Primary Study On Urban Forestry Arranging Mode For The Remediation Of The Heavy Metal Contamination

The pollution characteristics of heavy metals in the soils of Nanjing city and the concentration of heavy metals in different plant living on the sample places are studied in this paper to find out forest plants that can absorb more heavy metals than orthers. The plant and soil samples are collected from Tangshan Cu diggings,Nanjing refinery,Meishan steel plant,Nanjing forestry university and Xinzhuang cloverleaf junction in this paper. The concentration of heavy metals in different soils and plants are mensurated by ICP. Based on the concentration of heavy metals and accumulation coefficient, the forest plants which can absorb more heavy metals than others are finded out. Based on theories of biology and botany, combined with the results of my experiment and other scientist', the urban forestry arranging mode for the remediation of heavy metal-contaminated soils is discussed in the paper. The plants of the arranging mode must live well and multiply. The main results received are as follows:1. Manning is pelted by heavy metal in some degree and the pollution of cadmium is serious. There is a trend of soil heavy metal concentration in different sample places, the soil heavy concentration in Tangs an diggings>Tangs an farm>Tangshan transit>Meishan steel plant>Tangshan Pinus thunbergii Parl. forestry >Nanjing refinery>Xinzhuang cloverleaf junction.2. The concentration of heavy metals in different plants of the same sample place are much different. For example, the concentration of Zn in the leaf of Pterocarya stenoptera and Robinia pseudoacacia are 53.7mg/kg and 70.75mg/kg in turn.3. The same plant absorbs quite different heavy metals on different contaminated soils and different plants on the same contaminated soil absorb quite different heavy metals. Different organs of a plant absorb quite different heavy metals and the trend of heavy metals absorption are root>leaf>branch or cortex>stem.4. Based on the concentration of heavy metals and accumulation coefficient, the forest plants that can absorb more heavy metals than others are finded out to arrage in the urban forestry. These plants include: Cedrus deodara,Metasequia glyptostroboides,Robinia pseudoacacia,Broussonetia papyrifera,Cinnamomum camphora,Populus canadensis,Platanus deodara,Ligustrum Lucidum,Quercus glandulifera,Buxus bodinieri,Ophiopogon japonicus etc...