Domestic Sewage Discharge Research Articles

Chemical Characteristics and Genetic Analysis of Karst Groundwater in the Beijing Xishan Area

As an important water supply source in Beijing， karst groundwater has played an irreplaceable role in the security of urban water supply and ecological environment protection in the past 70 years. The Xishan karst groundwater system， located in the upper reaches of western Beijing， belongs to ecological conservation areas. There are several centralized water supply fields in this area. In this study， the Xishan karst groundwater system was taken as the research object. A total of 120 karst groundwater samples in this area were investigated by using statistical analysis， ion ratio， and principal component analysis （PCA） methods to explore the spatial distribution characteristics and formation mechanism of groundwater hydrochemistry. The research results showed that： ① the groundwater quality of the Xishan system was generally good， with the characteristics of neutral pH and low salinity. A total of 84.17% of the water samples were classified as hard water. The chemical type of groundwater was mainly HCO3-Ca·Mg. ② The chemical composition of groundwater was mainly affected by the water-rock interaction， and the weathering source of rock was mainly the dissolution of carbonate. ③ The results of principal component analysis showed that 34.41% of the chemistry formation of groundwater could be explained by carbonate dissolution， 27.33% by rock salt and evaporate dissolution， 11.76% by aquifer sediment dissolution， and 10.30% by domestic sewage discharge. From the recharge area to the runoff area and then to the discharge area， the TH and TDS gradually increased. Coal mining drainage and human activities were the main factors that caused groundwater degradation and variable hydrochemical types in the piedmont. In the future， it is necessary to further strengthen environmental governance， control point and non-point source pollution， and continuously monitor key areas to provide scientific support for ecological and environmental protection.

Characteristics and Impact Evaluation of Hydrological and Water Quality Changes in the Northern Plain of Cixi, Eastern China, from 2010 to 2022

This paper analyzes the spatiotemporal changes and patterns of a regional water environment based on the hydrological and water quality monitoring times and the geographical locations of the monitoring sections in the research area, the plain of Cixi, eastern China. Based on the calculation of runoff generation and concentration in the coastal plain river network and based on the characteristics and impact evaluation of the regional water pollution, the migration and diffusion mechanisms of surface water pollutants were studied for different sources and characteristics of pollutants entering the river in different river sections. The analytic results show that the water environment and water resource security of the coastal plain mainly cause the problem of eutrophication in the water bodies, and the input of nitrogen and phosphorus from land sources is the main cause of eutrophication in the water bodies, mainly including the production and discharge of domestic sewage, nutrient loss in aquaculture water bodies, affecting agricultural activities, etc. The evaluation also demonstrates that with the development of coastal zones and the rapid development of coastal towns, as the population in coastal plain areas continues to increase, industrial development and population growth are the main driving factors for water quality changes.

High nutrient availability modulates photosynthetic performance and biochemical components of the economically important marine macroalga Kappaphycus alvarezii (Rhodophyta) in response to ocean acidification

Increased atmospheric CO2 concentrations not only change the components of inorganic carbon system in seawater, resulting in ocean acidification, but also lead to decreased seawater pH, resulting in ocean acidification. Consequently, increased inorganic carbon concentrations in seawater provide a sufficient carbon source for macroalgal photosynthesis and growth. Increased domestic sewage and industrial wastewater discharge into coastal areas has led to nutrient accumulation in coastal seawaters. Combined with elevated pCO2 (1200 ppmv), increased nutrient availability always stimulates the growth of non-calcifying macroalgae, such as red economical macroalga Gracilariopsis lemaneiformis. Here, we evaluated the interactive effects of nutrients with elevated pCO2 on the economically important marine macroalga Kappaphycus alvarezii (Rhodophyta) in a factorial 21-day coupling experiment. The effects of increased nutrient availability on photosynthesis and photosynthetic pigments of K. alvarezii were greater than those of pCO2 concentration. The highest Fv/Fm values (0.660 ± 0.019 and 0.666 ± 0.030, respectively) were obtained at 2 μmol L−1 of NO3–N at two pCO2 levels. Under the elevated pCO2 condition, the Chl-a content was lowest (0.007 ± 0.004 mg g−1) at 2 μmol L−1 of NO3–N and highest (0.024 ± 0.002 mg g−1) at 50 μmol L−1 of NO3–N. The phycocyanin content was highest (0.052 ± 0.012 mg g−1) at 150 μmol L−1 of NO3–N under elevated pCO2 condition. The malondialdehyde content declined from 32.025 ± 4.558 nmol g−1 to 26.660 ± 3.124 nmol g−1 with the increased nutrients at under low pCO2. To modulate suitable adjustments, soluble biochemical components such as soluble carbohydrate, soluble protein, free amino acids, and proline were abundantly secreted and were likely to protect the integrity of cellular structures under elevated nutrient availability. Our findings can serve as a reference for cultivation and bioremediation methods under future environmental conditions.

