Characteristics of nitrogen loading and its influencing factors in several typical agricultural watersheds of subtropical China
Characteristics of nitrogen loading and its influencing factors in several typical agricultural watersheds of subtropical China
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DOI：
10.1007/s11356-014-3446-y
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发表时间：
2015-02
影响因子：
5.8
通讯作者：
Yuyuan Li;J. Jiao;Yi Wang;Wen Yang;Cen Meng;Baozhen Li;Yong Li;Jinshui Wu
中科院分区：
文献类型：
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作者：
Yuyuan Li;J. Jiao;Yi Wang;Wen Yang;Cen Meng;Baozhen Li;Yong Li;Jinshui Wu
随着水体富营养化的加剧，氮负荷的变化对流域水质的维持和恢复起着至关重要的作用。以我国亚热带地区10个以林地和农业用地为主的小流域为研究对象，在为期23-29个月的观测期内，对流域氮负荷进行了估算，并对其影响因素进行了研究。结果表明，总氮（TN）、NH 4 +-N和NO3−-N的平均浓度在森林流域分别为0.83、0.07和0.46 mg N L− 1，在农业流域分别为1.49-5.16、0.21-3.23和0.99-1.30 mg N L− 1。这种浓度大大超过了国家地表沃茨营养物污染标准，表明所研究的农业流域存在严重的溪流污染。农业流域的年平均总氮负荷（ANL）估计为1，640.8 kg N km− 2 year − 1，其中63.3%-86.1%由溶解无机氮（DIN;包括NO3−-N和NH 4 +-N）组成。集约化畜牧生产的流域（即，最大牲畜密度为2.66个动物单位（Au）ha−1，显示出与污水排放的氮损失相关的最高ANL（2，928.7 kg N km− 2 year −1）。相关分析和主成分分析结果表明，畜牧业生产是影响流域TN和NH 4 +-N负荷的主要因素，农田面积的增加会显著增加流域NO3−-N负荷。因此，为了恢复和维持水质，在中国亚热带农业流域，有必要制定畜牧生产法规并更仔细地规划土地利用。
Increasingly, the characteristics of nitrogen (N) loading have been recognized to be critical for the maintenance and restoration of water quality in agricultural watersheds, in response to the spread of water eutrophication. This paper estimates N loading and investigates its influencing factors in ten small watersheds variously dominated by forest and agricultural land use types in the subtropics of China, over an observation period of 23–29 months. The results indicate that the average concentrations of total nitrogen (TN), NH4+–N, and NO3−–N were 0.83, 0.07, and 0.46 mg N L−1in the forest watersheds and 1.49–5.16, 0.21–3.23, and 0.99–1.30 mg N L−1in the agricultural watersheds, respectively. Such concentrations exceed the national criteria for nutrient pollution in surface waters considerably, suggesting severe stream pollution in the studied agricultural watersheds. The average annual TN loadings (ANL) were estimated to be 1,640.8 kg N km−2year−1in the agricultural watersheds, 63.3–86.1 % of which was composed of dissolved inorganic N (DIN; comprising NO3−–N and NH4+–N). The watershed with intensive livestock production (i.e., the maximum livestock density of 2.66 animal units (AU) ha−1) exhibited the highest ANL (2,928.7 kg N km−2year−1) related to N loss with effluent discharge. The results of correlation and principle component analysis suggest that livestock production was the dominant influencing factor for the TN and NH4+–N loadings and that the percentages of cropland in watersheds can significantly increase the NO3−–N loading in agricultural watersheds. Therefore, to restore and maintain water quality, animal production regulations and more careful planning of land use are necessary in the agricultural watersheds of subtropical China.