Abstract: 【Objective】 The objective of this study was to explore the annual variability of soil heavy metals and its influencing factors with the aim to provide a basic scientific foundation for soil environmental quality assessment and management. 【Method】The annual variability and statistical characteristics of heavy metals As, Hg, Cu, Cd, Cr, and Pb in Beijing agricultural soils were presented, on the basis of continuous yearly monitoring from 2005 to 2009. Combined with the information of soil type, sampling location, and agricultural land use type, the possible sources of heavy metals in the soils were discussed. 【Result】The results showed a growth trend of Hg and Cr concentrations in Beijing agricultural soils from 2005 to 2009, and the concentrations of Hg were 0.053, 0.065, 0.077, 0.090 and 0.116 mg•kg -1, and that of Cr were 50.0, 53.3, 55.8, 56.1 and 61.8 mg•kg -1, respectively. There was no significant trend for other metals. Furthermore, compared with backgroand values of the heavy metals in Beijing soil, Cr accumulated in the soils the most, followed by Hg, Cd, Cu, As and then Pb. Statistical analyses using T-test showed the significant differences in As concentration between fluvo-aquic soil and cinnamon soil, and also in Hg and Pb concentrations between the suburban and the outer suburban farmlands. However, there was no significant difference in the metal concentrations in the soils among different agricultural land uses. 【Conclusion】 It was concluded that As mainly originated from soil parent materials, Hg and Pb largely came from atmospheric deposition, and Cu, Cd and Cr were mainly associated with agricultural fertilization.

Key words: Beijing, agriculturalsoil, heavymetal, annualvariability, sourceassessment