佛山城市森林公园表层土壤重金属累积特征、影响因素及其评价

Accumulation Characteristics,Influencing Factors and Evaluation of Heavy Metals in Surface Soil in Urban Forest Park of Foshan

研究区域经济快速发展对城市森林生态系统影响,明确城市森林公园土壤重金属污染程度,可为城市森林公园土壤管理和城市土壤安全利用与保护提供理论依据。以佛山市城市森林公园林区为研究对象,依据其分布格局随机选取11个林区,分析了样地土壤中8种重金属(Cd、Pb、Cr、Cu、Ni、Zn、Hg、As)累积特征,通过单因子评价指标进行评价及影响因素分析。结果表明,(1)佛山市城市森林公园表层土壤重金属环境质量整体良好,不同样地质量分数差异较大,其中重金属Ni元素质量分数均值略超珠三角背景值,其余重金属元素质量分数均值都低于珠江三角洲背景值,均不构成人身接触健康风险。(2)佛山城市森林公园土壤重金属主要受森林土壤成土过程及干湿沉降影响,其次为林业管理和汽车燃油。(3)中央公园样地8种重金属均低于背景值,其余样地均有不同重金属、不同程度超出珠三角土壤重金属环境背景值,其中Ni在王借岗公园、As在西樵山公园分别是区域背景值的4.34倍和3.80倍,达到重污染级别;Pb在李小龙乐园、As在大南山林场是区域背景值2.28倍和2.09倍,达到中度污染级别,各影响因素叠加累积效应可能是导致土壤重金属超出背景值的种类多和强度大的原因。(4)佛山城市森林公园11个样地中,超出珠三角土壤背景值频度最高的为Cr元素,其次为As元素,其中王借岗公园样地Cd、Cr、Cu、Zn、Ni超出区域背景值;西樵山公园样地Hg、Zn、As超出区域背景值;李小龙乐园样地、大南山公园样地、桫椤保护区样地和佛山植物园样地均有2种重金属超出区域背景值,其余样地为单元素超出区域背景值或没有重金属超出区域背景值。

Studying the impact of rapid regional economic development on urban forest ecosystems and clarifying the degree of heavy metal pollution in urban forest park soils can provide a theoretical basis for urban forest park soil management and urban soil safety utilization and protection.According to the forest area of Foshan City Forest Park,11 forest areas were randomly selected,and the cumulative characteristics of 8 heavy metals(Cd,Pb,Cr,Cu,Ni,Zn,Hg,As)were analyzed.Evaluation and analysis of influencing factors were carried out through single-factor evaluation indicators.The results showed that:(1)The environmental quality of heavy metals in the surface soil of foshan urban forest park was in good condition,but the content of different heavy metal in each research sample were obviously different,average values of soil Ni mass fraction was slightly higher than the background value of the Pearl River Delta,while others were lower than that,each average values of soil heavy metal elements mass fraction had no health risks.(2)The soil heavy metals in foshan urban forest park were mainly affected by the soil formation process and dry and wet settlement of forest soil,followed by forestry management and automobile fuel.(3)There were 8 heavy metals beyound the background value in the Central Park,and other sampling points had different heavy metals,which exceeded the environmental background value of the soil heavy metals in the Pearl River Delta to varying degrees.Ni at Wangjiegang Park and As at Xiqiaoshan Park were 4.34 times and 3.80 times of the regional background value respectively,reaching the heavy pollution level,Pb at Lixiaolong Park and As at Dananshan were 2.28 times and 2.09 times of the regional background value respectively,reaching the medium pollution level,the cumulative effect of various influencing factors may be the cause of the large number and intensity of soil heavy metals exceeding the background value.And(4)among the sampling points,the element with the highest frequency of exceeding the soil background value of the Pearl River Delta was Cr,followed by As,of which Cd,Cr,Cu,Zn and Ni were beyond the area in the Wangjiegang Park;Hg,Zn,As in the Xiqiaoshan Park were exceed the regional background values;Lixiaolong Park,Dananshan Forest Farm,Spinulose tree fern Protected Area and Foshan Botanical Garden all had 2 heavy metals exceed the regional background values.The rest of the others had single or no heavy metal exceeding the regional background value.