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.

Methyl Mercury Exposure through Seafood Diet and Its Effect on Aquatic Life and Health in United Arab Emirates

“…Although some research has suggested that the structure of DOM may have an indirect impact on the rate of Hg photoreactions; however the exact mechanism of DOM is unknown that facilitates mercury reduction (O'Driscoll et al, 2006). A study conducted by Wedyan, Ababneh, and Al-Rousan (2012) established the fact that there is strong affinity between organic matter and mercury which is primarily related to the physical characteristic of these compounds and not to their chemical reactivity, these physical characteristics play the most significant role in the Hg distribution in the sediments. DOM facilitates the mobility of Hg across the column of water and sediment and also results in enhanced sequestration and concentrations of mercury in sediments (Wallschlager et al, 1996;Cossa & Gobeil, 2000).…”

“…The DOM in these sediments are consumed by different types of bacteria, as the mercury deposited under new layers of sediments and these bacteria live few millimeters under the water interface, a level where oxygen cannot reach. Chemical reactions that involve iron and sulfur are the source of energy for bacteria and these reactions also generate toxic byproduct which is methylmercury (Wedyan, Ababneh, & Al-Rousan, 2012). Accumulation of mercury in fish is a public health concern globally, reason being fishes are the primary source of toxic MeHg to humans.…”