Jane Kirk | University of Toronto (original) (raw)

Papers by Jane Kirk

Research paper thumbnail of The importance of open marine waters to the enrichment of total mercury and monomethylmercury in lichens in the Canadian High Arctic

Environmental science & technology, Jan 16, 2015

Caribou, which rely on lichens as forage, are the most important dietary source of neurotoxic mon... more Caribou, which rely on lichens as forage, are the most important dietary source of neurotoxic monomethylmercury (MMHg) to many of Canada's Arctic Aboriginal people. However, little is understood about the sources of MMHg to lichens in the High Arctic. We quantified MMHg, total mercury (THg) and other chemical parameters (e.g., marine and crustal elements, δ13C, δ15N, organic carbon, calcium carbonate) in lichen and soil samples collected along transects extending from the coast on Bathurst and Devon islands, Nunavut, to determine factors driving lichen MMHg and THg concentrations in the High Arctic. Lichen MMHg and THg concentrations ranged from 1.41 to 17.1 ng/g, and from 36.0 to 361 ng/g, respectively. Both were highly enriched over concentrations in underlying soils, indicating a predominately atmospheric source of Hg in lichens. However, MMHg and THg enrichment at coastal sites on Bathurst Island was far greater than on Devon Island. We suggest that this variability can be e...

Research paper thumbnail of Point-of-care hand hygiene: preventing infection behind the curtain

American journal of infection control, 2012

Best practices for hand hygiene provide indications for performance of hand hygiene at specific p... more Best practices for hand hygiene provide indications for performance of hand hygiene at specific points in time during patient care. For hand hygiene to prevent infections, hand hygiene resources must be readily available to health care workers whenever required. This article reviews practices and recommendations intended to facilitate hand hygiene behavior at the point of care (POC) within the health care setting. Key aspects of POC hand hygiene include the provision of alcohol-based hand rub products, integration of dispensing solutions within the patient zone, consideration of patient care workflow, and dispenser designs that optimize acceptance and usage.

Research paper thumbnail of Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic

The Science of the total environment, Jan 15, 2015

In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biom... more In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ(13)C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ(15)N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification ...

Research paper thumbnail of Mercury in the marine environment of the Canadian Arctic: Review of recent findings

The Science of the total environment, Jan 15, 2015

This review summarizes data and information which have been generated on mercury (Hg) in the mari... more This review summarizes data and information which have been generated on mercury (Hg) in the marine environment of the Canadian Arctic since the previous Canadian Arctic Contaminants Assessment Report (CACAR) was released in 2003. Much new information has been collected on Hg concentrations in marine water, snow and ice in the Canadian Arctic. The first measurements of methylation rates in Arctic seawater indicate that the water column is an important site for Hg methylation. Arctic marine waters were also found to be a substantial source of gaseous Hg to the atmosphere during the ice-free season. High Hg concentrations have been found in marine snow as a result of deposition following atmospheric mercury depletion events, although much of this Hg is photoreduced and re-emitted back to the atmosphere. The most extensive sampling of marine sediments in the Canadian Arctic was carried out in Hudson Bay where sediment total Hg (THg) concentrations were low compared with other marine re...

Research paper thumbnail of Methylation of inorganic mercury in polar marine waters

Nature Geoscience, 2011

Monomethylmercury is a neurotoxin that accumulates in marine organisms, with serious implications... more Monomethylmercury is a neurotoxin that accumulates in marine organisms, with serious implications for human health. The toxin is of particular concern to northern Inuit peoples, for example, whose traditional diets are composed primarily of marine mammals and fish. The ultimate source of monomethylmercury to marine organisms has remained uncertain, although various potential sources have been proposed, including export from coastal

Research paper thumbnail of Atmospheric mercury in the Canadian Arctic. Part I: A review of recent field measurements

Science of The Total Environment, 2014

This paper reviews progress made in the study of the transport, transformation, deposition and re... more This paper reviews progress made in the study of the transport, transformation, deposition and reemission of atmospheric Hg in the Canadian Arctic, focusing on field measurements. • Redox processes control the speciation of atmospheric Hg and bromine radicals are the primary oxidant of atmospheric Hg depletion in the spring • It is expected that a smaller fraction of deposited Hg will be reemitted from coastal snowpacks.

