This study evaluated the heavy metal pollution level of tannery effluent-affected lagoon and canal water in the southwestern Dhaka, Bangladesh. The measured physicochemical parameters (electrical conductivity, chemical oxygen demand, pH, SO²⁻₄, PO³⁻₄, Cl-, and NO⁻₃) and metals (As, Ca, Cd, Co, Cr, Cu, Fe, K, Mn, Ni, Pb, and Zn) were subjected to principal component (PCA) and hierarchical cluster analyses, and examining correlation matrix as well in order to explain the behavior and sources of the parameters/metals. The mean concentrations of the heavy metals in the lagoon and canal water were very high and, in most cases, exceeded the standard limits recommended by the Bangladesh Government. The following elemental associations were obtained from PCA and CA: Ca-Cd-Cr-Fe-K-Mn-Pb-Zn, Co-Cu-Ni, and As, which could be linked to anthropogenic sources (i.e., processes of the tannery and paint industries with some contributions from the municipal waste system). Potassium, Ca, Cr, Mn, Fe, Zn, As, and Cd occurred as important anthropogenic markers in the lagoons and lower part of the canal. Copper, Co, and Ni were importantly distributed in the lower part of the canal, which also received metal inputs from the municipal waste and other industrial sources, including paint industry. GIS-based factor score maps, generated to show the spatial controls of the major processes affecting surface water hydrochemistry, suggest that the activities of paint and tannery industries and municipal sewage are pervasive processes in the area, whereas the contribution from pesticides (used for tanning and disinfecting hides) has localized effects. This study has provided the evidence that effluents discharged from the tannery and auxiliary industries and urban sewage system are the main sources of heavy metal pollution in the lagoon and canal water systems in the Hazaribagh area of southwestern Dhaka. The high mean concentrations (in mg/l) of Cr (5.27), Pb (0.81), As (0.59), and Cd (0.13) observed in the water samples may have serious public health and potential environmental hazard implications.
This study deals with the natural and anthropogenic processes that influence the surface water quality in the central Bangladesh using multivariate statistical techniques.
We present precipitation isotope data (δ2H and δ18O values) from 19 stations across the tropics collected from 2012 to 2017 under the Coordinated Research Project F31004 sponsored by the International Atomic Energy Agency. Rainfall samples were collected daily and analysed for stable isotopic ratios of oxygen and hydrogen by participating laboratories following a common analytical framework. We also calculated daily mean stratiform rainfall area fractions around each station over an area of 5° x 5° longitude/latitude based on TRMM/GPM satellite data. Isotope time series, along with information on rainfall amount and stratiform/convective proportions provide a valuable tool for rainfall characterisation and to improve the ability of isotope-enabled Global Circulation Models to predict variability and availability of inputs to fresh water resources across the tropics.
Groundwater quality study of the Birimian, Cape Coast granitoid and the Densu River have been carried out using Water Quality Index (WQI) and multivariate statistics with the aim of determining their suitability for drinking and irrigation. The results showed that the Cape Coast granitoid generally had elevated values of dissolved ions as compared to the Birimian and surface waters. The WQI values were found ranging from 0 to 50 belonging to "excellent" and "good" water quality. The visualization of the WQI distributions using GIS software suggests point source pollution to areas of deteriorating water quality. Chemical indices like percentage of sodium (Na%), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), and permeability index (PI) indicate that the groundwater in the study area are suitable for irrigation. Cluster and Principal Component Analysis with varimax rotation were also used as a complementary tool to help organize and interpret the chemical analysis. Four principal components with eigen-values greater than unity accounting for 73.16% of the variability in the data were delineated. The factor score plot also separated the polluted areas and identified areas with potential deteriorating water quality. Even though the geology is the main factor controlling the presence of the dissolved ions, the study shows an increase in anthropogenic contributions in some areas.
Stable isotopes of oxygen-18 and deuterium content in groundwater, surface water and rainfall in the northern part of the Densu river basin were studied with the main aim of identifying the origin and sources of ions in the groundwater in the area. The conversion of stable isotopes to d-excess was also exploited as a complementary tool to understand the processes of recharge. A comparison of the isotopic data with the rainfall, Local Meteoric Water Line (LMWL) and Global Meteoric Water Line (GMWL) indicates that the groundwater in the study area is mainly meteoric with few groundwater and all the surface water showing an evidence of evaporation. The study has also shown that, mineral dissolution from the geology is the main factor controlling the chemistry of the groundwater with evaporation having a minimal effect. The d-excess values show that the groundwater has undergone dilution with the rainfall and this is observed from the decrease of the d-excess of the groundwater with increase in Oxygen-18. This observation also suggests a modern day recharge to the groundwater
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