Key Laboratory of Karst Georesources and Environment, Ministry of Education, College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China; Institute of Surface-Earth System Science, School of Earth System Science, Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China.
Institute of Surface-Earth System Science, School of Earth System Science, Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China.
Sci Total Environ. 2023 Jan 15;856(Pt 2):159229. doi: 10.1016/j.scitotenv.2022.159229. Epub 2022 Oct 5.
Phytoliths are silica biomineralization products within plants and have been considered as a promising material to sequester carbon (C). However, there is considerable uncertainty and controversy regarding the C content in phytoliths due to the lack of detailed information on variation of C under different extraction procedures. Herein, we established a series of batch digestion experimental procedures coupled with analyses of phytoliths using Scanning Electron Microscopy and Energy-Dispersive X-ray Spectroscopy to divide phytoliths into three fractions. We then reported an approach for standardizing across hundreds of values found in the literature. Combining this standardized approach with C contents in phytoliths extracted from different digestion degrees, we revaluated the potential production rates of phytolith-occluded carbon (PhytOC) input globally in rice paddy fields. The results showed that the C content in recovered phytoliths exhibited a significantly fitting exponential relationship (p < 0.01) with digestion degrees and decreased from 30 to 75 g kg under moderate digestion to <5 g kg under over digestion. On a global scale, the production of total PhytOC in the world paddy fields reached up to (2.71 ± 0.85) × 10 t year. Therein, the contribution of sub-stable PhytOC fraction, stable PhytOC fraction, and recalcitrant PhytOC fraction was 63 %, 28 %, and 9 %, respectively. Our results imply that the estimation of phytolith C sequestration potential across the global paddy fields is associated with specific PhytOC fractions. Therefore, further determining the storage time limits of these specific PhytOC fractions after returning to soil will be vital for predicting terrestrial biogeochemical C sequestration potentials of phytoliths.
植物硅酸体是植物体内形成的硅质生物矿化产物，被认为是一种有前途的碳 (C) 固定材料。然而，由于缺乏不同提取程序下 C 变化的详细信息，植物硅酸体中的 C 含量存在相当大的不确定性和争议。在此，我们建立了一系列批处理消化实验程序，并结合扫描电子显微镜和能谱分析对植物硅酸体进行分析，将植物硅酸体分为三个部分。然后，我们报告了一种标准化跨文献中数百个值的方法。将这种标准化方法与不同消化程度提取的植物硅酸体中的 C 含量相结合，我们重新评估了全球稻田中植物硅酸体固定碳（PhytOC）输入的潜在产生速率。结果表明，回收植物硅酸体中的 C 含量与消化程度呈显著拟合指数关系（p < 0.01），从中度消化到过度消化，C 含量从 30 到 75 g kg-1 下降到 <5 g kg-1。在全球范围内，世界稻田中总 PhytOC 的产生量达到（2.71 ± 0.85）×10 t year-1。其中，亚稳定 PhytOC 部分、稳定 PhytOC 部分和难分解 PhytOC 部分的贡献分别为 63%、28%和 9%。我们的结果表明，全球稻田中植物硅酸体 C 固定潜力的估计与特定的 PhytOC 部分有关。因此，进一步确定这些特定 PhytOC 部分在返回土壤后的储存时间限制，对于预测植物硅酸体的陆地生物地球化学 C 固定潜力至关重要。
