三峡库区人类活动净氮输入量估算及其影响因素

建立包括食品/饲料，氮肥，大气沉降和生物固氮4部分的人类活动净氮输入模型（NANI），采用单因素方差分析法（one-way ANOVA）和灰色关联度法，研究2006~2016年三峡库区人类活动净氮输入估量的时空分布、组成特征及其贡献率、影响因素.结果表明：（1）三峡库区的NANI估量存在明显的时空差异特征，从2006年的10715.2kg/（km²·a）到2016年的11974.1kg/（km²·a），整体呈现先线性上升后下降的年际变化趋势，以及库首，库尾高，库区腹地低且南部高，北部低的空间分布特征.（2）三峡库区的NANI的组成中，氮肥施用量所占比重最大为50%~56%，是主要输入源，其次是大气氮沉降量，所占比重为22%~24%；相关性分析中，氮肥施用量与NANI相关性最强，R²达到了0.81（P<0.0001）.（3）人口密度，粮食产量，农业生产总值和地区生产总值等与NANI的关联度均较高，分别为0.901，0.867，0.794，0.689，NANI值随人口密度的增大而增大，但当人口密度到达一定值（500人/km²）时，其值不再变化；NANI值随着耕地面积的增加而增大，随着森林面积的增加而减小.

Evaluating of net anthropogenic nitrogen inputs and its influencing factors in the Three Gorges Reservoir Area

In this study, the Net Anthropogenic Nitrogen Input (NANI) model was first developed combining data for food/feed, nitrogen fertilizer, atmospheric sedimentation and biological nitrogen fixation. Based on the model, we investigated the spatial and temporal distribution, characteristics of the components and their contribution rate, and influencing factors of the net anthropogenic nitrogen inputs in the Three Gorges Reservoir Area from 2006 to 2016 with one-way ANOVA and gray correlation method. The results showed that:(1) Obvious spatial and temporal differences were found in the NANI estimation of the Three Gorges reservoir area. The NANI amount was 10715.2 and 11974.1kg/(km²·a) in 2006 and 2016, respectively, and from 2006 to 2016, the overall inter-annual trend showed a pattern of rising linearly first and then decreasing. Spatially, the NANI amount was high in the head and tail of the reservoir while low in the hinterland of the reservoir, and high in the south while low in the north. (2) Among the components of NANI in the Three Gorges reservoir area, the nitrogen fertilizer application was the main input source, which accounted for 50%~56% of the total NANI, followed by the atmospheric nitrogen deposition, which accounted for 22%~24% of the NANI. In the correlation analysis, the relationship between the application rate of nitrogen fertilizer and NANI was most significant with R²=0.81 (P<0.0001). (3) The correlations between NANI and the population density, grain yield, gross agricultural product and gross regional product were also high, with the value of 0.901, 0.867, 0.794 and 0.689, respectively. The NANI value increased first with the increase of population density, but reached a plateau stage when the population density reached a certain value (500people/km²). NANI value increased with the increase of cultivated land area, while decreased with the increase of forest area.