|Zobeck, Teddy - Ted|
Submitted to: International Conference on Aeolian Research
Publication Type: Proceedings
Publication Acceptance Date: 5/14/2002
Publication Date: 7/22/2002
Citation: AMANTE-OROZCO, A., ZOBECK, T.M. CLAY AND CARBONATE EFFECT ON FINE DUST EMISSIONS MEASURED IN A ROTATING-TUBE DUST GENERATING SYSTEM. PROCEEDINGS OF THE ICAR5/GCTE-SEN JOINT CONFERENCE. INTERNATIONAL CONFERENCE OF ARID AND SEMIARID LAND STUDIES, TEXAS TECH UNIVERSITY, LUBBOCK, TX PUB NO. 02-2 pp. 79-82 Interpretive Summary: Frequently, human activities and the force of the wind give rise to blowing dust. Dust created in this way is called "fugitive dust". Since field measurement of fugitive dust is difficult, considerable effort is now directed toward developing equipment and techniques to create and analyze these fine airborne particles in the lab. The fugitive dust we are most interested in is called PM_10 and PM_2.5. PM_10 is particulate matter less than 10 microns in size, about 1/10th the diameter of a human hair. PM_2.5 is particulate matter less than 2.5 microns in size and can travel deep into human lungs. In this study, we test a new device we have developed to create dust in a chamber and measure the dust created. We used the device to test how a soil sample carbonate and clay content, two physical soil characteristics, affected the PM_10 and PM_2.5 dust. We also tested two different types of commercial instruments used to measure dust, a MiniVol and DataRam. The MiniVol measures PM by weighing the amount deposited on filters and the DataRam monitor measures PM dust by measuring its optical properties. The DataRam observations were about 2/3 those of the MiniVol but they were very consistent and highly correlated. About 27% of the PM_10 dust was PM_2.5. We found that the PM_10 dust increased as clay and carbonate content of the soil increased. The carbonate levels produced greater increases in dustiness than the clay levels tested.
Technical Abstract: Frequently, human activities and the force of the wind give rise to suspended dust in the atmosphere. Dust created in this way is called "fugitive dust". Because field evaluation of fugitive dust presents serious difficulties, considerable effort is now directed toward developing equipment and techniques to generate and analyze aerosol PM10 emissions in the laboratory. In this study, we used the Lubbock Dust Generation, Analysis and Sampling System (LDGASS) developed by the USDA-ARS Wind Erosion and Water Conservation Research Unit in Lubbock, Texas. This system is capable of generating fugitive dust, measuring particle characteristics of the generated dust in situ, and collecting PM_10 and PM_2.5 particulate aerosol samples. In this study, eight agricultural soils from the Southern High Plains near Lubbock, Texas, with combinations of carbonate and clay content classified into two levels (low and high) of soil clay content and two levels (low and high) of soil CaCO3 content were evaluated. In addition, we tested two different aerosol monitors, a MiniVol monitor that measured particulate matter gravimetrically and a DataRam, an optical instrument. Significant differences were found among measurements of PM_10 concentration made by DataRAM and MiniVol instruments. DataRAM PM_10 measurements were on average 66% of measurements made by the MiniVol. Measurements between instruments, however, were proportional with a correlation coefficient of 0.97. PM_2.5 concentrations obtained with a DataRAM were also proportional to PM_10 production. The overall average proportion of PM_2.5 in relation to PM_10 as measured by a DataRAM was 27%. Aerosol PM_10 and PM_2.5 concentrations significantly increased with an increase of soil CaCO3. The increase of particulate matter concentrations with the increase of soil clay content was significant for the PM_10 data set from the MiniVol dust monitor, but was not significant for PM_10 and PM_2.5 as measured with a DataRAM,. Differences in soil CaCO3 content produced greater differences in aerosol PM_10 and PM_2.5 concentrations than the differences in soil clay content.