Restriction of Reactive Iron to Acid Volatile Sulfides Formation in Licun Estuary Sediments of Jiaozhou Bay

In estuary environment, acid volatile sulfide (AVS) is usually one of the most important or reactive phases. 13 short column sediment cores were collected from Licun estuary of Jiaozhou Bay, and the acid volatile sulfides (AVS) of sediment samples were extracted by cold diffusion method and analyzed. The grain size, reactive iron contents, and organic carbon contents of sediment samples were also analyzed in part cores. The AVS contents of sediment vary in a large range as 0.4 ~198.4 mumol/g, with an average value of 28.1 mumol/g. Reactive iron contents range from 25.52 mumol/g to 169.26 mumol/g, with an average value of 91.22 mumol/g. Organic carbon contents are 0.4~198.4 mumol/g, with an average value of 28.1 mumol/g. Characters of high AVS, organic carbon content, and reactive iron content are obvious in three cores which close with the Licun River. And the AVS have good relationships with reactive iron content either in single core or between cores. So, the formation of AVS in the sediments is controlled by the availability of reactive iron in area near the Licun River where organic carbon is supplied from river and it´s content is abundant. The bottom water is in a reductive environment at this area. In the area which has a little distance with the Licun River, the supply of organic carbon and the changing of environment redox state become the controlling factor of AVS formation in the sediments since the organic carbon supply lessens from the Licun River. The geochemistry character of sediment in the estuary area is influenced remarkably by the material inputted form river.