公路两侧农田土壤及作物中重金属的累积

Accumulation of Heavy Metals in Roadside Farmland Soil and Crops

通过对江苏省内4个断面公路两侧距路基不同距离的农田土壤、水稻、杨树和蔬菜取样测定,研究了公路交通尾气及粉尘中重金属对公路两侧农田土壤及植株的污染。结果表明:①所有断面公路两侧分别距路基25 m至100 m范围内土壤铅累积达显著水平(P<0.01),并随距路基距离的增加而降低;断面2公路两侧分别在距路基5 m范围内土壤铜含量比背景值显著增加;断面1、断面3和断面4公路两侧分别在距路基5 m范围内土壤锌均显著累积;断面1距路基西0 m处和75 m处土壤镉含量分别达到0.365 mg/kg和0.329 mg/kg,超出了生产无公害农产品对土壤含镉量的限制要求(≤0.3 mg/kg)。②断面1路西75 m、断面4路北75 m、和150 m处稻米中铅含量超出国家无公害稻米重金属铅的限量标准(≤0.4 mg/kg),且在同一个断面距路基不同距离的稻米铅含量、秸秆铅含量与土壤铅含量之间没有明显的正相关。③杨树中铅、镉、铜、锌4种重金属含量均为杨树叶>1年生枝条>2年生枝条;断面3路南100 m处的胡萝卜和青菜中铅含量超出国家无公害农产品重金属铅的限量标准。

By determination of heavy metal content of soil, rice, poplar and vegetable sampled from 4 sections at different distances away from highways, influences of heavy metal pollution from the tail gas and dust on soil and crops in the fields on both sides of the highway was studied, The results showed：①the contents of Pb in soil samples within 25-100 m were higher than the value of background, especially within 0-50 m. The contents of Zn in soil samples within 0-5 m were a little bit higher than the value of background. The contents of Cd and Cu didn＇t have the regular variation. The contents of Pb,Cd,Cu,and Zn were various with different sections. In section 1 at 0 m and 75 m away from the highway the Cd contents of soil were 0. 365 mg/kg and 0. 329 mg/kg, respectively,which exceeded Cd contents of limit standard（ ≤0. 3 mg/kg）.② the Pb contents of three rice samples were higher than that of limit standard （ ≤0.4 mg/kg） ,although the Pb contents of all soil samples were not higher than that of limit standard.③Pb, Cd, Cu, and Zn contents of leaves in poplar were all higher than those of annual branches,and those of annual branches were higher than those of old branches. In section 3, Pb contents of carrot and Chinese cabbage at 100 m to the south of the highway were higher than those of limit standard.