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硫铵等铵态氮(NH_4-N)在酸性状况时,由于土壤硝化作用,生成 NO_2~-和 NO_3~-。这些 NO_2~-和 NO_3~-在还原性土壤中由于反硝化细菌的作用,还原成分子状态的氮气(N_2)和亚硝态氮(N_2O),释放于大气之中。业已确认,N_2O 是由 NH_4-N 经过硝化作用生成的。土壤中的反硝化作用除降低施入氮肥的利用率外,其中间产物 N_2O 与太阳的紫外线相反,在一定程度上起到破坏臭氧层的作用,还可能像 CO_2的温室效应那样导致地球表面温度上升。这些现象都已引起人们极大关注。为评价土壤的反硝化作用,除需要探讨正确的测定方法,亦要探讨其影响大气等问题。
Ammonium nitrogen (NH 4 -N), such as ammonium sulfate, generates NO 2 - and NO 3 - in the acidic condition due to soil nitrification. These NO 2 - and NO 3 - are reduced to molecular nitrogen (N 2) and nitrous nitrogen (N 2 O) due to the action of denitrifying bacteria in the reducing soil and released into the atmosphere. It has been confirmed that N2O is formed by the nitration of NH4N. The denitrification in soil can reduce the utilization of nitrogen fertilizer, and its intermediate product N2O, which is contrary to the ultraviolet light of the sun, can destroy the ozone layer to a certain extent. It may also cause the temperature of the Earth’s surface to rise like the greenhouse effect of CO2 . These phenomena have drawn great attention. In order to evaluate the denitrification of soil, it is necessary to discuss the correct measurement methods and to explore such issues as the impact on the atmosphere.