Research paper thumbnail of Atmospheric deposition of mercury and methylmercury to landscapes and waterbodies of the athabasca oil sands region

Atmospheric deposition of metals originating from a variety of sources, including bitumen upgradi... more Atmospheric deposition of metals originating from a variety of sources, including bitumen upgrading facilities and blowing dusts from landscape disturbances, is of concern in the Athabasca oil sands region of northern Alberta, Canada. Mercury (Hg) is of particular interest as methylmercury (MeHg), a neurotoxin which bioaccumulates through foodwebs, can reach levels in fish and wildlife that may pose health risks to human consumers. We used spring-time sampling of the accumulated snowpack at sites located varying distances from the major developments to estimate winter 2012 Hg loadings to a ∼20 000 km 2 area of the Athabasca oil sands region. Total Hg (THg; all forms of Hg in a sample) loads were predominantly particulate-bound (79 ± 12%) and increased with proximity to major developments, reaching up to 1000 ng m −2 . MeHg loads increased in a similar fashion, reaching up to 19 ng m −2 and suggesting that oil sands developments are a direct source of MeHg to local landscapes and water bodies. Deposition maps, created by interpolation of measured Hg loads using geostatistical software, demonstrated that deposition resembled a bullseye pattern on the landscape, with areas of maximum THg and MeHg loadings located primarily between the Muskeg and Steepbank rivers. Snowpack concentrations of THg and MeHg were significantly correlated (r = 0.45−0.88, p < 0.01) with numerous parameters, including total suspended solids (TSS), metals known to be emitted in high quantities from the upgraders (vanadium, nickel, and zinc), and crustal elements (aluminum, iron, and lanthanum), which were also elevated in this region. Our results suggest that at snowmelt, a complex mixture of chemicals enters aquatic ecosystems that could impact biological communities of the oil sands region.

Research paper thumbnail of Mercury in freshwater ecosystems of the Canadian Arctic: Recent advances on its cycling and fate

Science of The Total Environment, 2014

Research paper thumbnail of Methylated Mercury Species in Marine Waters of the Canadian High and Sub Arctic

Environmental Science & Technology, 2008

Distribution of total mercury (THg), gaseous elemental Hg(0) (GEM), monomethyl Hg (MMHg), and dim... more Distribution of total mercury (THg), gaseous elemental Hg(0) (GEM), monomethyl Hg (MMHg), and dimethyl Hg (DMHg) was examined in marine waters of the Canadian Arctic Archipelago (CAA), Hudson Strait, and Hudson Bay. Concentrations of THg were low throughout the water column in all regions sampled (mean ( standard deviation; 0.40 ( 0.47 ng L -1 ). Concentrations of MMHg were also generally low at the surface (23.8 ( 9.9 pg L -1 ); however at mid-and bottom depths, MMHg was present at concentrations sufficient to initiate bioaccumulation of MMHg through Arctic marine foodwebs (maximum 178 pg L -1 ; 70.3 ( 37.3 pg L -1 ). In addition, at midand bottom depths, the % of THg that was MMHg was high (maximum 66%; 28 ( 16%), suggesting that active methylation of inorganic Hg(II) occurs in deep Arctic marine waters. Interestingly, there was a constant, near 1:1, ratio between concentrations of MMHg and DMHg at all sites and depths, suggesting that methylated Hg species are in equilibrium with each other and/or are produced by similar processes throughout the water column. Our results also demonstrate that oceanographic processes, such as water regeneration and vertical mixing, affect Hg distribution in marine waters. Vertical mixing, for example, likely transported MMHg and DMHg upward from production zones at some sites, resulting in elevated concentrations of these species in surface waters (up to 68.0 pg L -1 ) where primary production and thus uptake of MMHg by biota is potentially highest. Finally, calculated instantaneous ocean-atmosphere fluxes of gaseous Hg species demonstrated that Arctic marine waters are a substantial source of DMHg and GEM to the atmosphere (27.3 ( 47.8 and 130 ( 138 ng m -2 day -1 , respectively) during the ice-free season.

Research paper thumbnail of Some Sources and Sinks of Monomethyl and Inorganic Mercury on Ellesmere Island in the Canadian High Arctic

Environmental Science & Technology, 2005

the increase in concentrations of Hg observed in certain Arctic marine mammals in recent decades.... more the increase in concentrations of Hg observed in certain Arctic marine mammals in recent decades. Concentrations of MMHg in warm and shallow freshwater ponds on Ellesmere Island were also quite high (up to 3.0 ng/L), leading us to conclude that there are very active regions of microbial Hg(II) methylation in freshwater systems during the short summer season in the High Arctic.

