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Eight heavy metal concentrations were analyzed from a 60.35-m-long sediment core in the Jiangsu intertidal area, China. Based on the lithofacies characteristics, mean grain size, downcore distributions of elements, and accelerator mass spectrometry (AMS) 14C and optically stimulated luminescence (OSL) data, the sediments in the core were divided into three units that formed during marine isotope stages 4 (MIS 4), MIS 3, and MIS 1. Except for Cd, all the other heavy metals had the lowest average concentrations in U3, which formed during MIS 4 with the coarsest sediment, representing a fluvial deposit. Most of the heavy metals were positively correlated with Al, Fe, and the total organic carbon (TOC), indicating these metals had the same sources. Pearson's correlation coefficient, enrichment factor, geoaccumulation index, and principal component analysis suggested that there was no element enrichment or contamination in the core sediments and that all heavy metals were naturally sourced. • Apart from Cd and As, all other metals had similar vertical distribution patterns. • Trace metals geochemical sources were natural sourced over the study geologic period. • All the metals showed no enrichment and pollution in the core sediments. [ABSTRACT FROM AUTHOR]

A total of 25 surface sediment samples collected from Laoshan Bay, China, during 2018, were analyzed for heavy metal concentrations, sources, and pollution status. The Cu, Zn, and Cr distributions were similar, whereas the distributions of other metals and the total organic carbon (TOC) content were irregular, and high concentrations appeared in one or two areas. Pearson's correlation coefficient, the geoaccumulation index, and principal component analysis were used to distinguish the sources and assess the pollution risk of heavy metals. The results showed that the surface sediments in Laoshan Bay were not polluted by Cu, Zn, Cr, or As, but were unpolluted to strongly polluted with Pb, Cd, and Hg. Cu, Zn, Cr, and As were mainly derived from natural sources; Pb and Cd were mainly derived from anthropogenic sources; and Hg may have had compound sources. • Spatial distributions and pollution status of seven heavy metals were assessed. • Multiple indices of Cu, Zn, Cr, and As suggested their natural sources. • High I geo values for Pb, Cd, and Hg indicated their anthropogenic sources. [ABSTRACT FROM AUTHOR]

Abstract The heavy metals (Cu, Cr, Zn, Cd, Pb) were analysed for 217 surface sediment samples collected across 14 typical intertidal zone areas in China. The data reveals the heavy metals spatial distribution patterns and correlations among their concentrations. Cu, Zn, Cd and Cr showed similar trends of spatial variation and the correlations between the concentrations of every two heavy metals were significantly positive except for the correlation between Pb and Cr concentrations. By using Nemerow index method, Enrichment factor and Sediment Quality Guidelines, it is found that Hangzhou Bay and Jiulong River Estuary were polluted, Yingluo Bay and Dongzhaigang Bay were Cd-rich areas. Except Beidaihe shoal, Sishili Bay and Yingluo Bay that were not exposed to any ecological risk of heavy metals and had no adverse biotoxic effects, the other 11 typical intertidal zone areas were exposed to moderate ecological risk of heavy metals in the sediment with potential adverse biotoxic effects. Highlights • The ecological risk of 14 typical areas across China heavy metals was assessed by using multiple methods. • The survey sites were classified into five bays and six typical estuaries to compare differences heavy metal concentrations. • Heavy metals Cu, Zn, Cd and Cr in intertidal zone environments of 14 typical areas showed similar trends of spatial variation. • High-value heavy metals were located in East China Sea and the second highest value appeared in Bohai intertidal zone area. [ABSTRACT FROM AUTHOR]