Potential Toxic Elements in the Sediments of an Urban River Near Industrial Areas of Bangladesh: Pollution Status, Source Identification and Environmental Risk Assessment

Abstract

Sediments of urban river near industrial regions are increasingly polluted by potential toxic elements (PTEs), posing severe impact on aquatic ecosystems and human health. This study investigated the distribution, pollution status, source identification, and ecological and human health risks of PTEs in the sediments of the Tongi Khal, a heavily industrialized urban river of Bangladesh. The concentrations of PTEs (i.e., As, Pb, Cd, Cr, Ni, Cu, Zn, Hg, Mn, and Co) were determined using ICP-MS, while the pollution status, source identification, ecological and human health implications were assessed using various established indices and multivariate statistical analyses. The results revealed that the mean concentrations of several PTEs, including Ni, Hg, Zn, Cr, Cd, and Cu surpassed the TEL level. Notably, Ni (79.71 mg/kg), Hg (1.55 mg/kg), and Zn (371.2 mg/kg) are in alarming concern, exceeding both the TEL and PEL levels. The I_geo values indicate that As, Pb, Cr, Hg, Co, and Mn are largely in unpolluted to moderately polluted category. Mercury (Hg) showed extremely high enrichment, with EF values ranging from 0.43 to 53.99, while Zn (2.12) showed the most substantial contamination concerning CF values, demonstrating a significant anthropogenic contribution. The composite pollution indices, such as MCD and PLI demonstrated low to moderate degree of pollution among majority of the sampling sites. The ERI values ranged from 40.738 to 940.801, indicating moderate to high ecological risks in Tongi Khal sediment. Multivariate statistical analyses, such as PCA and HCA revealed industrial effluents and urban runoff as the key sources of contamination. The HI values indicated children have higher susceptibility to non-carcinogenic risks than adults, while CR values reflected Cr and Pb as the major contributor to pose carcinogenic risks, particularly for children. This study delivers valuable insights into the extent of pollution, its sources, and the potential risks posed by PTEs in Tongi Khal, highlighting the necessity of improved environmental management strategies.