The assessment of localized remobilization and geochemical process of 14 metals at sediment/water interface (SWI) of Yingkou coast (China) by diffusive gradients in thin films (DGT)

Abstract

A passive sampling technique—diffusive gradients in thin films (DGT) was used to determine profiles of 14 metals on fine scale at SWI of two sites in Yingkou coast and to investigate biogeochemical process of Mn/Fe and other metals. Based on DGT concentration/flux and biogeochemical mechanism, remobilization character of metals in sediment profile was studied. Both profiles of two sites indicated sharp peaks of Fe and Mn at anoxic sediment, which verified redox process of Fe/Mn with large fluxes. Especially, very large peaks of Mn at −9.75 cm (7.239 × 10−4 µg cm−2 s−1) and Fe at −9.25 cm (1.420 × 10−3 µg cm−2 s−1) at site 2 corresponding with sulfide concentrations at same depths in profile were used for the calculation of saturation index to assess the solubility of metal sulfide. Other metals in certain segments of profiles at two sites indicated coupled geochemical process between them and Fe/Mn. DGT probe should be a reliable tool to measure multi-metals in sediment porewater and to assess geochemical process in coastal area.