Distribution of Organic Matter, Iron, Mangenese in Surface Sediments in the Nansha Islands Sea Area, South China Sea

摘要

Concentrations of organic matter, iron and manganese in the deep sea surface sediments in the Nansha Islands sea area, South China Sea are measured. Horizontal and vertical distributions of iron and manganese are discussed. The vertical distribution of iron and manganese in the sediments results from reduction, diffusion, and redeposition of manganese (or iron) oxide and hydroxide in the sediment. There are the maxima of iron and manganese in solid phase in the top of the sediment, which is caused by the penetration of O_2 and the upward flux of Mn~(2+) ( or Fe~(2+)). Manganese bacteria play a very important role in the cycle of solid-phase iron and manganese in the ocean environment. Manganese bacteria oxidize Mn~(2+) (or Fe~(2+)) in dissolved state to Mn~(4+) ( or Fe~(3+)) in oxidized state under the aerobic condition, whereas they reduce iron and manganese in anaerobic conditions.