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Groundwater is one of the most valuable natural resources, and the most dependable source of fresh water. For sustainable groundwater management, the present study aimed to model groundwater potential zones in the north–central region of Bangladesh using GIS, remote sensing, and the analytical hierarchy process. The present study included eight thematic layers: lineament density, geomorphology, soil types, slope, land use/land cover, drainage density, elevation, and rainfall features to delineate a groundwater potential zone of the area. Integration of the eight thematic layers was performed through weighted overlay analysis, which assisted in delineating groundwater potential zones. This simple and systematic method successfully provides a satisfactory result concerning the delineation of groundwater potential zones. The study resulted in a groundwater potential zone map, which identifies about 11.51% of the study area as being under a very high groundwater potential zone, covering an area of 504.09 km2. The AHP analysis shows that the physiographical parameters, such as lineament density, slope, and drainage density, and meteorological factors such as annual rainfall, have greater influence over groundwater potentiality. The result obtained from the weighted overlay analysis was verified with actual well yield and groundwater depth data, which show a significant positive correlation. The outcome of the study will help in taking effective measures to ensure sustainable use and extraction of groundwater in this region. [ABSTRACT FROM AUTHOR]

Trace metal contamination in sediments is a global concern. This study aimed to assess the contamination level of trace metals, their sources, and ecological risk in surface sediments of Karnaphuli River—a tropical urban river in Bangladesh. Forty-five sediment samples were analyzed by atomic absorption spectrophotometry (AAS) for Cu, Fe, Zn, Pb, Cr, Cd, and Ni metals along with physicochemical parameters like pH and organic matter (OM). The pollution status and potential ecological risk were assessed by using the geo-accumulation index (Igeo), contamination factor (CF), and potential ecological risk index (PERI). Source identification of trace metals was performed by correlation analysis, cluster analysis, and principal component analysis (PCA). The results show that the range of Cu, Fe, Zn, Pb, Cr, Cd, and Ni concentrations were 0.62–1.61 mg/kg, 23.95–85.70%, 0.52–1.89 mg/kg, 7.99–12.90 mg/kg, 33.91–65.47 mg/kg, 0.77–1.17 mg/kg, and 2.73–5.36 mg/kg, respectively. The concentrations of Fe, Cd, and Cr were above the permissible limits while the contamination factor (CF) and geo-accumulation index (Igeo) values revealed that Fe and Cd were the most dominant pollutants. Cluster analysis and PERI exhibited significant anthropogenic intrusions of trace metals. A significant positive correlation between Fe-Cr, Cr-Ni, Fe-Ni, and Pb-Cd shows their common anthropogenic source and influences. PERI also revealed that Cr, Fe, and Cd have a significant contribution with a moderate to considerable potential threat. [ABSTRACT FROM AUTHOR]

The rapid growth of industrial and agricultural activities in Malaysia are leading to the impairment of most of the rivers in recent years through realising various trace metals. This leads to toxicity, particularly when the toxic has entered the food chain. Perak River is one of the most dynamic rivers for the Malaysian population. Therefore, in consideration of the safety issue, this study was conducted to assess the concentration of such metals (Cd, Cu, Zn, Fe, and Pb) in the muscles of most widely consumed fish species (Barbonymus schwanenfeldii, Puntius bulum, Puntius daruphani, Hexanematichthys sagor, Channa striatus, Mystacoleucus marginatus, and Devario regina) from different locations of Perak River, Malaysia by employing inductively coupled plasma optical emission spectroscopy (ICP-OES). Among the trace metals, Fe and Cd were found to be the highest (29.33–148.01 μg/g) and lowest (0.16–0.49 μg/g) concentration in all of the studied species, respectively. Although the estimated daily intakes (μg/kg/day) of Cd (0.65–0.85), Fe (79.27–352.00) and Pb (0.95–12.17) were higher than their reference, the total target hazard quotients values suggested that the local residents would not experience any adverse health effects from its consumption. In contrast, the target cancer risk value suggested that all fish species posed a potential cancer risk due to Cd and cumulative cancer risk values, strongly implying that continuous consumption of studied fish species would cause cancer development to its consumers. [ABSTRACT FROM AUTHOR]

Corbicula fluminea has been a traditional food for the locals from both Kelantan and Southern Thailand. However, the ecology of C. fluminea has not been fully explored in Malaysia and also in Southern Thailand. The objective of this study is to compare the size and density of C. fluminea in Pattani and Saiburi rivers. C. fluminea were sampled in two different rivers at Southern Thailand; Pattani River and Saiburi River. The water quality parameters measured are dissolved oxygen, pH, temperature and the nutrient analysis of phosphate and nitrate. Both rivers have a suitable pH levels range (6.53-6.7), temperature range (31-34°C) and dissolved oxygen (3.3-8.1 mg/L) that ensure the survival of C. fluminea. C. fluminea were collected and measured its shell length which is most abundant in length size 11-20 mm. The highest density of C. fluminea recorded at Pattani River was 369 clams per m2 while only 196 per m2 at Saiburi River. The over-exploitation by the villagers at Saiburi River has caused the density of C. fluminea to differ significantly. The substrate type of these rivers were also analysed; Pattani River has sandy loam substrate while the substrate in Saiburi River is loamy sand. The availability of the phytoplankton was also identified in both rivers and overall there were 29 species from 22 different families in both rivers. This study shows that the density of C. fluminea is likely to be influenced by the water quality rather than substrate types and also the phytoplankton availability. Findings of this research are able to add to the existing database of C. fluminea nationally and internationally. [ABSTRACT FROM AUTHOR]

