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 μmol Si g⁻¹, respectively. Their extents of authigenic alteration are correspondingly estimated as ~55.6 and ~70.6%. The average biogenic Si accumulation rate is calculated as 1.91 × 10⁹ mol Si year⁻¹, which translates into storage of ~7.15% of the annual riverine dissolved silica input. By contrast, the total reactive Si accumulation rate is as high as 6.49 × 10⁹ mol Si year⁻¹, improving annual riverine silicic acid storage to ~24.19%. Detailed investigation is required for a good understanding of early diagenetic process of biogenic and reactive silica in this subtropical area.