Measurement and Modeling of PBT Transport in Lake Superior

Emphasis Area: Atmospheric Chemistry

Perlinger, J.A.

Sponsor: Great Lakes Commission

Funding Level: $156,865

Period: April 1 2006 – July 31 2008

Abstract :

Semivolatile organic chemicals (SOCs) including legacy chemicals and chemicals of emerging concern enter and exit the Great Lakes in large part through air-water exchange.  In a previous Great Lakes Atmospheric Deposition Project to measure concentrations of SOCs in dry deposition in the Great Lakes region, we designed and fabricated multicapillary collection devices (MCCDs), which operate at flowrates similar to those utilized in conventional high-volume air sampling yet avoid artifacts and expense of high-volume sampling and analysis.  We developed methods to thermally extract analytes from MCCDs into a gas chromatograph for measurement.  In the current project, MCCDs are being characterized for use to determine concentrations in remote and urban environments of a suite of SOCs including polybrominated diphenyl ethers, polychlorinated biphenyls, and pesticides.  MCCDs will be characterized in terms of SOC detection limits and breakthrough character.  We are also developing a Lagrangian transport-exchange model for trace gases in the Great Lakes.  We are utilizing micrometeorological methods developed previously in the PI’s group to measure concentrations and fluxes of trace gases in dry deposition in Lake Superior in two field seasons to parameterize and validate the model.  Flux and concentration measurements will be carried out on a given day along transects parallel to the mean wind direction during offshore flow.  The project will provide information regarding the applicability of the SOC concentration measurement techniques so that these methods can be considered for future applications, including determination of SOC loadings into the Great Lakes.  It will provide concentration and flux measurements that can be used in mass balance computations.  The project will provide a validated transport-exchange model that can be used to evaluate effects of environmental conditions on in-lake trace gas atmospheric transport and exchange.