Yang Feng, Wang Peng-ju, Yang Shan-shan, Wu Jin-shui, Hu Rong-gui
Hubei Institute of Forestry Survey and Design, Wuhan 430079, China.
Huan Jing Ke Xue. 2012 Aug;33(8):2652-8.
This study was conducted in Jintuo watershed of Changsha City, Hunan Province, in the suburban agriculture regions, by selecting 8 sub-basins to examine the effect of land use on watershed runoff nitrogen output. The land use map of watershed was interpreted from Spot-5 image of 2009, and by using hydraulic analysis function and spatial analysis extensions of ArcGIS 9.3, the catchment areas were delineated from DEM. Water sampling was carried out from Dec. 2009 to Nov. 2010, and the relationships between different types of nitrogen export and land use were analyzed. The results showed that nitrogen pollution in the watershed was extremely serious. There was a distinct seasonal variation in the following order: WI > SP > SU approximately = FA in the output concentration of total nitrogen and ammonium nitrogen which was not observed in the nitrate output. Moreover, land use was a dominant factor that determined the export of nitrogen, and especially a significant correlation was figured out between the nitrate output concentration and the land use structure. Forest and water body had a negative impact on nitrate output concentration while dry land, paddy field and habitation road had a positive effect. However, the effects varied with time. Dry land had the most significant important effect on nitrate output concentration in winter and fall, but in spring and summer was the forest land. The correlation between land use structure and the output concentration of total nitrogen and ammonium nitrogen was not found. The resident number, pig number and fertilization also had a major impact on nitrogen output quantity.
本研究在湖南省长沙市郊区农业区的金托流域开展，通过选取8个子流域来考察土地利用对流域径流氮输出的影响。流域土地利用图由2009年的Spot-5影像解译而来，并利用ArcGIS 9.3的水力分析功能和空间分析扩展模块，从数字高程模型（DEM）中勾画出集水区。于2009年12月至2010年11月进行水样采集，并分析了不同类型氮输出与土地利用之间的关系。结果表明，该流域的氮污染极其严重。总氮和铵态氮的输出浓度存在明显的季节变化，顺序为：冬季 > 春季 > 夏季 ≈ 秋季，而硝态氮输出未观察到这种季节变化。此外，土地利用是决定氮输出的主要因素，尤其是硝态氮输出浓度与土地利用结构之间存在显著相关性。森林和水体对硝态氮输出浓度有负面影响，而旱地、水田和居民点道路则有正面影响。然而，影响随时间而变化。旱地在冬季和秋季对硝态氮输出浓度的影响最为显著，但在春季和夏季则是林地。未发现土地利用结构与总氮和铵态氮输出浓度之间的相关性。居民数量、猪的数量和施肥对氮输出量也有重大影响。
