Study On Heavy Metals Pollution Of The Roadside Plant-Soil System In Nanjing

This paper discussed the impact of heavy metals pollution on soil and agro-products' quality along belt road in Nanjing city of JiangSu province. Roadside farmland and forest land's soil and plant such as crop (rice, wheat and vegetables), forest belt tree (Taxodium sp and Populus sp), greening plants (tree (Cinnamomun camphora (L.) Presl, shrubs Pittosporum tobiro (Thunb.) Ait. and Buxus sinica (Rehd. et Wils.) Cheng, turfs Cynodon dactylon (L.) Pars, and Zoysia matrella (L.) merr. ) were collected from both sides of main roads including Belt Road, Airport Highway and Urban Trunk Road, and analysed for the contents of Al, Fe, Mn, Cu, Zn, Cr, Pb and Ni in soils and crops to estimate characteristic and sources of the heavy metals pollution. Accumulation effect to heavy metals (excepting Ni) of different forest belt trees together with Assimilation, adsorption and monitor function to heavy metals of different parts of Populus sp's trees were compared too, moreover, we also studied the accumulation effect to heavy metals (excepting Ni) of different hierarchical structure tree, brush and turf plant leaf layers. Based on these results, following conclusions were achieved:1. With the exception of part or whole contents of Mn, Cu, Zn and Pb in belt roadside different vegetation form surface layer soils, other heavy metals contents generally are lower than the soil elemental average background values in Nanjing area. Total or majority heavy metals contents in rice, vegetable field (excepting Al, Ni on the north side) and south side forest land on road exceed those of references (relative clean point—botanic garden). On the north, contents of Al, Fe, Cr and Ni in paddy field are obviously higer than those in vegetable field; On the south, either contents of Cu, Pb and Zn in vegetable field nor Mn, Cu, Zn and Pb in forest land significantly surpass those in the paddy field. As to Cr and Ni contents in rice field, the north side are higher than the south side; but for which in vegetable field, the former are lower than the latter.2. Within the scope of 200 meters apart from north roadside, pollution index of Mn (rice field) and Cu, Zn, Pb (vegetable field) obviously increase with the distance, the latter generally appears pollution after 30m. Influence range of road environmental heavy metals...