Seasonal and spatial variations of acid-volatile sulphide and simultaneously extracted metals in the Yangtze River Estuary

Abstract

Surface sediments were collected from the Yangtze River Estuary (YRE) in to analyse the seasonal and spatial distributions of acid-volatile sulphide (AVS), simultaneously extracted metals (SEM) and the sediment toxicity. An optimised method was used for the AVS and SEM analysis and the results showed that the seasonal variations of AVS were positively correlated with changes in water temperature and the position of higher AVS was relatively fixed. The average of SEM was gradually increased from May 2012 to February 2013 and there were abnormally high values of SEM Cu and SEM Ni in the YRE. Concentrations of the five SEM components were in the following order: Cd < Pb < Cu ≈ Ni < Zn. The correlations among the concentrations of the five metals suggested that these metals in the sediments of the YRE did not have stable anthropogenic and/or natural origin. The mean values of AVS and SEM in the YRE were closer to those in the Huanghe Estuary and were lower than those in the Pearl River Estuary. The results of two sediment toxicity assessments showed that the sediments of most areas in the YRE had potential sediment toxicities, especially the Ni and Cu contamination.

Sulfate reduction and alterability of sulfur species in sediments of an estuary with irregular hydrological regime

“…Those factors lead to an increase of metals, sulfate ion, and organic matter, which facilitates sulfate reduction and, consequently, metal sulfide formation in bottom sediments (Jørgensen and Kasten, 2005). Under such conditions, other variables such as temperature and bioturbation/bioirrigation must be included to better understand the sulfate reduction intensity and zonation, as well as local and temporal variations of sulfides in sediments (Marvin-DiPasquale and Capone, 1998;Panutrakul et al, 2001;Marvin-DiPasquale et al, 2003;Koretsky et al, 2008;Yang et al, 2013;Wang et al, 2015).…”