Eco-Friendly Method for Wood Aerogel Preparation with Efficient Catalytic Reduction of 4-Nitrophenol.

The advancement of science and technology and the growth of industry have led to an escalating discharge of domestic sewage and industrial wastewater containing dyes. This surge in volume not only incurs higher costs but also exacerbates environmental burdens. However, the benefits of green and reusable catalytic reduction materials within dye processes are still uncertain. Herein, this study utilized the eco-friendly deep eutectic solvent method (DESM) and the chlorite-alkali method (CAM) to prepare a cellulose-composed wood aerogel derived from natural wood for 4-nitrophenol (4-NP) reduction. The life cycle assessment of wood aerogel preparative process showed that the wood aerogel prepared by the one-step DESM method had fewer environmental impacts. The CAM method was used innovatively to make uniform the chemical functional groups of different wood species and various wood maturities. Subsequently, palladium nanoparticles (Pd NPs) were anchored in the skeleton structure of the wood aerogel with the native chemical groups used as a reducing agent to replace external reducing agents, which reduced secondary pollution and prevented the agglomeration of nanoparticles. Results showed that the catalytic reduction efficiency of 4-NP can reach 99.8%, which shows promises for applications in wastewater treatment containing dyes. Moreover, investigation of the advantages of preparation methods of wood aerogel has important implications for helping researchers and producers choose suitable preparation strategies according to demand.

Network Analysis of Ship Domestic Sewage Discharge—The Yangtze River Case

Water transportation has always occupied a large proportion of China’s transportation and has become the key to China’s economic development. Water transportation is called “green transportation” in the industry due to the advantages of low transportation cost, high safety factor, and large capacity. However, water transportation has caused a great impact on the ecological environment of the waters for a long time, and solving the problem of sewage pollution from ships has also become an unavoidable problem. To control pollution from ships, it is essential to analyze the characteristics of ship domestic sewage discharge. In this study, a ship domestic sewage discharge complex network (SDCN) is established based on the ship voyage data to analyze the discharge characteristics in the Yangtze River. According to the topological analysis, the SDCN is a small-world network with the power-law degree distribution and superliner betweenness-degree correlation as distinguishing characteristics. The top five MDs with the highest in-vertex strength are Chaotianmen MD (S = 165,129,561), Tongling MD (S = 66,426,616), Maanshan MD (S = 62,087,158), Baqu MD (S = 59,964,550), and Shashi MD (S = 55,569,399), which indicates that these MDs receive a large amount of sewage. And the volume of domestic sewage between Chaotianmen MD and Baqu MD is the largest. The results can help us understand the discharge characteristics of ship domestic sewage and how they can be targeted to develop control measures for the countermeasures of “zero discharge” for inland ships.

Research on the treatment of heavy metal ions by immobilized microbial technology

With the development of human industry, the mining and utilization of heavy metals has become more and more extensive, especially in the past 200 years. However, the excessive discharge of industrial and domestic sewage, overuse of pesticides and fertilizers in the production process, as well as electronic waste and medical waste in human life have led to many heavy metal ions entering the environment, exceeding the environmental capacity and entering organisms in large quantities, threatening the ecosystem and human health. Therefore, how to economically and efficiently deal with the heavy metal ion pollution generated in the process of production and life has become a hot issue. Currently, the main methods for treating heavy metal ions are chemical precipitation, ion exchange, adsorption, membrane filtration, electrochemical treatment technology, etc. However, the traditional methods for heavy metal treatment are usually faced with the problems of high cost, high complexity and high energy consumption. In recent years, microbial immobilization technology has received wide attention for its advantages of improved microbial stability, high heavy metal ion removal rate, etc. The corresponding microorganisms are encapsulated and aggregated by immobilized carriers, which enhances the cellular bioburden capacity and environmental resistance and improves the microbial removal efficiency of heavy metals.

