TY - JOUR

T1 - Atmospheric mercury over sea ice during the OASIS-2009 campaign

AU - Steffen, Alexandra

AU - Bottenheim, Jan

AU - Cole, Amanda

AU - Douglas, Thomas A.

AU - Ebinghaus, Ralf

AU - Friess, Udo

AU - Netcheva, Stoyka

AU - Nghiem, Son

AU - Sihler, Holger

AU - Staebler, Ralf

PY - 2013/7/24

Y1 - 2013/7/24

N2 - Measurements of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate mercury (PHg) were collected on the Beaufort Sea ice near Barrow, Alaska, in March 2009 as part of the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) and OASIS-Canada International Polar Year programmes. These results represent the first atmospheric mercury speciation measurements collected on the sea ice. Concentrations of PHg averaged 393.5 pg m -3 (range 47.1-900.1 pg m -3) and RGM concentrations averaged 30.1 pg m -3 (range 3.5-105.4 pg m -3) during the two-week-long study. The mean concentration of GEM during the study was 0.59 ng m -3 (range 0.01-1.51 ng m -3) and was depleted compared to annual Arctic ambient boundary layer concentrations. It is shown that when ozone (O 3) and bromine oxide (BrO) chemistry were active there is a positive linear relationship between GEM and O 3, a negative one between PHg and O 3, a positive correlation between RGM and BrO, and none between RGM and O 3. For the first time, GEM was measured simultaneously over the tundra and the sea ice. The results show a significant difference in the magnitude of the emission of GEM from the two locations, with significantly higher emission over the tundra. Elevated chloride levels in snow over sea ice are proposed to be the cause of lower GEM emissions over the sea ice because chloride has been shown to suppress photoreduction processes of RGM to GEM in snow. Since the snowpack on sea ice retains more mercury than inland snow, current models of the Arctic mercury cycle may greatly underestimate atmospheric deposition fluxes because they are based predominantly on land-based measurements. Land-based measurements of atmospheric mercury deposition may also underestimate the impacts of sea ice changes on the mercury cycle in the Arctic. The predicted changes in sea ice conditions and a more saline future snowpack in the Arctic could enhance retention of atmospherically deposited mercury and increase the amount of mercury entering the Arctic Ocean and coastal ecosystems.

AB - Measurements of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate mercury (PHg) were collected on the Beaufort Sea ice near Barrow, Alaska, in March 2009 as part of the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) and OASIS-Canada International Polar Year programmes. These results represent the first atmospheric mercury speciation measurements collected on the sea ice. Concentrations of PHg averaged 393.5 pg m -3 (range 47.1-900.1 pg m -3) and RGM concentrations averaged 30.1 pg m -3 (range 3.5-105.4 pg m -3) during the two-week-long study. The mean concentration of GEM during the study was 0.59 ng m -3 (range 0.01-1.51 ng m -3) and was depleted compared to annual Arctic ambient boundary layer concentrations. It is shown that when ozone (O 3) and bromine oxide (BrO) chemistry were active there is a positive linear relationship between GEM and O 3, a negative one between PHg and O 3, a positive correlation between RGM and BrO, and none between RGM and O 3. For the first time, GEM was measured simultaneously over the tundra and the sea ice. The results show a significant difference in the magnitude of the emission of GEM from the two locations, with significantly higher emission over the tundra. Elevated chloride levels in snow over sea ice are proposed to be the cause of lower GEM emissions over the sea ice because chloride has been shown to suppress photoreduction processes of RGM to GEM in snow. Since the snowpack on sea ice retains more mercury than inland snow, current models of the Arctic mercury cycle may greatly underestimate atmospheric deposition fluxes because they are based predominantly on land-based measurements. Land-based measurements of atmospheric mercury deposition may also underestimate the impacts of sea ice changes on the mercury cycle in the Arctic. The predicted changes in sea ice conditions and a more saline future snowpack in the Arctic could enhance retention of atmospherically deposited mercury and increase the amount of mercury entering the Arctic Ocean and coastal ecosystems.

KW - Chemistry

KW - arctic environment

KW - atmospheric chemistry

KW - atmospheric deposition

KW - atmospheric pollution

KW - bromine

KW - chloride

KW - concentration (composition)

KW - mercury (element)

KW - sea ice

KW - snowpack

UR - http://www.scopus.com/inward/record.url?scp=84880868912&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/e53abc13-b6c6-341d-8be4-a7a651206ae3/

U2 - 10.5194/acp-13-7007-2013

DO - 10.5194/acp-13-7007-2013

M3 - Journal articles

AN - SCOPUS:84880868912

VL - 13

SP - 7007

EP - 7021

JO - Atmospheric Chemistry and Physics

JF - Atmospheric Chemistry and Physics

SN - 1680-7316

IS - 14

ER -