Trace metal contamination in urban soils of Hong Kong using GIS and multivariate statistics approaches

Category Geochemistry
Group GSI.IR
Location International Geological Congress,oslo 2008
Author Li, Xiangdong۱; Lee, Celine S.L.۱; Shi, Wenzhong۱; Cheung, Sharon C.N.۱; Thornton, Iain۲
Holding Date 08 September 2008

The urban environment quality is of vital importance for large populations living in cities. Due to the continuous urbanisation and industrialisation, trace metals are continuously emitted into the environment and pose a great threat on human health. Geographical information system (GIS) and multivariate statistical methods were used to assess the degree of trace metal contamination in the soils of the urban, suburban, and country park areas of Hong Kong. The urban and suburban soils were highly enriched with trace metals such as Cu, Pb, and Zn, in comparison with the country park soils. The results of the principal component analysis (PCA) and cluster analysis (CA) showed distinctly different elemental associations and clustering patterns among trace metals and major elements in the urban, suburban, and country park soils. The soil pollution maps of Cd, Cr, Co, Cu, Ni, Pb, and Zn were generated using a GIS technique. The soil pollution index was formulated to indicate the degree of trace metal contamination (Cu, Pb, and Zn) in the soils. The three-dimensional map of the soil pollution index was overlaid with the thematic map of the Annual Average Daily Traffic (AADT). Many of the hot-spot areas were found in high traffic zones with an AADT figure of over 40,000 vehicles. The Pb isotopic composition analysis suggested that vehicular emissions in the past were the major sources of Pb in the urban and suburban soils. The present study demonstrated the value of GIS and multivariate statistical methods in studying metal contamination in complex urban settings.