the tributaries and industrial and agricultural activities in the main stream.

Differential characteristics and source contribution of water pollutants before and after the extreme rainfall event in the Huaihe River Basin

Various pollutants are collected into rivers through runoff when rainstorms occur, which can harm the aquatic ecological environment, therefore, strengthening the analysis of river pollution sources before and after rainstorms can reduce the impact of rainstorm runoff periods in regard to the risk from river water pollutants. In this study, the water pollutant differential characteristics and pollution source identification in the Henan section in the Huaihe River Basin were explored before and after the extreme rainfall event, and the monitoring data for nine water quality indicators in the monitoring sections were selected. The changing and differential characteristics and processes of the water quality indicators in the Huaihe River Basin before and after the rainstorm were analyzed by using statistical analytical methods and the comprehensive water quality identification index (IWq), and the absolute contribution rates of pollution sources were calculated by the absolute principal components-multiple linear regression model (APCS-MLR). The results showed that the values of pH, DO (Dissolved oxygen) and EC (Electrical conductance) after the rainstorm were lower than those before the rainstorm, while the turbidity, CODMn (Permanganate index), NH3−N (Ammonia nitrogen), TP (Total phosphorus) and TN (Total nitrogen) increased after the rainstorm. The correlations between pH and DO and other water quality indicators increased after the rainstorm, while the correlations between WT (Water temperature), turbidity, CODMn, NH3−N, TP and TN decreased significantly after the rainstorm. The water pollution of each monitoring section increased after the rainstorm; for example, the water quality conditions at Zhoukou Kangdian (ZKKD), Xihua Zhifang (XHZF) and Suixian Banqiao (SXBQ) increased by 42.11, 36.84 and 25.73% to Class V of the environmental quality standards for surface water in China, respectively. The absolute contribution rates of the PC1 to CODMn and TP were 33.86 and 41.11% before the rainstorm, respectively. The absolute contribution rates of the PC2 to DO and TN were 50.77 and 60.26% after the rainstorm, respectively.

Effects of environmental and agronomic factors on pond water quality within an intensive agricultural landscape in subtropical southern China

Water quality deterioration, such as eutrophication, can contribute to the degradation of farm pond ecosystems, threatening numerous ecological services and socioeconomic benefits. However, the variability of water quality and the complexity of influencing variables pose large uncertainties for pond management practices and watershed planning. This study integrated a self-organizing map (SOM) and partial least squares structural equation modeling (PLS-SEM) to evaluate the nitrogen (N) and phosphorus (P) variations in 39 typical farm ponds in the Dongting Lake basin, and related the variations to pond internal factors, external environment, and agronomic management. The results indicated that 39 monitored farm ponds faced a high risk of eutrophication owing to high N and P levels, and that total N (TN), total P (TP), and particulate P (PP) generally exceeded the threshold of level V surface water quality standards in China (2.0 mg N L−1 and 0.2 mg P L−1). Simultaneously, pond water quality showed high spatiotemporal variability, and pollution hotspots occurred mostly during the overlapping periods of fallow-dry-winter and planting-rainy-spring. Based on the constructed SEM model, external environmental factors (meteorology, catchment landscape composition, configuration, topography, and soil chemical properties), pond internal characteristics, and agronomic management combined explained 60.2 ± 2.9 % and 54.2 ± 3.1 % of the N and P variations, respectively. There were intricate interactions among the above latent variables, including such meteorology positively moderated the paths of soil chemical properties→pond P and landscape composition→pond N and P; landscape composition, soil, and pond internal characteristics mediated the effects of other variables on variations of N and P. The total effects (indirect effects + direct effects) of landscape composition on the variations of pond N and P were higher than those of other variables. Among all the indicators composing latent variables, agricultural and residential land area percentage, rainfall, water depth, and fish farming were relatively important in pond water quality variations. The constructed model and analytical results offer essential information for the accurate management and restoration of pond water quality.

Pollution and risk assessment of heavy metals in rivers in the antimony capital of Xikuangshan

