木本植物对大气重金属污染物耐性的研究

本文在污染现场调查研究、试验研究和单一毒物接触试验的大量数据基础上，论述了木本植物对大气重金属污染物一一铅、镉、铜、锌的耐性。查明了大气重金属污染物引起叶片可见伤害症状需要很高的剂量。糖槭以2000ppm硝酸铅溶液浸泡涂抹枝叶，三天后出现轻度可见伤害症状，叶中铅积累量高达802ppm。旱柳以500ppm氯化镉溶液浸泡涂抹枝叶，叶中积累量达66ppm，十天内未出现可见症状。大气重金属污染物——铅、镉、铜、锌对叶片造成的急性伤害症状是相似的，而与土壤中相同污染物引起的急性伤害具有差别。木本植物对大气重金属污染物的耐性很强，在以大气重金属污染为主的复合污染现场，一些幼龄树木的叶片吸铅量达500—800ppm，超过背景浓度的120倍；吸镉量10—18ppm，超过背景浓度的139倍，吸铜量100—239ppm，超过背景浓度的5—12倍，吸锌量500—700ppm，超过背景浓度的9—20倍只出现较轻的受害症状。在相对清洁区，对幼树叶片进行单一毒物接触试验，一些主要绿化树木的叶片吸铅量达200—600ppm，吸镉量20—60ppm并不出现可见症状。木本植物对大气重金属污染物具有较强的耐性，因而为生物防治大气重金属污染开辟了广阔的前景。

Study on Tolerance of Woody-plants to Heavy Metal Pollutants in Air

The research results shows that tolerance of woody-plants to air borne metal pollutants-lead, cadmium, copper and zinc is strong.According to the data from 20 tree species, their leaves in growing season could absorb from atmosphere about 500--800ppm of lead, 120 times. over its background concentration; about 10--18ppm of cadmium, 139 times over the background;about 100--239Ppm of copper, 5--12 times over the background and about 500--700 ppm of zinc, 9--20 times over the background, without serious injure. Under experimental condition, some tree species can probably accumulate 200--600ppm of lead, 20--60ppm of cadmium in leaves without visible symptoms. The acute injury to willow (Salix matsudana) does not occur below 66ppm of cadmium. The injury symptoms of woody-plants leaves caused by heavy metal pollutants in air are typical. The injury symptoms in leaves by lead, cadmium, copper and zinc in air are similar.Therefore, it is an urgent task to use forests and trees for improving the environment and controlling pollution by heavy metals in air.