Faculty of Environmental Sciences, University of Science, Vietnam National University, Hanoi (VNU), 334 Nguyen Trai, Thanh Xuan, Hanoi, Viet Nam; Hanoi University of Natural Resources & Environment, 41A Phu Dien, Bac Tu Liem, Hanoi, Viet Nam.
Faculty of Environmental Sciences, University of Science, Vietnam National University, Hanoi (VNU), 334 Nguyen Trai, Thanh Xuan, Hanoi, Viet Nam.
Sci Total Environ. 2021 Jun 10;772:145469. doi: 10.1016/j.scitotenv.2021.145469. Epub 2021 Jan 30.
Phytoliths, silica structures derived from plant residues in silicon (Si)-accumulating plant species, have recently been recognized as a sink and source of nutrients and a hosting phase for carbon sequestration in soil. While the solubility of phytoliths in relation to their respective nature and solution chemistry has been intensively studied, the combined effects of CO and temperature, two highly variable parameters in soil, have not been fully understood. We hypothesized that changes in CO and temperature may affect the dissolution rate, thereby resizing the soil phytolith pool. Rice straw phytoliths were obtained from either open burning or controlled heating of straw from 300 to 900 °C and used to determine their batch incubation kinetics in a closed chamber at CO concentrations of 0 to 15% vol. and a temperature range of 20 to 50 °C for six days. The results revealed a contrasting effect in which temperature and CO were correspondingly found to accelerate or decelerate the dissolution rate of phytoliths. Under the most dissimilar conditions, i.e., 0% vol. CO and 50 °C and 15% vol. CO and 20 °C, the discrepancy in solubility was approximately six-fold, indicating a high vulnerability of phytoliths to CO and temperature changes. This finding also suggests that the soil phytolith pool can be diminished in the case of either increasing soil temperature or decreasing CO flux. Calculations based on these data revealed that the dissolution rate of phytoliths could be increased by an average of 4.5 to 7.3% for each 1 °C increase in temperature. This finding suggests a possible impact of current global warming on the global biogenic silica pool, and more insight into the relationship between this pool and climate change is, therefore, necessary to maintain the function of the phytolith phase in soil.
植硅体是在富含硅（Si）的植物物种中植物残体衍生的硅质结构，最近被认为是土壤中养分的汇和源，也是碳封存的宿主相。虽然植硅体的溶解度与其各自的性质和溶液化学性质有关，但 CO 和温度这两个土壤中高度可变的参数的综合影响尚未得到充分理解。我们假设 CO 和温度的变化可能会影响溶解速率，从而改变土壤植硅体库的大小。从露天燃烧或从 300 到 900°C 控制加热稻草中获得水稻秸秆植硅体，并将其用于在封闭室中以 0 至 15%体积 CO 和 20 至 50°C 的温度范围下进行为期六天的批量孵育动力学测定。结果显示出相反的效果，即温度和 CO 相应地加速或减缓了植硅体的溶解速率。在最不同的条件下，即 0%体积 CO 和 50°C 以及 15%体积 CO 和 20°C，溶解度的差异约为六倍，表明植硅体对 CO 和温度变化非常敏感。这一发现还表明，在土壤温度升高或 CO 通量降低的情况下，土壤植硅体库可能会减少。基于这些数据的计算表明，溶解速率可能会增加 4.5%至 7.3%，每升高 1°C。这一发现表明，当前全球变暖可能对全球生物成因二氧化硅库产生影响，因此，需要更多地了解这个库与气候变化之间的关系，以维持土壤中植硅体相的功能。
