Ecological risk assessment of heavy metals in seawater and sediments in Jinghai Bay: Evidence for ecosystem degradation in a coastal bay of the Yellow Sea

Abstract

Jinghai Bay is plagued by heavy metal (HM) pollution that is likely to increase in the coming decades along with social and demographic trends. However, relatively little is known about the pollution levels and ecological risks associated with HMs in seawater and sediments of the bay, limiting our ability to assess their impacts on local aquatic environment and to develop effective management strategies. We investigated the concentrations and spatial distribution of HMs (i.e., Cu, Zn, Pb, Cd, Hg, and As) in both seawater and sediments of Jinghai Bay, focusing on their pollution levels and associated ecological risks. The HM concentrations in seawater of Jinghai Bay during the study period were ranked as follows: Zn > Cu > Pb > As > Cd > Hg, while in the sediments, the ranking was: Zn > Pb > Cu > As > Cd > Hg. The spatial distributions of Cu, Zn, Pb, Cd, Hg, and As in seawater and sediments of the bay varied largely between the spring and summer, probably owing to local environmental conditions, sediment resuspension, and anthropogenic influences. In terms of pollution levels and associated ecological risks, Cd and Hg in seawater were the primary pollutants in the bay. HMs in sediments were also present at elevated concentrations, with Cu, Pb, and Hg emerging as the most concerning pollutants, leading to potential ecological risks. The correlation analyses indicated that salinity and DO were the key factors driving the dynamics of HMs in seawater. In addition, the distinct seasonal groupings of HMs in both seawater and sediments suggested that similar anthropogenic sources and/or geochemical processes governed the levels of these metals. Collectively, assessing the concentrations, spatial distribution, and ecological risks of HMs in aquatic ecosystems is vital for understanding the impacts of human activities and natural processes and for enacting management strategies to reduce HM pollution in Jinghai Bay.

Keywords: Ecological risk; Heavy metals; Jinghai Bay; Seawater; Sediment.