Factorial Analysis of Heavy Metal Concentration in Roadside Farmland Plants around Kathmandu, Nepal

摘要

Traffic activities are one of major sources leading to roadside soil contamination due to their long-term accumulation effect. The typical elements of Cd, Pb, Zn, and Cu in the roadside soil can transport through food chain to human body and result in a strong toxicity to people. In agricultural area, intake of heavy metals through the soil-crop system could play a predominant role on human exposure to environmental heavy metals. The study investigates concentrations and distributions of the four heavy metals' in herbaceous plants growing in the roadside farmland around Kathmandu, Nepal. Totally, 60 plant samples including 26 samples from rural mountainous farmland and 34 samples from suburban farmland were collected from April 2011 to May 2011. The sampling distances to the road edge are 0 m, 10 m, 30 m, 50 m, and 100 m. The samples are classified into tree protection or no tree protection. It is found that the heavy metals' distributions are not consistently decreasing as roadside distance; the heavy metal concentration in rural area is significantly lower than those in suburban area; and tree has a significant protection effect on roadside plants from the Cu contamination.