Land use mediates riverine nitrogen export under the dominant influence of human activities
Land use mediates riverine nitrogen export under the dominant influence of human activities
复制标题
在人类活动的主导影响下，土地利用调节河流氮输出
DOI：
10.1088/1748-9326/aa84bc
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发表时间：
2017-09-01
影响因子：
6.7
通讯作者：
Gu, Baojing
中科院分区：
文献类型：
--
作者：
Chen, Binhui;Chang, Scott X.;Gu, Baojing
河流氮（N）输出是连接上下游生态系统和沿海地区的关键过程。然而，与水体氮污染密切相关的河流氮输出的驱动力仍不清楚。在本研究中，我们以中国浙江省为例，采用质量平衡方法来量化氮排放源，并分析了土地利用结构对河流氮输出的影响。我们发现，从2000年到2015年，浙江河流的活性氮排放总量从0.22 Tg yr(-1)增加到0.26 Tg yr(-1)。在流域尺度上，我们对氮输出的估计与浙江8个主要流域的监测河流氮浓度非常吻合。生活污水和污水处理厂出水的直接排放是河流氮输出的主要来源，其次是农业面源。尽管河流氮输出随着城市和农业土地利用比例的增加而增加，但我们没有发现土地利用变化与河流氮输出变化之间存在任何关系。这表明影响河流氮输出的主导因素应该是人类活动（如废水排放和施肥水平），而土地利用仅调节河流氮输出。
Riverine nitrogen (N) export is a crucial process that links upstream and downstream ecosystems and coastal zones. However, the driving forces of riverine N export that is closely related to water N pollution are still not well understood. In this study, we used a mass balance approach to quantify the sources of N discharge and analyzed the effect of land use composition on riverine N export, taking Zhejiang Province, China as a case study. We found that the total reactive N discharge to rivers in Zhejiang increased from 0.22 to 0.26 Tg yr(-1) from 2000 to 2015. At the watershed scale, our estimate of N export agrees well with the monitored riverine N concentration in the eight major watersheds in Zhejiang. Direct discharge of domestic wastewater and effluents from wastewater treatment plants are dominant sources of riverine N export, followed by agricultural non-point sources. Although riverine N export increases with the increasing proportion of urban and agricultural land uses, we did not find any relationship between land use change and changes in riverine N export. This suggests that the dominant factor affecting riverine N export should be human activities (e.g. wastewater discharge and fertilization level), while land use only mediates riverine N export.