Water Quality Research Articles

Study of Estimation of Hardness of Water Using pH-Meter

The hardness of water is one of the important parameters of water quality. The complexometric titration method is a prevalent technique to estimate concentrations of and ions individually, which are primarily responsible for the hardness of water. However, the method needs two external indicators to mark the end points of titrations. Furthermore, accuracy of the method is sacrificed due to inevitable parallax errors during marking of the endpoint of titration. This present work reports that during titration of a hard water sample with a complexing agent (here, solution), changes continuously. This change in is closely monitored and recorded graphically. Hence the endpoint of titration is determined. The neutralization volume, thus obtained, is used to estimate and hardness of the water sample separately. This novel technique obviates the use of any external indicators and eliminates any possible parallax error.

Comparative analysis of ensemble learning algorithms in water quality prediction

ABSTRACT Water is an essential resource necessary for the survival of all life forms, yet it is continually at risk of contamination. Accurate water quality prediction is essential for protecting ecosystem health. This study aims to assess the effectiveness of ensemble learning techniques, namely AdaBoost, gradient boosting, XGBoost, CatBoost, and LightGBM, in predicting water quality parameters in the Bara River Basin, Pakistan. Initially, a random forest model was used to determine the input water quality parameters combination for the selected target water quality variable. Then, the ML models were developed for each combination of input parameters and target water quality variables. The ML model's performance was assessed via statistical performance indicators, namely R2, mean squared error, and mean absolute error. The most suitable model was highlighted using compromise programming. The results reveal that the XGBoost and gradient boosting models outperform other algorithms based on statistical indicators, displaying remarkable predictive ability with near-perfect R2 values for HCO3, CO3, and Mg on the XGBoost model and electrical conductivity, SO4, Temp, and Ca on the gradient boosting model. Whereas CatBoost and LightGBM have a more robust performance on some parameters, such as pH and dissolved solids while its performance in other water quality parameters was weak.

Growing mismatches of supply and demand of ecosystem services in the Netherlands

A sufficient supply of goods and services from ecosystems is vital to ensure human well-being. This study evaluates whether the demand for goods and services within the Netherlands is met by Dutch ecosystems, could otherwise be provided through technology and/or by imports, or remains (partially) unmet. Additionally, this study shows the dynamics of supply and demand of these services over time. The results reveal that no ecosystem service supply is fully meeting the total demand provided by Dutch ecosystems. Additionally, for the majority of the services (10 out of 17), the gap between supply and demand widened over the last two decades, indicating a growing mismatch. Imports and technology only partly close the gap between supply and demand. The growing mismatch between supply and demand is expected to lead to increasing negative impacts on human well-being, such as poor air and water quality, heat stress in urban areas, increasing flood risks, limiting opportunities for outdoor recreation and loss of biodiversity. Our findings show that current policy goals to maintain and restore ecosystem services are not on track in the Netherlands. Urgent action is necessary to enhance the sustainable utilization of natural resources and to optimize the balance between supply and demand. Priority should be given to goods and services facing unmet demand where imports or technological solutions are not feasible, particularly those where the gap between supply and demand is widening.

Short-term forecasting of dissolved oxygen based on spatial-temporal attention mechanism and kernel-based loss function

Dissolved Oxygen (DO) is a fundamental indicator of the health of aquatic ecosystems. This study introduces a novel spatial-temporal attention model combined with Kernel Mean Squared Error loss function (STA-KMSE) for forecasting short-term DO. An attention-based Convolutional Neural Network (A-CNN) is used to incorporate the influence of upstream stations in the spatial module, a factor often overlooked in prior studies. The temporal module captures the influence of both previous hours and days using attention-based Long Short-Term Memory (A-LSTM), offering a more comprehensive temporal context. Our approach addresses the issue of outlier sensitivity and non-linear error patterns by utilizing the KMSE loss function, which improves the model's robustness and more effectively captures intricate variations in DO levels compared to the standard Mean Squared Error (MSE) commonly used in water quality modelling. The model is trained on an extensive dataset consisting of various water quality parameters collected from twenty locations along the Ganga River, its tributary, and nallahs spanning from 1 April 2017 to 30 April 2021. In terms of RMSE, STA-MSE outperforms A-CNN by 62.669 % and A-LSTM by 7.419 %. Compared to STA-MSE, the STA-KMSE shows an average reduction in RMSE by 3.067 % for one-step, 3.197 % for two-step, and 3.428 % for three-step forecasting. Experiments indicate better performance for river locations than for nallahs. SHapley Additive exPlanation (SHAP) analysis highlights pH and temperature as crucial factors for estimating DO in rivers, while level, temperature, conductivity, total suspended solids, pH, chlorine, and chemical oxygen demand are significant for nallahs.

