招远市区土壤及常见绿化植物汞污染特征

为查明长期黄金开采冶炼对城市汞污染的影响,以"金都"招远为研究对象,于2011年4月,采集了招远市区常见绿化植物柏树、落叶松、冬青的茎叶样品30份,并同步采集相应表层土壤样品34份。采用冷原子吸收法测定样品总汞含量,分析了土壤的理化性质。结果表明,招远市区表层土壤中汞含量范围为0.002~0.815 mg·kg-1,平均值为0.149 mg·kg-1。土壤汞含量与有机质呈极显著正相关,与p H、粗颗粒比例呈显著正相关关系,而与阳离子交换量、黏粒比例呈显著负相关。不同城市区域相比,处于金矿区污染源下风向、且与矿区距离较近的梦芝区土壤汞含量要显著高于其它区域。常见绿化植物茎叶汞含量范围为0.021~0.782 mg·kg-1,不同植物中的汞含量没有显著差异,但同种植物中茎、叶中汞含量存在极显著正相关。植物中的汞在各城市区域没有显著差异,与土壤汞含量也不存在显著相关性。研究结果显示,招远市区土壤和植物受周边金矿开采和黄金冶炼的影响,存在一定程度汞污染。

Pollution Pattern of Mercury in Topsoil and Common Landscape Plants in the Downtown Zhaoyuan

To determine the pollution pattern of mercury (Hg) in topsoil and plants in Zhaoyuan, which is well known as capital of gold in China, a total of 30 samples of plant, such as Ilex, Cyparissus, Pinus, and 34 samples of the corresponding topsoil from Zhaoyuan were collected in April 2011. The total Hg content in the gathered samples was measured by the method of Cold Vapor Atomic Absorption Spectrometry (CVAAS) using F-732V mercury vapour analyzer. Results indicated that the total Hg content in topsoil ranged from 0.002 to 0.815 mg·kg^-1, with the average value of 0.149 mg·kg^-1. Hg contents in topsoil were remarkably positively correlated to the content of organic matter, pH values, and 0.02~1 mm particle size. It is also negatively correlated to the content of CEC and<0.002 mm particle size. Mengzhi district, which was downstream of the dominant wind direction and close to the gold-mining pollution sources, presented a significant higher Hg content than other districts in Zhaoyuan. The range of Hg contents in samples of common landscape plants was from 0.021 mg·kg^-1 to 0.782 mg·kg^-1. Hg contents in stem samples are significantly correlated to that in leaf samples. Contrary to the distribution of Hg in topsoil, Hg content in plants showed no significant difference among the different administrative regions. Moreover, there was no apparent relationship between mercury content in plant samples and topsoil samples. This study indicated that Hg contents and distribution in urban soil and landscape plants in Zhaoyuan were affected by the surrounding gold mining and smelting. The common landscape plant and topsoil samples from Zhaoyuan showed a certain degree of mercury pollution.