ABSTRACT

Downwind odor impact can be very different depending upon the size of the upwind point-source, interim topography and wind pattern. At one extreme, the downwind odor plume from a relatively large CAFO can be rather broad, sustained and predictable relative to a fixed downwind receptor site. Conversely, the plume from a small point-source such as a small vent stack can be intermittent and fleeting. These transient odor events can be surprisingly intense and offensive. This work reports on efforts by the authors to develop a downwind odor sampling strategy which is optimized for such transient odor ‘spikes’. Initial results, for example, have shown ~10 fold increases in target odorant yields for adsorbent tube collection and transfers from two second ‘burst’ odor event bag-captures; when compared to equivalent direct collections during perceived odor ‘lull’ periods. Results-to-date targeting refinement and validation of this integrated strategy for ‘transient’ odor events will be presented.

ABSTRACT

Past experience with crisis-driven odor investigations has shown that there is an odor impact priority ranking which is definable for virtually every malodor issue; whether from natural or synthetic source. An accurate definition of such odorant priority ranking is, in turn, critical to the development of accurate and objective instrument-based methods for odor assessment and monitoring relative to that source. This paper reports on the results-to-date relative to the Carthage Bottoms Area Odor Study; a test case undertaken by the Missouri DNR to evaluate the concept of odorant prioritization by MDGC-MS-Olfactometry. The ultimate goal of this study was to explore the utility of odorant prioritization as a first step toward the translation of sensory-only odor monitoring protocols to sensory-directed but instrument based alternatives. The Carthage Bottoms Area was selected by the Missouri DNR for this exploratory effort based upon a number of factors: including; (1) an intermittent but long-standing unresolved odor issue with respect to downwind citizenry; (2) a uniquely complex, diverse and densely co-located source industry mix within the combined Bottoms Area; (3) limited past success in point-source differentiation utilizing sensory-only protocols and (4) a past history of cooperation between citizenry, community officials, industry leaders and regulatory agencies in the exploration and implementation of technologies targeting enhanced mutually beneficial co-existance. MDGC-MS-O odorant profile and prioritization results are presented for SPME collections taken near and at-distance downwind as well as reference upwind with respect to the combined Bottoms Area.