第二松花江下游稻田土壤重金属含量特征及来源分析

于2008年秋季，在长期引用第二松花江（二松）江水进行灌溉的前郭灌区，采集了具有不同灌溉历史的稻田耕层土壤样品65个，测定了土壤中7种重金属含量，分析重金属在表层土壤中的累积特征，探讨发生累积的重金属的输入途径和来源.结果表明：稻田土壤中Cu、Pb、Zn、Cd、Ni、As、Hg的含量分别为14.1～28.4、37.6～57.4、53.3～84.4、0.044～0.367、18.4～37.0、3.25～12.11、0.031～0.155 mg·kg^-1.Pb、Hg、Cd表现出明显的累积趋势，其含量超过基线值的比例分别为100.0%、38.7%和66.1%，其余重金属元素未出现累积现象.随着灌溉历史的增长，稻田土壤中Pb含量呈逐渐降低趋势，Hg含量呈逐渐升高趋势.Cd含量与灌溉历史的关系不明显.稻田土壤中累积的Pb主要与过去使用含Pb汽油产生的废气沉降有关；Hg主要来源于曾受污染的二松江水，随引水灌溉输入；Cd主要来源于化肥、农药等农用化学品的施用.尽管本区稻田土壤中Pb、Hg、Cd出现明显累积现象，但其生态风险水平很低，不会对当地农业生产及粮食安全构成威胁.

Quantitative characteristics and source analysis of heavy metals in paddy soils in downstream of the Second Songhua River, Jilin Province

In autumn 2008, a total of 65 plough layer soil samples were collected from the paddy fields in Qianguo Irrigation Area located at the downstream of the Second Songhua River. These paddy fields were irrigated with water from the River, and had different irrigation histories. The Cu, Pb, Zn, Cd, Ni, As, and Hg concentrations in the soil samples were determined, and the accumulation characteristics, input approaches, and pollution sources of these heavy metals were analyzed. The Cu, Pb, Zn, Cd, Ni, As, and Hg concentrations in the samples were 14.1- 28.4 mg·kg^-1, 37.6-57.4 mg·kg^-1, 53.3-84.4 mg·kg^-1, 0.044-0.367 mg·kg^-1, 18.4-37.0 mg·kg^-1, 3.25-12.11 mg·kg^-1, and 0.031-0.155 mg·kg^-1, respectively. The Pb, Hg, and Cd exhibited an obvious accumulation trend, with their concentrations being 100.0%, 38.7%, and 66.1% higher than the baselines, respectively, while Cu, Zn, Ni, and As had less accumulation. With the increase of irrigation history, the Pb concentration showed a decreasing trend, while the Hg concentration was in reverse. There was no significant correlation between the Cd concentration and the irrigation history. According to source analysis, soil Pb mainly originated from the atmospheric Pb deposition via historical use of leaded gasoline, soil Hg was from the polluted irrigation water from the Second Songhua River, and soil Cd was from the use of chemical fertilizers, pesticides, and other agrochemicals. Though the Pb, Hg, and Cd had obviously accumulatied in the paddy fields in Qianguo Irrigation Area, their potential ecological risk was still low, and would not pose threat on the local agricultural production and food security.