National Water Quality Standards Research Articles

Water Quality and Prevalence of Extended Spectrum Beta Lactamase Producing Escherichia coli (ESBL E. coli) in Sungai Terengganu, Malaysia

Antimicrobial resistance (AMR) is a significant global issue impacting human, animal, and environmental health, as well as economic security. Water bodies, especially, are now recognized for their role in the spread of antimicrobial-resistant pathogens, though standardized monitoring methods are lacking. This study investigates the presence of extended-spectrum beta-lactamase (ESBL) producing Escherichia coli in the Sungai Terengganu River in Malaysia, focusing on water quality and ESBL E. coli monitoring. Sampling was conducted twice in 2023 at 13 locations along the river. Overall, the water quality index (WQI) classified the river as Class II (WQI = 81), with upstream regions rated as Class I, indicating minimal anthropogenic impact. Higher Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Total Suspended Solids (TSS) in downstream areas suggested organic pollution from anthropogenic activities. Four metal elements exceeded the National Water Quality Standards (NWQS): Al (0.88 mg/L), Fe (3.45 mg/L), Cu (0.102 mg/L), and Hg (2.525 mg/L). No Pb, Cr, Se, Sn, or As were detected. Statistical analysis showed better water quality correlates with lower microbial contamination. ESBL E. coli was found in 8 of 13 sampling sites (61.5%), with the highest concentration at 800 CFU/100 mL. From 40 presumptive ESBL isolates tested, 87.5% (35 isolates) were positive for ESBL and carried additional drug resistance genes, including mcr-1, tetW, sul-1, and sul-2. These findings indicate a concerning presence of multidrug-resistant E. coli in the river, representing a potential public health risk.

Application of batch electrocoagulation treatment system with aluminium electrodes for simultaneous removal of organic and heavy metal contaminants from Borneo urban rivers

The challenges of sludge management and complex water treatment systems hinder the effectiveness of chemical coagulation in treating heavily contaminated urban river water. Realizing these issues, this study aims to develop a batch electrocoagulation system using aluminum electrodes to generate in-situ aluminum hydroxide coagulants for simultaneous removal of organic contaminants and heavy metals from Borneo urban river water. Subsequent, the treatment system achieves a reduction of 91.67 % of turbidity, 98.29 % of color, 95.16 % of total suspended solids (TSS), 97.78 % of iron, 94.21 % of lead, 21.94 % of pH, and 98.58 % of chemical oxygen demand (COD) with an electric current of 5 A and a residence time of 25 min. Besides, the treated water meets the Malaysia National Water Quality Standards for Class I which making it suitable for domestic consumption. The energy consumption cost for the treatment is only RM 1.48 (USD 0.31) per cubic meter of treated water. Additionally, the analysis of the electrocoagulation flocs reveals the presence of carbon, iron, lead, and various dissolved minerals which indicates effective contaminant removal from urban river. Overall, this study demonstrates the potential of the batch electrocoagulation treatment system as an effective and cost-efficient solution for treating urban river water in Borneo industrial areas.

Rainwater Quality Disparities Across Malaysian Peninsula Sites

This research describes the physicochemical quality of harvested rainwater at four distinct locations in Peninsula Malaysia. The evaluation of rainwater quality across different geographic areas aims to provide valuable insights into potential variations and trends in rainwater quality to reduce water demand globally. This analysis is conducted to determine seven properties, namely ammoniacal nitrogen, biochemical oxygen demand (BOD5), chemical oxygen demand (COD), dissolved oxygen (DO), pH, total dissolved solids (TDS), and turbidity. The results demonstrate that the quality of harvested rainwater meets the raw water quality standards set by the World Health Organization (WHO) and the National Water Quality Standards for Malaysia (NWQSM), indicating good quality rainwater in Malaysia. However, the COD for rainwater in all locations exceeded the limit, with a range of 14.1 to 29.7 mg/L, while the maximum limit for COD set by WHO is 10 mg/L, and according to NWQSM standards, it is 10–100 mg/L. The average pH of the collected rainwater is acidic ranged from 4.7 to 5.56. BOD5 for the collected rainwater is excellent; however, L2 has a slightly higher BOD5 at 6.5 mg/L, whereas the recommended limit by WHO is 6 mg/L, and the NWQSM standard suggests a range of 1–12 mg/L, with a standard limit of 5–7 mg/L. Nevertheless, DO levels ranged from 7.71 to 7.76 mg/L, indicating an ambient gas concentration in the rainwater. The collected rainwater can be used for portable purposes, gardening, smart farming, and toilet flushing.