Research paper thumbnail of Rapid Reduction and Reemission of Mercury Deposited into Snowpacks during Atmospheric Mercury Depletion Events at Churchill, Manitoba, Canada

Environmental Science & Technology, 2006

Mercury (Hg) in some Arctic marine mammals has increased to levels that may be toxic to Northern ... more Mercury (Hg) in some Arctic marine mammals has increased to levels that may be toxic to Northern peoples consuming them as traditional food. It has been suggested that sunlight-induced atmospheric reactions called springtime atmospheric Hg depletion events (AMDEs) result in the loading of -150-300 tons of Hg to the Canadian Arctic archipelago each spring and that AMDEs are the ultimate source of Hg to Arctic foodwebs. AMDEs result from the oxidation of gaseous elemental Hg0 (GEM) in Arctic atmospheres to reactive gaseous Hg (RGM) and particulate Hg (pHg), both of which fall out of the atmosphere to snowpacks. We studied the springtime cycling of Hg between air and snowpacks near Churchill, Manitoba, for 2 years to determine the net input of Hg to Hudson Bay from AMDEs. In 2004, we monitored atmospheric concentrations of GEM, pHg, and RGM while simultaneously measuring concentrations of total Hg (THg) in surface snow collected over the sea ice on Hudson Bay. During numerous springtime AMDEs, concentrations of THg in surface snow increased, often to over 60 ng/L, demonstrating that AMDEs resulted in deposition of oxidized Hg (Hg(II)) to snowpacks. However, immediatelyfollowing AMDEs, average concentrations of THg in snow declined drastically from between 67.8+/-7.7 ng/L during AMDEs to only 4.25+/-1.85 ng/L four or more days following them. In 2003, we measured THg in surface snow collected daily over the sea ice and total gaseous Hg (TGM) concentrations in the interstitial airspaces of snowpacks. When concentrations of THg in the surface snow decreased, concentrations of TGM in interstitial airspaces of the snowpack increased sharply from between approximately 1.4-3.4 ng/m(3) to between approximately 20-150 ng/m(3), suggesting thatthere was a reduction of deposited Hg(II) to GEM, which then diffused out of snowpacks. At snowmelt in both 2003 and 2004, average concentrations of THg in meltwater collected over Hudson Bay were only 4.04+/-2.01 ng/L. Using concentrations of THg in meltwater and snow water equivalent, we estimated a net springtime loading of only 2.1+/-1.7 mg/ha of Hg to Hudson Bay from AMDEs, indicating that only a small portion of the Hg(II) deposited during AMDEs enters Hudosn Bay each spring.

Research paper thumbnail of A realistic approach towards hand hygiene for long-term care residents and health care personnel

American Journal of Infection Control, 2011

The Centers for Disease Control and Prevention and The World Health Organization's hand hygiene r... more The Centers for Disease Control and Prevention and The World Health Organization's hand hygiene recommendations focus on health care personnel in all health care settings. In the long-term care facility (LTCF) environment, where, for many residents, the LTCF is also their home, the recommendations may not be applicable to commonly encountered LTCF situations. The recommendations also do not address the importance of resident hand hygiene program to promote health and prevent infection.

Research paper thumbnail of Effectiveness of a comprehensive hand hygiene program for reduction of infection rates in a long-term care facility

American Journal of Infection Control, 2013

Research paper thumbnail of Methylated Mercury Species in Canadian High Arctic Marine Surface Waters and Snowpacks

Environmental Science & Technology, 2007

We sampled seawater and snowpacks in the Canadian high Arctic for methylated species of mercury (... more We sampled seawater and snowpacks in the Canadian high Arctic for methylated species of mercury (Hg). We discovered that, although seawater sampled under the sea ice had very low concentrations of total Hg (THg, all forms of Hg in a sample; on average 0.14-0.24 ng L -1 ), 30-45% of the THg was in the monomethyl Hg (MMHg) form (on average 0.057-0.095 ng L -1 ), making seawater itself a direct source of MMHg for biomagnification through marine food webs. Seawater under the ice also contained high concentrations of gaseous elemental Hg (GEM; 129 ( 36 pg L -1 ), suggesting that open water regions such as polynyas and ice leads were a net source of ∼130 ( 30 ng Hg m -2 day -1 to the atmosphere. We also found 11.1 ( 4.1 pg L -1 of dimethyl Hg (DMHg) in seawater and calculated that there could be a significant flux of DMHg to the atmosphere from open water regions. This flux could then result in MMHg deposition into nearby snowpacks via oxidation of DMHg to MMHg in the atmosphere. In fact, we found high concentrations of MMHg in a few snowpacks near regions of open water. Interestingly, we discovered a significant log-log relationship between Clconcentrations in snowpacks and concentrations of THg. We hypothesize that as Clconcentrations in snowpacks increase, inorganic Hg(II) occurs principally as less reducible chloro complexes and, hence, remains in an oxidized state. As a result, snowpacks that receive both marine aerosol deposition of Cland deposition of Hg(II) via springtime atmospheric Hg depletion events, for example, may contain significant loads of Hg(II). Overall, though, the median wet/dry loads of Hg in the snowpacks we sampled in the high Arctic (5.2 mg THg ha -1 and 0.03 mg MMHg ha -1 ) were far below wet-only annual THg loadings throughout southern Canada and most of the U.S. (22-200 mg ha -1 ). Therefore, most Arctic snowpacks contribute relatively little to marine pools of both Hg(II) and MMHg at snowmelt.

