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| Distribution and diffusion flux of arsenic in sediment and overlying-water of Lake Caohai, Guizhou Province |
| Received:October 24, 2015 |
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| KeyWord:Caohai;arsenic;sediment;pore water;diffusion flux |
| Author Name | Affiliation | E-mail | | TU Han | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China | | | WU Pan | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China | pwu@gzu.edu.cn | | HAN Zhi-wei | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China | | | CAO Xing-xing | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China | | | ZHANG Shui | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China | |
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| Abstract: |
| This paper investigated the distribution and concentration of arsenic in overlying water and sediment pore water of Caohai as well as the nearby rivers and rainwater in different areas. Utilizing one-dimensional pore water diffusion model, we estimated arsenic diffusion flux across the sediment-water interface. Results indicated that arsenic concentrations at the Caohai exit was 1.59 μg·L-1, obviously higher than at the entry of Caohai(averagely 0.32 μg·L-1) as well as rainwater(0.37 μg·L-1). The spatial distribution of arsenic concentrations in the overlying water was as follows:emergent plant zone(2.99~3.45 μg·L-1)> submerged plant zone(1.79~2.34 μg·L-1). The arsenic in the overlying water existed as H3AsO3 form in emergent plant zone but as HAsO42- form in submerged plant zone. The total arsenic concentrations in sediments and pore water showed large vertical variation and were emergent plant zone>submerged plant zone. The arsenic in the sediments in emergent plant zone was between 19.86 mg·kg-1 and 36.45 mg·kg-1, with average value of 27.84 mg·kg-1, while in submerged plant zone arsenic concentrations ranged from 13.05 mg·kg-1 to 32.32 mg·kg-1, averaging 19.79 mg·kg-1. The diffusion flux across the sediment-water interface in emergent plant and submerged plant zons were 73.84 μg·m-2·d-1 and 18.99~11.45 μg·m-2·d-1, respectively, showing that arsenic stored in sediment pore water released into the overlying water and that sediment might thus be significant source of arsenic in Lake Caohai water. |
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