Anthropogenic influence on surface water quality of the Nhue and Day sub-river systems in Vietnam

Spatio-temporal assessment of water quality of a tropical decaying river in India for drinking purposes and human health risk characterization

River water pollution and water-related health problems are common issues across the world. The present study aims to examine the Jalangi River's water quality to assess its suitability for drinking purposes and associated human health risks. The 34 water samples were collected from the source to the mouth of Jalangi River in 2022 to depict the spatial dynamics while another 119 water samples (2012-2022) were collected from a secondary source to portray the seasonal dynamics. Results indicate better water quality in the lower reach of the river in the monsoon and post-monsoon seasons. Principal component analysis reveals that K+, NO3-, and total alkalinity (TA) play a dominant role in controlling the water quality of the study region, while, CaCO3, Ca2+, and EC in the pre-monsoon, EC, TDS, Na+, and TA in the monsoon, and EC, TDS and TA in the post-monsoon controlled the water quality. The results of ANOVA reveal that BOD, Ca2+, and CaCO3 concentrations in water have significant spatial dynamics, whereas pH, BOD, DO, Cl-, SO42-, Na+, Mg2+, Ca2+, CaCO3, TDS, TA, and EC have seasonal dynamics (p < 0.05). The water quality index depicts that the Jalangi River's water quality ranged from 6.23 to 140.83, i.e., excellent to unsuitable for drinking purposes. Human health risk analysis shows that 32.35% of water samples have non-carcinogenic health risks for all three groups of people, i.e., adults, children, and infants while only 5.88% of water samples have carcinogenic health risks for adults and children. The gradual decay of the Jalangi River coupled with the disposal of urban and agricultural effluents induces river pollution that calls for substantial attention from the various stakeholders to restore the water quality.

Combination of water quality, pollution indices, and multivariate statistical techniques for evaluating the surface water quality variation in Can Tho City, Vietnam

This study assessed the surface water quality in Can Tho city, Vietnam, using a combination of water quality, pollution indices, and multivariate statistical methods. Surface water samples were collected at 38 locations with a frequency of 4 times in 2020 (March, June, September, and December) and at the time of high and low tides to analyze for 18 indicators. Results showed that surface water in Can Tho city was contaminated with organic matters and microorganisms. Parameters of pH, turbidity, total suspended solids (TSS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), N-NH₄⁺, and N-NO₃^- are significantly increased with low tide. Comprehensive pollution index indicated mild to moderately polluted water in March, June, and September and moderately to severely polluted water in December. Organic pollution index revealed that surface water quality in all locations was polluted with organic matters during the study period especially in March and December. The water quality index also indicated that water quality in December was mostly classified as moderate and bad. The principal component analysis indicated that surface water quality could be affected by five main sources that explain 64.40% of the total variation. This significantly caused the fluctuation of pH, temperature, turbidity, TSS, DO, BOD, COD, N-NH₄⁺, P-PO₄^3-, Fe, and As, which should all be the focus for future monitoring. Surface water management in Can Tho city should also emphasize on the wastewater from urbanization and agriculture, which has been recognized by the analysis to have highest contribution to organic, nutrient, and microbial pollutants in the water bodies.

A spatiotemporal analysis of water quality characteristics in the Klip river catchment, South Africa

Understanding the spatial and temporal patterns of water quality is central to its management as it provides information essential to the restoration as well as protection of water resources. The main objectives of this study were (i) to analyze the spatial and temporal trends of water quality and (ii) to identify the critical sources of pollution in the Klip River catchment (KRC). Water samples were collected at 12 sampling points along the Klip River, monthly from February 2016 to January 2017 and analyzed using inductively coupled plasma mass spectrometry (ICP-MS) and spectrophotometry for heavy metals and nutrients, respectively. Multivariate statistical techniques (cluster analysis and discriminant analysis) were used to delineate homogeneous water quality zones and seasons, and principal component analysis was used to identify pollution sources. Comprehensive pollution index (CPI) was also computed to classify the overall pollution of the river. The spatial grouping yielded two homogenous water quality zones namely upstream and downstream. Temporal grouping yielded two clusters, which were attributed to the effects of the El Nino (2015/16 season) and La Nina phenomena (2016/17 season). The CPI revealed that the KRC was critically polluted in the upstream for domestic (162.16-323.28) and aquatic uses (617.70-837.09) in both the 2015/2016 and 2016/2017 seasons. It can be concluded that pollutants, which influence water quality in the KRC in one season and/or location, may not necessarily be the same in the other season or location. Therefore, there is need to develop a water quality management plan in the KRC that targets the most impaired uses, pollutants of priority, and the critically polluted areas.

