Seasonal Variations in Air-Water Exchange of Polychlorinated Biphenyls in Lake Superior

Hornbuckle, Keri C.; Jeremiason, Jeff D.; Sweet, Clyde W.; Eisenreich, Steven J.

doi:10.1021/es00057a018

Cited by 178 publications

(179 citation statements)

References 30 publications

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“…K OL (meters per hour) is the overall air-water mass transfer coefficient compromising the resistances to mass transfer in both water (K W , meters per hour) and air (K A , meters per hour) (Hornbuckle et al 1994). Fugacity ratios (FR) calculated with paired seawater and air concentrations of PFASs are shown in Fig.…”

Section: Air-water Gas Exchange Of Pfass In the North Seamentioning

confidence: 99%

Neutral poly- and perfluoroalkyl substances in air and seawater of the North Sea

Xie¹,

Zhao

Møller

et al. 2013

Environ Sci Pollut Res

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Concentrations of neutral poly-and perfluoroalkyl substances (PFASs), such as fluorotelomer alcohols (FTOHs), perfluoroalkane sulfonamides (FASAs), perfluoroalkane sufonamidoethanols (FASEs), and fluorotelomer acrylates (FTACs), have been simultaneously determined in surface seawater and the atmosphere of the North Sea. Seawater and air samples were taken aboard the German research vessel Heincke on the cruise 303 from 15 to 24 May 2009. The concentrations of FTOHs, FASAs, FASEs, and FTACs in the dissolved phase were 2.6-74, <0.1-19, <0.1-63, and <1.0-9.0 pg L −1 , respectively. The highest concentrations were determined in the estuary of the Weser and Elbe rivers and a decreasing concentration profile appeared with increasing distance from the coast toward the central part of the North Sea. Gaseous FTOHs, FASAs, FASEs, and FTACs were in the range of 36-126, 3.1-26, 3.7-19, and 0.8-5.6 pg m −3 , which were consistent with the concentrations determined in 2007 in the North Sea, and approximately five times lower than those reported for an urban area of Northern Germany. These results suggested continuous continental emissions of neutral PFASs followed by transport toward the marine environment.Air-seawater gas exchanges of neutral PFASs were estimated using fugacity ratios and the two-film resistance model based upon paired air-seawater concentrations and estimated Henry's law constant values. Volatilization dominated for all neutral PFASs in the North Sea. The air-seawater gas exchange fluxes were in the range of 2.5×10 3 -3.6×10 5 pg m −2 for FTOHs, 1.8 × 10 2 -1.0 × 10 5 pg m −2 for FASAs, 1.1 × 10 2 -3.0 × 10 5 pg m −2 for FASEs and 6.3×10 2 -2.0×10 4 pg m −2 for FTACs, respectively. These results suggest that the air-seawater gas exchange is an important process that intervenes in the transport and fate for neutral PFASs in the marine environment.

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Section: Air-water Gas Exchange Of Pfass In the North Seamentioning

confidence: 99%

Neutral poly- and perfluoroalkyl substances in air and seawater of the North Sea

Xie¹,

Zhao

Møller

et al. 2013

Environ Sci Pollut Res

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“…Higher summer temperatures also increased the H values (~6.5 times) favoring the shift in the direction of air-water exchange for this OCP. Hornbuckle et al (1994) have reported that the ∑PCB fluxes ranged between −110 and 40 ng m − 2 day − 1 in Lake Superior. The fluxes of ∑PCBs in spring were depositional while they were volatilized in summer.…”

Section: Air-water Exchangementioning

confidence: 99%

Air–water exchange of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) at a coastal site in Izmir Bay, Turkey