Shoreline change pattern analysis of Nagapattinam coastal stretch, Tamilnadu, India using digital shoreline analysis system (DSAS)

We analysed Nagapattinam coastal zones of southeast coast of India, using Multitemporal satellite images for five equal interval of time period (i.e. 2000, 2005, 2010, 2015, 2020 and 2021). The EPR and LLR methods enumerate the maximum accretion at rates of 22.35, 17.02 m/year and maximum erosion rates of -22.82, -10.84 m/year at the study area coastal stretch. This modification is due to several disasters (like Tsunami, cyclone) and anthropogenic activities (like construction of harbours, excavation of beach sand, industrialisation of garbage dump, urbanisation and discharge of domestic sewage). The Kalman filter model forecasting the shoreline by using statistical analysis shows 242 and 236 m in 2031 and 2041 accretion and erosion of -239 and -226 m in same period. The accretion was mainly observed in Vedaranyam and Thirupoondi and erosion was observed in Tharangambadi, Nagapattinam Poompuhar, Karaikal and Thirumullaivasal region. The outcome of this research ensures to create awareness to protect our shoreline and manage our coastal zones properly with several remedial measures for the future.

The distinct phases of fresh-seawater mixing intricately regulate the nitrogen transformation processes in a high run-off estuary: Insight from multi-isotopes and microbial function analysis

Excessive anthropogenic nitrogen inputs lead to the accumulation of nitrogen, and significantly impact the nitrogen transformation processes in estuaries. However, the governing of nitrogen during its transport from terrestrial to estuary under the influence of diverse human activities and hydrodynamic environments, particularly in the fresh-seawater mixing zone, remains insufficient researched and lack of basis. To address this gap, we employed multi-isotopes, including δ15N-NO3−, δ18O-NO3−, δ15N-NH4+, and δ15N-PN, as well as microbial function analysis, to investigate the nitrogen transformation processes in the Pearl River Estuary (PRE), a highly anthropogenic and terrestrial estuary. Principle component analysis (PCA) confirmed that the PRE could clearly partitioned into three zone, e.g., terrestrial area (T zone), mixing area (M zone) and seawater area (S zone), in terms of nitrogen transportation and transformation processes. The δ15N-NO3− (3.38±0.60‰) and δ18O-NO3− (6.35±2.45‰) results in the inner estuary (T area) indicate that NO3−attributed to the domestic sewage and groundwater discharge in the river outlets lead to a higher nitrification rate in the outlets of the Pearl River than in the reaching and seawater intrusion areas, although nitrate is rapidly diluted by seawater after entering the estuary. The transformation of nitrogen in the T zone was under significant nitrogen fixation (0.61 ± 0.22 %) and nitrification processes (0.0043 ± 0.0032 %) (presumably driven by Exiguobacterium sp. (14.1 %) and Cyanobium_PCC-6307 (8.1 %)). In contrast, relatively low δ15N-NO3− (6.83 ± 1.24‰) and high δ18O-NO3− (22.13±6.01‰) imply that atmospheric deposition has increased its contribution to seawater nitrate and denitrification (0.53±0.13 %) was enhanced by phytoplankton/bacterial (such as Psychrobacter sp. and Rhodococcus) in the S zone. The assimilation of NH4 results from the ammonification of NO3− reduces δ15N-NH4+ (5.36 ± 1.49‰) and is then absorbed by particulate nitrogen (PN). The retention of nitrogen when fresh-seawater mixing enhances the elevation of δ15N-NH4+ (8.19 ± 2.19‰) and assimilation of NH4+, leading to an increase in PN and δ15N-PN (6.91 ± 1.52‰) from biological biomass (mainly Psychrobacter sp. and Rhodococcus). The results of this research demonstrate a clear and comprehensive characterization of the nitrogen transformation process in an anthropogenic dominated estuary, highlighting its importance for regulating the nitrogen dissipation in the fresh-seawater mixing process in estuarine ecosystems.

