The Correlations Between Mercury Speciation and Dissolved Organic Matter in the Sediment of the Red Sea

Abstract

This study addresses the correlations between Hg and organic matter in recent sediment; samples were collected from the Gulf of Aqaba, Red Sea coasts (oligotrophic regions) during 2010. In the present study TOC analyzer was used to determine Total Organic Carbon (TOC) and Total Nitrogen (TN) concentrations and the total amount of mercury (Hg_T) in sediment samples were analyzed by Hydra-C mercury analyzer. The obtained results indicated that, mercury, TOC and TN average concentrations in the Red Sea were 85.42 ng g^-1, 5.10 and 4.45 mg L^-1, respectively. The results show that the Total Organic Carbon (TOC) in sediment represents the sum of various organic compounds, which may play a completely different role in the distribution and accumulation of Hg. slightly correlations between the TOC and the concentration of Hg in the studied sediment arise mainly from the labile portion of organic matter released. These compounds primarily consist of easily degradable algal-derived lipids and various pigments, which are petrographically described as a soluble Organic Matter (OM). The preserved OM in sediment is commonly entrapped within the cell walls of phytoplankton and also appears as a surface coating on sediment particles. The strong affinity between Hg and OM is due not only to its chemical reactivity, but also to the physical characteristic of these labile compounds, which plays the most important role in the distribution of Hg in sediment.