Estimation of authigenic alteration of biogenic and reactive silica in Pearl River estuarine sediments using wet-chemical digestion methods

The extent of authigenic alteration of biogenic and reactive silica in Pearl River estuarine sediments has been estimated using wet-chemical digestion methods. Results show relatively constant distributions of biogenic and reactive Si horizontally and vertically. Based on three core measurements, the biogenic and total reactive Si average 77.91 and 264.77 mu mol Si g(-1), respectively. Their extents of authigenic alteration are correspondingly estimated as similar to 55.6 and similar to 70.6%. The average biogenic Si accumulation rate is calculated as 1.91 x 10(9) mol Si year(-1), which translates into storage of similar to 7.15% of the annual riverine dissolved silica input. By contrast, the total reactive Si accumulation rate is as high as 6.49 x 10(9) mol Si year(-1), improving annual riverine silicic acid storage to similar to 24.19%. Detailed investigation is required for a good understanding of early diagenetic process of biogenic and reactive silica in this subtropical area.