降雨强度与坡度对径流中七种阳离子流失量的影响

针对密云水库周边地区坡地地貌,采用室内模拟降雨装置和ICP-MS质谱分析技术,研究了密云地区农田褐土在5种坡度和3种降雨强度交叉实验表层径流中K、Na、Ca、Mg、Al、Fe、Mn7种阳离子在不同降雨时段下的流失规律。结果表明在坡度和降雨时间段相同时,随着雨强的增加,大部分阳离子最大流失量逐渐增加,K、Mg、Fe、Mn规律性较强;在相同雨强和降雨时间段下,各阳离子流失量最大值所呈现的坡度不尽一致,但在雨强120mm/h时,K、Na、Ca、Mg、Fe流失量的最大值均呈现在25o坡度下;在坡度、雨强一致时,不同降雨时段内7种阳离子的流失量均呈现出随着时间的递增而逐渐增加的趋势。不同阳离子的流失总量之间随坡度的变化存在相关性,如在60mm/h和120mm/h降雨强度下,K、Ca流失量之间的相关系数分别达到0.974和0.953。各阳离子流失量在连续时间段下受径流量的影响不明显,但7种阳离子在1h的流失总量与径流量之间在相同降雨强度下随坡度变化均存在二次曲线关系,复相关系数平方>0.9。

EFFECTS OF RAINFALL INTENSITY AND SLOPE ON LOSSES OF CATIONS WITH RUNOFFs

An indoor rainfall simulation experiment was designed according to the landform of the slope lands around the Miyun Reservoir and carried out with the aid of the ICP-MS mass spectrum analyzing technology, to determine regularities of the loss of seven different kinds of metal cations with surface runoff from fields of cinnamon soil different in slope under different rainfall intensities and durations. Results showed that when the slopes and rainfall durations were the same, cation losses increased gradually with rainfall intensity, which fitted more K, Mg, Fe and Mn. When intensities and durations of the rainfalls were the same, the occurrence of maximum cation losses disagreed with the slopes, but when the rainfall intensity was 120mm/h and slope was 25° the losses of K, Na, Ca, Mg, and Fe all reached maximum. When the slopes and the rainfall intensities were the same, the losses of cations increased with the duration of rainfalls. Relativities were also found between the total losses of different cations with the change in slope. For example, when the rainfall intensity was at 60mm/h and 120mm/h, the correlation coefficients of K losses and Ca losses were 0.974 and 0.953 separately. The loss of each cation within a duration was little related to volume of the runoff. But when the rainfall intensities were the same, quadratic curve relations existed between hourly total losses of seven different kinds of cations and volumes of runoff with the slope, and the square of multiple correlation coefficient is bigger than 0.9.