The Yellow Sea Large Marine Ecosystem (YSLME) is an important socioeconomic zone in Asia, but has been deteriorated by various environmental pollutants over the last half century. However, comprehensive coastal pollution assessments, particularly for heavy metals (HMs), have been limited from an international perspective. Here, we first evaluate coastal HM pollution in sediment and water from 119 riverine, estuarine, and marine locations along the BS and Yellow Sea to perform a comparative assessment between the two countries of China and South Korea. The occurrence, distribution, sources, multimedia fate, interactions, associated environmental factors, and potential ecological risks relating to the HM pollution are widely addressed. Eight typical HMs (As, Hg, Zn, Cu, Pb, Cd, Cr, and Ni) were targeted in both sediments and water, and in situ water properties (pH, dissolved oxygen, salinity, and temperature) and sediment properties (pH and organic matter (OM) content) were analyzed. The results indicated that As, Cd, Cr, Cu, Ni, and Pb concentrations in water were higher in the estuarine area than those in riverine and marine areas and that particularly severe HM pollution was evidenced in the BS. The dominant elements in pollution hot spots varied greatly among the countries and regions. According to the geo-accumulation index (Igeo) and pollution load index (PLI) values, the sediments exhibited high Hg and Pb pollution in the BS; high As, Hg, and Pb pollution in the Yellow Sea of China; and high Cd and Hg pollution in the Yellow Sea of South Korea. In general, the sediments were moderately contaminated by HMs based on the high PLI (>1.0) and risk index (RI) values (>160). Ni and Cr in the sediment mainly originated from geogenic sources, while the other elements (Zn, As, Cd, Cu, Hg, and Pb) were primarily linked to anthropogenic sources. Based on the partial redundancy analysis, we found that environmental factors, especially OM, contributed significantly to the concentrations of HMs in both the sediments and water. The sediment HMs significantly contributed to the waterborne HMs due to their release from the sediments to the water column. An overall assessment of the contamination status, spatial distribution, and potential sources of HMs suggested that the water-sediment interaction of HMs and the influence by environmental factors should be subsequently considered for a better understanding of the multimedia fate of HMs in the given dynamic YSLME system or similar environments elsewhere.

Heavy metal pollution from various industrial activities has raised global concern. The present study collected 71 surface and 67 subsurface soils from the area with intensive industrial activities in South China. The typical heavy metals, including Cd, As, Hg, Cu, Ni, Pb, Zn, and Cr concentrations, were detected for studying their spatial distribution patterns. Sources apportionment and risks were analyzed using geographical information system and combined approach, including principal component analysis (PCA), positive matrix factorization (PMF), and geo-accumulation index. The concentrations of Cd, As, Hg, Cu, Ni, Pb, and Zn (except Cr) were higher than relevant background levels while exhibiting different pollution degrees in surface and subsurface soils. The PMF results showed that agriculture, industry, transportation, and nature were the four primary contributing sources of heavy metals in soils from the study area. In general, anthropogenic activities were the dominant factors, significantly influencing heavy metal distributions in surface and subsurface soils. Health risks of heavy metals in soil to the population via soil inhalation, skin contact, and ingestion indicated the non-carcinogenic and carcinogenic risks were at an unacceptable level. Each exposure route contribution is higher for adults than for children, whereas there is a relatively high risk of cancer for adults than for children. Therefore, increasing attention shall be needed for monitoring the heavy metal pollution in soils in the areas with dramatic economic development, e.g., South China.