文山三七(Panax notoginseng)种植区三七与土壤中Pb、Cd、Cu和Zn的分布特征及评价

摘要

Field investigation was conducted in order to assess the situation of Pb, Cd, Cu and Zn contamination of the soils in some major P.notoginseng growing regions in Qiubei County, Yanshan County, Wenshan County and Guangnan County of Wenshan Prefecture, Yunnan Province and plants of P.notoginseng produced therein with the aid of GPS positioning, 30 soil samples from the 0-15 cm soil layer and 30 samples of P.notoginseng plants were collected for analysis of totals and various forms of Pb, Cd, Cu and Zn in the soils and in various parts of the plants, their contents and distributions with ArcGIS.Results show that: (1) The mean content of total Pb, Cd, Cu and Zn in the soils was 55.56, 0.36, 43.53 and 119.62 mg·kg-1, respectively, and about 6.67%, 53.3%, 13.33% and 0 of the soil samples exceeded the threshold value, respectively, for Pb, Cd, Cu and Zn set in HJ/T 332-2006.Fractionations of Pb, Cu and Zn all show an order of residue > organic matter bonded > Fe/Mn oxide bonded > carbonate bonded > exchangeable in terms of content, while that of Cd does a different one, Fe/Mn oxide bonded > residue > carbonate bonded > organic matter bonded > exchangeable;(2) In terms of contents of total and Pb, Cd, Cu and Zn and their fractions in the soil and P.notoginseng, Qiubei County ranked on the top, while Guangnan County at the end;and (3) The mean content of total Pb, Cd, Cu and Zn in the roots of P.notoginseng was 2.93, 0.35, 5.21 and 11.11 mg·kg-1, respectively.Distribution of the heavy metals in the plant of P.notoginseng followed a sequence of roots > rhizome > shoot > flower/ fruit.Spatial variation was quite obvious of the distribution of the heavy metals in the soil and P.notoginseng and Cd was found to be the major pollutant.It is, therefore, essential to take certain measures to reduce Cd content in P.notoginseng.%为了调查文山州三七(Panax notoginseng)主要种植区(丘北县、砚山县、文山县和广南县)土壤和三七Pb、Cd、Cu和Zn含量,通过GPS定位采集三七根区0~15 cm深度土壤样品和三七样品各30个,分析土壤中重金属总量和不同形态含量及三七中对应重金属含量,并进行空间分布分析.结果表明:(1)土壤Pb、Cd、Cu和Zn平均含量分别为55.56、0.36、43.53和119.62 mg·kg-1,超标率分别为6.67%、53.3%、13.33%和0.各形态Pb、Cu和Zn含量表现为残渣态>有机物结合态>铁锰氧化物结合态>碳酸盐结合态>可交换态.各形态Cd含量表现为铁锰氧化物结合态>残渣态>碳酸盐结合态>有机物结合态>可交换态.(2)三七和土壤Pb、Cd、Cu和Zn总量和不同形态含量均以丘北县最高,广南县最低.(3)三七根系Pb、Cd、Cu和Zn平均含量分别为2.93、0.35、5.21和11.11 mg·kg-1,三七植株各部位重金属含量表现为根系>剪口>茎叶>花果.调查区三七和土壤重金属含量存在空间差异,且以土壤Cd污染为主,应采取一定措施降低三七Cd含量.