Study was conducted for six times from November 2008 to June 2010 to determine the effect of land use on benthic macroinvertebrate assemblages in Mengkibol, Madek and Dengar rivers. Eight stations were selected which two stations from each river except Dengar which has two sampling reach comprised of four stations. A 500 meter reach of the stream was selected for each sampling site. One sampling reach comprises of two sampling stations where one station is located at the upper reach, while the other station is situated at the lower reach. Surber Net measuring 500 micron mesh size combined with a rectangular quadrat of 30 cm x 30 cm (0.09 m²) was used to sample macroinvertebrates. The results showed that un-disturbed river has complete sensitive taxa namely Ephemeroptera, Plecoptera and Trichoptera (EPT). Mean while, there were only two sensitive taxa namely Ephemeroptera and Trichoptera were found in the river which flows through palm oil plantation. Similar scenario was found in the river which flows through logging area where there were also two sensitive taxa namely Ephemeroptera and Trichoptera found in this river. In addition, the results obtained for urban river was the other way round where there was an absent of all three sensitive taxa (EPT) in the river which flows through urban area. Most of the macroinvertebrate taxa that were found in this station are pollution resistant taxa comprised Diptera, Odonata, Mesogastropoda, Basommatophora, Hirudinea and Haplotaxida. The results can be use as a biological indicator for river water quality assessment. [ABSTRACT FROM AUTHOR]

The study was conducted to determine the effect of logging activities on water quality and benthic macroinvertebrate assemblages for the Madek River basin. The study area was situated in Kluang, Johor, Malaysia. Two sampling stations 500 meters apart are upstream and the other, downstream located at Madek River which flows through a logging area in Kluang Forest Reserve were identified. The sampling was conducted four (4) times from November 2008 to August 2009. Surber Net measuring 500 micron mesh size combined with a rectangular quadrat of 30 cm x 30 cm (0.09 m²) was used to sample the macroinvertebrates. The organisms were identified up to genus level except for Chironomidae which was only identified up to Sub-family level. For water quality, six in-situ parameters based on the standard procedure of U. S. Environmental Protection Agency were measured at each station. The parameters such as temperature, conductivity, dissolved oxygen (DO), pH, turbidity and salinity were measured using a multi parameter probe Model YSI 6920 with 650 MDS Display/Logger as well as a single parameter probe. All the physico-chemical water quality parameters were well below Class I as provided for under Interim National Water Quality Standards for Malaysia (INWQS), except turbidity which fell under Class II of the INWQS. There were only two (2) sensitive taxa namely Ephemeroptera and Trichoptera found in this station. Ephemeroptera that was found in the logging area was from genus Potamanthus, Pseudiron, Ephemerella and Rhithrogena, while Trichoptera was from genus Hydropsyche and Macrostemum. [ABSTRACT FROM AUTHOR]

Despite significant contributions to the national economy of Bangladesh, various urban developments, massive industrial and growing shipping activities are making the water of many urban rivers, including Karnaphuli River, extremely polluted. To find out the pollution sources and their possible health effects, 45 water samples were collected from 15 sampling stations. Investigation of six physicochemical parameters (pH, temperature, total dissolved solids, conductivity, salinity, and turbidity) through in-situ measurements and eight heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) status using atomic absorption spectrophotometer (AAS) was carried out in this research. Both the physicochemical parameters and heavy metals exceeded the World Health Organization (WHO)'s permeable threshold limit. The calculated hazard quotient (HQ) and hazard index (HI) ingestion values indicate non-carcinogenic risk both for adults and children, but dermal exposure was within the safety limit. Carcinogenic risk analysis revealed that Cd could cause a risk of cancer in those using the river water for a long period. Spatial analysis and metal pollution index (MPI) results exhibit that downstream of the river water is more polluted than upstream of the river. Overall, the findings of this study imply that polluted water is a threat to human health and the results will also help to undertake proper management strategies and incorporate monitoring programs that study river water for the implementation of safety measures to protect human health. [ABSTRACT FROM AUTHOR]

Atmospheric particulate matter (PM) has major threats to global health, especially in urban regions around the world. Dhaka, Narayanganj and Gazipur of Bangladesh are positioned as top ranking polluted metropolitan cities in the world. This study assessed the performance of the application of hybrid models, that is, Autoregressive Integrated Moving Average (ARIMA)-Artificial Neural Network (ANN), ARIMA-Support Vector Machine (SVM) and Principle Component Regression (PCR) along with Decision Tree (DT) and CatBoost deep learning model to predict the ambient PM2.5 concentrations. The data from January 2013 to May 2019 with 2342 observations were utilized in this study. Eighty percent of the data was used as training and the rest of the dataset was employed as testing. The performance of the models was evaluated by R2, RMSE and MAE value. Among the models, CatBoost performed best for predicting PM2.5 for all the stations. The RMSE values during the test period were 12.39 µg m−3, 13.06 µg m−3 and 12.97 µg m−3 for Dhaka, Narayanganj and Gazipur, respectively. Nonetheless, the ARIMA-ANN and DT methods also provided acceptable results. The study suggests adopting deep learning models for predicting atmospheric PM2.5 in Bangladesh. [ABSTRACT FROM AUTHOR]