Spatial Distribution and Potential Health Risks of Arsenic (As) and Associated Metals (Fe and Mn) in the Coastal Accreted Land of Meghna River Estuary and Their Implication on the Agricultural Aspects.

Arsenic (As),iron (Fe), and manganese (Mn) pollution in the coastal areas of Bangladesh are severe problems. by shallow wells in the agricultural lands is the primary source of these metals. Being a part of the Ganges, Brahmaputra, and Meghna (GBM) Delta, the coastal accreted land of the Meghna River estuary has experienced a series of erosion and accretion phenomena and deposited a vast amount of sediments along with potentially toxic elements. This study investigated the spatial distribution, source, fate, and potential environmental and human health risks of As, Fe, and Mn from 25 sites across the coastal accreted land in the lower Meghna River estuary, Bay of Bengal. The mean concentration of As, Fe, and Mn in the surface soil samples ranged from 0.1-5.16, 12,000-23,810, and 50.6-1025.12 mg/kg, respectively, where high concentrations of metals were found in the southern belt of the estuary. A high As concentration (> 2 mg/kg) was observed at stations 3-4, 15, and 17. Igeo values of As, Fe, and Mn were estimated as -1.05, -0.50, and -0.55, respectively. The Igeo values analyzed in the sediments were below zero for all the metals, suggesting no contamination from these metals. The pollution load index (PLI) for As, Fe, and Mn was lower than the contamination level, indicating that contamination levels remain below harmful thresholds but require regular monitoring. Potential ecological risk index (PERI) values (1.32-10.75) showed low ecological risks in the studied area. Moreover, "no risk" to "low level" of carcinogenic risk was identified. According to the threshold values, except in the southern belt (stations 3-4, 15, and 17), most of the accreted agricultural land can be considered adequately safe for food production. This study suggests that plant analyses be incorporated into future research; however, it would be more impactful to emphasize bioavailability studies and their relevance to agricultural safety.