Levels and ecological risk of heavy metals in the surface sediments of tidal flats along the North Jiangsu coast, China

We investigated the contamination levels of nine heavy metals (Mn, Pb, V, Cr, Co, Ni, Cu, Zn, and As) in 153 surface sediment samples collected along five tidal flats on the North Jiangsu coast, China. The spatial distributions of most heavy metals gradually decreased from the northern Sheyang region to the southern Jianggang region, while slightly increasing in the Rudong region. Principal component analysis indicated that Co, Ni, Cu, Zn, and As were mainly derived from the natural environment, V and Cr were mainly derived from human activities. Additionally, Mn and Pb influenced by both natural and human sources. The geo-accumulation index and the contamination factor indicated that heavy metal contamination in the sediments exhibited little to no pollution levels. The potential ecological risk index exhibiting low ecological risks. Meanwhile, the mean probable effect level quotient values indicating slight toxicity. Cr and Ni were the major contributors to toxicity.