SOURCES OF NITRIC-OXIDE AND NITROUS-OXIDE FOLLOWING WETTING OF DRY SOIL
SOURCES OF NITRIC-OXIDE AND NITROUS-OXIDE FOLLOWING WETTING OF DRY SOIL
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DOI：
10.2136/sssaj1992.03615995005600010015x
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发表时间：
1992-01-01
影响因子：
2.9
通讯作者：
DAVIDSON, EA
中科院分区：
文献类型：
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作者：
DAVIDSON, EA
据报道，当干燥的土壤湿润时，NO 和 N2O 的通量显着增加。这些气体的来源很难确定，因为许多生物和非生物过程都会产生这两种气体。旱季结束时从加利福尼亚州中部的一年生草地上取样的土壤被润湿至土壤含水量高于或低于田间持水量。加水后几分钟内就开始产生 NO 和 N2O。低于田间持水量时，NO 净产量超过 N2O，而高于田间持水量时，N2O 净产量超过 NO。在两种水含量下，乙炔 (C2H2) 都会抑制 NO 的产生，表明 NO 来源依赖于硝化作用。相比之下，只有当土壤水低于田间持水量时，C2H2 才会抑制 N2O 的产生，这表明当土壤水高于田间持水量时，反硝化作用是主要来源。添加 NO2- 也会刺激无菌和非无菌土壤中 NO 的产生，这表明非生物反应可能对 NO 排放产生显着影响。 NH4+ 氧化细菌产生 NO2- 和 H+，然后对产生的一小部分 NO2- 进行化学硝化，可以解释观测到的干燥和潮湿土壤中的 NO 通量。硝化细菌和反硝化细菌似乎能够很好地适应极端干旱，并在湿润干燥土壤的几分钟内变得活跃。
When dry soil is wetted, significant fluxes of NO and N2O have been reported. The sources of these gases have been difficult to identify because a number of biological and abiological processes can produce both gases. Soil sampled from an annual grassland in central California at the end of the dry season was wetted to soil water contents above and below field capacity. Production of NO and N2O began within minutes of adding water. Below field capacity, the net production of NO exceeded N2O, whereas above field capacity the production of N2O exceeded NO. Production of NO was inhibited by acetylene (C2H2) at both water contents, indicating that the NO source was dependent on nitrification. In contrast, N2O production was inhibited by C2H2 only when soil water was below field capacity, indicating that denitrification was the dominant source when soil water was above field capacity. Addition of NO2- also stimulated NO production in both sterile and nonsterile soil, suggesting that abiological reactions could contribute significantly to NO emissions. Production of NO2- and H+ by NH4+-oxidizing bacteria, followed by chemodenitrification of a small fraction of the NO2- produced, could account for the observed NO fluxes from dry and moist soil. Nitrifying and denitrifying bacteria appear to be well adapted to surviving extreme drought and to becoming active with minutes of wetting dry soil.