A Novel Approach to CAFO Odor Assessment: Odorant Field Collection by Sorbent Tube / Thermal Reconstitution in the Laboratory

摘要

Historically, odor emission monitoring of high density livestock operations has been limited to direct, whole-air assessment utilizing remote site sampling by plastic bags, human sensory panelists and dynamic dilution olfactometry. On-going efforts by these authors are directed at enabling the translation of these sensory ‘only’ monitoring protocols to instrument ‘primarily, with sensory oversight’ alternatives. This current work attempts to address the latter requirement for sensory oversight and the associated need for improved methods of remote site whole-air sample collection. Published works by these authors as well as others places in serious question the appropriateness of the use of plastic bags for the challenge of CAFO odor assessment; especially relative to sample points at increasing downwind distance from the source. Concerns increase due to the associated natural dilution effects relative to priority semi-volatile odorants. This current submission reports on the progress to date in the development and evaluation of alternative whole-air sampling strategies which attempt to address the primary limitation of plastic sampling bags; the adsorption loss-to-wall of high impact semi-volatile odorants such as p-cresol. In this approach the actual field air sampling is carried out utilizing sorbent tubes for on-site collection of the volatiles/odorants from a measured volume of air. These sorbent tube collections are then transported to the laboratory for reconstitution within a heat traced, passivated and piston-displaced vessel prior to composite odor assessment. The sample reconstitution process is accomplished simply by thermally desorbing the collected odorants into a flowing diluent gas stream and making up to final volume to yield a match of the originally sampled environment.