et al. 2008

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The air-water exchange of polychlorinated biphenyl (PCB) and organochlorine pesticides (OCPs) were investigated using paired air-water samples (n = 16) collected in July and February-March, 2005 from Guzelyali Port in Izmir Bay, Turkey. Atmospheric PCBs and OCPs were mainly in gas-phase in both periods. However, their dissolved and particle-phase water concentrations were comparable. For PCBs, 3 and 4-Cl congeners were dominant while chlorpyrifos, endosulfans and HCHs were the most abundant OCPs for all samples. Especially in summer, calculated net gas-exchange PCB fluxes were mainly volatilization from the water ranging from − 0.2 (volatilization, PCB-101) to −30.0 (volatilization, PCB-31) ng m − 2 day − 1 . For OCPs, net flux ranged from −0.03 (volatilization, cis-nonachlor) to 1568 (deposition, endosulfan I) ng m − 2 day − 1 and they have seasonal variations with generally deposition in winter and volatilization in summer. However, endosulfan I, II, endosulfan sulfate, α-and γ-HCH deposited in both periods. The calculated residence times of PCBs and OCPs in the water column indicated that the gasexchange in the Bay is at least as or a more important mechanism than advection. Annual gaseous absorption and volatilization fluxes were calculated and were used along with the estimated dry deposition fluxes and wet deposition fluxes measured recently at a suburban site in Izmir to determine the relative contributions of different atmospheric mechanisms to the pollutant inventory of the Bay water column. Results suggested that the relative contributions of all studied mechanisms to the water column PCB and OCP inventories were significant.

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“…Briefly, K w (cm h −1 ) can be correlated with the mass transfer of CO 2 across the airwater interface through (Wanninkhof et al 1985, Hornbuckle et al, 1994 K w = (0.45 U 1.64 10 ) [Sc w (Hg 0 ) / Sc w (CO 2 )] 0.5 where U 10 is the wind speed (m s −1 ) at 10 m and Sc's are the Schmidt numbers for CO 2 and Hg 0 in water, respectively. The Schmidt number of CO 2 is calculated using the temperature-corrected dependency (Hornbuckle et al, 1994;Bidleman and McConnell, 1995) Sc w (CO 2 ) = 0.11 T 2 − 6.16 T + 644.7 with T in • C. The Schmidt number of Hg 0 is directly derived from its definition Sc = ν/D where the temperature ( • C) dependant ν (kinematic viscosity of water, cm 2 s −1 ) and D (diffusivity of Hg 0 in water, cm 2 s −1 ) are estimated by ν = 0.017 exp(−0.025 T ) (Thibodeaux,1996) D = 6.0 × 10 −7 T + 10 −5 (Kim and Fitzgerald, 1986) The re-emissions of Hg 0 in the model domain accumulated over a 4-week period from 20 June 1995 to 18 July 1995 are presented in Fig. 2.…”

Section: Re-emissions and Dry Deposition Of Hg 0 From And To Natural mentioning

confidence: 99%

A numerical modelling study on regional mercury budget for eastern North America

Lin

Tao

2003

Atmos. Chem. Phys.

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Abstract. In this study, we have integrated an up-to-date physio-chemical transformation mechanism of Hg into the framework of US EPA's CMAQ model system. In addition, the model adapted detailed calculations of the air-surface exchange for Hg to properly describe Hg re-emissions and dry deposition from and to natural surfaces. The mechanism covers Hg in three categories, elemental Hg (Hg 0 ), reactive gaseous Hg (RGM) and particulate Hg (HgP). With interfacing to MM5 (meteorology processor) and SMOKE (emission processor), we applied the model to a 4-week period in June/July 1995 on a domain covering most of eastern North America. Results indicate that the model simulates reasonably well the levels of total gaseous Hg (TGM) and the specific Hg wet deposition measurements made by the Hg deposition network (MDN). Moreover, results from various scenario runs reveal that the Hg system behaves in a closely linear way in terms of contributions from different source categories, i.e. anthropogenic emissions, natural re-emissions and background. Analyses of the scenario results suggest that 37% of anthropogenically emitted Hg was deposited back in the model domain with 5155 kg of anthropogenic Hg moving out of the domain during the simulation period. Overall, the domain served as a net source, which supplied ∼a half ton of Hg to the global background pool over the period. Our model validation and a sensitivity test further rationalized the rate constant for gaseous oxidation of Hg 0 by hydroxyl radical OH used in the global scale modelling study by Bergan and Rodhe (2001). A further laboratory determination of the reaction rate constant, including its temperature dependence, stands as one of the important issues critical to improving our knowledge on the budget and cycling of Hg.Correspondence to: X. Lin (Xiude. Lin@kinectrics.com)

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Seasonal Variations in Air-Water Exchange of Polychlorinated Biphenyls in Lake Superior

Cited by 178 publications

References 30 publications

Neutral poly- and perfluoroalkyl substances in air and seawater of the North Sea

Neutral poly- and perfluoroalkyl substances in air and seawater of the North Sea

Air–water exchange of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) at a coastal site in Izmir Bay, Turkey

A numerical modelling study on regional mercury budget for eastern North America

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