Assessing the potential risks, sources and the relationship between the dissolved and particulate polycyclic aromatic hydrocarbons (PAHs) in the typical semi-enclosed bay, Bohai Bay of China

This study aimed to investigate the spatial and temporal distribution as well as the partitioning behavior of dissolved and particulate polycyclic aromatic hydrocarbons (PAHs) during the summer and autumn seasons of 2020. It was found that the average concentration of PAHs in surface seawater was significantly higher in autumn (58.16 ng L−1) than in summer (40.47 ng L−1) due to a large amount of input in autumn and more photodegradation and biodegradation affected by higher temperatures in summer. The spatial distribution indicated that the river had a significant dilution effect on PAHs in summer and became a significant input source in autumn. In addition, a large number of oil and gas development platforms were distributed throughout the Bohai Bay, and the discharge of production and domestic sewage contributed to the PAHs pollution level. As a semi-enclosed bay, the water exchange capacity of Bohai Bay was poor, leading to a greater accumulation of PAHs in the marine environment. The diagnostic ratios and PCA-MLR indicated that petroleum was the most important source of PAHs with a contribution of 45%, followed by fuel combustion (39%) such as coal and oil. Photooxidation in seawater resulted in a reduction of BaP/BeP, indicating that seasonal variations in photooxidation had a significant impact on the composition of PAHs (summer: 1.49, autumn: 2.96). The concentration of particulate PAHs was correlated with the concentration of dissolved PAHs and SPM, and the proportion of 3-rings (43.8%) and 4-rings (49.8%) PAHs was significantly higher on SPM. The distribution coefficients Log Kd and φspm-water showed a trend of increasing and then decreasing as the number of rings increased, with the 4-rings Pyr exhibiting the highest value. According to the ecological risk assessment, the ecological risk of total PAHs was low (RQNCs < 800, RQMECs < 1), but the ecological risk of individual PAHs and the carcinogenicity of high-ring PAHs could not be ignored (＞96.5%). This study is significant for investigating the “sources and sinks” of PAHs in the complex marine environment by analyzing the partitioning behavior of PAHs in different phases.

Groundwater chemistry and entropy weighted water quality index of tsunami affected and ecologically sensitive coastal region of India

Quality groundwater is the most essential prerequisite for the better livelihood of the coastal villages and a vital resource for a safe living. Seawater interaction and coastal inundation modify hydro geochemical cycles leading to gross utility as a challenge. Poor quality water intake causes diseases and seriously affects human health. In this study, the suitability of shallow drinking water sources (10–15 m) has been studied with a focus on coastal village in south west of India (Alappad coast, Kollam, Kerala) which is a host of huge placer mineral reserve of the country. This coastal stretch has good deposition of Late Quaternary sediments of heavy mineral placers subjected to severe seawater interactions. Mineralogically, garnet and heavy minerals comprises the beaches and most coastal plains of the Alappad. A concerted geological process where moving water and waves causes erosion, leads to lowering of the earth's surface -is prominent in this fragmented land. This study critically evaluates the temporal-spatial impact of these interactions in an age of varying climatic conditions and hence for reference beyond. Water quality index analysis has been attempted using the entropy weighted water quality index (EWQI) method for a total of 45 samples (15 samples season-wise). It aims to ascertain better choices of groundwater sources for domestic uses for isolated settlers endowed with estuaries, and old coastal plains with barrier beaches. Irrigation suitability was evaluated using sodium adsorption ratio (SAR) and Na%. Observed EWQ Indices (38.2 ± 14.5) for post-monsoon (80% samples), (66.1 ± 77.7) for monsoon (66% samples), and (71.4 ± 71.3) for pre-monsoon (53% samples) fall in excellent category. Post-monsoon is most favoured for a better quality groundwater as evidenced by WQI of 80% among the samples tested. Ca–HCO3 is the dominant hydrochemical type observed. The mean value of iron (0.9 ± 1.3 mg/L) exceeded the permissible limit of 0.3 mg/L during monsoon season due to mineral-water interactions. In pre-monsoon season the parameters Na+ (95.9 ± 200.7 mg/L), Cl− (173.4 ± 510.2 mg/L), EC (1559.3 ± 2510.6 μS/cm), and TDS (492.5 ± 629.7 mg/L) were observed in higher ranges. Significant correlation (p < 0.05) prevailed between EWQI, and parameters-conductivity (0.75), TDS (0.75), Iron (0.59), Ca2+ (0.66), and Mg2+ (0.74). Principal component analysis (PCA) on chemical parameters accounted for the total variance of 84.2% in pre-monsoon, 89.9% in monsoon and 82.9% in post-monsoon. Groundwater quality is influenced by geochemical processes, salt intrusion, and human activities like fertiliser application and domestic sewage discharge. Hierarchical cluster analysis (HCA) grouped the samples into three clusters. Cluster 3 represents poor quality water (13%) in pre-monsoon (EWQI ranged 32.2–192.7), and monsoon (EWQI ranged 171.8–309.7). Cluster 3 in post-monsoon (20%) indicating good water quality (EWQI ranged 51.4–72.6). Ultimate finding is that post-monsoon groundwater is more suitable for drinking and domestic purposes for the selected coastal area.

