Heavy Metal Contamination and Health Risk Assessment in the Meghna River Estuary During Monsoon

Author: Md. Ashik Ullah, Sadia Haque Sadi, Md. Omur Faruk, K M Azam Chowdhury, Erfanul Haque Chowdhury Albin
DOI: doi.org/10.70279/bmj-v2-1102

The estuarine region, due to its transitional location and dynamic physiochemical influ ences on component distribution, is very susceptible to heavy metal pollution. This study investigates the spatial and vertical distribution of 11 heavy metals (Al, As, B, Ba, Cu, Fe, Mn, Ni, Pb, Sr, Zn) during monsoon in the Meghna River estuary, the possible contributing geochemical processes and associated health risks. Samples were procured from bottom and surface of five stations from the river and analyzed for their concentration. Results unraveled, the bottom waters in upstream favored the resuspension of metals like Fe, Mn and Al, presumably impacted by slightly acidic conditions. On the other hand, Sr and B concentrated in the downstream stations possibly enhanced by increased salinity. Cu and Ni showed trivial presence in the sample waters and Zn and Ba had medium concentra tions, which increased slightly at the bottom samples in downstream. Distribution patterns and Principal Component Analysis revealed, altogether the elements are distributed by hydrodynamic sorting, estuarine mixing and sediment-water interactions. Risk assessment results indicate that non-carcinogenic risks are mainly associated with the oral exposure pathway, with Al and As contributing most strongly to elevated hazard indices at several stations, whereas dermal exposure posed negligible risk across the study area. Carcino genic risk estimates suggest that As is the dominant contributor, with cumulative risk values exceeding the commonly accepted guideline at selected stations. Given the limited spatial and temporal coverage of the study, these findings should be regarded as indicative and highlight the need for continued monitoring and more comprehensive investigations to better understand the processes controlling heavy metal distribution and associated health risks in the Meghna River estuary. Risk assessment and indices revealed immense non-car cinogenic risks as Hazard Index exceeded the threshold in all the stations, primarily due to Al, As and Pb. Arsenic concentration surpassed the permitted threshold level in almost every sample raising the Carcinogenic Risks over the acceptable limits. The study under scores the need for urgent need for mitigation strategies, along with comprehensive studies to delineate the contribution of geogenic and physiochemical processes responsible for element distribution, to safeguard the health of populations reliant on the Meghna estuary.