title: The delivery of organic contaminants to the Arctic food web: why sea ice matters.
abstract: For decades sea ice has been perceived as a physical barrier for the loading of contaminants to the Arctic Ocean. We show that sea ice, in fact, facilitates the delivery of organic contaminants to the Arctic marine food web through processes that: 1) are independent of contaminant physical-chemical properties (e.g. 2-3-fold increase in exposure to brine-associated biota), and 2) depend on physical-chemical properties and, therefore, differentiate between contaminants (e.g. atmospheric loading of contaminants to melt ponds over the summer, and their subsequent leakage to the ocean). We estimate the concentrations of legacy organochlorine pesticides (OCPs) and current-use pesticides (CUPs) in melt pond water in the Beaufort Sea, Canadian High Arctic, in 2008, at near-gas exchange equilibrium based on Henry's law constants (HLCs), air concentrations and exchange dynamics. CUPs currently present the highest risk of increased exposures through melt pond loading and drainage due to the high ratio of melt pond water to seawater concentration (Melt pond Enrichment Factor, MEF), which ranges from 2 for dacthal to 10 for endosulfan I. Melt pond contaminant enrichment can be perceived as a hypothetical 'pump' delivering contaminants from the atmosphere to the ocean under ice-covered conditions, with 2-10% of CUPs annually entering the Beaufort Sea via this input route compared to the standing stock in the Polar Mixed Layer of the ocean. The abovementioned processes are strongly favored in first-year ice compared to multi-year ice and, therefore, the dynamic balance between contaminant inventories and contaminant deposition to the surface ocean is being widely affected by the large-scale icescape transition taking place in the Arctic.
authors.affiliation: Centre for Earth Observation Science, University of Manitoba, Wallace Building, 125 Dysart Road, Winnipeg R3T 2N2, Canada. Electronic address: Monika.Pucko@umanitoba.ca.
authors.forename: Monika
authors.initials: M
authors.lastname: Pućko
authors.affiliation: Centre for Earth Observation Science, University of Manitoba, Wallace Building, 125 Dysart Road, Winnipeg R3T 2N2, Canada.
authors.forename: Gary A
authors.initials: GA
authors.lastname: Stern
authors.affiliation: Centre for Earth Observation Science, University of Manitoba, Wallace Building, 125 Dysart Road, Winnipeg R3T 2N2, Canada; Institute of Ocean Sciences, Department of Fisheries and Oceans, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada.
authors.forename: Robie W
authors.initials: RW
authors.lastname: Macdonald
authors.affiliation: Air Quality Processes Research Section, Environment Canada, 6248 Eighth Line, Egbert, Ontario L0L 1N0, Canada.
authors.forename: Liisa M
authors.initials: LM
authors.lastname: Jantunen
authors.affiliation: Chemistry Department, Umeå University, Umeå SE-901 87, Sweden.
authors.forename: Terry F
authors.initials: TF
authors.lastname: Bidleman
authors.affiliation: Air Quality Processes Research Section, Environment Canada, 6248 Eighth Line, Egbert, Ontario L0L 1N0, Canada; Department of Applied Environmental Science (ITM), Stockholm University, Stockholm SE-106 91, Sweden.
authors.forename: Fiona
authors.initials: F
authors.lastname: Wong
authors.affiliation: Centre for Earth Observation Science, University of Manitoba, Wallace Building, 125 Dysart Road, Winnipeg R3T 2N2, Canada.
authors.forename: David G
authors.initials: DG
authors.lastname: Barber
authors.affiliation: Centre for Earth Observation Science, University of Manitoba, Wallace Building, 125 Dysart Road, Winnipeg R3T 2N2, Canada; Department of Geological Sciences, University of Manitoba, Wallace Building, 125 Dysart Road, Winnipeg R3T 2N2, Canada; Greenland Climate Research Centre, Greenland Institute of Natural Resources, 3900 Nuuk, Greenland; Arctic Research Centre, Aarhus University, 8000 Aarhus, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Rysgaard
mesh_terms: D001110:Arctic Regions; D002170:Canada; D004784:Environmental Monitoring; D020387:Food Chain; D046448:Ice Cover / Q000737:chemistry*; D010575:Pesticides / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical
keywords: Arctic; Beaufort Sea; Current use pesticides; Melt ponds; Organic contaminants; Organochlorine pesticides