武夷山茶园土壤重金属环境风险等级评价及溯源分析

ttttt目的ttttt研究新平县茶园核心区土壤重金属含量特征及来源，评价茶园土壤重金属生态风险与预警状况。ttttttttttttt方法ttttt共采集30个新平县茶园核心区土壤混合样品，采用污染负荷指数(pollution load index，PLI)、潜在生态风险指数(potential ecological risk index，RI)和生态风险预警指数(ecological risk warning index，I_ER)对土壤重金属污染及生态风险进行评价。tttttttttttttttttt结果ttttt新平县茶园核心区土壤中Cd、Pb、Hg、As、Cr、Cu、Zn的平均含量分别为0.11、58.14、0.142、12.24、83.01、32.61、67.97 mg/kg，均未超出国家土壤环境质量Ⅱ级标准，仅Hg、Cr和Pb平均值超过云南省土壤背景值，分别是对应背景值的2.60、1.15和1.11倍。各重金属元素单因子污染指数(contamination factor，C_fⁱ)从大到小依次为：Hg>Cr>Pb>As>Cd>Zn>Cu，其中，Hg为中度污染，Cr和Pb轻度污染，As、Cd、Zn和Cu属无污染；PLI平均值为0.81，为无污染。潜在生态风险评价结果显示：单个重金属潜在生态风险(E_rⁱ)顺序为：Hg>Cd>Pb>Cr>Zn>Cu>As，茶园核心区土壤RI平均值为28.07，存在轻微生态风险。8个乡镇茶园土壤RI依次为：建兴乡(35.7)>平掌乡(35.2)>漠沙镇(31.3)>者竜乡(25.2)>戛洒镇(25.1)> 水塘镇(22.13)>平甸乡(22.07)>新化乡(19.4)。土壤I_ER平均值为−4.36，属于无警级别。Hg是生态风险等级最高的重金属元素，对研究区土壤PLI、RI和I_ER的贡献非常大。tttttttttttttttttt结论ttttt新平县茶园核心区土壤整体上存在轻微生态风险，属于无预警态势，可在维持原生态环境的同时发展高品质农业。tttt

Heavy metal transfer from soil to vegetable in Southern Jiangsu Province,China

tttttPurposestttttTo study the characteristics and sources of heavy metals, and to evaluate their ecological risk and early warning of tea plantations soil in Xinping County.tttttttttttttMethodstttttWe collected 30 samples of soil mixture to evaluate the heavy metal pollution and ecological risk of tea plantations soil in Xinping County by the pollution load index (PLI), potential ecological risk index (RI) and the ecology risk warning index (I_ER).ttttttttttttttttttResultstttttThe average values of Cd, Pb, Hg, As, Cr, Cu and Zn in the soils were 0.11, 58.14, 0.142, 12.24, 83.01, 32.61 and 67.97 mg/kg, respectively; Hg, Cr and Pb concentrations were as 2.60, 1.15 and 1.11 times as the background values of soil in Yunnan Province, were mainly affected by human activities. But their concentrations were all lower than the threshold values II of the National Environmental Quality Standard for Soil (GB 15618—1995). Each single contamination factor (C_fⁱ) revealed that the level of heavy metal pollution in the soils was in order of Hg>Cr>Pb>As>Cd>Zn>Cu, Hg pollution was of moderate level while Cr and Pb pollution were slight. The average PLI was 0.81, there was no soil pollution caused by heavy metals. The sequence of potential ecological risk of heavy metal was Hg>Cd>Pb>Cr>Zn>Cu>As. The integrated factor RI of heavy metal pollution in the soils was 28.07, suggesting a low ecological risk. The RI of tea plantation soils in 8 villages or towns was in order of Jianxing Village (35.7)>Pingzhang Village (35.2)>Mosha Town (31.3)>Zhelong Village (25.2)>Gasa Town (25.1)>Shuitang Town (22.13)>Pingdian Village (22.07)>Xinhua Village (19.4). The average value of the soilI_ER was −4.36, which belonged to the no warning. Hg was the heavy metal element with the highest ecological risk level, the contribution of soil PLI, RI and I_ER in the research area was very large.ttttttttttttttttttConclusionstttttThe potential ecological risk analysis suggested a slight risk to local ecosystem originated from heavy metal contamination in the soils of tea plantation in Xinping, which belonged to the no-warning situation, and could develop high quality agriculture while maintaining the original ecological environment.tttt