Temporal and spatial assessment of pollen, radionuclides, minerals and trace elements in deposited dust within Kuwait

Sixty-seven dust collectors were installed in 47 sites all over Kuwait. Nine of these sites contain four collectors for radionuclide collection. The monitoring of dust fallout and associated pollen was conducted for 2 years from August 2009 to August 2011. The highest dust depositional rates were detected within the western areas of Kuwait. The annual amount of dust in Kuwait varies from 10 to 1065 unit with an average of 278 t/km(2). The year 2010-2011 was found dustier compared to 2009-2010 by 43 %. The analysis leads to a conclusion that the northwestern, western, and northern winds play a key role in producing dust within Kuwait. Regional areas represent the dominant sources of dust fallout, while local sources contribute appreciable amounts. The very fine and fine sand particles originate from local sources as they move in the form of saltation for a short distance and represent 37 % of the average dust fallout percentages in Kuwait. There is a trend of fining in mean size of dust particles towards the east and the northeast. Mineralogically, carbonates and quartz are the major components of dust in Kuwait, feldspars are found in considerable amounts. Other minerals in the dust are gypsum, anhydrite, bassonite and heavy minerals. Carbonates are more and quartz is less towards the coastal areas compared to desert areas. Natural K-40 and Pb-210, man-made (anthropogenic) Cs-137, and cosmogenic Be-7 radionuclides were determined. The average monthly depositional rates were 35.4, 11.2, 13.2 and 0.3 Bq m(-2) for 7Be, Pb-210, K-40 and Cs-137, respectively, which are were comparable to similar climatologically areas around the globe. Pollen originates predominantly from regional sources. However, the presence of a large amount of pollen from Haloxylon sp. Cyperus sp. indicates that close-by regional and local areas are a major contributor of fallen dust.