Historical trends of riverine nitrogen loading from land to the East China Sea: a model-based evaluation
Historical trends of riverine nitrogen loading from land to the East China Sea: a model-based evaluation
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DOI：
10.1088/2515-7620/ac1ce8
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发表时间：
2021-08
影响因子：
2.9
通讯作者：
K. Nishina;A. Ito;F. Zhou;X. Yan;S. Hayashi;W. Winiwarter
中科院分区：
文献类型：
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作者：
K. Nishina;A. Ito;F. Zhou;X. Yan;S. Hayashi;W. Winiwarter
东亚地区是人类活动氮输入过多的热点地区之一。在这里，我们使用生物地球化学模型VISITE和新开发的VISITORN离线河流氮方案(VISITORN)来评估历史上通过东中国海周边河流从陆地到海洋的总无机氮(TIN)负荷。VISIToRN计算了自然和农业生态系统中的N循环，VISIToRN计算了半度空间分辨率下的无机N迁移和河流中的反硝化作用。从1961年到2010年，估计从陆上到中国海周围海域的锡负荷从2.7Tg-N年−1增加到5.5Tg-N年−1，增加了一倍，而人为输入到东中国海盆地的氮(N沉积、N肥料、粪便和人类污水)从12.9Tg-N年−1增加到36.9Tg-N年−1，大约增加了3倍。这种增长率的差异在很大程度上是由于陆地氮素收支，模型平衡的结果表明，化肥施用量、农田收获和森林氮素积累的改善抑制了流向河流的锡负荷。模型平衡结果表明，2000年以来，我国河流氮素径流增长率呈下降趋势。在VISIToRN的估算中，河口前河道的反硝化脱氮量不容忽视，从1.6Tg·N年−1到2.16Tg·N年−1不等。农业来源的N负荷仍然很大，需要进一步减少。锡负荷在降水较多的年份有增加的趋势。为了有效降低TIN负荷，有必要考虑适应气候变化的农业氮素管理。
East Asia is the one of the hotspot regions with too much reactive nitrogen (N) inputs from anthropogenic sources. Here, we evaluated historical total inorganic N (TIN) load from land to sea through the rivers surrounding the East China sea using biogeochemical model ‘VISIT’ combined with a newly developed VISIT Off-line River Nitrogen scheme (VISIToRN). VISIT calculated N cycling in both natural and agricultural ecosystems and VISIToRN calculated inorganic N transport and riverine denitrification through the river channels at half degree spatial resolution. Between 1961 and 2010, the estimated TIN load from land to the sea surrounding the East China Sea increased from 2.7 Tg-N Year−1 to 5.5 Tg-N Year−1, a twofold increase, while the anthropogenic N input to the East China Sea basin (N deposition, N fertilizer, manure, and human sewage) increased from 12.9 Tg-N Year−1 to 36.9 Tg-N Year−1, an increase of about 3 times. This difference in the rate of increase is due in large part to the terrestrial nitrogen budget, and the results of the model balance indicate that TIN load to rivers has been suppressed by improvements in fertilizer application rates, harvesting on agricultural land, and nitrogen accumulation in forests. The results of the model balance showed that the increase rate of nitrogen runoff from Chinese rivers has been declining since 2000. In our estimation by VISIToRN, the amount of nitrogen removed by river denitrification in the river channel before the mouth is not negligible, ranging from 1.6 Tg-N Year−1 to 2.16 Tg-N Year−1. The N load from agricultural sources is still significant and needs to be further reduced. TIN load tended to increase in years with high precipitation. In order to effectively reduce TIN load, it is necessary to consider climate change-adaptive agricultural N management.