基于Ordinary Kriging路域土壤重金属含量的空间分布——以国道316线福州至闽清段为例

Spatial distribution of heavy metals in roadside soils based on ordinary kriging: A case study of No.316 national road between Fuzhou and Minqing

土壤重金属污染日渐加重,道路交通活动产生的重金属污染导致路域土壤重金属含量上升,构成潜在生态威胁。为探明路域土壤重金属污染范围及其变化趋势,在316国道福州-闽清段外侧100 m×100 m范围内布设5条与道路垂直的采样断面,每条断面依据道路远近布设11个采样点,在距离道路路侧200 m处采集2个对照土壤样品,共采集57个采样点表层的土壤样品,并采用XRF-DP 4050测定土壤中重金属(Cr、Pb、Zn、Mn和Fe)含量。在此基础上,对土壤中不同重金属间进行相关性分析,并用普通克里金进行插值分析路域土壤重金属的空间分布特征。结果表明,测量领域内的土壤中Cr、Pb、Zn含量整体趋势呈现随道路距离增加而递减,其对照区含量较低,含量受道路交通影响;其中Cr呈指数分布,在0 m处含量最高;Pb、Zn呈偏态分布,峰值出现在10~20 m。Fe、Mn在对照区含量较高,其测量领域含量不易受道路交通影响,含量主要与成土母质有关。

Soil heavy metal pollution is becoming more and more severe. Road traffic activities lead to the increase of soil heavy metal content in roadside soils, which constitutes a potential ecological threat. In order to determine the range of heavy metal pollution in roadside soil and its changing trend, five sampling sections perpendicular to the road were arranged within 100 m × 100 m outside of the Fuzhou-Minqing section along the State Road 316. Each section was arranged 11 sampling points according to the distance of the road, and two soil samples were collected from 200 m roadside. A total of 57 soil samples were collected from the sampling sites. The contents of heavy metals（Cr, Pb, Zn, Mn and Fe） in the soil samples were determined by XRF-DP4050. Using these data, a correlation analysis of heavy metals in the soils was carried out, and the spatial distribution characteristics of soil heavy metals in the roadside area were interpolated by ordinary Kriging. The results showed that the contents of Cr, Pb and Zn in the control area were low and the overall trend of Cr, Pb and Zn in the survey area was decreased with an increase of the road distance, indicating that the heavy metal content was affected by the road traffic in which Cr showed an exponential distribution with the highest content at 0 m and Pb and Zn were of skewed distribution with the peak appearing in 10-20 m. The contents of Fe and Mn in the control zone were relatively high, and the contents in the measurement area were not easily affected by the road traffic. The contents of Fe and Mn were mainly related to the soil parent material.