Distribution of Biogenic Silica in Sediments of the Yellow River (Upper and Middle Reaches)

Abstract

An experiment is held to extract the biogenic silica from Yellow River sediments to explore how such four influencing factors as extraction time, the type and concentration of extracting agent, and solid-liquid ratio affect the content of biogenic silicon in the samples. Besides, the distribution characteristics of biogenic silica in sediments of the Yellow River (upper and middle reaches) are discussed based on the measured results. The experiment results demonstrate the optimal conditions for the extraction of biogenic silica in sediments of the Yellow River: weight 0.050g of sediment sample at 90°C and extract biogenic silica for 7 hours with 40mL 1.0mol/L Na2CO3 solution as the extracting agent. The biogenic silica content of the surface sediments in the upper and middle reaches of the Yellow River varies greatly from 0.07-3.06mg/g. In descending order, the samples are arranged as: MD1>XH2>BT9>WLT8>SSG7>SZS5>XG4>GD3>WH6. The highest content appears in Maduo segment at the source of the Yellow River, and the lowest content appears in Wuhai segment.