Biogenic Silica Composition and Storage in the Yellow River Delta Wetland with Implications for the Carbon Preservation

The composition and accumulation of BSi and its role in C sequestration in the YRDW were quantified based on field investigation combined with remote sensing observation in the Yellow River Delta Wetland (YRDW). Results show that the soil BSi pool in the YRDW mainly consists of phytoliths. The pools of BSi, TOC, and BSi-occluded C (OCBSi) for aboveground plants in the YRDW are 7.6 g m−2, 129 g m−2 and 0.13 g m−2, respectively. Surface soil (0–10 cm) stocks of BSi, TOC, and OCBSi are 1780 g m−2, 840 g m−2 and 40 g m−2. Our results showed that BSi preservation efficiencies of BSi (52%) and (OCBSi) (51%) in deep soil layers exceed those of TOC (35%) based on the vertical variation of BSi in the sediment. Approximately 333 t of C fixed by plants is occluded in the phytoliths as OCBSi in the YRDW. Almost half of this OCBSi is preserved in the sediment in stable form. The YRDW is therefore an important sink for BSi and BSi-occluded C.