Comparative analysis of water quality index and river classification in Kereh River, Penang, Malaysia: Impact of untreated swine wastewater from Kampung Selamat pig farms.

The Kereh River in Penang, Malaysia, has faced severe pollution for over 40 years due to untreated wastewater from swine farms in Kampung Selamat, discharged via stormwater drains. Despite official claims that all 77 swine farms treat their wastewater to meet regulatory standards, local non-governmental organizations and villagers have challenged this, though their concerns lack scientific backing. This study evaluates the river's water quality by analyzing samples from upstream (US), midstream (MS), and downstream (DS), and from Parit Cina-Parit Besar, a conduit for untreated swine wastewater. Fourteen parameters were measured against Malaysia's National Water Quality Standards (NWQS). Significant differences were found in six parameters: ammonium nitrogen (AN), biochemical oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), total suspended solids (TSS), and oil and grease (OG). While Dunn's post hoc pairwise comparison showed no significant differences among river segments, mean values indicated increased pollution downstream, particularly after the convergence with untreated swine wastewater. River classification worsened, with water quality index dropping from 69.88 ± 11.37 score (Class III) US to 38.49 ± 12.74 and 50.44 ± 3.14 scores (Class IV) MS and downstream, respectively. A significant positive correlation between E. coli and AN (r = 0.71, p < 0.01) suggests a common point source pollutant, particularly the untreated swine wastewater. The river exhibits low oxygen levels and high organic matter and nutrient concentrations, especially MS and downstream, highlighting substantial ecological and public health risks. Effective enforcement of waste treatment regulations and enhanced monitoring are crucial for mitigating pollution and restoring the river's ecosystem. Collaboration between authorities and pig farmers is essential to improve water quality and maintain the river's ecological balance. PRACTITIONER POINTS: Severe Kereh River pollution: Untreated swine wastewater from Kampung Selamat pig farms, primarily via Parit Cina-Parit Besar, has degraded the river for over 40 years. Regulatory non-compliance: Despite official claims, untreated swine wastewater continues to pollute the river, challenging regulatory standards. Significant pollution indicators: Elevated levels of AN, BOD, COD, DO, TSS, OG, and E. coli signal severe pollution midstream and downstream. Water quality index drop: WQI scores classify midstream and downstream sections as polluted, indicating worsening conditions downstream. Urgent need for action: Enforcing regulations, improving wastewater treatment, and relocating pig farms are crucial for restoring the Kereh River.

Occurrence, transport and sources of metals and metalloids in the Bangpakong River in the eastern economic corridor area of Thailand

The occurrence of elements in river water is affected by various factors, including mobility, weathering and transport processes and anthropogenic contributions. A total of six water sampling campaigns were conducted from 2021 to 2022 to study the factors affecting the occurrence of twelve elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn and Se) in the Bangpakong River. The total concentrations of all the elements were within the levels set by the national surface water quality standard. Comparisons of dissolved elemental concentrations in the study area with the global average for dissolved elemental concentrations in pristine rivers indicated contamination with Al, As, Co, Mn, Zn and Se in the river water. Based on the percentage of each element in particulates to the total concentration, Al (80.6 %), Cr (71.9 %), Cu (69.9 %), Fe (95.6 %), Mn (76.6 %), Pb (74.7 %), and Zn (70.6 %) were mainly transported in the particulate phase in both the dry and wet seasons. However, As (65.5 %), Co (60.3 %), and Se (77.6 %) were mainly transported in the dissolved phase in both seasons. The ratios of the dissolved Se concentration in river water to the Se concentration in the Earth's crust indicated significant and high mobility, especially in downstream sites, likely due to Se leaching from alluvial sediments. Seawater intrusion is likely the cause of As and Zn contamination in the dry season. Weathering of rocks and soils likely causes Al, Co, and Mn contamination in the wet season. The anthropogenic sources of contamination include the discharge of Mn and Zn from fertilizers in agriculture and the use of formulated feed in aquaculture. Approximately 52.98, 25.23, 5.68 and 0.63 tons of Fe, Al, Mn and Zn, respectively, are estimated to be transported from the river into the Gulf of Thailand each year.