Xikuangshan (XKS) is the world's largest antimony mining region, and its exploitation for hundreds of years has also resulted in serious soil erosion, fragile ecology, contaminated water, and shortage water. Through systematic and scientific collection samples from the rivers in XKS, the Nemerow index (NI), modified heavy metal pollution index (m-HPI), ecological risk index, and health risk indexeswere used to evaluate and analyze the water quality, pollution levels and risks of heavy metals (Sb, As, Mn, Pb, Zn, Hg, Cd) to ecology and humans in XKS. The results showed that the average concentrations of TN, TP, Sb, As and Hg in surface water were 0.48 mg/L (0–4.34 mg/L), 2.58 mg/L (0–4.34 mg/L), 1.05 mg/L (0.0009–5.33 mg/L), 1.06 mg/L (BDL–19.60 mg/L) and 0.00084 mg/L (LDBL–0.0036 mg/L), respectively, exceeding the limits of the Chinese surface water quality standards. Based on the m-HPI method, only 8.57% of the sampling points are classified as the worst water quality. However, according to the NI method, about 7.14% and 87.16% of the sampling points in the study area are moderately and severely polluted, respectively. The results of heavy metal pollution based on the NI evaluation is were more serious than that on the m-HPI method. The values of ecological risk assessment varied from 22.69 to 7351.20, revealed that heavy metals pose a very serious risk to the surface water ecosystem at more than 50% of the sampling sites, and Sb and As are the main pollutants, followed by Hg. The total non-carcinogenic risk index (TCR) for adults and children were 47.70 and 90.10 respectively, Sb and As is the main non-carcinogenic risk factor. For adults and children, the average carcinogenic risk (CR) of As was 6.49 × 10–3 and 1.05 × 10–2, respectively, and exceeded the threshold of 1 × 10–4, indicating a high carcinogenic risk.

Multiple reinforcement of chloride ion on oxidizing acetaminophen with zero-valent copper particles: In-site formation and catalysis of hydrogen peroxide

Zero-valent copper particles (Cu0) used to degrade pollutant due to its in-site generation and activation of hydrogen peroxide (H2O2), while the disproportionation of Cu+ limited the efficacy. In this study, spiking chloride ion (Cl−) into zero-valent copper (Cu0) system (Cl−/Cu0 system) enhanced greatly acetaminophen degradation. The addition of Cl− not only reduced the dismutation reaction of Cu+, but also helped the comproportionation reaction of Cu0 and Cu2+, leading to much generation of Cu+ and H2O2. Hydroxyl radical (OH) and reactive chlorine species were identified as the dominant reactive oxidants in the Cl−/Cu0 system with its contribution ratio of degrading acetaminophen being respectively 73.4 % and 23.8 %. In the Cl−/Cu0 system, Cu+ was released by H+ corrosion from Cu0, and then Cu+ coupled with Cl− forming Cu-Cl complexes; Meanwhile, the reaction of O2 and the species of Cu+ (e. g. Cu-Cl complexes and Cu+) produced H2O2 and, then the species of Cu+ catalyzed H2O2 to form OH; Thereinto, partial OH was shifted by Cl− to reactive chlorine species. Except for fulvic acid, coexisting substrates such as sulphate, nitrate and phosphate ions had no obvious inhibition impact on oxidizing acetaminophen in the Cl−/Cu0 system. Furthermore, the Cl−/Cu0 system presented a good removal rate of acetaminophen in three actual water samples. Moreover, three kinds of dyes and painkillers was removed over 78 % in the Cl−/Cu0 system. The residual total dissolved copper was under II-level of environmental quality standards for surface water in China by alkali precipitation and filtration after reaction. Therefore, the study provided a new idea to enhance Cu0 for the purification of pollutants.

Microalgae-bacteria tandem-type ponds simultaneously removing ammonia nitrogen and phosphorus towards municipal wastewater advanced treatment

Low C/N municipal wastewater is difficult to be treated effectively via traditional biological methods, leading to concentrations of pollutants in effluent far exceeding increasingly strict standards. In this work, we propose a novel microalgae-bacteria tandem-type process to simultaneously remove ammonia nitrogen (NH4+-N) and phosphorus (P) from municipal wastewater. A 4.5 L microalgae-bacteria tandem-type reactor was constructed and operated stably for 40 days. The removal efficiencies of NH4+-N and P reached 97.5% and 92.9%, respectively, effluent concentrations were 0.53 and 0.17 mg/L on average, which met the Environmental quality standards for surface water in China (GB 3838–2002). Remarkably, microalgae ponds accounted for 69.3% and 76.3% of the overall NH4+-N and P removal via microalgae assimilation. Furthermore, 16 S rRNA gene amplicon sequencing revealed the abundance of bacteria changed, suggesting that the presence of microalgae leads to some species extinction and low-abundance bacteria increase. This work demonstrated that the microalgae-bacteria tandem-type processes can be efficient and widely applied in the advanced treatment of municipal wastewater.

