Concentrations and Deposition Fluxes of Heavy Metals in Precipitation in Core Urban Areas,Chongqing

Concentrations and deposition fluxes of heavy metals in the precipitation of core urban areas of Chongqing were investigated for one year from December 2011 to November 2012. Precipitation samples were collected with an automated precipitation sampler from three sampling sites. Concentrations of 13 heavy metals were analyzed using ICP-MS. Results showed that the concentrations and annual deposition fluxes of most elements in precipitation were higher than those in other domestic cities and regions overseas. For instance,the concentrations of Cd,Pb and As at the three sampling sites were up to 0. 55 μg·L- 1,37.94 μg·L- 1and 5. 65 μg·L- 1respectively,and annual deposition fluxes of Cd,Pb and As reached 0. 44 mg·( m2·a)- 1,30.25 mg·( m2·a)- 1,and 4.50mg·( m2·a)- 1respectively. In addition,there were no obviously spatial differences for concentrations and deposition fluxes of heavy metals in urban Chongqing,but significantly seasonal variations were found. Maximum concentrations occurred in autumn and winter,while the highest deposition fluxes appeared in spring and summer. Moreover,the enrichment factor( EF) was employed to estimate the pollution level of heavy metals. Results showed that EFs of Cu,Pb,Zn,Cd,Ag,As and Se were over 100,suggesting that these metals in atmosphere were seriously influenced by human activities,especially for Cd and Se,the EFs of which were 1 740 and 4 133respectively.