Physicochemical and microbiological assessment of multi‐village drinking water source in diarrheal hotspot areas of north Shoa zone, Amhara region, Ethiopia

AbstractQuality water is essential to people's health and social and economic well‐being. Evaluation of the quality of the water sources provides benchmark data on quality status and insights into the development of further protective measures. A laboratory‐based cross‐sectional study design was conducted in the diarrheal hotspot area of the North Shewa zone. The contamination risks of water sources were assessed using the World Health Organization (WHO) sanitary inspection checklist. A grab water sample was collected from 138 multi‐village drinking water sources according to WHO guidelines. The collected sample was processed for physicochemical and microbiological analysis. Data were recorded and analyzed using SPSS version 25 software. The inspection survey indicated there was no proper handling of the water sources. The water temperature range was between 7 and 32°C, while the turbidity values ranged from 1.8 to 6 NTU. Electrical conductivity, pH, and total dissolved solutes were 100% within the acceptable limits of WHO and the Ethiopian Ministry of Health (EMoH) water quality guidelines. However, only (77/138, 55.79%) and (101/138, 73.29%) drinking water sources were within the acceptable range of temperature and turbidity, respectively. The mean bacteriological counts in multi‐village drinking water sources were a mean value of 72.14, 29.78, 21.09, and 15.64 for TMC, TCC, FC, and FSC, respectively. A total of (19/138, 13.8%) drinking water samples were positive for total coliform (Tc) and/or fecal coliforms (Fc). The remaining (119/138, 86.2%) water samples were bacteriologically potable. The physicochemical quality of the drinking water sources was consistent with WHO and national water quality standards, except that turbidity exceeded the acceptable range. The results also showed that some water sources were contaminated with fecal and total coliform, which was supported by an inspection survey in which most water sources were poorly protected. These research findings can serve as a valuable evidence base for informing policy decisions and guiding practical interventions aimed at ensuring access to safe drinking water in diarrheal hotspot areas.

Spatial Trends and Distribution Patterns of Toxic Heavy Metal Contamination in an Urbanized Watershed

Rapid urban growth in developing nations exacerbates pressures on water resources through increased pollution loading if management practices cannot adapt efficiently. This study evaluated industrial effluent impacts on river systems in Nigeria contaminated by discharge from beverage, oil and biscuit manufacturing plants. Physicochemical parameters and heavy metal concentrations were monitored at sites upstream and downstream from waste outfalls during wet and dry seasons. Results demonstrated exceedances of national water quality standards for indicators of organic pollution like biochemical oxygen demand and chemical oxygen demand. Notably, highly toxic heavy metals exceeded World Health Organization limits by over 100 times, posing serious public health concerns through various exposure pathways. Seasonal variations reflected changes in pollution inputs. Spatial trends showed metal levels decreasing with distance, though remaining well above safe levels 100m downstream. A predictive transport model was formulated based on field measurements incorporated into the advection-dispersion equation. Key coefficients for the dispersion rate and velocity/dispersion ratio were quantified, allowing simulation of concentration changes under differing scenarios. Model predictions closely aligned with observed metal distribution patterns. Findings highlight the need for upgraded wastewater treatment and emissions controls to mitigate pollution over-burdening natural assimilative capacity. Continuous monitoring programs should track remediation effectiveness. This study provides insights to help authorities balance rapid industrialization, environmental protection and sustainable development goals through evidence-based regulatory strategies ensuring public health.

A Seasonal Analysis of the Quality of and Safety of Drinking water harnessed from Roadside Entombments in East Rural, St. Andrew Jamaica

Due to the increase in population density in urban areas and the uncertainty associated with the availability of municipal water supplies, roadside water entombments have remained an important water source for many residents of Jamaica. This research focused on the seasonal, quality and safety of water harnessed from two non -municipal roadside water supplies. The study employs a cross sectional quantitative approach and uses international and national water quality standards as the benchmark. The aim of the study was to describe the seasonal quality and safety of water harnessed from roadside water entombments in East Rural St. Andrew Jamaica. The physiochemical, microbiological quality and safety of the water supplies were assessed. Two microbiological samples were collected from each source during the wet and dry months. In 100 % of the microbiological samples the Total Coliform levels exceeded national and international limits of Zero CFU/L for safe drinking water.

