大气N_2O的稳定氮同位素质量平衡探讨

IMPROVED ESTIMATES FOR NITROGEN ISOTOPE BUDGET BALANCE OF TROPOSPHERIC N_2O

地表释放源释放的N2 O均比对流层大气N2 O贫15N ,对流层N2 O的氮同位素质量由平流层回流的富15N的N2 O来平衡 ,若全球N2 O源汇质量估算结果是平衡的 ,则地表释放源对对流层N2 O的氮同位素质量的贡献量应与平流层回流的贡献量相等。本文根据全球N2 O释放源最近的年释放量估算值 ,在考虑土壤N2 O生成过程中的氮同位素分馏效应后 ,推论出全球N2 O释放源最近的年释放量估算值能使对流层大气N2 O稳定氮同位素质量接近于平衡。

Nitrogen isotope ratios in N\-2O from global sources are uniformly depleted in heavy nitrogen isotope and isotopically lighter than those in tropospheric N\-2O. These data show that the input budgets of light N\-2O are balanced by returned N\-2O from the stratosphere enriched in heavy nitrogen isotope. If the estimated total N\-2O emission of global sources is equal to N\-2O sink, the total nitrogen isotope budget from all sources will be balanced toward the isotopic budget of returned N\-2O from the stratosphere. Based upon global N\-2O sources and their current emissions and by considering isotopic fractionation effects during N\-2O production in soils, it is deduced that the nitrogen budget of tropospheric N\-2O can get approximately balanced.