Metal bioavailability, bioaccumulation, and toxicity assessment through sediment and edible biota from intertidal regions of the Aghanashini Estuary, India

The sediment cores and edible biota from the intertidal regions of the Aghanashini Estuary were studied for the assessment of metal toxicity. The estuarine sediments received natural input of metals through the weathering of Dharwar and peninsular gneisses, and laterites. The sediments were enriched in Fe, Mn, Zn, Cu, Co and Ni than the upper crustal value. Also, the concentration of Fe, Zn, Cu, Co and Ni was more in the Aghanashini Estuary than other estuaries around the world. The Enrichment Factor (EF) revealed enrichment of Zn, Cu, Co and Ni in sediments, while the Geo-accumulation Index (Igeo) exhibited unpolluted-moderately-strongly polluted class of Fe, Zn, Cu, Co and Ni. The enrichment and pollution of metals in sediments was due to anthropogenic sources (domestic sewage, aquaculture and agricultural discharge) in the estuary. The presence of metals at a high concentration in the residual fraction and at a significant proportion in the bioavailable fractions construed both natural and anthropogenic sources of metal, and their bioavailability in the estuary. The physico-chemical factors (ionic composition, H+ ions, redox potential, and microbial activity) regulated the adsorption and desorption of metals in sediments. The Screening Quick Reference Table (SQUIRT) revealed level of bioavailable Mn and Co higher than the Apparent Effects Threshold (AET) and thus, indicated adverse toxic effects on biota. The Risk Assessment Code (RAC) indicated medium-high-very high risk of Mn, Zn, Co, Cu and Ni to biota. Also, the concentration of Fe, Mn, Zn, Cu and Ni in biota was in excess of permissible limit which pointed to their toxicity to biota and their consumers. The Target Hazard Quotient (THQ) value > 1, and Hazard Index (HI) value > 10 revealed risk of metal toxicity to humans.

Spatial-temporal variation characteristics and coupling coordination of the “water resources – water environment – water ecology” carrying capacity in the Three Gorges Reservoir Area

