天然林冠层的水质效应

Effects of Canopy of Natural Forest on Water Quality

通过对秦岭火地塘天然林林区大气降水和林内雨pH值等相关水质指标进行测试和对测试结果进行对比分析,发现天然林冠层对酸性降水有显著的调节作用,可使其酸性降低并趋于中性,而起关键作用的是林木的叶。林冠层对降水中NO3-有一定的净化作用。降水通过林冠层后,NH4+、K、PO43-、Na、Mg、Fe含量增加,其中K含量增加非常显著;其次,林冠层还对NH4+、Na、Ca、Mg有调节作用。林内雨中,K、Na、Ca、Mg含量在林木落叶期较高。林冠层对Cd、Pb、Mn、Zn均有吸附作用,对Cd的吸附能力平均在0.8μg/L左右,其中对Pb、Zn吸附作用不但非常强,而且还有调节和稳定作用。

The indicators of water quality, such as pH and so on, of rainfall and throughfall of natural forest in Huoditang region, Qinling mountain, were measured from collected samples, and then analyzed through comparing and contrasting. The result shows that the canopy of natural forest has several effects on water quality. Firstly, the canopy has a notable ability of buffering the pH of acidierain, reducing the degree of acidity of rain to be medium when rain becomes throughfll. It is foliage that plays an important role in buffering the pH. Secondly, the canopy can reduce NO3^- to some degree in rain. Thirdly, the canopy enriches NH4^＋, K, PO4^3-, Na, Mg and Fe in throughfall, especially K. It was enriched greatly. At the same time, the canopy adjusts NH4^＋, Na, Ca and Mg in water when rain becomes throughfall. The concentrations of K, Na, Ca and Mg in throughfall are higher in leave-falling time. Fourthly, the canopy can absorb toxic elements Cr, Pb and heavy mentals Mn, Zn in rain, especially Pb and Zn. The capability of absorbing Cd in rain is about 0.8 μg/L. In addition to absorbing Pb and Zn significantly, it still stabilizes and regulates them when rain becomes throughfall.