Multi-media compartments for assessing ecological and health risks from concurrent exposure to multiple contaminants on Bhola Island, Bangladesh

Abstract

In this study, a set of coupled multi-media compartments (i.e., sediment, soil, water and vegetable) was used to assess ecological and health risks from the ingestion of 11 PTEs (Pb, Cd, Cr, As, Hg, Cu, Zn, Ni, Co, Fe, and Mn) and their transportation routes in the water-soil-plant system from the coastal Bhola Island, Bangladesh. The mean concentrations of Cd, Pb, and Co for soil and Cd, Co, and As for sediment were higher than their reference values. In contrast, Cd, Pb, and Ni concentrations in water surpassed the acceptable limits set by national and international laws and were considered unsuitable for drinking purposes. Vegetables demonstrated high Pb and Cd contents, demonstrating a potential food safety risk to the inhabitants. Results of principal component analysis (PCA) revealed that Cd, Pb, Hg, Cu, Ni and Zn sources were likely to be anthropogenic, especially agro-farming inputs, whereas the Fe, As, Cr, Mn, and Co sources were similar to natural origin. So, Cd, Pb and Co are the key contaminants in the study area and pose the elevated health and ecological risks in the coastal area. Cd and Pb exhibited higher ecological risks in soils and sediments, as Pb had the highest bio-accessibility (BA; 0.02 ± 0.003) and Cd possessed a high bioaccumulation factor (BCF; 0.004 ± 0.006). The self-organizing map analysis recognized three spatial patterns which are good agreement with PCA. The average hazard index (HI) values for soil were above the permissible level (HI > 1) set by the respective agency; two times higher HI values were noticed for children than adults, suggesting children are highly susceptible to health risk. Continuous monitoring and source controls for Cd and Pb, along with agro-farming management practices, need to be implemented to reduce the risk of PTE contamination to the aquatic ecosystem and its inhabitants.