Study of water quality in ex-mining pits for fish cultivation in Gunung Mas regency, Central Kalimantan

Ex-mining pit is a wide expanse, often becomes a problem, especially for the environment. Lack of information about the use of mining pits for fishing activities, especially for the studies on the quality of mining pits to support the growth of cultivated fish. This research was conducted in the village of Tanjung Riu, Gunung Mas Regency, Central Kalimantan Province, using two ex-mining ponds belonging to the community. The results show that the water quality for both mine pits with water parameters for: dissolved oxygen (DO) on average 6.09 mg/l – 7.45 mg/l, pH 2.94 – 3.54, Biological Oxygen Demand (BOD) 4.78 mg/L, temperature 30 -32 oC, turbidity 51.7-53.5 NTU, value of Total Dissolved Solids (TDS) 0.003 – 0.017 gr/L, mercury (Hg) content of 0.000247 mg/l - 0.000359 mg/l, the depth of the pool is 1.7 m – 2.74 m. The abundance of plankton is between 869 - 1106 cells/L, and abundance of benthos is between 264 - 352 ind/m2. The range of pond water quality based on second-class national water quality standards, which is suitable for fish cultivation with moderate abundance of plankton.

Characterization of Peat Water Electrocoagulation Flocs from Sarawak Southern Region

Sarawak located in Borneo is endowed with the vast availability of peat water sources, particularly for the state southern region. Several investigations have shown that electrocoagulation treatment with aluminium electrodes is feasible to treat peat water in which the quality is comparable to the National Water Quality Standard (NWQS). Even though electrocoagulation treatment is feasible to treat peat water, the characteristics of peat water electrocoagulation flocs have not been reported. As such, this study aims to investigate the characteristics of the electrocoagulation flocs from peat water derived from the Sarawak southern region by using batch electrocoagulation treatment. The objectives of this study are to conduct an experimental study analysis of and identify the minerals on the electrocoagulation flocs along with operating energy cost analysis of peat water batch electrocoagulation treatment. Consequently, this study has found that reaction time and current density affect the production of flocs in which the amount of flocs increases with the increasing reaction time and current density. The flocs produced are found to consist of a large fraction of oxygen (O), carbon (C), iron (Fe), and aluminium (Al) along with a small fraction of potassium (K), magnesium (Mg), calcium (Ca) and Silicon (Si). The presence of Al observed in the flocs is due to the aluminium hydroxide generated during the electrocoagulation process. The total operating cost for peat electrocoagulation with a current density of 5A and reaction time of 20 minutes is about RM0.31 per m3. As a result, the electrocoagulation of peat water process is able to treat peat water as well as produce flocs in which earth elements and heavy metals could be recovered.

Performance of Chlorella vulgaris in Phycoremediation of Livestock Effluent

Livestock effluent is known to contain significantly higher concentrations of organic matter and challenging-to-degrade organic compounds compared to urban wastewater. This makes the effluent treatment challenging and adversely affects nearby aquatic environments if improperly treated. Phycoremediation uses microalgae in water and wastewater treatment. This research aim was to evaluate pollutant removal efficiencies, including chemical oxygen demand (COD), total suspended solids (TSS), nitrate (NO₃-N), turbidity, and phosphate (P), using microalgae Chlorella vulgaris (C. vulgaris) cultivation systems for livestock effluent treatment. The biomass weight of C. vulgaris in the cultivation systems was also observed. In this study, C. vulgaris was cultivated in closed cultivation systems in 5 L water bottles with different dilutions (100%, 75%, 50%, and 25%). The water effluent was compared to permissible values using the National Water Quality Standard (NWQS) class II for recreational water use. TSS was significantly removed by 61.97%, while COD and P were removed by 39.1% and 36.4%, respectively. The biomass growth was observed through the dry weight of the C.vulgaris. Therefore, the removal of nutrients from cattle farm effluent by phytoremediation using C. vulgaris demonstrates potential for treatment efficacy.

