滁州花山水文实验流域氮流失特征分析

Analysis of characteristics of nitrogen loss in Huashan hydrological experimental watershed

以滁州花山水文实验流域为研究对象，研究不同土地利用类型中各种形态的氮随径流流失的特征。基于2012年10月-2013年9月滁州花山水文实验流域氮素实验观测数据，对流域的氮随径流流失的特征进行了分析。结果表明：林地比重较大的集水区域径流中的TN质量浓度和N03-N质量浓度较高，农田比重较大的集水区域径流中的NH3-N质量浓度较高；在林地面积比例较大集水区域，TN质量浓度与N03-N质量浓度有较好的相关性；而在耕地面积比例较大的集水区域，TN质量浓度与NH3-N质量浓度表现出较好的相关性。对于嵌套子流域，N03-N质量浓度沿河道往下游随集水区域的增大和森林覆被比例的减少而呈逐渐递减趋势；在农田非施肥季节，各个月的TN质量浓度空间上自上而下随森林覆被比例的减少而呈逐渐递减趋势，而NH3-N质量浓度变化较小；在施肥季节，TN质量浓度随NH3-N质量浓度的上升而上升。研究还发现：研究区域汪郢左支断面和军事牌断面的集水区域林地比重高达99．92％以上，虽然人类活动较少，但TN质量浓度较高，分别为2．830mg／L和4．028mg／L，高于集水区域农田比重较大的竹园沟断面和新坝断面（两断面农田比重分别为39．59％和35．63％），分别是竹园沟断面和新坝断面的1．42～2．5l倍、2．02-3．57倍；这一事实与人们通常的认识不一致，值得进一步深入研究。

In this paper, the characteristics of nitrogen loss with runoff under different land use patterns in Huashan hydrological experimental watershed are studied. Based on the data of sample measurement of nitrogen mass concentrations from October, 2012 to September, 2013 in Huashan hydrological experimental watershed, the characteristics of nitrogen loss with runoff are analyzed. The results show that, there are higher total nitrogen mass concentration and nitrate nitrogen mass concentration in the runoff of the large proportion of the forest catchment as well as higher ammonia nitrogen mass concentration in the runoff of the large proportion of the farmland catchment. The mass concentration of total nitrogen highly correlates with the mass concentration of nitrate nitrogen in catchments with a higher proportion of forest, while the mass concentration of total nitrogen highly correlates with the mass concentration of ammonia nitrogen in catchments with a higher proportion of farmland. For the nested subcatchments the mass concentration of nitrate nitrogen decreased along the river channel downstream with the increase of catchment area and the reduction of forest coverage ; in non-fertilization seasons, the mass concentration of total nitrogen decreased along the river channel downstream with the increase of catchment area and the reduction of forest coverage, and the mass concentration of ammonia nitrogen has a small change, while in fertilization seasons, the mass concentration of total nitrogen increased with the increase of the mass concentration of ammonia nitrogen. The study found that, in the catchment of the Junshipai section and the Wangyingzuozhi section, the proportion of forest is as high as more than 99.92% and human activities are quite limited, however, the mass concentration of total nitrogen in these sections are 2. 830 mg/L and 4. 039 mg/L respectively, being 1.42 - 2. 51 times and 2.02 - 3.57 times higher than the one in the catchment of Zhuyuangou section and Xinba section respectively, where the proportion of farmland is 39.59% and 35.63% respectively. This fact is inconsistent with the common knowledge of people, which is worth further studying.