皖南低山丘陵地区流域氮磷径流输出特征

通过对安徽南部宣城地区梅村小流域的定位监测,研究了该小流域地表径流中氮磷输出特征。结果表明:氮输出以NO-3N为主,占氮素输出总量的60%,磷输出以悬浮颗粒结合态磷(PAP)为主,占磷输出总量的92%;各类形态氮素输出量间存在极显著线性正相关关系;PAP随悬浮颗粒输出量的增加而增加,PAP与水溶性磷(DP)输出量间存在着极显著的对数关系;氮磷输出具有明显的季节性变化规律,夏季输出量最大,其次是春季,再次是秋季,冬季最少,这是由降雨量的季节性变化所引起的。而且暴雨对氮磷输出的贡献率极大,因此控制雨季土壤侵蚀是有效控制氮磷通过径流输出的最重要方式。

Characteristics of nitrogen and phosphorus discharge with runoff from a watershed in the northern subtropical low hilly areas

The study was carried out in the Meicun Watershed,Xuancheng County,Anhui Province,in the northern subtropical low hilly areas by monitoring stream water,in order to illustrate characteristics of nitrogen and phosphorus discharge with surface runoff.The results show that nitrate was the main form of the nitrogen discharged,accounting for 60% of the total lost nitrogen,while particulate-associated phosphorus(PAP)was the main form,accounting for more than 90% of the total phosphorus discharged.There existed positive linear relationships between NO~-_3-N,NH~+_4-N and total nitrogen(TN).The discharge of PAP was correlated well with suspended particulates.A significant logarithmic relationship was observed between the discharges of dissolved phosphorus(DP)and PAP.A dramatic seasonal change of nitrogen and phosphorus discharges with runoff was found,showing a decreasing sequence of summer>spring>autumn>winter as a result of seasonal rainfall distribution.Furthermore,rainstorms contributed the most to the discharge of nutrients.Therefore,soil erosion control should be an effective countermeasure in limiting nitrogen and phosphorus loss in the rainy season.