ARB Research Seminar
This page updated June 19, 2013
Molecular Markers for Sources of Fugitive Dust in the San Joaquin Valley
Wolfgang F. Rogge, Ph.D., P.E., School of Engineering, University of California, Merced
November 26, 2007
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA
In the San Joaquin Valley of California, a sizeable portion of the ambient PM10/PM2.5 concentrations are the result of agricultural activities. Major contributions of these mainly fugitive sources are related to wind blown dust from agricultural fields post harvesting and agricultural activities such as tilling, harvesting, and traffic over paved and unpaved roads. Likewise, cattle husbandry in open lot dairies and beef cattle feedlots can at times be major sources of fugitive dust. Due to the nature of these pollutant sources, it is difficult to access the actual emissions and therefore contributions of fugitive dust to nearby towns.
Here, as part of the San Joaquin Valley Fugitive Dust Characterization Study, a total of 47 surface soil samples were available for analysis that were collected during the autumn of 1997 by Ashbaugh and coworkers (2003).
More than 200 organic compounds were quantified with the aim of identifying potential organic source specific markers that then can be used in source-receptor models to determine the actual contribution of airborne particulate matter to location of interest within the San Joaquin Valley.
Biohydrogenation of plant lipids and sterols in the cattle rumen results in distinctive alteration products. Animal and plant derived steroids are most abundant. Here, it is shown that 5B -stigmastanol and epi-5B -stigmastanol, two biohydrogenation products of sitosterol and stigmasterol, are the most distinctive molecular marker compounds. While stearic (C18) and palmitic (C16) acids are as individual compounds not source specific, biohydrogenation of the more abundant C18 unsaturated fatty acids, causes the ratio of C18/C16 fatty acids to shift from below 0.5 for vegetation to an average of 3.0.
Surface soils derived from fields growing cotton, safflower, tomato, almonds, and grapes have been analyzed for natural lipids, saccharides, pesticides, herbicides, and polycyclic aromatic hydrocarbon (PAH). Saccharides, among which a- and B-glucose, sucrose, and mycose show the highest concentrations in surface soils, have been proposed to be generic markers for fugitive dust from cultivated land. Similarly, steroids are strongly indicative of fugitive dust. Yet, triterpenoids reveal the most pronounced distribution differences for all types of cultivated soils examined here and are by themselves powerful markers for fugitive dust that allow differentiation between the types of crops cultivated.
Wolfgang F. Rogge, Ph.D., P.E., is an associate professor in the School of Engineering at University of California Merced and is a member of the Sierra Nevada Research Institute (SNRI). Dr. Rogge conducted and participated in several ambient air pollution characterization studies, including EPA PM Supersites at Pittsburgh and Baltimore. Over the years he has investigated a large number of different indoor and outdoor pollutant sources with the aim to provide suitable source profiles and source specific molecular markers that then can used together with source/receptor models to apportion the contribution of individual sources to a receptor site of interest. Dr. Rogge is considered to be one of the pioneers that made organic aerosol research popular. Dr. Rogge has published extensively and the Web of Science (ISI) lists him among the highly cited authors with in total more than 2,500 citations. Dr. Rogge received his Ph.D. and MS in Environmental Engineering Science from the California Institute of Technology, and a degree as Diplom Ingenieur from the Technical University in Berlin, Germany.