Wastewater Quality Assessment at Amarah Sewage Treatment Plant: Implications for Agricultural Use and Environmental Safety

This study examines the quality of treated wastewater from the Amarah Sewage Treatment Plant (ASTP) in Iraq for potential agricultural use and compares it to the water quality standards of Iraq, Egypt, and the USA. The effluent was analyzed over a five-month period for various parameters, including pH, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), and concentrations of ions, such as chloride (Cl-), sulfate (SO4-2), phosphate (PO43-), nitrate (NO3-), and ammonia (NH3). The findings showed that the pH and TDS measurements of the treated wastewater fell within the acceptable range, according to the regulations set by all three countries. The concentrations of Cl-, SO4-2, PO43-, NO3-, and NH3 in the treated wastewater were also within the acceptable limits set by the Iraqi standards. However, chloride and sulfate levels occasionally exceed permissible thresholds. The treated wastewater from ASTP is generally suitable for the irrigation of certain crops, but it is important to implement a monitoring and control system to ensure consistent water quality. Finally, investments are needed to improve treatment processes and establish educational programs for farmers to enhance their understanding of proper wastewater usage. These measures are crucial for protecting public health and conserving water resources, particularly in regions facing water scarcity.

Feed Retention of Silver Pompano (Trachinotus blochii) on Commercial Feeding with The Addition of Turmeric Extract (Curcuma domestica)

Silver pompano is a high-value fish, yet the cost of commercial feed is a major challenge for fish farmers. This study explores the addition of turmeric extract to commercial feed as a potential strategy to improve feeding efficiency and reduce production costs. Conducted at the Lombok Marine Aquaculture Center, the 50-day experiment used a Completely Randomized Design (CRD) with four treatment levels (control, 10 ml, 15 ml, and 20 ml of turmeric extract per kg feed) and three replications, totaling 12 experimental units. Parameters measured included growth performance indicators like specific growth rate (SGR), feed conversion ratio (FCR), protein and fat retention, and water quality. Data was analyzed using ANOVA and Duncan tests to assess treatment effects. Results showed that turmeric extract significantly improved SGR, FCR, protein retention, and fat retention, although it had no significant impact on absolute weight, length, survival rate, or feeding efficiency. The optimal treatment was 20 ml/kg of turmeric extract, yielding an SGR of 4.92%, FCR of 2.48, protein retention of 18.64%, and fat retention of 22.37%, likely due to the presence of bioactive compounds such as flavonoids, alkaloids, tannins, terpenoids, and phenols.

Evaluation of Buffalo Health and Prevalence of Metabolic Disorders in Pulivendula: A Urine Analysis Approach

Aim: The study aims to evaluate the health status of buffaloes in selected villages of Pulivendula, detect potential metabolic disorders, and assess the prevalence of common health issues using urine analysis via the dipstick method. Objectives: The main aim of this study is to identify abnormalities, correlates the findings with nutrition and health data and emphasizes student participation in community-based animal health programs. Materials and Methods: A total of 25 buffaloes from five villages in the Pulivendula region were randomly checked as part of the study. The dipstick method was chosen for urine sample collection and analysis because of its ease of use, affordabilitys and speedy findings. Tests were conducted on parameters including Blood, Bilirubin, Nitrite, Leucocytes, Sp. Gravity Glucose, Protein, pH, Urea, RBC and Ketones. Students also completed surveys that yielded information about the diet, living circumstances, and overall health of the buffaloes. Results and Discussion: The investigation found that a less number of buffaloes had aberrant urine parameters, indicating subclinical illnesses. Proteinuria and ketonuria were more common in buffaloes from settlements with limited access to quality feed and water. The study results revealed a link between dietary behaviours and observed urine abnormalities, highlighting the need for better nutritional management and health monitoring in these locations. This study highlights the importance of the dipstick method in routine veterinary health checks, as well as the need for focused interventions to improve buffalo health and productivity in the Pulivendula region.

