[1] Boruvka L, Vacek O, Jehlicka J, 2005. Principal component analysis as a tool to indicate the origin of potentially toxic elements in soils. Geoderma, 128: 289–300.

[2] Chen Tongbin, Song Bo, Zheng Yuanming et al., 2006. A survey of arsenic concentrations in vegetables and soils in Beijing and the potential risks to human health. Acta Pedologica Sinica, 61(3): 297–310. (in Chinese)

[3] Chen Tongbin, Zhen Xibo, Hu Qingxiu, 2002. Utilization efficiency of chemical fertilizers among different countries of China. Acta Pedologica Sinica, 57(5): 531–538. (in Chinese)

[4] Chen Tongbin, Zheng Yuanming, Chen Huang et al., 2005. Arsenic accumulation in soils for different land use types in Beijing. Geographical Research, 24(2): 229–235. (in Chinese)

[5] DCSB (Dongguan Municipal Bureau of Statistics), 2005. Dongguan Statistical Year Book. Beijing: China Statistics Press, 68. (in Chinese)

[6] DCSB (Dongguan Municipal Bureau of Statistics), 2007. Dongguan Statistical Year Book. Beijing: China Statistics Press, 68. (in Chinese)

[7] Facchinelli A, Sacchi E, Mallen L, 2001. Multivariate statistical and GIS-based approach to identify heavy metal sources in soils. Environmental Pollution, 114: 313–324.

[8] Filzek P D B, Spurgeon D J, Broll G et al., 2004. Pedological characterization of sites along a transect from a primary cadmium/lead/zinc smelting works. Ecotoxicology, 13: 725–737.

[9] Garcia R, Maiz I, Millan E, 1996. Heavy metal contamination analysis of road soils and grasses from Gipuzkoa (Spain). Environmental Technology, 17(7): 763–770.

[10] GPEMC (Guangdong Province Environmental Monitoring Centre), 1990. Handbook of Data for Environmental Background Values of Guangdong. Beijing: China Environment Science Press. (in Chinese)

[11] Gray C W, McLaren R G, Roberts A H C et al., 1999. The effect of long-term phosphatic fertiliser applications on the amounts and forms of cadmium in soils under pasture in New Zealand. Nutrient Cycling in Agroecosystems, 54: 267–277.

[12] Guo Zhaohui, Xiao Xiyuan, Chen Tongbin et al., 2008, Heavy metal pollution of soils and vegetables from midstream and downstream of Xiangjiang River. Acta Pedologica Sinica, 63(1): 3–11. (in Chinese)

[13] Hanesch M, Scholger R, Dekkers M J, 2001. The application of fuzzy cluster analysis and non-linear mapping to a soil data set for detection of polluted sites. Physical Chemical Earth Science, 26: 885–891.

[14] Lee C S, Li X, Shi W et al., 2006. Metal contamination in urban, suburban, and country park soils of Hong Kong: A study based on GIS and multivariate statistics. Science of the Total Environment, 356(1–3): 45–61.

[15] Liu Fengzhi, 2001. Manual of Environmental Monitoring for Agriculture. Beijing: China Standards Press. (in Chinese)

[16] Liu H Y, Probst A, Liao B H, 2005. Metal contamination of soils and crops affected by the Chenzhou lead/zinc mine spill (Hunan/China). Science of the Total Environment, 339: 153–166.

[17] Liu Qing, Wang Jing, Shi Yanxi et al., 2007. Heavy metal pollution in cropland soil in Cixi city of Zhejiang province. Journal of Agro-environment Science, 26(2): 639–644. (in Chinese)

[18] Loska L, Wiechula D, 2003. Application of principal component analysis for the estimation of source of heavy metal contamination in surface sediments from the Rybnik Reservoir. Chemosphere, 51: 723–733.

[19] Martin J A R, Arias M L, Corbi J M G, 2006. Heavy metals contents in agricultural topsoils in the Ebro basin (Spain). Application of the multivariate geostatistical methods to study spatial variations. Environmental Pollution, 144 (3): 1001–1021.

[20] Ministry of Health, PRC, 1991. Tolerance Limit of Zinc (GB13106-91) in Foods. Beijing: Standards Press of China. (in Chinese)

[21] Ministry of Health, PRC, 1991. Tolerance Limit of Copper (GB15119-94) in Foods. Beijing: Standards Press of China. (in Chinese)

[22] Ministry of Health, PRC, 2005. National Committee of Standardization. The Maximum Levels of Contaminants in Foods (GB2762-2005). Beijing: Standards Press of China. (in Chinese)

[23] Ociel M, Oscar P D, Irma L et al., 2002. Vegetables collected in the cultivated Andean area of northern Chile: Total and inorganic arsenic contents in raw vegetables. Journal of Agricultural and Food Chemistry, 50: 642–647.

[24] Oscar P D, Irma L, Ociel M et al., 2004. Contribution of water, bread, and vegetables (raw and cooked) to dietary intake of inorganic arsenic in a rural village of northern Chile. Journal of Agricultural and Food Chemistry, 52: 1773–1779.

[25] SEPAC (State Environmental Protection Administration of China), 1995. Environmental Quality Standard for Soils (GB15618-1995). Beijing: Standards Press of China. (in Chinese)

[26] Song Bo, Chen Tongbin, Zheng Yuanming et al., 2006. A survey of cadmium concentrations in vegetables and soils in Beijing and the potential risks to human health. Acta Scientiae Circumstantiae, 26(8): 1343–1353. (in Chinese)

[27] Zhang Chaosheng, Zhang Shen, He Jianbang, 1997. Spatial distribution characteristics of heavy metals in the sediments of Changjiang River system. Acta Pedologica Sinica, 52(2): 184–192. (in Chinese)

[28] Zheng Yuanming, Chen Tongbin, Chen Huang et al., 2005a. Lead accumulation in soils under different land use types in Beijing city. Acta Geographica Sinica, 60(5): 791–797. (in Chinese)

[29] Zheng Yuanming, Chen Tongbin, Zheng Guodi et al., 2005b. Soil copper accumulation under different land use types: The case of Beijing. Journal of Natural Resources, 20(5): 690–696. (in Chinese)

[30] Zheng Yuanming, Chen Tongbin, Zheng Guodi et al., 2005c. Chromium and nickel accumulations in soils under different land uses in Beijing Municipality. Resources Science, 27(6): 162–166. (in Chinese)

[31] Zheng Yuanming, Luo Jinfa, Chen Tongbin et al., 2005d. Cadmium accumulation in soils for different land uses in Beijing. Geographical Research, 24(4): 542–548. (in Chinese)

[32] Zheng Yuanming, Song Bo, Chen Tongbin et al., 2006. Zinc accumulation and pollution risk in soils under different land use types in Beijing. Journal of Natural Resources, 21(1): 64–72. (in Chinese)