title: An updated Quantitative Water Air Sediment Interaction (QWASI) model for evaluating chemical fate and input parameter sensitivities in aquatic systems: application to D5 (decamethylcyclopentasiloxane) and PCB-180 in two lakes.
abstract: The QWASI fugacity mass balance model has been widely used since 1983 for both scientific and regulatory purposes to estimate the concentrations of organic chemicals in water and sediment, given an assumed rate of chemical emission, advective inflow in water or deposition from the atmosphere. It has become apparent that an updated version is required, especially to incorporate improved methods of obtaining input parameters such as partition coefficients. Accordingly, the model has been revised and it is now available in spreadsheet format. Changes to the model are described and the new version is applied to two chemicals, D5 (decamethylcyclopentasiloxane) and PCB-180, in two lakes, Lake Pepin (MN, USA) and Lake Ontario, showing the model's capability of illustrating both the chemical to chemical differences and lake to lake differences. Since there are now increased regulatory demands for rigorous sensitivity and uncertainty analyses, these aspects are discussed and two approaches are illustrated. It is concluded that the new QWASI water quality model can be of value for both evaluative and simulation purposes, thus providing a tool for obtaining an improved understanding of chemical mass balances in lakes, as a contribution to the assessment of fate and exposure and as a step towards the assessment of risk.
authors.affiliation: Canadian Centre for Environmental Modelling and Chemistry, Trent University, Peterborough, ON K9J 7B8, Canada. Electronic address: dmackay@trentu.ca.
authors.forename: Donald
authors.initials: D
authors.lastname: Mackay
authors.affiliation: Canadian Centre for Environmental Modelling and Chemistry, Trent University, Peterborough, ON K9J 7B8, Canada.
authors.forename: Lauren
authors.initials: L
authors.lastname: Hughes
authors.affiliation: Dow Corning Corporation, Health and Environmental Sciences, Midland, MI 48686, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Powell
authors.affiliation: Dow Corning Corporation, Health and Environmental Sciences, Midland, MI 48686, USA.
authors.forename: Jaeshin
authors.initials: J
authors.lastname: Kim
mesh_terms: D000388:Air; D001272:Atmosphere; D052918:Environmental Restoration and Remediation; D019015:Geologic Sediments / Q000737:chemistry; D060106:Lakes / Q000737:chemistry*; D008962:Models, Theoretical; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D012833:Siloxanes / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*
chemical_list: D012833:Siloxanes; D014874:Water Pollutants, Chemical; D014867:Water; C114768:decamethylcyclopentasiloxane; C410127:PCB 180; D011078:Polychlorinated Biphenyls
keywords: Fugacity; Multimedia model; PCBs; Sensitivity analysis; Siloxanes; Uncertainty analysis