Study On Soil Contamination Of Lead Along The Freeways And Phytoremediation

With the development of freeways in our country,the pollution of soil because of the use of gasoline,becomes a urgent question to slove.The soil samples along the seven freeways in Jiang Su province are analyzed.The results say that the lead pollution distributes along the freeways,and attains the most pollution in the distance of 5 meters,then decreases with the addment of the distance.The lead pollution has no impact on the soil of 100 meters away from the freeways.According to the index of muller , the degrees of lead pollution of the different freeways are summarized.The existence forms of lead in the soil are an important reference point to study the rule of lead cumulation. .An eluviate test of the soil samples is made. The results tell that the water form of lead is 3.9-5.4% of the total lead, the exchange form of lead is 30.2-33.1%,the rudimental form of lead is 50.6-55.7% of the total lead.The forecasting formula of lead cumulation based on the conversation law is found, the lead pollution of the different freeways in the coming years is forecasted. For example ,the lead pollution along the Hu Ning freeway can arrive at 163.3 mg/l,249.2 mg/l,323.4 mg/l, in the year of 2010,2020,2030.The phytoremediation as one of low cost and no second pollution attaches importance to the treatment of heavy metal pollution .A laboratory test on the plants used along the freeways is made. The polluted concentration is 100 mg/l,200 mg/l,400 mg/l,800 mg/l. The results tell that the abilities of lead cumulation of the four plants are different from each other. The sequence of lead quantity in four plants is white clover>candida>styracifolium>dichondra. The sequence of lead cumulation abilities is white clover> candida >dichondra> styracifolium .