| The health implications of inhalation and/or ingestion of dust particles with high concentrations of heavy metals from urban soil are the subject of intense concern. Understanding the accumulation and chemical forms of the elements in the soils in residential sites is necessary to predict possible effects on human health. However, there is minimum information on the behavior of heavy metals in the soils in residential sites. Hangzhou city is an attractive socio-economic center of Zhejiang province, China. Due to the rapid growth of population and industrial activity, the soils in the city have been seriously polluted with heavy metals, which resulted in a series of environmental problems. The objectives of this study were to: (1) assess the distribution of the metals and phosphorus in the soils from residential sites of the Hangzhou City; and (2) understand differentiation of environmental geochemistry in related to land use history.In March 2002, a total of fifty surface soils were collected from different residential sites in Hangzhou city. Each sampling location was positioned by the GPS, and the information, including age and size of the residential sites, land use history, vegetation cover and pollution sources, was recorded. Based on the ages of residential sites and the land use history, the soils were divided into four groups: (1) group I: residential sites formed from the former agricultural lands after 1991; (2) group II: residential sites formed from the former agricultural lands before 1990; (3) group III: residential sites formed from the former industrial lands; and (4) group IV: old residential sites with residential history of more than 50 years. In addition to measurements of pH, particle composition, organic matter, total N, total concentrations of heavy metals (Cd, Co, Cr, Cu, Ni, Pb, Zn, Mn and Mo), P, K, Ca, Fe, Mg, Na, and Al, the soils were also subjected to fractionations and testing of acid solubility of the heavy metals and phosphorus.The pollution degree of soils by heavy metal (Cd Zn Cu Pb Ni Cr) was assessed using both single pollution index and comprehensive pollution index methods, based on the Chinese Soil Environment Quality Standard. The first, second and third levels of the standard were used as the initial value of low-level, medium-level and high-level pollution, respectively. In addition, a database of heavy metal concentrations was established with the support of Arclnfo8.2, Mapinfo5.0 and Arcview3.2 for analyzing spatial variation of the pollution. Spatial distribution maps of the heavy metal pollution were developed.The results showed that the soils in residential sites in Hangzhou city had been anthropogenically contaminated by heavy metals to a different extent, and heavy metals in the soils, including Cd, Cr, Cu, Mo, Pb, Zn, and Mn, were higher than those in the suburban agricultural soils, and the concentrations of metals Cu, Pb, Zn and Mn increased with ages of the residential sites. Cadmium, Co, Cr and Ni were mainly associated with residual fraction, while Cu, Pb, Zn and Mn were majorly extractable fractions. Except for Zn and Mn, the concentrations of acid extractable metals were generally low. Amounts of the heavy metals dissolved in dilute acid (pH2.5) increased with decreasing pH in equilibrium solution. Low potential solubility of the heavy metals in the dilute acid was due to their low percentage of acid-extractable fraction of the heavy metals in the soils. Measured data indicated a low environmental health hazards for heavy metals from the soils in residential sites in the Hangzhou city.Accumulation of phosphorus in soils increases the potential of P runoff from the soils and thus affects environmental quality. Soils of the residential sites in the Hangzhou city had been enriched with P to a great extent. Mean total P in the residential sites was twice of that in agricultural land. About 86% of the residential soils had water soluble P higher than 10 mg kg'1. The soil P was mainly composed of HC1-P, which accounted for 50-60% of the total P. The acc...
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