Heavy Metals Contents In Soil Of Shanghai Industrial Area And Accumulation In The Woody Plants

In this thesis,the industrial sites localized in Yuepu,Baosteel and Wujing and Laogang municipal solid waste landfill were selected as the sample areas to analyze the heavy metals pollution situations.Soil samples were collected from three different depths of 0～5cm,5-20 cm,20～50cm.After wet digestion,the Cd,Pb,Zn contents in soil were determined by inductively coupled plasma spectrometer(ICP).The heavy metal contamination of the 3 sample areas was evaluated through Single Factor Pollution Index,Nemerow Pollution Index and Potential Ecological Risk Index.The results showed that the highest content of Cd was 3.118mg/Kg,which was found in the 5 ～ 20 cm soil layer in Wujing industrial zone.The lowest Cd content was 0.079 mg/Kg in the 20～50cm soil layer in Baosteel.The highest content of Pb was 54.690 mg/Kg in the 20～ 50 cm soil layer in Wujing industrial zone;the lowest content of Pb was15.785 mg/Kg in the 20～50cm soil layer in Yuepu industrial zone.The highest content of Zn was recorded in the 0 ～ 5cm soil layer in Yuepu industrial zone,and it reached 182.862mg/Kg;the Zn content in 20～50cm soil layer of Baosteel was 74.385 mg/Kg,that was the lowest Zn content among the soil samples.Due to the serious Cd pollution,pollution index of Wujing industrial area was in the grade of heavy pollution.The heavy metal pollution index of Yuepu、Baosteel and Laogang was in the controllable degree,but the Cd pollution in each sample area should be alert.The absolute value of Cd content was the least among the three metals,but its pollution index was higher than those of Pb and Zn.So Cd became the main pollution element.At the same time,the roots,stems and leaves of woody plants in the sample areas were collected,and the contents of Cd,Pb and Zn in plants were determined using ICP.By analyzing the Biological Accumulating Coefficient(BAC)and Biological transfer coefficient(BTC)of the three heavy metals,the heavy metal accumulation abilities of the greening trees in Shanghai were evaluated.The top three plants which had higher ability to accumulate heavy metals were as follows: for Cd the plants were Populus Canadensis,Salix babylonica,Cinnamomum camphora;for Pb the trees were Forsythia viridissima,Prunus Cerasifera,Ginkgo biloba;for Zn the woody plants were Buxus sinica,Paulownia tomentosa,Magnolia grandiflora.To assess the integrative competences of the plants to accumulate Cd,Pb and Zn,the Membership Function was utilized.The plants which had higher capacity to accumulate the three metals were as follows: Pyracantha fortuneana,Salix babylonica,Ginkgo biloba,Distylium racemosum,Melia azedarach.