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Jason Kelsey ’90, a professor in the department of environmental science/chemistry at Muhlenberg College, will give a talk on “Biological Availability of Organic Pollutants in Soil” noon Friday in Van Wickle Hall room 108.
Lunch will be provided free of charge to students and for $3 to faculty and staff.
After earning degrees in geology and English from Lafayette, Kelsey received a master’s in environmental toxicology with a minor in microbiology from Cornell in 1993, and a Ph.D. in environmental toxicology with minors in microbiology and ecology from Cornell in 1996.
His main research areas are the effect of soil residence time (aging) on the bioavailability of organic chemicals and the biodegradation of organic compounds during their transport through soil.
Kelsey has published his research at forums sponsored by the American Chemical Society’s Division of Chemical Education and Marymount University, Arlington, Va., and in the publications Chemosphere, Environmental Toxicology and Chemistry, Annals of the New York Academy of Sciences, Environmental Science and Technology, Soil Science Society of America Journal, and Geological Society of America Abstracts with Programs.
Kelsey gives the following description of his research:
Risk assessments of persistent pollutants in soil tend to be based on either the total amount of a chemical that is extractable from soil or on models which assume equilibrium conditions in the soil. Recent research conducted by myself and others has suggested that neither of these two approaches is correct. Data indicate that organic chemicals become increasingly unavailable to test species with increasing residence time of the compounds in sterile soil.This decline in availability is observable despite the fact that the total recovery (by chemical extraction) of the compounds does not change as a function of soil residence time. The mechanisms by which this phenomenon occurs are not well understood, but are thought to involve the slow movement of the compounds into soil micropores and organic matter, where they become sequestered and inaccessible to soil organisms.
I am continuing this work by examining the effects of species differences on the bioavailaiblity of soil-aged chemicals.The degree to which sequestration will affect bioavailaiblity will depend in part upon the ability of an organism to extract compounds from the soil matrix.For example, the bioavailability of a sequestered compound may be higher to an organism that is able to digest soil organic matter than to an organism that cannot digest organic matter.Other differences in feeding strategies and efficiencies could also influence the extent to which a particular organism is affected by the sequestration of compounds in soil.This work will enhance our ability to predict the bioavailability of soil-aged organic compounds and improve the risk assesssment and regulation of persistent pollutants in soil.
An understanding of the factors that affect the movement of pollutants through the unsaturated zone is critical to the preservation of groundwater.Since chemical contamination often reaches the water table by way of vertical movement through surface and subsurface layers, transport and fate processes in these regions above the saturated zone are of utmost importance to groundwater quality.In previous work, I have examined the effects of several environmental factors on biodegradation (a major mechanism by which pollutants can be detoxified before they reach groundwater) in unsaturated soil columns.The results of those studies indicate that, in general, any physical factor that reduces the contact time between soil microorganisms and a pollutant that is flowing through the unsaturated zone will increase groundwater contamination.However, an exception to this trend was observed when preferential flow channels were inserted through soil columns. Under some conditions, the total amount of a test compound that leached from columns (i.e., into groundwater) containing open vertical channels was reduced relative to the amount that leached from columns that did not contain channels. The reason for this phenomenon is not clear.
I am continuing to explore the problem by studying the distribution of bacteria, oxygen, pollutant, and bacterial metabolites during the transport of a pollutant through soil columns that contain open channels. These studies will further our understanding of the factors that affect groundwater pollution and would aid in the development of realistic transport and fate models.