Effects of Salinity of Magnetized Water on Water–Salt Transport and Infiltration Characteristics of Soil Under Drip Irrigation

The shortage of fresh water resources and soil salinization restrict the sustainable development of oasis agriculture in Xinjiang, China. Magnetically treated brackish water can physically improve the quality of water used for irrigation, and this technology is being gradually applied in agricultural production. However, the infiltration characteristics of magnetized brackish water and its response to the distribution of soil water and salt are still unknown. We conducted infiltration tests using a one-dimensional soil column system, employing magnetized water at concentrations of 0.2, 1, 3, and 5 g·L⁻1, with a magnetization strength of 3000 gauss (GS), and explored the effects of salinity of magnetized water on water–salt transport and infiltration characteristics of soil under drip irrigation. The migration rate of the wetting front of magnetized water infiltration slowed, and the cumulative infiltration content increased. Specifically, compared to the unmagnetized control, the infiltration time at a depth of 40 cm for magnetized water concentrations of 0.2, 1, 3, and 5 g·L−1 increased by 17.42%, 42.16%, 47.02%, and 39.19%, respectively. Correspondingly, the cumulative infiltration volume increased by 7.88%, 8.09%, 10.60%, and 5.38%. Further, the infiltration of magnetized brackish water increased the water retention capacity of soil, effectively reduced the salt content of soil layers, and had a remarkable desalting effect. Salinity of the soil profile showed an L-shaped trend of salt accumulation in the lower layer and desalting in the upper layer. For water salinity of 3 g·L−1, soil desalting intensity was greatest. In addition, KShf, suction rate, empirical coefficient a, initial infiltration rate, and stable infiltration rate all decreased under magnetization treatment with the same salinity. Thus, this study provides a new way to alleviate the shortage of fresh water resources in arid areas, a guideline for safely using brackish water and also increasing productivity of saline–alkali land.

Feasibility of classification of drainage and river water quality using machine learning methods based on multidimensional data from a gas sensor array

Feasibility of classification of drainage and river water quality using machine learning methods based on multidimensional data from a gas sensor array

Management of Broodstock for Pacific White Shrimp (Litopenaeus vannamei) at the Center for Superior Shrimp and Shellfish Broodstock Production (BPIU2K) Karangasem, Bali

Shrimp (Litopenaeus vannamei), as it directly impacts the quality and quantity of larvae produced for aquaculture. This study investigates the management practices at the Center for Superior Shrimp and Shellfish Broodstock Production (BPIU2K) in Karangasem, Bali, focusing on the broodstock selection, breeding, and maintenance processes. The research evaluates the performance of broodstock in terms of growth, reproductive health, and overall productivity, aiming to optimize practices for sustainable shrimp farming. Data was collected through direct observation, water quality analysis, and broodstock health assessments. The findings highlight the importance of proper environmental conditions, nutritional management, and genetic selection in enhancing the reproductive success of L. vannamei. The study also discusses challenges faced by the facility, including disease management and genetic diversity, offering recommendations for improving broodstock management to ensure consistent, high-quality shrimp production. The number of male broodstock in the maintenance tank was around 250, and female broodstock was around 200, with a survival rate of 70%. This research contributes to advancing sustainable aquaculture practices and improving the shrimp farming industry in Indonesia.

Heavy Metals in Water and Sediments and Their Impact on Water Quality in Andean Micro-watersheds: A Study of the Colorado and Alajua Rivers in the Ambato River Watershed, Tungurahua, Ecuador

