地表径流中碱土金属流失规律及调控机制研究

Law and Control Mechanism of Alkaline Earth Metal Losses in Runoff

采用模拟降雨装置,对密云县农田褐土进行了在不同地表状况、降雨强度和坡度下的交叉试验,测试分析了径流泥沙和径流水携带的Ca、Mg流失量。结果表明,相同降雨强度、坡度条件下,Ca、Mg流失量为秸秆覆盖<草皮覆被<裸地。相同地表状况与坡度下Ca、Mg流失量与雨强呈正相关,相同雨强下泥沙携带流失量随坡度的增加而增大,草皮覆被和秸秆覆盖的地表径流水中Ca、Mg的流失量随坡度的增加而增大,坡度对裸地地表径流水携带Ca、Mg的流失量峰值有影响。相同雨强和坡度条件下,裸地地表泥沙中Ca、Mg的流失量超出径流水的携带量,草皮覆被和秸秆覆盖下,在坡度10°、15°时泥沙中Ca、Mg的流失量接近于径流水携带量,而且此时径流水中Ca、Mg的流失量占泥沙携带量的百分比高于坡度为20°、25°、30°时的百分比。秸秆覆盖,雨强90、120mm·h-1条件下,径流水中Mg的流失量已经超过了泥沙携带量,结果证明径流液中Ca、Mg均存在不容忽视的流失状况,而且Ca的流失量高于Mg。

Alkaline earth metal is the necessary nutrition for plant and is important to soil physical and chemical characteristics and environment. The cross-experiments were carried out at farmland cinnamon soil of Miyun County underdifferent surface conditions, rainfall intensities and slopes. The Ca and Mg losses in runoff and sediment were determined and analyzed. The results showed that Ca and Mg losses expressed that straw mulching<turf mulching<bare land under the same rainfall intensities and slope. The Ca and Mg losses were positively correlated to rainfall intensities under the same surface conditions and slope. Under the same rainfall intensity, the Ca and Mg losses in sediment and in turf andstraw mulching runoff went up with the increase of slope. Slopes affected the peak value of Ca and Mg losses in bare land. Under the same rainfall intensity and the same slope, Ca and Mg losses in bare land sediment was higher than that inrunoff. When land surface was covered with turf and straw, Ca and Mg losses in sediment were similar to that in runoff in slopes of 10°and 15°, and the percentage of Ca and Mg losses in runoff accounting for that of sediment was higher than that in slopes of 20°, 25°, 30°. Mg losses in runoff were exceeded that in sediment carrying under straw mulching and 90 mm·h-1, 120 mm·h-1rainfall intensities. These implied that Ca and Mg losses in runoff could not be ignored and the Ca losses were higher than Mg losses.