THE PM10 AND PM2.5 DUST GENERATION POTENTIAL OF SOILS/SEDIMENTS IN THE SOUTHERN ARAL SEA BASIN, UZBEKISTAN

Authors: SINGER, ARIEH - HEBREW UNIV OF JERUSALEM; Zobeck, Teddy; POBEREZSKY, L - VODPROJECT, UZBEKISTAN; ARGAMAN, E - HEBREW UNIV OF JERUSALEM

Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2002
Publication Date: 8/1/2003
Citation: Singer, A., Zobeck, T.M., Poberezsky, L., Argaman, E. 2003. The PM10 and PM2.5 dust generation potential of soils/sediments in the Southern Aral Sea Basin, Uzbekistan. Journal of Arid Environments. 54(4): 705-728.

Interpretive Summary: Extensive drying of the Aral Sea in Central Asia has exposed large portions of the former sea bed. Enormous dust storms originate from the area and have disastrous ecological consequences. The dust constitutes a major threat to the health of the population. Since the dust contains large amounts of salts, dust deposition causes both water bodies and huge tracts of agricultural lands to become severely salty. The objective of this study was to determine which major land surfaces in the Southern Aral Sea Basin cause the wind blown dust in this region. Eight soil crusts and sediments from 7 sites, representative of these surfaces, were sampled and their major soil physical and chemical properties related to blowing dust were determined. The potential of the soil to create very fine blowing dust (called PM10 and PM2.5) was used to rate the dustiness of the soils. The dustiness was determined in the laboratory using a special device developed by the USDA. The experimental results indicated that the silty soil called the Takyr and Takyr-like soils, which occupy over 1 million hectares in the Southern Aral Sea Basin, had the greatest potential for being the source for the severe dust storms of the area. Second to the Takyr soils, the mildly to strongly salty soils called Solonchaks and Solonchak-like soils, also with an extent of over 1 million hectares, contributed highly salty dust.

Technical Abstract: Enormous dust storms have become common in the area of the Aral Sea in Central Asia due to exposure of large portions of the former sea bed, resulting from the extensive desiccation. The objective of this study was to assess the contribution of the major soil/sediment surfaces in the Southern Aral Sea Basin to the dust generation potential of the region. The exposed surfaces include wetlands in the delta close to the Amu Darya River bed; with transitions to Solonchak soils commonly with a salt crust; Takyr and Takyr-like soils exhibiting a fine-grained crust more removed from the river bed; and shallow, stony soils on the more elevated terrain and Solonchak-like soils on exposed Aral Sea bed. Eight crusts and soils/sediments from 7 sites representative of these surfaces, were sampled in the field and their major characteristics (particle size distribution, organic carbon, carbonate, and salt content) that are related to dust generation were determined. The PM10 and PM2.5 dust generation potential of the materials was accepted as a general indicator for their dust generation capability, and was determined in the laboratory using the Lubbock Dust Generation, Analysis and Sampling System. The highest amount of PM10 dust (579.3 mg.m-3) was generated from the Takyr crust material. The lowest, by one Solonchak salt crust material (39.6 mg.m-3). Salt crusts from the desiccated Aral Sea bottom generated intermediate amounts of dust. Salt crusts seem to generate much lower PM10 dusts, possibly due to dense interlocking matrix of the salt crystallites forming the crust. The results of these determinations indicate that the Takyrs and Takyr-like soils, roughly of an extent of over 1 million ha in the Southern Aral Sea Basin, constitute the surfaces with the highest potential for being the source for the severe dust storms of the area. Second to the Takyr soils, the Solonchaks and Solonchak-like soils contribute highly saline dust.