The present study aims to characterize the water and sediment quality of the Colorado and Alajua rivers within Ecuador’s Ambato River watershed, with a specific focus on the presence of heavy metals. Measurements were conducted at five sampling points along the upper and lower zones of each river, where both physicochemical and microbiological parameters, as well as concentrations of heavy metals in water and sediments, were analyzed. Most parameters exhibited statistically significant differences, as determined by the analysis of variance (ANOVA), between the values observed in the upper and lower zones of the micro-watersheds. Water quality in the mentioned rivers was assessed using specific water quality indices, WQI, namely the NSF-WQI and Dinius WQI. Additionally, the impact of heavy metal presence in the water and sediments was evaluated using the Heavy Metal Evaluation Index (HEI). While most parameters met the Ecuadorian quality standards for water sources intended for human consumption, concerns emerged regarding elevated levels of total and fecal coliforms along both rivers, which could limit the suitability of these rivers as a water source for human use and consumption. At various sampling points, water quality criteria for the preservation of aquatic life were not met for several heavy metals. For example, the Colorado River exhibited elevated levels of zinc (59-76 μg.L-1), copper (12-47 μg.L-1), lead (1.2-3.9 μg.L-1 ), iron (0.33-0.37 mg.L-1 ), and manganese (0.37-0.47 mg.L-1), while the Alajua River showed excess copper (11 μg.L-1), iron (0.61-0.72 mg.L-1), and manganese (0.62-0.98 mg.L-1). Geological factors likely contribute to the concentration of heavy metals in the upper segments of the rivers, while agricultural runoff may contribute to concentrations in the lower segments. Sediments exhibited higher average values of the Heavy Metal Evaluation Index (HEI) (20.6-26.7) compared to water samples (13.9-15.4), indicating a potential accumulation of heavy metals in the river sediments. Overall, both rivers exhibited contamination levels ranging from regular to moderate, as indicated by the calculated average Water Quality Indices (WQI), with certain areas showing slight contamination or meeting acceptable standards. These results highlight the influence of anthropogenic activities on water quality, emphasizing the necessity of continuous monitoring to assess and control their impact.

Landscape fragmentation of built-up land significantly impact on water quality in the Yellow River Basin

Urbanization development often leads to significant changes in the extent in area and fragmentation of built-up land landscape pattern (BLLP) in river basins, which greatly impact the processes of rainfall runoff and pollutant migration. Understanding the spatial scale effects and driving mechanisms of BLLP changes on water quality in large river basins is a challenging research topic and an international frontier in the interdisciplinary fields of geography and environment. This study analyzes the spatial variations of BLLP and water quality throughout the Yellow River Basin (YRB) during the rainy seasons from 2019 to 2021 (4hours scale). Utilized the random forest model to quantitatively separates the contributions of rainfall processes to surface runoff and water pollution, revealing the scale effects and non-linear driving mechanisms of BLLP impacts on water environment changes. The results indicate that: 1) The YRB exhibits great spatial heterogeneity in terms of both BLLP and water quality, with places with lower water quality displaying bigger areas and higher degrees of BLLP fragmentation. 2) The patch density and built-up land area (PD.B and CA.B) have a major impact on changes in water quality in the YRB, with notable impacts noted in circular buffer zones with radii of 20 km and 5 km, respectively. 3) PD.B is sensitive to water quality in the YRB, explaining 39.1% to 49.5% of the variance under different rainfall conditions, and exhibits a significant non-linear relationship, with an impact threshold of 0.38 (n/100 ha). The study suggests that for large-scale regions like the YRB, the degree of BLLP fragmentation is more likely to lead to degradation of water environmental quality compared to its area. BLLP fragmentation due to higher PD.B and CA.B disrupts the original ecosystem and hydrological connectivity, resulting in poorer retention and filtration of pollutants carried by rainfall runoff, while increasing the export of other pollutants. However, once urbanization surpasses a certain threshold, the BLLP fragmentation can enhance water quality by reducing the impermeable surface connectivity, as they are no longer impacted by expanding areas. To achieve ecologically sustainable development, it is necessary to apply rational landscape management and water resource management policies that consider the dual process of how BLLP fragmentation affects the water environment.

