Estimation of Uncertainty in Air-Water Exchange Flux and Gross Volatilization Loss of PCBs: A Case Study Based on Passive Sampling in the Lower Great Lakes.
Compared with dry and wet deposition fluxes, air-water exchange flux cannot be directly measured experimentally. Its model-based calculation contains considerable uncertainty because of the uncertainties in input parameters. To capture the inherent variability of air-water exchange flux of PCBs across the lower Great Lakes and to calculate their annual gross volatilization loss, 57 pairs of air and water samples from 19 sites across Lakes Erie and Ontario were collected using passive sampling technology during 2011-2012. Error propagation analysis and Monte Carlo simulation were applied to estimate uncertainty in the air-water exchange fluxes. Results from both methods were similar, but error propagation analysis estimated a smaller uncertainty than Monte Carlo simulation in cases of net deposition. Maximum likelihood estimations (MLE) of wind speed and air temperature were recommended to quantify the site-specific air-water exchange flux. An assumed 30-40% of relative uncertainty in overall air-water mass transfer velocity was confirmed. MLEs of volatilization fluxes of total PCBs across Lakes Erie and Ontario were 0.78 and 0.53 ng m-2day-1, respectively, and gross volatilization losses of total PCBs over the whole lakes were 74 kg year-1for Lake Erie and 63 kg year-1for Lake Ontario. Mass balance analysis across Lake Ontario indicated that volatilization was the uppermost loss process of aqueous PCBs.
State Key Laboratory of Pollution Control and Resource Reuse, Shanghai Key Lab of Chemical Assessment and Sustainability, College of Environmental Science and Engineering, Tongji University , Shanghai 200092, China.|Graduate School of Oceanography, University of Rhode Island , Narragansett, Rhode Island 02882-1197, United States.
Ying
Y
Liu
State Key Laboratory of Pollution Control and Resource Reuse, Shanghai Key Lab of Chemical Assessment and Sustainability, College of Environmental Science and Engineering, Tongji University , Shanghai 200092, China.
Siyao
S
Wang
Graduate School of Oceanography, University of Rhode Island , Narragansett, Rhode Island 02882-1197, United States.
Carrie A
CA
McDonough
Graduate School of Oceanography, University of Rhode Island , Narragansett, Rhode Island 02882-1197, United States.|Department of Environmental Sciences, Faculty of Science, Alexandria University , 21511 Moharam Bek, Alexandria, Egypt.
Mohammed
M
Khairy
Environment Canada, Atmosphere, Water, and Soil Contaminant Dynamics, 867 Lakeshore Road, Burlington, Ontario L7R 4A6, Canada.
Derek
D
Muir
Graduate School of Oceanography, University of Rhode Island , Narragansett, Rhode Island 02882-1197, United States.
Rainer
R
Lohmann
D000393:Air Pollutants; D004784:Environmental Monitoring; D006114:Great Lakes Region; D006801:Humans; D060106:Lakes; D011078:Polychlorinated Biphenyls; D035501:Uncertainty; D014835:Volatilization; D014867:Water; D014874:Water Pollutants, Chemical
D000393:Air Pollutants; D014874:Water Pollutants, Chemical; D014867:Water; D011078:Polychlorinated Biphenyls