东莞市4种人工林土壤重金属含量的特征及评价

Characteristics and Assessment of Heavy Metals in Soil of Four Plantations in Dongguan City

以东莞尾叶桉林、马尾松林、马占相思林和针阔混交人工林为对象，分析林地0～25cm表层土壤Cu、Zn、Pb、cd4种重金属含量，并以广东省土壤背景值为标准，采用单因子污染指数和综合污染指数评价林地土壤重金属的污染状况。结果表明，尾叶桉林和马尾松林以土壤Ph含量最高，其他两种林型以zn含量最高；4种重金属含量高低为Zn〉Pb〉Cu〉Cd，它们的单因子污染指数大小顺序为Pb〉Cu〉Zn〉Cd。4种林型土壤综合污染指数依次为马占相思林〉尾叶桉林〉马尾松林〉针阔混交林。土壤pH值与Zn、cd之间相关性显著，土壤全钾与Zn、Cd间呈极显著正相关。结合主成分分析结果可知，东莞市4种人工林土壤Cd与自然因素有关，土壤Cu主要受人为输入影响；Zn含量高于背景值，受自然与人为因素的共同影响。

Taking Eucalyptus urophylla, Pinus massoniana, Acacia mangium, coniferous and broadleaf mixed plantation （P. massoniana ＋ E. citriodora） in Dongguan City as research objectives, the contents of heavy metals including Cu, Zn, Pb, and Cd in 0 ＋ 25 cm soil layers were analyzed. Single factor pollution index and compre- hensive pollution index were used to assess heavy metals pollution of forest soil, based on the soil background val- ues in Guangdong Province. The results showed that the content of Pb was the highest in E. urophylla forest and P. massoniana forest, while the content of Zn was the highest in A. mangium forest and mixed plantation. The se- quence of the contents of heavy metals was Zn 〉 Pb 〉 Cu 〉 Cd, the single factor pollution index of four heavy met- als was in the order of Pb 〉 Cu 〉 Zn 〉 Cd, while the comprehensive pollution index of forest soil was decreased in the order of A. mangium 〉 E. urophylla 〉 P. massoniana 〉 mixed plantation. There existed positive significant correlations between soil pI-I and Zn and Cd, and soil total potassium was very significantly related to Zn and Cd. Principal component analysis showed that Cd mainly came from soil materials and Cu from anthropogenic inputs in the tested plantations, Zn was affected by both soil materials and anthropogenic inputs and its concentration was higher than the background value.