Effects of Channelization on Macroinvertebrate Assemblages in a Small Stream: The Case of Awetu in Jimma City, Ethiopia

Freshwater ecosystems are increasingly modified worldwide by anthropogenic activities. Land use change is one of the leading factors responsible for stream ecosystem degradation. Physical habitat disturbance due to channelization is among the factors responsible for the loss of biodiversity and degradation of river water quality worldwide. Since 2020, Jimma City municipality has been beautifying the city and one of the activities is channelizing using concrete embankment, a part of the Awetu stream that runs through the city. The main aim of this study is to assess the effect of channelization on macroinvertebrate assemblages and the water quality of the Awetu stream. A cross-sectional study was conducted in April 2022. Macroinvertebrates, water samples, and habitat data were collected from 21 sampling sites along the three segments of the stream (upstream, channelized, and downstream). Data were analyzed for different macroinvertebrate metrics and water quality parameters. Canonical Correspondence Analysis was used to examine the overall relationship between macroinvertebrate assemblages and water quality parameters. The upstream site has better macroinvertebrate assemblages than channelized and downstream sites (p<0.05). The downstream site showed better assemblage compared to the channelized site, though it was not significant. Regarding water quality parameters, a significant variation was observed between channelized and, un-channelized sites (upstream and downstream) (p<0.05). The habitat condition score varied from 47 (poor) at channelization to 150 (suboptimal) upstream. Upstream sites were found to have relatively better macroinvertebrate assemblages, better water quality, and good habitat conditions. The downstream sites had lower macroinvertebrate assemblages, poor habitat conditions, and degraded water quality compared to the upstream sites. The channelized segment had the poorest habitat, with poor macroinvertebrate assemblages and water quality. Thus, the conservation of habitat conditions along the channelized segments of the Awetu stream is recommended to improve the water quality and macroinvertebrate assemblage.

Untangling the coupling effect of water quality and quantity on lake algal blooms in Lake Hulun from a dual perspective of remote sensing and sediment cores

Algal blooms and sediment diatoms are crucial indicators of lake water ecology, influenced by water quantity and quality. However, the coupled effects of water quality and quantity changes on algal blooms are still unclear, especially for lakes in cold and arid regions. This study assessed the long-term variations in algal blooms in Hulun Lake using a novel approach combining remote sensing and sediment core samples for diatom analysis. Two mutation points from the structural change test were identified in approximately 2000 and 2010 for algal bloom area (MBE) and sediment diatom richness, indicating asynchronous algal blooms. A structural equation model (SEM) demonstrated that water level (WL) changes were the dominant influencing factor, co-driving the variations in algal blooms and sediment diatoms in conjunction with total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD). The results revealed nonlinear relationships between the lake WL, TN, Chla, and COD. The water level of 543 m emerged as a critical threshold affecting the relationship between water quality and quantity. Distinct differences in this relationship were observed when water levels were above or below this threshold. These variations became particularly pronounced during periods of high and low water levels. The results provide novel insights into the dynamics of algal blooms and can further support lake ecosystem conservation and management.

Assessment of water quality and trophic state using a multipara-metric index-based approach for Lake Guineo, Lake Carraizo and Lake Cidra, Puerto Rico

To ensure a safe drinking water supply, it is necessary to protect water quality. The proposed project aims to understand water quality data analyzed from a temporal and spatial perspective on the following physiochemical parameters: DO, pH, temperature, Secchi disc turbidity, conductivity, nitrate, chlorophyll α &amp; phosphate. The results provide information to evaluate the status of the water quality and its suitability for human consumption. These variables related to the general characteristics of water quality and trophic level were used for calculation of a water quality index (WQI) and trophic state index (TSI) to assess 3 lakes in Puerto Rico: Lake Cidra, Lake Carraizo and Lake Guineo. Presence or absence of macrophytes were monitored during six months in the three reservoirs in Puerto Rico as well as the parameters mentioned above. The objective of this investigation is to discuss the trophic state and water quality in 3 different trophic state reservoirs in Puerto Rico. Results were correlated with the density of the macrophyte species, Eichhornia crassipes. Variations of water in situ multiparametric sampling were recorded for 6 months. Thus, integrating components that define the status of reservoirs using multiparameter measurements from various perspectives; a better diagnosis is expected regarding the water quality assessment. This investigation aims to undertake a comprehensive study of water quality by implementing the WQI and TSI indices, considering physical, chemical, and biological parameters with respect to eutrophication and ecological considerations for three reservoirs in the Puerto Rico, providing information regarding the quality of water and trophic state of the chosen reservoirs. Overall WQI results revealed that the water quality improved after the Hurricane Fiona’s occurrence. Trophic State Index after the hurricane showed slight fluctuations in the reservoirs.

