SUITMA 2005 Cairo - Heavy metal concentration and chemical fractions in soils of urban green space in Shenzhen city, China
SUITMA 2005 Cairo
| This abstract is about one of the papers of the Properties of unconventional soils theme of the SUITMA 2005 symposium. |
| Ying Lu,i | Haihua Gan,i |
| Zhengjun Shi.ii |
- i - College of Resources and Environmental Sciences, South China Agricultural University, Guangzhou, China
Urban green space is a very important part of the urban ecosystem. Heavy metal contamination in soils of urban green space can be harmful to the biota and human beings. Seventy-nine soil samples with 0-20 cm depths of park green space, road greenbelt, residential area and institutional affiliation green space were collected at central district in Shenzhen city, and the concentrations of Cu, Zn, Pb, Cd and their chemical fractions were studied. The results showed that the concentrations of Cu, Zn, Pb, and Cd were 6.38-188.25 (26.64), 34.88-284.84 (67.92), 15.21-245.55 (46.97), and 0.01-4.463 (0.505) mg/kg, respectively. The soils of urban green space were to some extent polluted by Cu, Zn, and Pb, but seriously polluted by Cd. Spatially, Cu and Zn concentrations were highest in the residential area, and least in the institutional affiliation green space. The concentrations of Cd and Pb were highest in soils of roadside green space. The concentration between Cu and Zn, Pb had significant correlations and the soil pH was significantly correlated with Cd. But other soil properties, such as the content of organic matter, clay, silt, and sand, had no significant correlations with the concentrations of Cu, Zn, Pb, and Cd.
On average, the order of Zn and Pb in each fraction was as follows: residual (59.05%, 61.95%, > Fe-Mn oxides (36.65%, 22.82%) > organic (3.60%, 14.36%) > carbonate (0.48%, 0.53%) > exchangeable (0.25%, 0.34%). Copper followed the order: residual (60.35%)> organic (30.47%)> Fe-Mn oxides (7.86%)> carbonate (0.73%)> exchangeable (0.59%). Cadmium followed the order: residual (61.64%), organic (13.43%)> Fe-Mn oxide (9.86%)> exchangeable (9.45%)> carbonate (5.62%).
The percentage of residual Zn and Pb decreased with increases in total Zn and Pb, whereas Cd increased with total Cd increase. The percentage of Fe-Mn oxides Cu, Zn and Pb increased with increases of total Cu, Zn and Pb, whereas Cd decreased with total Cd increase. Carbonate and organic fraction of Cd shows negative correlation with the total Cd but the percentages of organic Cd and Pb were positively correlated with the organic matter. The percentage of residual Cu had a significant positive correlation with soil pH.
On average, the order of Zn and Pb in each fraction was as follows: residual (59.05%, 61.95%) > Fe-Mn oxides (36.65%, 22.82%) > organic (3.60%, 14.36%) > carbonate (0.48%, 0.53%) > exchangeable (0.25%, 0.34%). Copper followed the order: residual (60.35%)> organic (30.47%)> Fe-Mn oxides (7.86%)> carbonate (0.73%)> exchangeable (0.59%). Cadmium followed the order: residual (61.64%)> organic (13.43%)> Fe-Mn oxides (9.86%)> exchangeable (9.45%)> carbonate (5.62%).
