广藿香重金属污染及潜在生态风险评价

Heavy Metal Pollution and Potential Ecological Risk Assessment of Pogostemon cablin

采用国标法测定10个产区广藿香Pogostemon cablin(Blanco)Benth.药材及其生境土壤中Cu、Pb、Cd、Cr、As、Hg的含量,以非参数检验分析6种重金属元素在广藿香药材、生境土壤中的分布规律,并结合富集系数确定广藿香对重金属的富集情况。以单因子污染指数(P_i)、Nemerow污染指数(P_(综合))和潜在生态风险指数(RI)对土壤样品进行污染等级评价。结果表明,生境土壤全部达标;广藿香药材中重金属含量总体合格,4个产区药材中Hg有不同程度的超标。重金属Pb、Cu、Cd在不同生境土壤中的分布、土壤Pb、Cr、As与药材中的含量、不同产地广藿香对Pb的富集均有显著性差异。P_(综合)和P_i分别显示四会广藿香种植区域土壤、长丰土样Cd、莲塘Pb以及四会Pb、Cd均达警戒限,其他生境土壤都属清洁级别;RI值方面,各产区均属于轻微污染级别。不同产地的广藿香植株都会富集土壤的Cd、Hg。因此,从药材安全性考虑,在种植广藿香时,应该选择重金属含量较低的土壤进行种植,确保药材安全性。

In this study, national standard methods were used to determine the concentrations of Cu, Pb, Cd, Cr, As and Hg in the medicinal materials of Pogostemon cablin and its habitat soil in 10 regions. The distribution of six heavy metals and the bioconcentration factors were analyzed by the Nonparametric Test. Then, the Single Factor Pollution Index(Pi), Nemerow Synthetical Pollution Index(Pcombined), and a Potential Ecological Risk Index(RI) were used to evaluate the pollution levels of the 10 soil samples. All habitat soils were qualified and the concentrations of heavy metals in P.cablin generally met the standard, while Hg in four producing areas exceeded the standard in varying degrees. Significant differences were obviously observed among the distributions of heavy metals Pb, Cu and Cd in different habitat soils, the concentrations of Pb, Cr and As in the medicinal materials and its habitat soil, as well as the bioconcentration factor of Pb in different areas of the medicinal materials. Pcombined and Pi showed that the soil in Sihui City, Cd in the soil in Changfeng County, Pb in the soil in Liantang Town, Pb and Cd in the soil in Sihui City were near the warning limit,while the other habitat soils were still clean. In terms of RI value, each production area were at slight pollution level. In addition, P. cablin from different habitats had an enrichment effect of Cd and Hg in the soil. Therefore soils with low level of heavy metals should be selected to ensure the safety of medicinal materials when farming P. cablin.