三峡库区紫色土坡耕地小流域氮收支估算及污染潜势

为了解三峡库区氮素收支情况,进行污染潜势评价,对三峡库区典型紫色土坡耕地（新政小流域）进行了调查分析,结果表明,小流域氮输入量为918.26 kg/(hm2·a),输出量为569.46 kg/(hm2·a)。化肥氮是小流域氮输入的主要来源,占氮输入总量的57.63%;作物收获是小流域氮的主要输出方式,占氮输出总量的36.22%;小流域氮损失负荷为258.77 kg/(hm2·a),气态氮损失是流域氮损失的主要形式,占流域损失氮总量的65.11%;流域氮养分平衡指数为3.4,氮素盈余负荷为348.80 kg

Input-output budgets for nitrogen in a typical purple soil sloping ploughland in Three Gorges areas

The Xinzheng watershed in Zhongxian county, Chongqing, is a typical purple soil sloping ploughland in the Three Gorges areas. In 2009, the input-output budgets in this watershed is investigated and the results indicate that the nitrogen input is 918.26 kg/(hm2·a) and the output are 569.46 kg/(hm2·a). Furthermore, chemical fertilizer nitrogen is the main input source, accounting for 57.63%, and the main output track is nitrogen in crops, accounting for 36.22%. In this small watershed, the nitrogen loss load is 258.77 kg/(hm2·a). And the primary lost nitrogen is gaseous species, which is approximately 65.11% of the total lost nitrogen. In addition, nutrient nitrogen balance index is 3.4 in this watershed and the nitrogen surplus load is 348.80 kg/(hm2·a), much higher than the risk value, indicating potential occurrence pollution in ploughland.