Stormwater characterisation and modelling for Sungai Air Hitam in Selangor, Malaysia using model for urban stormwater improvement conceptualisation (music)

The aim of this study is to evaluate the current water quality status of one of the urban rivers in Malaysia, called Sungai Air Hitam. The river's water supply is not only unsuitable for the inhabitants but also hazardous to the aquatic species that depend on it. In order to simulate the water quality formulation of the river, the Model for Urban Stormwater Improvement Conceptualization (MUSIC) was used. The effects of various best management practices (BMPs) components have been examined to improve the river's water quality. This study also investigated different scenarios of the expected future changes in the land cover and the quality of the river. As the proportion of impervious surfaces increases, the urban hydrology cycle can be significantly altered, resulting in an increase in volumes and peak flows, and a decrease in storage, infiltration, and interception. The MUSIC results have shown significant reductions in biochemical oxygen demand (BOD), total suspended solids (TSS), total phosphorus (TP), and total nitrogen (TN) after introducing BMPs. It was also noticed that the prediction of pollutants falls within the acceptable range set by the Urban Stormwater Management Manual for Malaysia (MSMA) 2nd edition. For the land cover, it was found that the total reduction of BOD, TSS, TP, and TN for existing land use is 92.5 %, 94.5 %, 90.7 % and 91.9 %. Meanwhile, the total reduction in future land use is 81.6 % for BOD, 86.2 % for TSS, 80.9 % for TP and 80.8 % for TN. From the simulation results, it was observed that the application of BMPs has successfully reduced the observed mean BOD concentration from 92.38 mg/L (Class V) to 6.93 mg/L (Class IV) of the national water quality standards, NWQS, water quality index. As a result, the water quality index of the overall catchment has improved from Class IV to Class III (WQ1, WQ3, and WQ4) and from Class V to IV (WQ2) with the application of the BMPs. This assessment aims to raise awareness within the Sungai Air Hitam community regarding the importance of preserving river cleanliness and understanding the long-term environmental impact of water quality. These findings underscore the importance of an integrated system in managing urban water systems, which can offer valuable insight to the decision-makers.

Developing a safe water atlas for sustainable drinking water supply in Sonargaon Upazila, Bangladesh

Bangladesh has been relying heavily on groundwater for drinking and irrigation purposes since the 1960s. The access to safe drinking water has always been a challenge for Bangladesh due to the geogenic contamination in shallow aquifers. The objective of this study was to identify the depth for extracting safe water and to develop a safe water atlas for different unions of Sonargaon Upazila to ensure a year-round safe water supply. The concentrations of Arsenic, Iron and Manganese in groundwater were measured from 63 random water samples and compared with WHO and national drinking water quality standards. A lithological profile of the study area was developed to validate the indigenous knowledge of targeting safe depth based on sediment color. To address the challenges of groundwater depletion and contamination, the study identified and developed the technique of preparing safe water atlas for a specific region in Bangladesh, serving as a decision-making tool for households. The atlas identifies depths at which tube-wells can be installed to obtain uncontaminated groundwater, helping people make informed choices and avoid potential health risks. Additionally, the safe water atlas can support the development of safe drinking water distribution plans and assist local drillers and residents in decision-making processes.

Assessment of routine operation and maintenance work of a small community water treatment plant in North Guwahati, Assam, India

A water treatment plant's efficiency is reliant on its regular maintenance and operation. Many water treatment plants across the world are outsourced to private enterprises for day to day operation and maintenance. However, the impact of outsourcing may not always be profitable as design of faulty treatment units or carrying out improper routine operation and maintenance works by the private enterprise may ultimately affect the quality of potable water produced. The current study aims to evaluate the routine operation and maintenance tasks performed by an outsourced private enterprise at a small community water treatment facility in Assam. The performance monitoring of the treatment plant indicates that the plant is unable to produce potable water meeting national water quality standards. The turbidity of treated water is not able to meet the BIS acceptable limit of 1 NTU but it complies with the BIS permissible limit of 5 NTU. In general, the plant operators lack the skills required to operate the treatment plant effectively. Coagulant dosing is completely based on personal experience of plant operators instead of using jar test results. The backwashing of filter beds is carried out arbitrarily without considering the turbidity of filtered water. These factors have resulted in malfunctioning of the treatment units ultimately affecting the quality of potable water produced from the plant. The skill set of plant operators and chemist has been enhanced with bilingual stepwise instruction charts and on-hand training at the site. This aids in raising the standard of produced potable water. The turbidity of treated water is observed to be close to the BIS acceptable limit of 1 NTU.

