Studies On Distribution And Contamination Of Lead In Surface Soils And Vegetables Along Highways

Studies on distribution and contamination of lead in surface soils and vegetables along highways The emission of lead from automobile exhaust and its deposition along highways have been reported worldwide. Since the 1970s,the possible health implications of chronic lead exposure have been discussed. One potential source for human lead intake is the inhalation of particulate matter from automobile exhaust; a second is the ingestion of lead in polluted food. The effects of lead are seen in brain, kidney, bone and erythrocytes. Children are especially susceptible to lead poisoning because of high metabolic rates. Soil is not only a medium for plants to grow, but also a transmitter of many pollutants, such as lead, to food. People are of course, more concerned about the potential pollution of soils and vegetables. It has been noted that roadside soils and vegetables along motorways or highways are easily polluted by lead from gasoline combustion and automobile exhaust. This paper was conducted to study the contamination and distribution of lead in surface vegetable-soils as well as vegetable roots, stalks and leaves along the highways connecting Changsha, Zhuzhou and Xiangtang. The results showed that: 1) Soils along highways were polluted by gasoline combustion. The roadside Pb samples for high, moderate, and low traffic volume categories had medians of as high as 161.55(mg.kg, 119.41 (mg.kg and 87.55 (mg.kg. As the local background levels were only 31 (mg.kg?, hence soils along every traffic volume category were considered as enriched. 2) The top-soil Pb contents raised first with the increasing distance from the highway and reached a maximi value in about 10 to 25 meters away from the highway, then declined afterwards. 3). The vegetable (Lectuca sativa) roots, stalks and leaves along the highways were polluted .Pb in vegetables including roots, stalks and leaves were all beyond the edible standard and background value to some degree. 4) A positive correlation was found between vegetable and soil Pb contents. 5)Both soil and vegetable Pb levels generally increased with higher traffic volumes. 6)The accumulating characteristics of vegetables were different among three samples. For high and moderate traffic volume categories, the Pb levels were higher in vegetable stalks and leaves than that of the vegetable roots. While in the low traffic volume categories, the Pb levels were higher in vegetable roots than that of the stalks and leaves.