Institute of Desert Meteorology, China Meteorological Administration/National Observation and Research Station of Desert Meteorology, Taklimakan Desert of Xinjiang/Taklimakan Desert Meteorology Field Experiment Station of China Meteorological Administration/Xinjiang Key Laboratory of Desert Meteorology and Sandstorm/Key Laboratory of Tree-ring Physical and Chemical Research, China Meteorological Administration, Urumqi 830002, China; College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China.
Collaborative Innovation Center for Western Ecological Safety, Lanzhou University, Lanzhou 730000, China.
Sci Total Environ. 2022 Sep 10;838(Pt 1):155988. doi: 10.1016/j.scitotenv.2022.155988. Epub 2022 May 16.
Studies showing that deserts can sequester CO through non-photosynthetic processes have contributed to locating missing carbon sinks. However, the contradiction between the desert CO flux obtained by different observation methods leads to uncertainty in evaluating desert carbon sequestration. This has caused scepticism regarding desert carbon sequestration after years of research. Through a comparative experiment in the non-vegetated shifting sand of the Taklimakan Desert (TD), it was found that if the abnormal negative CO flux observed by IRGASON during the day was not corrected, the carbon sequestration of the TD would be overestimated. The CO flux observed by EC155 is highly consistent with that of LI-COR8100A and can reflect the real CO exchange in the desert. The CO flux observed by EC155 was used to correct the results of IRGASON. Results show that the expansion/contraction of soil air containing CO caused by the change in the daily average soil temperature difference (T) drives CO exchange in shifting sand. This results in diurnal variation of CO release caused by shifting sand during the day and CO absorption at night, and a unimodal distribution of CO exchange caused by shifting sand throughout the year. From April to September (T > 2 °C), the shifting sand releases CO as a carbon source. In the other months (T < 2 °C), the shifting sand absorbs CO as a carbon sink. The stronger absorption shows that the shifting sand in the TD provides carbon sequestration, with a CO uptake rate of ~148.85 × 10 tons a. This suggests that deserts play an active role in locating the missing carbon sinks and mitigating climate change, and that the status of deserts in the global carbon cycle cannot be ignored.
研究表明，沙漠可以通过非光合作用过程封存 CO，这有助于找到缺失的碳汇。然而，不同观测方法得到的沙漠 CO 通量之间的矛盾，导致了评估沙漠碳封存的不确定性。这使得人们对沙漠碳封存产生了怀疑，尽管多年来一直在进行研究。通过在塔克拉玛干沙漠（TD）的无植被推移沙地上进行对比实验，发现如果不纠正 IRGASON 白天观测到的异常负 CO 通量，那么 TD 的碳封存将会被高估。EC155 观测到的 CO 通量与 LI-COR8100A 非常一致，可以反映沙漠中真实的 CO 交换。使用 EC155 观测到的 CO 通量来校正 IRGASON 的结果。结果表明，由于日平均土壤温差（T）的变化而引起的含有 CO 的土壤空气的膨胀/收缩，驱动了推移沙中的 CO 交换。这导致了推移沙在白天释放 CO 作为碳源，而在夜间吸收 CO，以及推移沙全年 CO 交换的单峰分布。从 4 月到 9 月（T > 2°C），推移沙作为碳源释放 CO。在其他月份（T < 2°C），推移沙作为碳汇吸收 CO。较强的吸收表明，TD 中的推移沙提供了碳封存，其 CO 吸收速率约为 148.85×10 吨 a。这表明沙漠在寻找缺失的碳汇和缓解气候变化方面发挥了积极作用，不能忽视沙漠在全球碳循环中的地位。