Drivers of water pollution and evaluating its ecological stress with special reference to macrovertebrates (fish community structure): a case of Churni River, India

The focus of this study is to measure ecological stress of Churni River based on the estimates of dissolved oxygen (DO), pH, biological oxygen demand (BOD), chemical oxygen demand (COD), nutrients imbalances of dissolved inorganic nitrogen or DIN (NO₃^- N and NO₂^- N) and dissolved inorganic phosphate or DIP (PO₄^3-). The present water quality measured in terms of overall index of pollution (OIP), eutrophication index (EI), organic pollution (OPI) and water pollution indexes for ecological status (WPI) portrays that the river is polluted having a high concentration of BOD, COD, nutrients (DIP and DIN) and a very low concentration of DO. Fish community structure taken as most sensitive indicator of ecological stress of water pollution depicts that out of 44 species, 28 fish species (63.63%) comprising 20.0% planktivore (PL), 9.09% benthic feeder (BE), 18.18% omnivorous (OM) and 15.90% carnivorous (CA) at Majhdia and 21 fish species (47.72%) comprising 18.18% PL, 4.59% BE, 13.63% OM and 11.36% CA at Ranaghat have been disappeared. The present investigation has found that anthropogenic interventions like disposal of industrial effluents and agricultural run-off from on-bed and off bed land use are the main drivers of the pollution. Furthermore, natural forcing in the form of neotectonic movements and monsoon regimes has intensified the problem.

Evaluation of the raw water quality: physicochemical and toxicological approaches

Environmental degradation has increased, mainly as a result of anthropogenic effects arising from population, industrial and agricultural growth. Water pollution is a problem that affects health, safety and welfare of the whole biota which shares the same environment. In Goiânia and metropolitan region, the main water body is the Meia Ponte River that is used for the abstraction of water, disposal of treated wastewater and effluents. In addition, this river receives wastewater from urban and rural areas. The aim in this present study was to evaluate the quality of raw water by some physical, chemical and toxicological tests. The physicochemical results found high levels of turbidity, conductivity, aluminum, phosphorus and metal iron, manganese, copper and lithium when compared to the standards of the Brazilian legislation. The values found of toxicity demonstrated a high degree of cytotoxicity and genotoxicity. Therefore, it was concluded that the Meia Ponte River has been undergoing constant environmental degradation, causing the poor quality of its waters. Thus, measures for the prevention and recovery should be adopted for the maintenance of the Meia Ponte River.

Chemical and microbiological risk assessment of urban river water quality in Vietnam

The contamination and risk by nutrients (NH₄⁺, NO₂^-, NO₃^- and PO₄^3-), COD, BOD₅, coliform and potentially toxic elements (PTEs) of As, Cd, Ni, Hg, Cu, Pb, Zn and Cr were investigated in urban river (Nhue River), Vietnam during 2010-2017. The extensive results demonstrated that concentrations of these contaminants showed significant spatial and temporal variations. The Nhue River was seriously polluted by NH₄⁺ (0.025-11.28 mg/L), PO₄^3- (0.17-1.72 mg/L), BOD₅ (5.8-179.6 mg/L), COD (1.4-239.8 mg/L) and coliform (1540-326,470 CFU/100 mL); moderately polluted by As (0.2-131.15 μg/L) and Hg (0.11-4.1 μg/L); and slightly polluted by NO₂^- (0.003-0.33 mg/L) and Cd (2.1-18.2 μg/L). The concentrations of NH₄⁺, PO₄^3-, COD, BOD₅ and coliform frequently exceeded both drinking water guidelines and irrigation water standards. Regarding PTEs, As, Cd and Hg concentrations were frequently higher than the regulatory limits. Human health risks of PTEs were evaluated by estimating hazard index (HI) and cancer risk through ingestion and dermal contacts for adults and children. The findings indicated that As was the most important pollutant causing both non-carcinogenic and carcinogenic concerns. The non-carcinogenic risks of As were higher than 1.0 at all sites for both adults (HI = 1.83-7.4) and children (HI = 2.6-10.5), while As posed significant carcinogenic risks for adults (1 × 10^-4-4.96 × 10^-4). A management strategy for controlling wastewater discharge and protecting human health is urgently needed.

