Tracing the fate of atmospheric nitrate deposited onto a forest ecosystem in Eastern Asia using Δ 17 O
Tracing the fate of atmospheric nitrate deposited onto a forest ecosystem in Eastern Asia using Δ 17 O
复制标题
DOI：
10.5194/acp-10-1809-2010
复制
发表时间：
2009-11
影响因子：
6.3
通讯作者：
U. Tsunogai;D. Komatsu;Satoko Daita;G. Kazemi;F. Nakagawa;I. Noguchi;Jing Zhang
中科院分区：
文献类型：
--
作者：
U. Tsunogai;D. Komatsu;Satoko Daita;G. Kazemi;F. Nakagawa;I. Noguchi;Jing Zhang
抽象的。测定了日本利尻岛降水（湿沉降）和地下水（泉水、湖水和溪水）中硝酸盐的稳定同位素组成，以利用17 O异常（Δ 17 O）追踪沉积到该岛生态系统（东亚典型的森林生态系统背景）上的大气硝酸盐的去向。沉积硝酸盐具有较大的17 O异常，Δ 17 O值变化范围为+20.8‰ ~+34.5‰（n = 32），年平均值为+26.2‰。2007年2月23日至24日的降水中，Δ 17 O的最大值为+34.5‰，在利尻所有降水样品中是一个非常大的值。样本中的大多数硝酸盐可能是通过亚洲大陆东海岸特大城市提供的高度污染的空气团中的NO3自由基产生的。地下水中硝酸盐的Δ 17 O值较小，为+0.9‰ ~ 3.2‰（n = 19），相当于大气中硝酸盐占总硝酸盐的（7.4±2.6）%。通过对海岛地下水中大气硝酸盐流入和流出的比较，估算出直接排泄的硝酸盐占沉积在海岛上的大气硝酸盐的（8.8±4.6）%，剩余部分经过生物处理后才从森林生态系统中输出。
Abstract. The stable isotopic compositions of nitrate in precipitation (wet deposition) and groundwater (spring, lake, and stream water) were determined for the island of Rishiri, Japan, so as to use the 17O anomalies (Δ17O) to trace the fate of atmospheric nitrate that had deposited onto the island ecosystem, which is a representative background forest ecosystem for eastern Asia. The deposited nitrate had large 17O anomalies with Δ17O values ranging from +20.8‰ to +34.5‰ (n = 32) with +26.2‰ being the annual average. The maximum Δ17O value of +34.5‰, obtained for precipitation on the 23rd to 24th of February 2007, was an extraordinarily large value among values for all samples of precipitation in Rishiri. Most nitrate in the sample might have been produced via NO3 radical in a highly polluted air mass that had been supplied from megacities on the eastern coast of the Asian continent. On the other hand, nitrate in groundwater had small Δ17O values ranging from +0.9‰ to 3.2‰ (n = 19), which corresponds to an mixing ratio of atmospheric nitrate to total nitrate of (7.4±2.6)%. Comparing the inflow and outflow of atmospheric nitrate in groundwater within the island, we estimated that the direct drainage accounts for (8.8±4.6)% of atmospheric nitrate that has deposited on the island and that the residual portion has undergone biological processing before being exported from the forest ecosystem.