Assessment of Physicochemical Properties of Water and Public Perceptions of Water Quality in Tasik Chini, Pahang, Malaysia

The study was conducted to evaluate the physicochemical parameters of water and assess the public perception of the water quality status in the Tasik Chini watershed based on a community survey. The water sample was analyzed based on standard methods and categorized according to WQI (Water Quality Index). Multivariate statistical analysis was adopted to find spatial variations in water quality, determining the pollution level and sources of contamination. The study results were compared with NWQS (National Water Quality Standard for Malaysia). The results showed that the value of dissolved oxygen (DO) was low (4.68 mg.L-1), while the level of biological oxygen demand (BOD), chemical oxygen demand (COD), and total dissolved solids (TDS) was found to be high, 2.92 mg.L-1, 26.10 mg.L-1 and 22.93 mg.L-1 respectively. High turbidity was recorded in a mining area in the rainy season (35.76 NTU). The DOE-WQI value categorized the lake under class II and class III. The Principal Component Analysis (PCA) revealed that the major sources of contamination were due to anthropogenic activities, especially settlement, mining, agriculture, and illegal activities. Overall, Tasik Chini’s water quality status was classified as slightly polluted to highly polluted based on hierarchical cluster analysis (CA) results. The survey showed that 55% of the local community reported that the water quality was poor. The knowledge and attitude level of the local people was medium category, while community practice was low. The Pearson correlation coefficient test showed a strong significant relationship at 0.01 level between knowledge and attitude and knowledge and practices. The scientific findings with public perceptions might be useful for policymakers and the general public to improve the management system for a desirable future.

Statistical analysis of water quality and cyclone impacts along the south Odisha coast, east coast of India

Water quality along south Odisha coast (25km stretch), east coast of India was studied collecting monthly samples at 10 different sampling stations from June 2008 to March 2011 and June 2012 to May 2017. The samples were analysed for salinity, dissolved oxygen (DO), total suspended solids (TSS) and pH. In addition, river discharge, siltation, rainfall and wind speed data were also collected from 2008 to 2017 at the study region and their impacts on coastal water quality were assessed along with the impacts of cyclonic storms. Anomalies of water quality parameters and their seasonal variability were assessed. Spatio-temporal variation of these parameters and multivariate statistical techniques such as factor analysis, correlation coefficient and, descriptive statistics were applied to the observed datasets. Results indicate that, salinity is positively correlated with wind speed at 0.05 significance level while negatively correlated with river discharge. TSS is positively correlated with siltation at 0.01 significance level. DO values are also positively correlated with strong wind speed. Nutrient driven primary production helps pH to be higher at Rushikulya river mouth during monsoon and post-monsoon as compared to at all other stations. Throughout the year, the study environment remains alkaline. Due to impacts of cyclonic storms, water quality parameters show significant reduction in salinity and enhancement in TSS, DO and pH during the post-cyclone period while the seasonal trend is maintained during the pre-cyclone period. Factor analysis reveals the factors controlling the hydrographic behaviour of seawater. The spatial variation in coastal water quality is very high and dominates over the temporal variation. Importance of coastal water quality assessment in relation to coastal ecosystem and disaster is discussed.

Global Trends in Research on Microplastic Contamination and River Water Quality: A Bibliometric Review

