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对北京密云水库集水区人工油松水源保护林降水化学性质研究表明 ,在研究区大气降水化学元素含量在观测时段内变幅较大 ;测定时段内各元素加权平均值之和为 12 0 0 1mg·L-1,大气降水中各元素含量按大小排序为Ca >N >K >Mg >Na >P >Fe >Zn >Cu >Mn ;大气降水经过林冠层后 ,林内穿透降水和树干茎流中各化学元素含量变化不一 ,但多数元素含量增加且总量呈增加趋势 ,林内穿透降水化学元素加权平均值之和为2 0 614mg·L-1,树干茎流为 73 3 2 4mg·L-1,比林外降水分别高出 8 613mg·L-1和 61 3 2 3mg·L-1,引起树干茎流和穿透降水中化学元素总量增加的主要原因是K含量增加所致 ,K在林内穿透降水和树干茎流中的含量约是大气降水含量的 3倍和 2 5倍 .
The study on the chemical properties of precipitation in the artificial forest of Pinus tabulaeformis water conservancy in Miyun Reservoir watershed in Beijing shows that the chemical elements contents of precipitation in the study area fluctuate greatly during the observation period and the sum of the weighted average values of the elements in the measurement period is 1200 1mg · L-1. The content of each element in the precipitation was Ca> N> K> Mg> Na> P> Fe> Zn> Cu> Mn. The content of each chemical element in the stream varied, but the contents of most elements increased and the total amount increased. The sum of the weighted average values of the chemical elements penetrating through the forest was 20 614 mg · L -1 and the stem flow was 73 32 4 mg · L-1, which is 8 613 mg · L-1 and 61 3 2 3 mg · L-1, respectively. The main reason for the increase of total chemical elements in trunk stem flow and penetration precipitation is the increase of K content As a result, K penetrates into the forest and precipitation in the stem stream is about three and twenty-five times that of the atmospheric precipitation.