The coordinated control and management of water resources, the water environment, and water ecology are essential for optimizing the management of water resources, improving the water environment, rehabilitating water ecosystems, and achieving sustainable development. Most studies conducted to investigate the water carrying capacity have focused primarily on water resources or water environment. However, it is challenging to conduct such research in areas where the interactions between water resources, the environment, and ecology are intricate. In this study, an evaluation indicator system for the water resources - water environment - water ecology carrying capacity (WCC) was constructed, and a coupling coordination model and GeoDetector were employed to systematically analyze the coupling coordination indices (CCI) among the water resource carrying capacity (WRECC), water environment carrying capacity (WENCC), and water ecology carrying capacity (WECCC), as well as the main influencing factors in the Three Gorges Reservoir Area (TGRA) from 2005 to 2018. The results showed that the numbers of counties and districts with a high CCI class gradually increased over this period. The percentage of Class V fluctuated from 0% to 7.7%, and the stability of the water system steadily increased. Spatially, the overall distribution pattern gradually increased from southwest to northeast, and both the single and interactive effects of anthropogenic factors on water systems gradually increased. The CCI was predominantly affected by factors such as the amount of surface water resources per capita, indices of water conservation, forest coverage, discharge of domestic sewage per capita, and water replenishment of the ecosystem. These results show that coordination between the WCC components should be strengthened to further improve water use and domestic water treatment efficiency. To achieve superior-class, effective, and environmentally friendly scientific governance, the productivity of water resources should be increased in areas where the disparity between water availability and the demand for socioeconomic development is severe, and sewage treatment processes should be closely regulated. It is also important to combine resource development and utilization with water ecological protection and management.

An appraisal to hydrochemical characterization, source identification, and potential health risks of sulfate and nitrate in groundwater of Bemetara district, Central India.

Gypsum-enriched aquifers (GEA) and intensive agriculture regions (IAR) in semi-arid regions are responsible for very high amounts of sulfate and nitrate in many groundwater systems of the world, respectively. However, in such regions, the problem of nitrate pollution and its associated health risk has been increasing and emerging as a global issue. However, along with nitrate, sulfate contamination and its potential health risks are often neglected worldwide in these regions. Therefore, considering sulfate along with nitrate as a significant threat to water quality in such regions, this study aimed to characterize hydrochemistry, factors controlling groundwater quality, and assessment of risk to human health. To accomplish this objective, 116 groundwater samples were collected over pre-monsoon (PRM) and post-monsoon (POM) (2019) seasons in Bemetara district. As per Bureau of Indian standards (BIS) for drinking, SO42- (28 and 19%) and NO3- (7 and 35%) exceeded the permissible limits in PRM and POM seasons, respectively; thereby, groundwater was not suitable for drinking. SO42- and NO3- pollution sources were identified and mainly attributed to gypsum dissolution and agricultural activities as well as domestic sewage discharge, respectively. In addition, SO42-and NO3- risk assessment results show that total 20% to 46% of all samples surpassed the permissible limit (HQ = 1) of risk to children and adults, over both seasons. To ensure drinking water security in this region, sustainable management of agricultural activities and treatment should be done to reduce the potential health risks due to SO42- and NO3-.

Reduction of pollution loads based on sewage treatment projects around a lake: A case study on Erhai Lake.

Erhai Lake is a highland freshwater lake in Dali, China. Rapid tourism development has generated large amounts of pollutants. Since 2015, six wastewater treatment plants (WWTPs) have been built to treat wastewater collected through sewage interception projects. In this study, reductions in the pollution load of wastewater from different sources were evaluated by considering the effects of groundwater leakage, microbial degradation, and rainfall-runoff. The results showed that the systems reduced the chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) loads by 85, 83, and 85%, respectively. Discharge wastewater has the characteristics of a low concentration of domestic sewage discharge, large tourist sewage discharge, and high concentration of livestock wastewater. Due to the high groundwater level, there is groundwater infiltration in the influent water of WWTPs, which dilutes the pollutant concentration of the influent and, therefore, results in a lower treatment efficiency. Further treatment of tailwater also reduced the pollution loads discharged into the lake as well as the COD and TN by 10.25 and 22.90%, respectively. The results indicate that groundwater infiltration in the sewer network system is the primary target to be addressed in future developments.

Mercury isotope compositions in seawater and marine fish revealed the sources and processes of mercury in the food web within differing marine compartments.