ABSTRACT This study aims to analyse global trends in research related to microplastic contamination and river water quality using a bibliometric approach. Microplastics have become one of the most pressing environmental issues in recent decades, mainly due to their significant impact on aquatic ecosystems and potential harm to human health. Along with the increasing attention to this issue, the scientific literature related to microplastics and river water quality has grown rapidly. However, a thorough understanding of the distribution of research, relationships between topics, as well as potential research gaps is still needed to direct future research more effectively. This study used a literature search method through the Publish or Perish app, with keywords including "microplastics," "water quality," "water pollution," "microplastic contamination," and "river." The search was conducted from 2014 to 2024, resulting in 50 relevant articles for further analysis. The data obtained was then processed using VOSviewer to map and visualise the bibliometric network, identify key clusters, and evaluate the temporal progression of these research topics. The resulting visualisations, including network visualisation, overlay visualisation, and density visualisation, provide deep insights into how key terms are connected and evolve in the literature. The analysis showed that research on microplastics in the context of rivers and water quality is heavily dominated by a few key terms such as "microplastic," "river," and "water," indicating the high level of scientific attention on this topic. In addition, it was found that research often focuses on the distribution of microplastics, physicochemical parameters of water, and sources of contamination. However, there are some significant research gaps, especially related to the effect of salinity on microplastic distribution, the accumulation of microplastics in river sediments, and the role of wastewater treatment plants in preventing the spread of microplastics to aquatic ecosystems. The conclusion of this study is that despite significant progress in understanding the distribution and impacts of microplastics, many aspects still require further research. In particular, research on the long-term impacts of microplastics and their interactions with other environmental components should be further enhanced. The findings are expected to provide guidance for future researchers to explore under-explored areas and contribute to better environmental management. Keywords: Microplastic, Water Quality, River Pollution, Bibliometric Analysis, Environmental Research

Insight into groundwater quality change before and after the 2016 Kumamoto earthquake

The Kumamoto Earthquake is named after the Kumamoto Prefecture where the series of earthquakes occurred in the city located on the island of Kyushu, in southwest Japan.In this area, 100 % of the population depends on groundwater for drinking water; hence, groundwater is an extremely important lifeline for people. The effect of earthquakes on the water quality of groundwater has been suggested based on monitoring data measured by public agencies once or twice a year. Frequent water quality monitoring of the groundwater in the Kumamoto area has continued once a month for six years since 2014. In this study, we aimed to statistically evaluate the changes in groundwater quality caused by the 2016 earthquake and provide further insights into its mechanisms. The Stiff diagrams using major ionic components showed no apparent overall water quality change before and after the earthquake for 14 groundwater samples in the area. However, statistically significant changes were indicated for 11 samples by k-medoids clustering (non-hierarchical cluster analysis), divided into two clusters before and after the earthquake. In addition, the samples showing water quality changes did not vary even over the four years after the earthquake, indicating that the change was not temporal. The magnitude and trend of the change in individual water quality parameters depended on the sampling sites, while some parameters, such as nitrate, showed seasonal fluctuations due to precipitation conditions more than the effect of the earthquake. No particular relationship was found between the distance from the sampling sites to the epicenters or active faults and the degree of water quality changes. Finally, it was considered that the aquifer breaching/fluid mixing model (AB/FM model), through the change in the bleeding channel of water due to seismic shaking, most likely explains the main mechanism of water quality change in groundwater in the Kumamoto area.

FISH ABUNDANCE AND DIVERSITY AS BIOINDICATOR OF WATER QUALITY IN SENGGURUH AND KARANGKATES RESERVOIR

Reservoirs serve as beneficial recreation areas for the surrounding community. Reservoirs are also habitats for various types of flora and fauna. Severalfamous reservoirs in East Java due to their fisheries potential are Sengguruh and Karangkates Reservoirs. This study aimed to determine the abundance and diversity of fish as bioindicators of water quality in Sengguruh and Karangkates Reservoirs. Fish and water quality parameters weresampled at three points in each reservoir, namely residential, tourism, and fisheries areas. All data were analyzed descriptively, while the correlations between fish abundance and diversity with water quality were determined using the Pearson’s correlation test. According to the results, three fishfamilies were found in Sengguruh Reservoir with a relative abundance of 26 - 55 ind/200 m and a diversity index ranging from 1.6510 to 1.7239. Meanwhile, in Karangkates Reservoir, four fishfamilies were found with a relative abundance of 41-43 ind/m and a diversity index of 1.7806 - 1.8787. The water quality parameters showed temperature of26-28.7℃, pH of 7.5-8.5, DO of 4.5-8.2 mg/L, CODof 20-28 mg/L, ammonia of 0.18-0.77 mg/L, and nitrate of 6.7 - 21 mg/L. Based on the diversity index value, both reservoirs are classified as lightly polluted, with abundance variables have no correlation with temperature, yet negative correlation is presented with DO, pH, and nitrate. In contrast, a positive correlation is shown with phosphate and ammonia.