State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Box 5003, NO-1432 Ås, Norway.
Sci Total Environ. 2019 Feb 15;651(Pt 1):1302-1309. doi: 10.1016/j.scitotenv.2018.09.301. Epub 2018 Sep 24.
The present estimate of global hydrogen sulfide (HS) emission from natural sources has large uncertainty mainly due to the lack of valid field data, particularly for subtropical forest soil in China with elevated atmospheric S deposition. In this study, the field observation of HS fluxes over subtropical forest soil was conducted for the first time in south China to measure the magnitude of emissions of HS, and evaluate its contribution to the large S sink, using the Dynamic Flux Chamber (DFC) method. Daily variations of HS fluxes showed an increasing emission with the increasing air temperature in the morning, a peak at the middle of the day, and a decreasing emission thereafter, then approximated to zero at night. The HS flux had positive values in all seasons, with the highest in summer, followed by spring, and relatively lower values in fall and winter. The HS flux measurements showed relatively large emission with annual average value of 0.028 g S m yr, possibly due to the elevated sulfate concentration in the soil solution by S deposition, the hot and humid climate, as well as the lower soil pH in subtropical China. Thus, not only tropical, subtropical soils need to be included as significant HS sources to accurately portray the global HS budget. Although the soil in subtropical forests acted as a strong source for HS to atmosphere, HS emission from soil had limited contribution (about 0.2%) to the large S sink in this forest catchment.
目前对自然源硫化氢（HS）排放的全球估算存在很大的不确定性，主要是因为缺乏有效的现场数据，特别是对于大气 S 沉降增加的中国亚热带森林土壤。本研究首次在中国南方进行了亚热带森林土壤 HS 通量的现场观测，以使用动态通量室（DFC）方法测量 HS 排放的幅度，并评估其对大 S 汇的贡献。HS 通量的日变化表现出随着清晨空气温度的升高而增加的排放，中午达到峰值，此后排放减少，然后在夜间近似为零。HS 通量在所有季节都呈正值，夏季最高，春季次之，秋季和冬季相对较低。HS 通量测量值显示出相对较大的排放量，年平均值为 0.028 g S m yr，这可能是由于 S 沉降导致土壤溶液中硫酸盐浓度升高、炎热潮湿的气候以及中国亚热带地区较低的土壤 pH 值所致。因此，不仅热带土壤，亚热带土壤也需要作为 HS 的重要来源，以准确描绘全球 HS 预算。尽管亚热带森林土壤是 HS 向大气的主要源，但土壤 HS 排放对该森林流域大 S 汇的贡献有限（约 0.2%）。