Anthropogenic activities and climate change have significantly increased mercury (Hg) levels in seawater. However, the processes and sources of Hg in differing marine compartments (e.g. estuary, marine continental shelf (MCS) or pelagic area) have not been well studied, which makes it difficult to understand Hg cycling in marine ecosystems. To address this issue, the total Hg (THg) concentration, methylmercury (MeHg) concentration and stable Hg isotopes were determined in seawater and fish samples collected from differing marine compartments of the South China Sea (SCS). The results showed that the estuarine seawater exhibited substantially higher THg and MeHg concentrations than those in the MCS and pelagic seawater. Significantly negative δ202Hg (-1.63‰ ± 0.42‰) in estuarine seawater compared with that in pelagic seawater (-0.58‰ ± 0.08‰) may suggest watershed input and domestic sewage discharge of Hg in the estuarine compartment. The Δ199Hg value in estuarine fish (0.39‰ ± 0.35‰) was obviously lower than that in MCS (1.10‰ ± 0.54‰) and pelagic fish (1.15‰ ± 0.46‰), which showed that relatively little MeHg photodegradation occurred in the estuarine compartment. The Hg isotope binary mixing model based on Δ200Hg revealed that approximately 74% MeHg in pelagic fish is derived from atmospheric Hg(II) deposition, and over 60% MeHg in MCS fish is derived from sediments. MeHg sources for estuarine fish may be highly complex (e.g. sediment or riverine/atmospheric input) and further investigations are warranted to clarify the contribution of each source. Our study showed that Hg stable isotopes in seawater and marine fish can be used to identify the processes and sources of Hg in different marine compartments. This finding is of great relevance to the development of marine Hg food web models and the management of Hg in fish.

Chemical and microbial evaluation of water of Rupa lake

Analysis of chemical and microbial features of Rupa lake water was carried out in summer season by adopting accepted analytical techniques. Water samples were collected at 28°C, and on-site observations were made for features like colour, odour, pH, transparency, dissolved oxygen, and free carbon dioxide. In the laboratory, the concentration of prominent mineral ions and microbial contamination were measured using accepted analytical techniques. Transparency of lake water was noted 91cm and electrical conductivity 41 µs/cm indicating the presence of suspended particulate at moderately higher concentration. This water is slightly alkaline with pH of 7.2 that is accounted by domination of alkali and alkaline metal ions. Presence of nitrogenous species mainly ammonium and nitrate in excess amount has detected to be major reason for rapid eutrophication in the lake. Analysis of Rupa lake water has shown the considerable presence of phosphate and sulphate which have added to the hardness 130 mg/L of the water as well. On the top of this fairly higher concentration of free carbon dioxide indicates presence of organic wastes in association with decaying matters. Domestic sewage discharge, the use of pesticides and fertilizers in agricultural areas, as well as other solid waste dumps has caused microbial contamination and the biggest dangers to the viability of Rupa lake. The risk of contamination and the eutrophication process needs to be managed by creating public awareness [1].The study shows that water quality of Rupa lake is contaminated for drinking but adequately suitable for all aquatic life and ecological balance.

Water Quality Evaluation, Spatial Distribution Characteristics, and Source Analysis of Pollutants in Wanquan River, China

Surface water quality assessment is an important component of environmental protection and sustainable development. In this study, 24 sampling sites were arranged in the Wanquan River area of Hainan Island, China, in 2021, and nine water quality indicators were measured. The water quality of the Wanquan River was assessed using the single factor pollution index method and the Nemerow pollution index method; the spatial distribution characteristics of pollutants were revealed, and the sources of pollution were further analyzed using factor analysis. The results show that the overall water quality of the Wanquan River basin is good, with the average values of all indicators meeting China’s Class III water quality standards. The results of the single factor pollution index method showed that 29% of the sampling sites were in the no pollution class, 38% in the slight pollution class, 25% in the light pollution class, and 8% in the moderate pollution class. The results of the Nemerow pollution index showed that 25% of the sampling sites were in the clean category, 17% in the cleaner category, 42% in the light category, and 17% in the moderate category. The results of the factor analysis show that agricultural activities and domestic sewage discharge are the main sources of pollution, with nitrogen and phosphorus being the most important factors affecting water quality. This paper proposes several measures to reduce water pollution in the Wanquan River, including improving agricultural activities, improving wastewater treatment, and strengthening environmental monitoring. The findings have practical implications for reducing water pollution in rivers and lakes and can provide a reference for policy decisions related to water resource management and environmental protection.

