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贵州喀斯特高原的毁林开荒往往引起严重的土壤侵蚀.喀斯特洼地沉积泥沙的137Cs断代用以调查贵州普定石人寨小流域1979年森林破坏后的坡地地表侵蚀的土壤流失量.该小流域集水面积0.054km2,洼地面积2652m2,2009年采集的洼地5个孔的顶层和峰值层的137Cs平均浓度分别为2.35和7.25Bq·kg-1,峰值层的深度介于84~113.5cm之间,平均深度为92.1cm.1979年以来的沉积泥沙的总体积和总重量分别为1965m3和2496t.洼地底部可视为一暂时性蓄水体,确定的泥沙输移比为0.7,1979年以来的坡地平均土壤侵蚀速率为2315t·km-2·a-1.5个孔的137Cs平均面积活度7693Bq·m-2,为本底值782Bq·m-2的9.8倍.洼地泥沙的137Cs总量为20.4×106Bq,1954年以来坡地的137Cs平均流失量为358Bq·m-2,相当于本底值的45.8%.由于森林破坏和随后的垦殖期的之前和之后,流域坡地土壤侵蚀并不强烈,估计石人寨小流域1979~1990期间的坡地侵蚀速率可能高达7000t·km-2·a-1.
Deforestation and reclamation in the Guizhou Karst Plateau often lead to serious soil erosion.The 137Cs dating from sediment deposition in the Karst depressions was used to investigate the soil erosion of slope land erosion after slope erosion in Shimenzhai, Guizhou Province, in 1979. This small watershed Water area of 0.054km2, depression area of 2652m2, the average concentration of 137Cs in the top and peak layers of the five wells in 2009 was 2.35 and 7.25Bq · kg-1 respectively, and the depth of the peak layer was between 84 and 113.5cm, With an average depth of 92.1 cm. The total volume and total reserves of the affected mines since 1979 are 1965 m 3 and 2496 t, respectively. The bottom of the depressions can be regarded as a temporary reservoir with a sediment transport ratio of 0.7. The average soil erosion rate at slope of 2315t · km-2 · a-1.5 was 13793bq · m-2, which was 9.8 times of the background value of 782Bq · m-2. The total amount of 137Cs in the depression Was 20.4 × 106Bq, and the average 137Cs loss on sloping land since 1954 was 358Bq · m-2, equivalent to 45.8% of the background value. Due to the forest erosion and the subsequent reclamation period, the soil erosion on sloping land was not strong , To estimate the slope erosion rate in Shirenzhai small watershed from 1979 to 1990 May be up to 7000t · km-2 · a-1.