The Capability of Rainwater Harvesting as an Alternative Water Supply

This Rainwater Harvesting System (RWH) is considered the Best Management Practice (BMP) which is being implemented in Malaysia. This system is not only intended to slow down the flow of runoff the surface is even used as a free and safe alternative source of water supply. However, it is mentioned that the system is not viable and impractical considering the construction and maintenance costs that had to be borne by the users of the system. However, several studies inside and outside the country show the Return on Capital (ROC) factor for this system only in a short period, i.e., between two and three years. This article aims to identify the capability of the experimental study site of Rabbitland Jengka Pahang, Malaysia in providing the most suitable or potential location to apply the RWH system. Moreover, it predicts the capability of the RWH system as well as the ROC ability of the system. Results indicate that the level of the system’s reliability is high and the ROC for the investment of the system takes only 36 months to recover the cost of the investment. The National Water Quality Standards (NWQS) for Malaysia proved that RWH and groundwater used are in class 3 which is suitable for livestock drinking, and external domestic uses, and needs extensive treatment for drinking purposes.

Water Quality of Ranowangko River That Crosses Tomohon City and Minahasa Regency, North Sulawesi Province

The Ranowangko River passes through Tomohon City and Minahasa Regency, ending in the Sulawesi Sea. Tombariri District, is the Bunaken National Park area. Ranowangko River Water Monitoring in 2022 by the Regional Environmental Service of North Sulawesi Province shows that Fecal Coli and Total Coli parameters in the Ranowangko River at Station 1 do not meet the requirements according to Government Regulation Number 22 of 2021 concerning Class 2 National Water Quality Standards (BMA). Research to assess water quality from biological, physical and chemical aspects as well as determine water quality status. Monitoring was carried out 4 times in 2 consecutive years at 3 observation stations. Quantitative data and qualitative data include water quality analysis through determination of 14 parameters compared according to BMA Class 2. The water quality data was analyzed using the Storet Method to determine water quality status in accordance with Minister of Environment Decree Number 115 of 2003. The results showed Fecal Coli and Total Coli (Biological Aspects), TSS (Physical Aspects), Total Phosphate (Chemical Aspects) exceeded the BMA. Score calculation results using the Storet method at Station 1: -68, Station 2: -72 and Station 3: -76. Based on the value system According to Minister of Environment Decree 115 of 2003, the score above shows that the Water Quality Status of the Ranowangko River is heavily polluted. Recommendations to the regional governments of Tomohon City and Minahasa Regency to carry out further monitoring of the water quality of the Ranowangko River.

Remote sensing estimation of water transparency for Saguling Dam in the past decade (2013-2022) based on Landsat 8

Water transparency (i.e., Secchi disk depth (SDD) reflects light transmission capacity of a water body and influences growth of aquatic plants, aquatic organisms, and primary productivity. In this study, using remote sensing reflectance (Landsat 8) and SDD datasets, we predicted the water transparency in Saguling Dam for the first time. The results indicated that the models in the visible (Band 1, Band 2, and Band 3) combined with near infrared (Band 4 and Band 5) are the most robust and reliable to estimate SDD for Saguling Dam. Subsequently, multiple linear regression model was built using 125 pairs of in situ SDD results and concurrent with Landsat images during the last decade (i.e., 2013-2022). The models were validated with an independent dataset of 33 SDD measurement. The in situ remote sensing model compared well with the in situ SDD measurement where determinant coefficient (adjusted R2) and root mean square error (RMSE) ranging from 0.35 - 0.94 and 0.3 - 1.4 m, respectively. Finally, the model was applied to Landsat 8 images acquired between 2013-2022 to elucidate the spatial distribution of SDD in Saguling Dam for each year (i.e. temporal variations) with water area around 33.7 km2. The estimation results indicated that water transparency values in the inlet and outlet zone have relatively low SDD, with SDD value ranging from 0.019 – 1.01 m and 0.24 – 1.04 m, respectively. Furthermore, based on the National Water Quality Standards (i.e., Indonesia Government Regulations No. 22 year 2021/ Peraturan Pemerintah No. 22 Tahun 2021), the estimation of spatial SDD results indicated that &gt; 99% of Saguling Dam water bodies were classified as Class IV (i.e., could be only used for irrigation). This study provides the first comprehensive remote sensing model for Saguling Dam and can provide essential information for local water quality conservation.

