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To assess the magnitude of water quality decline in the Turag River of Bangladesh, this study examined the seasonal variation of physicochemical parameters of water, identified potential pollution sources, and clustered the monitoring months with similar characteristics. Water samples were collected in four distinct seasons to evaluate temperature, pH, dissolved oxygen (DO) concentration, five-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), electrical conductivity (EC), chloride ion (Cl−) concentration, total alkalinity (TA), turbidity, total dissolved solids (TDS) concentration, total suspended solids (TSS) concentration, and total hardness (TH) using standard methods. The analytical results revealed that 40% of water quality indices were within the permissible limits suggested by different agencies, with the exception of EC, Cl− concentration, TA, turbidity, DO concentration, BOD5, and COD in all seasons. Statistical analyses indicated that 52% of the contrasts were significantly different at a 95% confidence interval. The factor analysis presented the best fit among the parameters, with four factors explaining 94.29% of the total variance. TDS, BOD5, COD, EC, turbidity, DO, and Cl− were mainly responsible for pollution loading and were caused by the significant amount of industrial discharge and toxicological compounds. The cluster analysis showed the seasonal change in surface water quality, which is usually an indicator of pollution from rainfall or other sources. However, the values of different physicochemical properties varied with seasons, and the highest values of pollutants were recorded in the winter. With the change in seasonal temperature and increase in rainfall, the seasonal Turag River water followed a self-refining trend as follows: rainy season > pre-winter > summer > winter.

Current research has been focused on the transfer of heavy metals (Fe, Pb, Co, Cd, V, Cu, Mo, Ni, Cr , Mn, Zn, As, Sr, Hg,) and radionuclides ( 40 K, 232 Th, 226 Ra, 238 U and 137 Cs) from soil to vegetables and plants in terms of transfer factor which is commonly used to estimate the food chain transfer of these elements and possible phytoremediation. Wide varieties of vegetables and plants and associated soils were collected from various regions of Bangladesh under actual field conditions. Contamination levels of the elements was measured and the Health Risk Index (HRI) and Plant Transfer Factor (PTF) of these elements from soil to vegetable/plant were calculated. Results reveal that there is a substantial build up of heavy metals (Mo, Sr, Fe, Cd, V, Cu, Ni, Cr , Mn, Zn , As) pollution in the soil of Bangladesh which varies with location depending on the sources. In addition, heavy metal (Fe, Sr, Ni, Zn, Cr, Mn, Pb, Cd ) content in plants grown near the industrial area showed higher values than in the non-polluted area and also exceeded the world average soil data. The HRI for heavy metals in the plants showed the order Mn > Fe > Cr > Pb > Zn > Cd > As where unsafe HRI values were found for Fe, Pb and Zn in Abelmoscus escultant and leafy vegetables indicated health risks associated with the ingestion of these contaminated vegetables to the inhabitants. The PTF value for heavy metals varied greatly with plant species and also with sampling location. A higher PTF value (0.4–4.5) was found for Mn, Zn, Cu in Enhydra fluctuans , Zea mays , Nephrolepis exaltata and Oryza sativa which could be used for phytoremediation of these metals from the contaminated soil. Conversely, the TF of the radionuclides were found in the following order: 40 K > 232 Th > 226 Ra > 238 U whereas 137 Cs was not transferred. The higher TF found in the study for all the natural radionuclides indicates that the area is a high background radiation area (HBRA) and radiologically unsafe to the inhabitants due to the harmful effects of ionizing radiation from natural radionuclides in soil.