对 205 国道无林带典型路段东西两侧 200 m 范围内的农田表层土壤、稻( Oryza sativa L.)叶及糙米中 Al、Cd、Cr、Cu、Fe、Ni、Pb、Zn 和 As 的含量及空间分布规律进行了分析研究。 结果表明,205 国道两侧农田表层土壤中 Cd、Cr、Cu、Ni、Pb 和 Zn 的含量达到土壤环境质量一级标准( GB15618 - 1995),As 含量超过土壤环境质量三级标准。西侧表层土壤中的 Al、Cr、Fe、Ni、Zn 和 As 含量,稻叶中的 Al、Cd、Cr、Fe 和 Ni 含量及糙米中的 Al、Cd、Cr、Cu、Fe 和Ni 含量均比东侧高,表明路西侧受汽车尾气扩散沉降影响比东侧明显,并与该路段主风向为偏东风有关;西侧表层土壤中的 Ni 和 Zn 含量及东侧表层土壤中的 Cd 含量、西侧稻叶中的 Al 和 Zn 含量、西侧糙米中的 Fe 含量和东侧糙米中的 Al 含量均有随路侧距离增加而显著递减的规律,负相关关系显著或极显著;稻叶和糙米中某些重金属的含量有明显的峰值区域,均位于路侧 10 ~ 20 m 区域内,并与土壤中的含量有显著或极显著的正相关关系;在糙米中未检出 As,且 Al、Cd、Cr、Cu 和 Zn 含量均未超出国家食品卫生标准,但部分样本 Ni 和 Pb 含量略有超标。 主成分分析结果显示,稻叶中的 Pb 主要来源于土壤,而稻叶中其他重金属含量明显受到公路环境污染物扩散沉降影响。 研究结果显示,重金属元素已在 205 国道两侧的农田表层土壤中显著累积,其中 As 的积累最严重;稻叶和糙米中重金属的含量水平明显受到公路汽车尾气扩散沉降的影响,且扩散沉降集中在距离公路边缘 10 ~ 20 m 的区域内。

 

Contents of Al, Cd, Cr, Cu, Fe, Ni, Pb, Zn and As in surface soil, rice leaf and brown rice (Oryza sativa L.) in farmland of 200 m range away from No. 205 national road without forest belt and
their spatial distribution rules were investigated. The results show that the contents of Cd, Cr, Cu, Ni,Pb and Zn in surface soil reach the first grade of Environmental Quality Standard for Soils (GB15618 -1995), and the As content exceeds the limit of the third grade. The contents of Al, Cr, Fe, Ni, Zn and As in surface soil, Al, Cd, Cr, Fe and Ni in rice leaf, and Al, Cd, Cr, Cu, Fe and Ni in brown rice on the western side are higher than those on the eastern side, indicating a greater influence of dispersion and deposition of vehicle emissions on the western side, and this phenomenon relates to the easterly prevailing wind. The contents of Ni and Zn in surface soil on the western side, Cd in surface soil on the eastern side, Al and Zn in rice leaf on the western side, Fe in brown rice on the western side and Al in brown rice on the eastern side have a rule of obviously decreasing with the distance away from road edge increasing, and have significant or extremely significant negative correlation with distance away from road edge. Content distributions of some heavy metals in rice leaf and brown rice have an obvious peak value
range, reach their peaks in range of 10 - 20 m away from the road edge, and have significant or extremely significant positive correlation with contents in surface soil. In brown rice, element As is not detected and the contents of Al, Cd, Cr, Cu and Zn don’t exceed the limits of the national food sanitary standards, but the contents of Ni and Pb in some samples are slightly higher. According to principal component analysis, Pb in rice leaf mainly comes from the surface soil and the contents of the other heavy metals in rice leaf are obviously influenced by dispersion and deposition of contaminants from the road. It is suggested that heavy metals accumulate obviously in farmland on both sides of No. 205 national road, in which the accumulation of As is the most serious. Contents of heavy metals in rice leaf and brown rice are obviously influenced by dispersion and deposition of vehicle emissions which are concentrated in range of 10 - 20 m away from the road edge.