Evaluation of water quality at national scale from 2011 to 2021: Advances and challenges

More environmental policies and larger investments in protecting the aquatic environment in China have been made in the last decade than previously. It is important to assess how this will affect river water quality. Here, changes in water quality in China between 2011 and 2021 are assessed. Water bodies meeting class III or better defined in the Chinese Environmental Quality Standards for Surface Water (GB3838-2002) were labeled WQI, water bodies meeting class V or better but below class III were labeled WQII, and water bodies below class V were labeled WQIII. The percentage of WQI water bodies increased from 66.1 % in 2011 to 81.0 % in 2021, and the percentages of WQII and WQIII water bodies decreased between 2011 and 2021. The percentage of WQI water bodies increased more quickly and the percentage WQIII water bodies decreased more quickly after 2017 than between 2011 and 2016. The percentages of WQI water bodies in the Northwest River Basin (RB), Pearl RB, Southeast RB, Southwest RB, and Yangtze RB were >80 %, and were higher than the percentages of WQI water bodies in the other five RBs. The percentages of WQI and WQII water bodies increased but the percentage of WQIII water bodies decreased in the Hai RB. The percentage of WQI water bodies increased but the percentages of WQII and WQIII water bodies decreased in the Huai RB, Liao RB, Yangtze RB, and Yellow RB. The river monitoring capacity increased and pollution sources, particularly point sources, became more controlled, and this improved river water quality. River management in China has passed the first stage of controlling pollution sources after 10 years of centralized management. The next stage should be focused on strengthening control of non-point sources of pollution and rehabilitating ecological systems to improve river health.

The performance and mechanism of iron-modified aluminum sludge substrate tidal flow constructed wetlands for simultaneous nitrogen and phosphorus removal in the effluent of wastewater treatment plants

Aiming at the poor N and P removal performance in the effluent of wastewater treatment plants by constructed wetlands (CWs), aluminum sludge (AS) from water supply plants was used to prepare iron-modified aluminum sludge (IAS), and tidal flow constructed wetlands (TFCWs) using IAS as substrates were constructed. By means of high-throughput sequencing, X-ray diffractometer (XRD), etc., the removal mechanism of N and P in the system and fate analysis of key elements were also interpreted. Results showed that an interlayer structure beneficial to adsorbing pollutants was formed in the IAS, due to the iron scraps entering into the molecular layers of AS. The removal rates of TP and TN by IAS-TFCWs reached 95 % and 47 %, respectively, when the flooding/resting time (F/R) and C/N were 6 h/2 h and 6. During the three-year operation of the IAS-TFCWs, the effluent concentrations of CODCr, NH4+-N, and TP could comply with Class IV Standard of “Environmental Quality Standards for Surface Water” (GB3838-2002). The mechanism analysis showed that the N removal was effectuated through Fe2+ as the electron donor of Fe(II)-driven the autotrophic denitrifying bacteria to reduce nitrate, while the P removal mainly depended on the adsorption reaction between FeOOH in IAS and phosphate. In conclusion, the stable Fe-N cycle in the IAS-TFCWs achieved simultaneous and efficient N and P removal.

Evaluation of hydrochemistry and identification of pollution hotspots of little Akaki river using integrated water quality index and GIS

Despite unwavering effort of the government, urban river pollution in Ethiopia has remained a worrisome phenomenon now a days. This research is conducted with a prime aim of assessing and evaluating the water quality status and identifying and mapping of the pollution hotspots in the Little Akaki River (LAR), Ethiopia by integrating the water quality index (CCME-WQI) and Geographic Information System (GIS). Accordingly, water quality samples were collected from 22 monitoring stations. The water samples were collected and analyzed for physico-chemical and heavy metal constituents using the American Public Health Association (APHA) standard methods. Most of the physico-chemical constituents analyzed have surpassed the standard guideline value of the country and World Health Organization (WHO). In addition, most of the middle (S3-S10) segments of the river is heavily polluted than the downstream segment (S11-S14) and upstream segments. Similarly, the heavy metals concentrations in the LAR have decreasing trend with Mn>Zn>Pb>Cu>Cd. On the other hand, the overall CCME-WQI modeling output ranged from 18.9 – 36.2. Accordingly, the finding of the study reveals that most water quality parameters were beyond ambient surface water quality standards and the CCME-WQI categorizes all the monitoring stations under poor water quality state. Besides, the spatial distribution of pollution in LAR shows intense deterioration at the middle segment of the river and needs a proper strategic management plan in the catchment and immediate protection and restoration of the natural ecology of the LAR. It is recommended to integrate river water pollution management and maintain ecologically to achieve healthy urban development.