Impact of anthropogenic activities on water quality and plankton communities in the Day River (Red River Delta, Vietnam)

Planktons are a major component of food web structure in aquatic ecosystems. Their distribution and community structure are driven by the combination and interactions between physical, chemical, and biological factors within the environment. In the present study, water quality and the community structure of phytoplankton and zooplankton were monthly investigated from January to December 2015 at 11 sampling sites along the gradient course of the Day River (Red River Delta, northern Vietnam). The study demonstrated that the Day River was eutrophic with the average values of total phosphorus concentration 0.17 mg/L, total nitrogen concentration 1.98 mg/L, and Chl a 54 μg/L. Microscopic plankton analysis showed that phytoplankton comprised 87 species belonging to seven groups in which Chlorophyceae, Bacillariophyceae, and Cyanobacteria accounted for the most important constituents of the river's phytoplankton assemblage. A total 53 zooplankton species belonging to three main groups including Copepoda, Cladocera, and Rotatoria were identified. Plankton biomass values were greatest in rainy season (3002.10-3 cell/L for phytoplankton and 12.573 individuals/m³ for zooplankton). Using principal correspondence and Pearson correlation analyses, it was found that the Day River was divided into three main site groups based on water quality and characteristics of plankton community. Temperature and nutrients (total phosphorus and total nitrogen) are key factors regulating plankton abundance and distribution in the Day River.

Consideration of rainwater quality parameters for drinking purposes: A case study in rural Vietnam

Rainwater, which is used for drinking purposes near Hanoi, Vietnam, was analysed for water quality based on 1.5 years of monitoring data. In total, 23 samples were collected from different points within two rainwater harvesting systems (RWHSs). Most parameters met the standard except micro-organisms. Coliform and Escherichia coli (E. coli) were detected when the rainwater was not treated with ultraviolet (UV) light; however, analysis of rainwater after UV sterilisation showed no trace of micro-organisms. The RWHSs appear to provide drinking water of relatively good quality compared with surface water and groundwater. The superior quality of the rainwater suggests the necessity for new drinking rainwater standards because applying all of the drinking water quality standards to rainwater is highly inefficient. The traditionally implemented standards could cause more difficulties for developing countries using RWHSs installed decentralized as a source of drinking water, particularly in areas not well supplied with testing equipment, because such countries must bear the expense and time for these measures. This paper proposes the necessity of rainwater quality guideline, which could serve as a safe and cost-effective alternative to provide an access to safe drinking water.

Dissolved concentrations, sources, and risk evaluation of selected metals in surface water from Mangla Lake, Pakistan

The present study is carried out for the assessment of water quality parameters and selected metals levels in surface water from Mangla Lake, Pakistan. The metal levels (Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, and Zn) were determined by flame atomic absorption spectrophotometry. Average levels of Cd, Co, Cr, Ni, and Pb were higher than the allowable concentrations set by national and international agencies. Principal component analysis indicated significant anthropogenic contributions of Cd, Co, Cr, Ni, and Pb in the water reservoir. Noncarcinogenic risk assessment was then evaluated using Hazard Quotient (HQ_ing/derm) and Hazard Index (HI_ing/derm) following USEPA methodology. For adults and children, Cd, Co, Cr, and Pb (HQ_ing > 1) emerged as the most important pollutants leading to noncarcinogenic concerns via ingestion route, whereas there was no risk via dermal contact of surface water. This study helps in establishing pollutant loading reduction goal and the total maximum daily loads, and consequently contributes to preserve public health and develop water conservation strategy.

Spatial and temporal characterization of trace elements and nutrients in the Rawal Lake Reservoir, Pakistan using multivariate analysis techniques

Rawal Lake Reservoir is renowned for its ecological significance and is the sole source of drinking water of the third largest city of Pakistan. However, fish kill in recent years and anthropogenic impacts from human-related activities in its catchment area have resulted in deterioration of its surface water quality. This study aims to characterize spatial and temporal variations in surface water quality, identify contaminant sources, and compare their levels with quality guidelines. Surface water samples were collected from 10 sites and analyzed for 27 physicochemical parameters for a period of 2 years on a seasonal basis. Concentration of metals in surface water in pre-monsoon were in the order: Fe > Mg > Ca > Mn > Zn > Ni > Cr > Cu > Co > Pb, whereas in post-monsoon, the order of elemental concentrations was: Ca > Mg > Na > Fe > K > Zn > Cr > Li > Pb > Co > Ni > Cu > Mn > Cd. Metals (Ni, Fe, Zn, and Ca), pH, electrical conductivity (EC), dissolved oxygen (DO), chemical oxygen demand (COD), and nutrients (PO (4) (3-) , NO(3)-N, and SO (4) (2-) ) were measured higher in pre-monsoon, whereas concentration of Cu, Mn, Cr, Co, Pb, Cd, K, Na, Mg, Li, Cl(-), and NH(4)-N were recorded higher in post-monsoon. Results highlighted serious metal pollution of surface water. Mean concentration of Zn, Cd, Ni, Cu, Fe, Cr, and Pb in both seasons and Mn in post-monsoon were well above the permissible level of surface water quality criteria. Results stress the dire need to reduce heavy-metal input into the lake basin and suggest that heavy-metal contamination should be considered as an integral part of future planning and management strategies for restoration of water quality of the lake reservoir.