3.4. SR 08-25-1997 - Laserfiche WebLink

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C. Source Contributions of Toxic Air Pollutants to Receptor Sites I. What types of emission surees are the most important contributors to ambient air concentrations of toxic air pollutants?- Industry has argued that mo.bile sources contn'bute si~iflcantly, to ambient air concentrations of toxic air pollutants. The MPCA's "urban soup study" (1992) is most often cited as a reference for industry's cia/ms in this regaZ~. II1 addition, industry states that k has been unfairly targeted for reductions ofto~ic air pollutant emi~ions whil~ thc MPCA has ignored the'contributions of mobile sources. Ambient air monitoring data, in conjunction with multivariate statistical analysis techniques, can be used to identify important contributors of specific toxic air pollutants at receptor sites. The 3M Cottage Grove Environmental Monitoring Study identified si~iflcant contributions of PM~0 from secondary sulfate, combustion/transportation sources, and crustal materials to receptor sites located at various distances from the facility ('RUST 1994a). In turn, the 3M incinerator was estimated to only contn'bute a a small amount of the particulate matter (ma~mum of 2.5%) for thc sampling days that were analyzed for source contn'butions. A statewide monitoring study can help collect data to identify the important contributors of toxic air pollutants in other areas. What are the most'important contributors to deposition of persistent and/or bioaccumulative pollutants in Minnesota? To date, there is considerable debate regarding the primary contributors of persiStent and bioaccumulative pollutants to Minnesota's environment.. There is also considerable discussion on the importance ofloeal source contibutions versus regional source contributions versus national and/or global contributions. No actual work has yet bden done in M{rmesota to identify the most important contributors of such pollutants as mercury or dioxin to recePtor areas. Some WOrk is progressing in the LCMR mercury study currently being conducted by the MPCA to collect data that can eventually be used to determine important source contributions. In addition, EPA is considering doing some "impacts analysis" by determining source contributions of mercury and other Great Waters "chemicals of concern" to the Great Lakes. However, the ability to do this source contribution es~mate is still several years away. A statewide toxics monitoring, study could collect additional data to help identify the important contributors of persistent and/or bioaccnmulative pollutants to important surface waters.