Luminescence Toxicological Analysis of Water Supply Systems in Dispersed Rural Areas: A Case Study in Boyacá, Colombia

The quality of water supply systems is still a major problem in developing countries, especially in rural areas. The acute bioluminescence V. fischeri inhibition assay is widely recognized as a toxicological method that can be used to detect the acute effects of different contaminants. In this study, the physicochemical characteristics and toxicology of 72 water samples collected in 18 rural aqueducts located in Boyacá (Colombia) were evaluated. The primary economic activities identified as potential influencers of water quality in the water supply basins were agriculture (n = 3), livestock (n = 2), and domestic sewage discharge (n = 1). The average luminescence inhibition rate was 66%, with a minimum of 29%, and a maximum of 97%. A total of 85% of the tested samples (n = 61) had “moderate acute hazard”, while 15% (n = 15) had “acute hazard”. A total of 95% of the aqueducts distributed water with high risk. There was a weak positive correlation between the apparent color and the V. fischeri inhibition rate (p &lt; 0.05). The water treatments, including disinfection, and the economic activities had no correlation with the inhibition rate of luminescent bacteria. The results of this investigation can be used by sanitary authorities to incorporate future toxicological monitoring of chemical contaminants, such as humic substances and metals, into water-quality monitoring in rural areas.

Effects of phosphorus species and zinc stress on growth and physiology of the marine diatom Thalassiosira weissflogii

Human activities, including industrial and agricultural production, as well as domestic sewage discharge, have led to heavy metal pollution and eutrophication in coastal waters. This has caused a deficiency of dissolved inorganic phosphorus (DIP), but an excess dissolved organic phosphorus (DOP) and high concentrations of zinc. However, the impact of high zinc stress and different phosphorus species on primary producers remains unclear. This study examined the impact of different phosphorus species (DIP and DOP) and high zinc stress (1.74 mg L−1) on the growth and physiology of the marine diatom Thalassiosira weissflogii. The results showed that compared to the low zinc treatment (5 μg L−1), high zinc stress significantly decreased the net growth of T. weissflogii, but the decline was weaker in the DOP group than in the DIP group. Based on changes in photosynthetic parameters and nutrient concentrations, the study suggests that the growth inhibition of T. weissflogii under high zinc stress was likely due to an increase in cell death caused by zinc toxicity, rather than a decrease in cell growth caused by photosynthesis damage. Nonetheless, T. weissflogii was able to reduce zinc toxicity by antioxidant reactions through enhancing activities of superoxide dismutase and catalase and by cationic complexation through enhancing extracellular polymeric substances, particularly when DOP served as the phosphorus source. Furthermore, DOP had a unique detoxification mechanism by producing marine humic acid, which is conducive to complexing metal cations. These results provide valuable insights into the response of phytoplankton to environmental changes in coastal oceans, particularly the effects of high zinc stress and different phosphorus species on primary producers.

Water and Geological Assessment in the Micro-Watersheds of the Alkaline Rocks of Tanguá and Soarinho in Rio de Janeiro State

Alkaline bodies of Tanguá and Soarinho in Rio de Janeiro present drainage areas that form the sources of the Soarinho and Caceribu Rivers. Due to its water and geological importance, we sought to investigate the relation between alkaline rocks and water bodies and the possible consequences of mining activity, as well as the use and occupation of land in water quality. Initially, the magnetometric profile was traced to confirm whether the locations selected for sample collection were located in the alkaline region. Then, water and sediment collections were carried out from the bed at three points on the Soarinho River and one point on the Caceribu River, all inserted in the drainages of the Soarinho and Tanguá alkaline massifs. Parameters necessary to calculate the Water Quality Index (WQI) and those related to contamination by mining activities were analyzed. Chemical analysis of the bed material sought to identify the deposition of contaminants. The context of alkaline rock interaction and water influence is confirmed through geophysical and lithogeochemical techniques through location maps and comparative results of bed material and direct samples of alkaline rocks that showed similar constitutions. In general, the WQI presented a median result, meeting the main requirements for appropriate water for conventional treatment aimed at public supply, and no indicators of contamination by mining activities were found, however, at point P3, representative of the headwaters of the Soarinho River, there were significant changes in BOD and fecal coliforms indicating direct discharge of domestic sewage in a nearby location. The results of the analyzes downstream of this point demonstrate the water bodies dilution capacity.