山仔水库典型样地次降雨径流过程磷流失特征研究

Phosphorus loss features in typical plots of Shanzi reservoir during the precipitation punoff process

降雨径流是农业非点源污染发生的主要动力。福州第二饮用水源地山仔水库是周边以农业用地为主的峡谷型水库,由降雨径流输入库区的农业非点源污染不容忽视,而磷污染是引起水体富营养化最关键的限制因子。选取山仔水库库区典型样地松竹林、水稻田和地瓜地为研究对象,同步监测4次降雨径流过程径流量、总磷和可溶性磷浓度,对次降雨产流和磷输出特征以及两者的相关性进行了研究。结果表明,径流量峰值滞后于降雨量峰值约20 min,样地按径流量从大到小排序为松竹林、水稻田、地瓜地;土壤中大部分的磷以颗粒态形式流失,地瓜地、水稻田和竹林在4次降雨径流过程输出总磷的平均质量浓度分别为0.145 1 mg/L、0.124 3 mg/L、0.097 0 mg/L,可溶性磷的平均质量浓度分别为0.036 9 mg/L、0.031 3 mg/L、0.022 8 mg/L;松竹林、水稻田、地瓜地的总磷输出负荷与降雨径流量之间存在典型的多项式正相关关系,其相关系数分别为0.998 2、0.997 8、0.998 4。

The present paper aims to introduce our statistic investigation over the phosphorus loss situation and analysis of the features of such loss with the typical plots of Shanzi reservoir during the precipitation runoff process. Shanzi reservoir is known as the second largest drinking water resource for Fuzhou city, but its eutrophication has not so far been well-preserved. One of the main reasons was the agricultural non-point source pollution. Generally speaking, plentiful rainfall is a good thing for a reservoir. But unfortunately rain-water＇s running has taken away large amounts of the nutrient substances of nitrogen and phosphorus to the waterbody of the reservoir, which should otherwise have been the fertilizer and pesticide to the farm fields. Besides, phosphorus is the restrictive factor of eutrophication in Shanzi Reservoir. However, little has been seriously studied over such losses. So in this paper, three main types of vegetation plots of Shanzi Reservoir have been selected as typical study topics, with experiments done in situ. In order to find out the features of the runoff and phosphorus output load, as well as the relationships between phosphorus content and precipitation runoff, We simultaneously monitored the surface runoff, concentration of dissolved phosphorus （DP） and the total phosphorus （TP） loss in the four typical precipitation runoff processes. The results of our study show that the peak value of runoff deferred about 20 minutes of the rainfall, with the most runoff being output from the pine and bamboo fields, next from the paddy fields, and the least output-from the sweet potato fields. Moreover, it can also be concluded that the main phosphorus loss was done in the tiny particle form. The average content of TP, mainly the output by the pine bamboo, paddy and sweet potato field, are 0.145 1 mg,/L, 0.124 3 mg/L, 0.097 0 mg/L, respectively, and the average DP content are 0.036 9 mg/L, 0.031 3 mg/L, 0.022 8 mg/L, respec- tively. The regression analysis results with the pinebamboo, paddy and sweet potato field indicated that polynomial relation exist between the runoff and TP output load, with the R2 values of theirs being 0.998 2, 0.997 8 and 0.998 4, respectively.