Bulk deposition of organic and inorganic nitrogen in southwest China from 2008 to 2013.
Bulk deposition of organic and inorganic nitrogen in southwest China from 2008 to 2013.
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DOI：
10.1016/j.envpol.2017.04.031
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发表时间：
2017-08
影响因子：
8.9
通讯作者：
Ling Song;F. Kuang;U. Skiba;B. Zhu;Xuejun Liu;P. Levy;A. Dore;D. Fowler
中科院分区：
文献类型：
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作者：
Ling Song;F. Kuang;U. Skiba;B. Zhu;Xuejun Liu;P. Levy;A. Dore;D. Fowler
中国是世界上氮沉降热点地区之一。迄今为止的测量主要集中在华北平原，忽视了全国各地大气化学和物理性质的差异，以及可能存在其他热点地区需要调查的事实。为此，我们进行了一项为期六年的研究，在中国西南部四川省的三个对比地点测量了还原性（NH4-N）、氧化性（NO3-N）和溶解性有机氮（DON）的大量沉积。研究地点为贡嘎山的高海拔森林（GG）、盐亭的农业主导地区（YT）和特大城市成都的城市遗址（CD）。2008 - 2013年，总溶解氮（TDN）在GG、YT和CD站点的年平均体沉降通量分别为7.4、23.1和36.6 kg N ha - 1yr - 1n。NH4-N、NO3-N和DON对TDN的贡献率分别为48.4 ~ 57.8%、28.8 ~ 43.7%和8.0 ~ 15.6%。DON堆积主要由农业活动主导。2008 - 2013年农业和城市样地TDN体沉降通量呈增加趋势，而偏远森林样地TDN体沉降通量变化不大。3个站点的总体氮沉降均以还原氮为主，但其贡献呈下降趋势，表明氧化氮的重要性逐渐增加。这些结果揭示了长期监测在检测这一快速变化地区大气化学成分变化方面的价值，并将其纳入政策讨论中，以减少氮沉降的长期影响，特别是在中国西南地区。那里的氮沉降量很少。
China is regarded as one of the nitrogen deposition hotspots in the world. Measurements to-date have focused mainly on the North China Plain, ignoring the fact that atmospheric chemical and physical properties vary across the country and that there may be other hotspots regions that should be investigated. For this reason we have conducted a six year study, measuring the bulk deposition of reduced (NH4-N), oxidized (NO3-N), and dissolved organic nitrogen (DON) at three contrasting sites in the Sichuan province, southwest China. The study sites were a high altitude forest in the Gongga Mountains (GG), an agriculture dominated region in Yanting (YT) and an urban site in the mega city Chengdu (CD). The annual average bulk deposition fluxes of total dissolved nitrogen (TDN) were 7.4, 23.1 and 36.6 kg N ha−1yr−1at GG, YT and CD sites, respectively, during the study period 2008 to 2013. The contributions of NH4-N, NO3-N and DON to the TDN were in the range of 48.4–57.8%, 28.8–43.7%, and 8.0–15.6%, respectively. DON bulk deposition was mainly dominated by agricultural activities. TDN bulk deposition fluxes showed increasing trends at the agricultural and urban sites from 2008 to 2013, but there was little change at the remote forest (GG) site. While reduced N dominated bulk N deposition at all the three sites, its contribution showed a decreasing trend, suggesting a gradual increase in the importance of oxidized N. These results reveal the value of long term monitoring in detecting changes in the atmospheric chemical composition of this rapidly changing region, and their inclusion in the policy debate regarding which sources should be controlled in order to reduce the long term impacts of N deposition, especially for southwest China, where there are few measurements of N deposition.