Anhui Provincial Key Laboratory of Polar Environment and Global Change, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
Department of Geography, University of California, Berkeley, CA 94720, United States.
Sci Total Environ. 2022 Aug 20;835:155449. doi: 10.1016/j.scitotenv.2022.155449. Epub 2022 Apr 26.
Carbon tetrachloride (CCl) is an anthropogenic gas with a long atmospheric lifetime and can catalyze the destruction of stratospheric ozone. Natural soils are believed to be important and widespread sinks of atmospheric CCl, although poorly characterized due to a limited number of measurements. In this study, for the first time in situ static-chamber measurements and laboratory-based incubations for CCl fluxes were conducted at coastal Antarctic tundra. Results showed that soil in remote Antarctica is also acting as a CCl sink, with an average uptake rate of -2.2 ± 0.6 nmol m d, which is comparable to the reported soil sinks in other regions of the world. No significant difference (p > 0.05) was found across different types of tundra, such normal upland tundra, coastal marsh tundra, and tundra in the sea animal colonies. Soil CCl fluxes did not show significant correlations (p > 0.05) with soil moisture, pH, TOC, TN, TP and Cl contents. Laboratory-based anoxic incubations showed that the uptake rates of CCl in tundra soil were suppressed; post-thermal sterilization incubations showed that soil CCl sink was enhanced; these results suggested that CCl degradation in tundra soil was likely an abiotic process preferring oxic environments. A rough extrapolation suggested that Antarctic tundra may degrade about 2.4 metric tons of atmospheric CCl each year. Combining soil CCl fluxes from this study and other literature reports, CCl partial lifetime with respect to the soil sink was evaluated to be 354 (235-474) years, which supported the recent viewpoint that the soil sink of CCl is smaller than previously thought.
四氯化碳（CCl）是一种人为产生的气体，具有很长的大气寿命，能够催化平流层臭氧的破坏。尽管由于测量次数有限，人们对其了解甚少，但天然土壤被认为是大气 CCl 的重要且广泛的汇。在这项研究中，首次在南极沿海冻原进行了现场静态室测量和基于实验室的 CCl 通量培养。结果表明，偏远南极的土壤也是 CCl 的汇，平均吸收速率为-2.2 ± 0.6 nmol m d，这与世界其他地区报道的土壤汇相当。不同类型的冻原（如正常高地冻原、沿海沼泽冻原和海洋动物群中的冻原）之间没有发现明显差异（p > 0.05）。土壤 CCl 通量与土壤水分、pH 值、TOC、TN、TP 和 Cl 含量均无显著相关性（p > 0.05）。基于实验室的缺氧培养表明，CCl 在冻原土壤中的吸收速率受到抑制；热后灭菌培养表明，土壤 CCl 汇得到增强；这些结果表明，CCl 在冻原土壤中的降解可能是一种优先有氧环境的非生物过程。粗略推断表明，南极冻原每年可能降解约 2.4 公吨的大气 CCl。将本研究和其他文献报道的土壤 CCl 通量结合起来，评估了 CCl 相对于土壤汇的部分半衰期为 354（235-474）年，这支持了最近的观点，即 CCl 的土壤汇比以前认为的要小。