Influence of Solar Photovoltaic System on the Concentration and Environmental Risks of Heavy Metals in Subsidence Pond Water from Coal Mining Area: A Case Study from Huainan Subsidence Pond

The subsidence pond is an important water resource for coal mining areas in China. In order to take full advantage of the subsidence pond, a floating photovoltaic cover or a pillaring photovoltaic cover were installed on the surface water of the subsidence pond in the Huainan coal field. Different photovoltaic systems (floating/pilling cover) equipped in the subsidence pond may affect the water quality; thus, assessing the metals in the subsidence pond with the solar photovoltaic system is of great importance for environment control. In this research, surface water samples were collected from three different subsidence ponds, with or without the solar photovoltaic system. The concentrations of Pb, Cr, Ni, Cu, As, Mn, and Zn in the water of the subsidence pond were determined using ICP-MS and AFS. Then, the health risk posed by the heavy metal in different subsidence pond waters via the ingestion pathway was evaluated and analyzed using the assessment model recommended by USEPA. The results indicated that the mean concentrations of Pb, Cr, Ni, Cu, As, Mn, and Zn in the water of different subsidence ponds were less than the environmental quality standards for surface water (China, Grade II). Cr showed a higher non-carcinogenic risk than the other metals, and the photovoltaic cover actually decreased the total non-carcinogenic risk in the photovoltaic subsidence pond compared with the natural subsidence pond. Non-carcinogenic risks of single and total heavy metals in the subsidence ponds with or without solar photovoltaic systems were below 1; thus, these risks in different subsidence ponds were considered to be at an acceptable level. However, the potential single carcinogenic risks of Cr, Ni, and As; and the multielement carcinogenic risks of Pb, Cr, Ni, and As exceeded the limits of 1 × 10−6 and 1 × 10−4, respectively, suggesting that these metals showed single and total potential health risks in the subsidence pond, with or without the solar photovoltaic system. Further, the subsidence pond with the photovoltaic cover showed higher total carcinogenic risks in comparison with the natural subsidence pond. Therefore, a subsidence pond with a solar photovoltaic system should be monitored periodically to ensure the water safety.

Analysis of Pollution Characteristics and Sources of Rainfall Runoff from Roofs in the Central District of Beijing

The rainwater and rainfall runoff of roofs in the central district of Beijing from June to September in 2019 were sampled and analyzed to study the characteristics of the water quality, the first flush effect, and the main influential factors and sources of pollutants. The results showed that the roof runoff was seriously polluted by total nitrogen, ammonia nitrogen, chemical oxygen demand, and total suspended solids whose event mean concentration (EMC) exceeded the fifth level of environmental quality standards for surface water (GB 3838-2002) (the EMC of suspended solids exceeded the second level of discharge standard of pollutants for municipal wastewater treatment plants (GB 18918-2002)). The rainwater was relatively less polluted than the rainfall runoff, but the EMC of ammonia nitrogen and total nitrogen of the rainwater also exceeded the standard in some rainfall events. The first flush intensity of the rainfall runoffs was between weak and medium. The sequence of strength of the first flush of different pollutants was ammonia nitrogen>total suspended solids>chemical oxygen demand>total nitrogen>mercury>zinc>total phosphorus>lead. The concentration of total suspended solids, chemical oxygen demand, and total phosphorus in roof runoff were significantly positively correlated with the length of rainfall and the dry period and negatively correlated with the rainfall intensity. According to the results of principal component analysis, the main pollutant in rainwater was nitrogen emitted by vehicles, and the main pollutants in roof runoffs were suspended solids, organic matters, and phosphorus pollutants released from the aging of roofing materials and the corrosion of metal down pipes.

Evaluation of polluted urban river water quality: a case study of the Xunsi River watershed, China.

Urbanization has caused severe negative impacts on intra-urban river water bodies. In this paper, 22 physicochemical parameters were measured at 20 locations in the level period and 29 locations in the wet and dry period using nearby urban area surface water samples from a medium-sized polluted river (a lake-river continuum, i.e., Xunsi River, Qingling River and Tangxun Lake) in the Yangtze River watershed in Wuhan, China. In this study, the environmental quality standards for surface water of China (GB3838-2002) and the WHO drinking water standard (2011) were used as reference standards. After the basic physicochemical parameters were evaluated, the possible sources of pollution in the study area under urban pressure were examined by applying multivariate statistical techniques. The factor analysis method and entropy weighting method identified three critical factors describing the type of surface water pollution in the watershed: (1) pollution from nutrients, mainly nitrogen pollution, (2) trace metals pollution, mainly from Fe and Pb, and (3) organic pollution. Based on multivariate analysis, the weighted arithmetic water quality index (WQI) was used to assess the water quality of each period. The WQI results show that the water near the urban area of the watershed temporally shows light to moderate pollution overall in the level and wet periods, and sever pollution in the dry period. The worst water quality indicating water that is not suitable for any practical use occurs in the dry period. Spatially distributed in clusters and strips visualized in kriging method, the water quality of the lake source and upstream is better than that of the downstream. In addition, Escherichia coli was detected at consistently high levels, and although the river is not a source of drinking water, it could pose a threat to downstream waterworks.