不同大气污染区林木根区土壤重金属和酶活性研究

黄埔区是广州市污染较严重的地区,其中林木也受到了大气等污染物的危害。林木根区的土壤重金属和酶活性是探讨污染对林木影响机制和反映污染程度的重要指标。作者分别在该区的石化厂、硫酸厂附近林地和非污染的华南农业大学校园(对照)共3个区选择了台湾相思、马尾松、尾叶桉和荔枝4个树种、11个采样点,共采集了33个供试土壤样品,分析了林木根区土壤重金属(Cu、Zn、Pb、Cd)全量、有效量和土壤酶(脲酶、过氧化氢酶、酸性磷酸酶和蛋白酶)活性。结果表明,(1)石化厂重金属含量总体上与对照区差异不大,而硫酸厂区重金属含量则显著地高于对照区,污染严重。(2)不同调查区根区土壤酶活性存在显著差异,各调查区平均土壤酶活性大小顺序基本上表现为:对照区>石化厂区>硫酸厂区,尤其是硫酸厂区显著地低于对照区;而同一调查区不同树种之间的酶活性也存在差异,台湾相思根区土壤脲酶的活性均比其它树种高;从酶活性看,在硫酸厂严重污染胁迫下,台湾相思比尾叶桉更耐污染。(3)对土壤重金属含量和酶活性进行典型相关分析得出:根区土壤有效Zn含量对过氧化氢酶和酸性磷酸酶活性有明显的刺激作用,但抑制了蛋白酶活性;有效Cd则抑制了过氧化氢酶和酸性磷酸酶活性,但刺激了蛋白酶活性。

Heavy metal contents and enzymatic activities of soil in tree root zone at different air-polluted areas

The Huangpu District is a serious polluted area in Guangzhou city,where the trees were imperiled by the pollution espe-cially by the air contaminations.The heavy metal contents and enzymatic activities of soil in tree root zone are the important indices for describing and discussing the process and pollution effect.In the study,4 tree species(Acacia confusa,Pinus massoniana,Euca-lyptus urophylla and Litchi chinensis),11 points for sample collection were selected and 33 samples of tree root zone soil were col-lected at the polluted area of the petrochemical,the vitriol factory and the unpolluted one of South China Agricultural University(as control area,CK).The heavy metal contents(total and available Cu,Zn,Pb and Cd)and enzymatic activities(urease,catalase,acid phosphatase and protease)were analyzed and the results showed:(1)For the soil heavy metal contents,there were no significantly differences between that of the petrochemical factory and that of the control area(CK),but at the vitriol factory area,they were re-markably higher than that of CK.(2)There were significantly differences for the soil enzymatic activities among the three areas.The order of soil enzymatic activities was that of CK> of the petrochemical industry area > of vitriol factory area.At each area,there were significantly differences soil enzymatic activities among the different tree species.Urease activity of Acacia confusa was higher than that of all the other tree species.From the comparison of soil enzymatic activities,Acacia confusa had stronger resistance than that of Eucalyptus urophylla to the contaminations under serious air-pollution stress at vitriol factory area.(4)Content of soil avail-able Zn increased the activities of catalase and acid phosphatase but decreased that of protease while available Cd increased the ac-tivity of protease but decreased that of catalase and acid phosphatase.