Distribution and Environment Significance of Redox Sensitive Trace Elements of the Changjiang Estuary Hypoxia Zone and Its Contiguous Sea Area

Key words: 
• Hypoxia zone /
• redox sensitive trace elements /
• redox environment /
• Changjiang Estuary and its contiguous sea area

Abstract: This study discusses the distribution and enrichment characteristic of redox sensitive elements defined both the seabottom surface sediments and in suspensions off the Changjiang Estuary hypoxia zone and its contiguous sea area. The distribution of RSE “enrich off the sea shore”. The results, after getting rid of the influence of “grain size effects”, terrigenous components and adsorption by organic matter, revealed that distribution of RSE still “enrich off the sea shore”. By comparison the RSE concentration between bottom layer suspension and surface sediments, the paper believes that the hypoxia zone of the bottom water induces the RSE to enrich in sediments. The authigenic precipitation mechanism and the potential energy of Mo, Cd and V is different, their different enrichment characteristics can be used as redox indicators of the hypoxia zone. So, redox sensitive elements such as Mo, Cd and V have the redox environmental significance of the Changjiang Estuary and its contiguous sea area. U are also sensitive to redox conditions of bottom sediments theoretically, the terrigenous components of U conceal the enrichment of U in hypoxia zone, and so U have no environment significance in the hypoxia zone of the research area.