State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
Sci Total Environ. 2022 Mar 10;811:152084. doi: 10.1016/j.scitotenv.2021.152084. Epub 2021 Dec 11.
Hydrogen sulfide (HS) is one of predominant biogenic sulfur gases, influencing aerosol formation and climate change. There is considerable uncertainty of the global budget of HS due to limited field data, especially in subtropical forests. In addition, an interaction between soil-emitted HS and ambient sulfur dioxide (SO) might exist within forest ecosystems. In this study, the aerodynamic gradient method was applied to consecutively measure HS and SO fluxes above a subtropical forest canopy in Southwest China under natural and disturbed conditions induced by temporal land-use changes. The average HS concentration and flux under natural conditions were 0.79 ± 0.07 ppbv and 0.04 ± 0.01 g S m yr, respectively. The emission was larger than that in most croplands and freshwater wetlands. Vegetation emissions might account for about 26% of the total forest HS emissions at this site. The deposition of SO was likely balanced by HS oxidization under the forest canopy, with the mean concentration and net flux as 1.23 ± 0.11 ppbv and -0.03 ± 0.10 g S m yr, respectively. Under disturbed conditions with soils excavation and scattering on the forest floor, simultaneously high emissions of HS and SO were observed above the canopy, reaching 5.78 ± 0.16 and 1.60 ± 0.87 g S m yr, respectively. This suggested that land-use change in subtropical forests might lead to release of legacy S in subsoils to the atmosphere in the form of HS and SO. Regarding the widely documented large S accumulation and expanding deforestation across subtropical forests, potentially high emissions of HS and SO from subtropical forests should be carefully considered in regional air quality control and forest management.
硫化氢（HS）是主要的生源硫气体之一，影响气溶胶形成和气候变化。由于有限的现场数据，特别是在亚热带森林中，HS 的全球预算存在相当大的不确定性。此外，土壤排放的 HS 和环境二氧化硫（SO）之间可能存在相互作用在森林生态系统内。本研究应用空气动力学梯度法连续测量中国西南亚热带森林冠层上方 HS 和 SO 通量在自然条件和由土地利用时空变化引起的干扰条件下。在自然条件下，HS 的平均浓度和通量分别为 0.79±0.07 ppbv 和 0.04±0.01 g S m yr。排放量大于大多数农田和淡水湿地。植被排放可能占该地点总森林 HS 排放量的约 26%。SO 的沉积可能通过 HS 在林冠下的氧化来平衡，平均浓度和净通量分别为 1.23±0.11 ppbv 和-0.03±0.10 g S m yr。在有土壤挖掘和森林地表散射的干扰条件下，林冠上方同时观察到 HS 和 SO 的高排放，分别达到 5.78±0.16 和 1.60±0.87 g S m yr。这表明亚热带森林的土地利用变化可能导致亚土壤中的残留 S 以 HS 和 SO 的形式释放到大气中。鉴于广泛记录的亚热带森林中大量的 S 积累和不断扩大的森林砍伐，亚热带森林中 HS 和 SO 的潜在高排放应在区域空气质量控制和森林管理中得到谨慎考虑。
