浑河上游不同类型农户氮负荷特征

Nitrogen load characteristics of different farmer types in upper reaches of Hunhe watershed,Liaoning Province of Northeast China

选取浑河上游大伙房水库上游的小流域为研究区域,对农户氮素非点源污染特征进行了分析。根据氮素流动的特点,将农户分为养殖型农户、蔬菜种植户、传统种植户3种类型。氮素污染负荷顺序为:养殖型农户(348±76kg·hm-2·a-1)>蔬菜种植户(307±127kg·hm-2·a-1)>传统种植户(213±126kg·hm-2·a-1)。不同农户农田氮损失量的大小顺序为:蔬菜种植户(256±21kg·hm-2·a-1)>养殖型农户(188±52kg·hm-2·a-1)>传统种植户(168±65kg·hm-2·a-1)。表明,该地区的蔬菜种植户、养殖型农户对水体质量影响较大,是氮素非点源污染重点防治对象。在农户氮排放中,居民生活排放的氮素占28%,农田氮损失占72%,说明农田是主要的氮污染源,但居民生活的氮素污染也不可忽视。该研究范围内最佳氮循环的临界值为395.5kg·hm-2·a-1,此时的总流动量是1883.3kg·hm-2·a-1,氮素输出是376.7kg·hm-2·a-1。

Taking a small watershed at the upstream of Dahuofang Reservoir in the upper reaches of Hunhe River as the study area,this paper analyzed the non-point source nitrogen pollution characteristics of different farmer types.According to the nitrogen flow characteristics in the watershed,the farmers were classified into three types,i.e.,livestock and poultry-based farmers,vegetable growers,and traditional farmers.The nitrogen pollution loads of the farmers were in the order of livestock and poultry-based farmers（348±76 kg·hm-2·a-1）〉 vegetable growers（307±127 kg·hm-2·a-1）〉 traditional farmers（213±126 kg·hm-2·a-1）,and the nitrogen losses from the lands of the farmers were in the order of vegetable land（256±21 kg·hm-2·a-1）〉 livestock and poultry-based land（188±52kg·hm-2·a-1） 〉traditional farmland（168±65 kg·hm-2·a-1）,indicating that the vegetable growers and livestock and poultry-based farmers in the watershed had greater contribution to the water quality,being the priorities of consideration for the prevention of the non-point source nitrogen pollution.As for the nitrogen pollution sources,inhabitant living and farmland nitrogen losses occupied 28% and 72%,respectively,suggesting that farmland was the main source of nitrogen pollution,whereas inhabitant living was the another important source not be ignored.The threshold of the optimal nitrogen cycle in the study area was 395.5 kg·hm-2·a-1,and the corresponding total nitrogen flow and nitrogen output were 1883.3 kg·hm-2·a-1 and 376.7 kg·hm-2·a-1,respectively.