The effects of seasonal variations on water quality at selected recreational rivers in Kelantan

Determining and assessing water qualities for recreational rivers are crucial for understanding its overall effects to environmental health and potential impacts to human health. Hence, this paper discusses seasonal variation effects on recreational river water quality at six selected recreational rivers in Kelantan namely Lata Janggut, Lata Goleng, Lata Turbo, Lata Keding, Lata Renyok and Lata Batapar. It is significantly important to determine whether these rivers are able to support and safe for recreational activities. The water qualities in the study areas were determined using the guidelines and parameters provided by the National Water Quality Standard (NWQS) and Department of Environment (DOE). The parameters tested in this study were in accordance to NWQS using six parameters, which were pH, BOD, COD, ammoniacal nitrogen, dissolved oxygen and TSS. The water qualities were tested via in situ and laboratory testing. According to DOE, water qualities that are suitable for recreational activities are in Class I and II. The findings from this study confirmed that all six rivers’ water qualities fall under Class I and II for both seasons, with one stream fell in Class II during dry season (Lata Goleng) and three streams fell in Class II during wet season (Lata Renyok, Lata Keding and Lata Batapar). Overall, the study areas were still clean and suitable for recreational activities.

A nationwide investigation on the characteristics and health risk of trace elements in surface water across China

Rapid urbanization accelerates the release of anthropogenic heavy metals from local to wider water systems, posing a serious threat to aquatic ecosystems and public health. The characteristics of trace elements were investigated to evaluate the environmental status of surface water in 40 cities of China. The concentrations of 22 elements in surface water ranged from 7.00 × 10−4 to 4.37 × 105 μg/L. The water quality can be classified as “excellent” except Songhuajiang. The levels of As, Cd, Cr, Pb, and Hg are all within the limits permitted by national drinking water quality standards. An obvious regional distribution characteristic was observed, with concentrations of Zn, Mn, Ni, Cu, Co, U, and Cr higher in surface water collected in the north than in the south, while the trends for Cd, Tl, and As are opposite. Notably, Tl shows significant geographical divergences, with the level of surface water collected from the south nine times higher than that from the north. The regional distribution of the mineral, industrial, or agricultural activity might be responsible for the south-to-north difference of these elements. The hazard index (HI) and total cancer risk (TCR) through oral or dermal contact with water-related heavy metals were further calculated. The average HI was 0.54 in the north and 0.29 in the south for adults, while HI for children was relatively higher. The value was 1.01 and 0.55 in the north and south, respectively. TCR in the north is 2.58 × 10−4 and mainly contributed by Cr (88.1 %), while TCR in the south is 4.48 × 10−5 and mainly contributed by As (98.4 %). The research results can provide essential data for effective water resources management and human health protection in China.

Importance of baseline assessments: monitoring of Brunei River's water quality

Abstract This study illustrated the changes, pollution status, and significant pollution causes for Brunei River, Brunei Darussalam. Eleven parameters (pH, temperature, oxidation–reduction potential (ORP), dissolved oxygen, biochemical oxygen demand, conductivity, total dissolved solids (TDS), salinity, turbidity, ammonia-nitrogen (NH3-N), and total coliform) were analyzed from eight monitoring sites in 1984, 2019, 2020, and 2021. Box plots were used for a comparative study between 1984 and 2019+ data, while hierarchical cluster analysis (HCA) and principal component analysis (PCA) tests were performed on data from recent years (2019+). The box plot analysis showed that pollution levels in 2019, 2020, and 2021 increased compared to 1984 values, especially for total coliform bacteria. The doubling of the coliform bacteria concentration in the river between 1984 and 2019+ is concerning because the Malaysia National Water Quality Standards (NWQS) guideline values for fishing have now been exceeded. HCA pointed out that upstream stations are more polluted than downstream. PCA of the 11 water quality datasets generated five factors with a total variance of 75.21% and identified anthropogenic activities, seawater intrusion, and hydrological processes as possible causes for Brunei River water quality degradation.