不同耕作方式对路旁土壤重金属分布的影响——以黄淮平原国道310开封段为例

Effects of Different Tillage Methods on Spatial Distribution of Heavy Metals in Roadside Soils: A Case Study of Kaifeng Section Along the National Highway 310 in Huanghuai Plain

在G310开封段的杜良和杏花营分别布设采样断面，共采集320个样品。用ICP．MS测定土壤Pb、Cu、Zn、Cd、Cr和Ni含量，用泛克里格插值法分析路旁土壤重金属含量空间分布特征。结果表明，不同耕作方式对路旁土壤重金属含量空间分布影响很大。水旱轮作农田在淹水期间，由于水分的流动性以及土壤Eh下降等原因，加速了重金属的迁移，其分布无明显规律性。旱旱轮作农田的土壤重金属含量呈现出与道路平行的带状分布，其中土壤Cr和Cu含量随着距路基距离增加而递减；土壤Pb、Ni、Zn和Cd含量随着距路基距离增加而先增大然后减小，峰值含量出现在距路基30～50m间。

Two soil sampling transects in Xinghuaying and Duliang on Kaifeng section along the National High- way 310 were chosen to investigate effects of upland-upland rotation and paddy-upland rotation on spatial dis- tribution of heavy metals in roadside soils. Five sampling sub-transects of 150 m were designed to be perpen- dicular to the road within 100 m on both sides of the highway. On each sub-transect, mixed topsoil samples （0-15 cm） were collected at 10 m intervals from the roadbed to the outside end. The total samples of 324 were collected, then, the concentrations of Pb, Cu, Ni, Cr, Cd and Zn in soils were detected by the inductively cou- pled plasma mass spectrometry （ICP-MS） respectively according to the recommended standard method. The spatial distribution of heavy metals concentrations in roadside soils was discussed by Universal Kriging Inter- polation model. The results show that the different tillage methods have great effects on spatial distribution of heavy metals in roadside soils. The distribution patterns of metal concentrations are not strips parallel to the road in paddy-upland rotation field on Duliang Transect （DT）, because the water in rice field changes pH, Eh of soils, and then accelerates the migration of soil heavy metals when the rice is grown. In contrast, the distri- bution patterns of metal concentrations in upland-upland rotation field on Xinghuaying Transect （XT） are strips parallel to the highway. The concentrations of Cr and Cu decrease exponentially with the distance from the roadbed, however, the concentrations of Cd, Pb, Ni and Zn reveal a skew distribution with the distance, which increase firstly, reach their highest values at 30 m or 50 m away from the roadbed, and then decrease gradually to the control values.