The chemistry of rain water in relation to dust fall over Mosul City and Ba’aj Town / Northern Iraq

The Journal of Environmental studies (JES) 
Vol.11 (11), 7 pages
doi:.
Author:Flyah 'Al-Khatony
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Abstract

Twenty four samples of mineral dust (Nov. 2010 – Oct. 2011) and fourteen samples of rain water (Dec. 2010 --- Apr. 2011) were collected at Mosul City and Ba’aj Town / North Iraq. All the samples were analyzed for (18) elements (Al, As, Ba, Ca, Cr, Cu, K, Li, Mg, Mn, Na, Ni, P, Rb, S, Sb, Sr, Zn) by ICP-MS technique in addition to separate tests and analysis of rain water (pH, EC µs/cm, TDS ppm, SO42- ppm). The imprints of the nature of the land use, the soil type and the geological setting noticed in the chemistry of the mineral dust suggest that mineral dust emission is of local source(s). The positive correlation between monthly dust-fall rate with rain content of most elements indicate to the atmospheric dissolution or leaching of element at dust grain/rain droplet boundary. Wash-out ratio (W) of the studied element show great deal of variation but they are held within two extremes i.e. the least mobile Al and most mobile S probably as SO4-2 (Al, Mn, Ni, Cr, Rb, Mg, K, Ba, As, P, Zn, Ca, Sr, Na, S as SO4-2). Element Cu, Li and Sb are neglected on the basis of poor analysis accuracy and precision. Some elements (Al, Ca, Sr, Na, S as SO4-2) in the series may comply with their known behavior in the weathering zone but the mobility of others is not common at the supergene environment. Mineral dust is considered to change composition and size once it is in the atmosphere. It is thought that such changes are the result of heterogeneous reactions with trace atmospheric gases. At present this type of reaction is not fully define for all and each element constituents of the mineral dust, especially those of environmental interest.

Keywords

chemistry of dust/droplet boundary, wash-out ratio, heterogeneous reactions

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