Research paper thumbnail of The importance of open marine waters to the enrichment of total mercury and monomethylmercury in lichens in the Canadian High Arctic

Environmental science & technology, Jan 16, 2015

Caribou, which rely on lichens as forage, are the most important dietary source of neurotoxic mon... more Caribou, which rely on lichens as forage, are the most important dietary source of neurotoxic monomethylmercury (MMHg) to many of Canada's Arctic Aboriginal people. However, little is understood about the sources of MMHg to lichens in the High Arctic. We quantified MMHg, total mercury (THg) and other chemical parameters (e.g., marine and crustal elements, δ13C, δ15N, organic carbon, calcium carbonate) in lichen and soil samples collected along transects extending from the coast on Bathurst and Devon islands, Nunavut, to determine factors driving lichen MMHg and THg concentrations in the High Arctic. Lichen MMHg and THg concentrations ranged from 1.41 to 17.1 ng/g, and from 36.0 to 361 ng/g, respectively. Both were highly enriched over concentrations in underlying soils, indicating a predominately atmospheric source of Hg in lichens. However, MMHg and THg enrichment at coastal sites on Bathurst Island was far greater than on Devon Island. We suggest that this variability can be e...

Research paper thumbnail of Point-of-care hand hygiene: preventing infection behind the curtain

American journal of infection control, 2012

Best practices for hand hygiene provide indications for performance of hand hygiene at specific p... more Best practices for hand hygiene provide indications for performance of hand hygiene at specific points in time during patient care. For hand hygiene to prevent infections, hand hygiene resources must be readily available to health care workers whenever required. This article reviews practices and recommendations intended to facilitate hand hygiene behavior at the point of care (POC) within the health care setting. Key aspects of POC hand hygiene include the provision of alcohol-based hand rub products, integration of dispensing solutions within the patient zone, consideration of patient care workflow, and dispenser designs that optimize acceptance and usage.

Research paper thumbnail of Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic

The Science of the total environment, Jan 15, 2015

In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biom... more In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ(13)C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ(15)N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification ...

Research paper thumbnail of Mercury in the marine environment of the Canadian Arctic: Review of recent findings

The Science of the total environment, Jan 15, 2015

This review summarizes data and information which have been generated on mercury (Hg) in the mari... more This review summarizes data and information which have been generated on mercury (Hg) in the marine environment of the Canadian Arctic since the previous Canadian Arctic Contaminants Assessment Report (CACAR) was released in 2003. Much new information has been collected on Hg concentrations in marine water, snow and ice in the Canadian Arctic. The first measurements of methylation rates in Arctic seawater indicate that the water column is an important site for Hg methylation. Arctic marine waters were also found to be a substantial source of gaseous Hg to the atmosphere during the ice-free season. High Hg concentrations have been found in marine snow as a result of deposition following atmospheric mercury depletion events, although much of this Hg is photoreduced and re-emitted back to the atmosphere. The most extensive sampling of marine sediments in the Canadian Arctic was carried out in Hudson Bay where sediment total Hg (THg) concentrations were low compared with other marine re...

Research paper thumbnail of Methylation of inorganic mercury in polar marine waters

Nature Geoscience, 2011

Monomethylmercury is a neurotoxin that accumulates in marine organisms, with serious implications... more Monomethylmercury is a neurotoxin that accumulates in marine organisms, with serious implications for human health. The toxin is of particular concern to northern Inuit peoples, for example, whose traditional diets are composed primarily of marine mammals and fish. The ultimate source of monomethylmercury to marine organisms has remained uncertain, although various potential sources have been proposed, including export from coastal

Research paper thumbnail of Atmospheric mercury in the Canadian Arctic. Part I: A review of recent field measurements

Science of The Total Environment, 2014

This paper reviews progress made in the study of the transport, transformation, deposition and re... more This paper reviews progress made in the study of the transport, transformation, deposition and reemission of atmospheric Hg in the Canadian Arctic, focusing on field measurements. • Redox processes control the speciation of atmospheric Hg and bromine radicals are the primary oxidant of atmospheric Hg depletion in the spring • It is expected that a smaller fraction of deposited Hg will be reemitted from coastal snowpacks.

Research paper thumbnail of Atmospheric deposition of mercury and methylmercury to landscapes and waterbodies of the athabasca oil sands region

Atmospheric deposition of metals originating from a variety of sources, including bitumen upgradi... more Atmospheric deposition of metals originating from a variety of sources, including bitumen upgrading facilities and blowing dusts from landscape disturbances, is of concern in the Athabasca oil sands region of northern Alberta, Canada. Mercury (Hg) is of particular interest as methylmercury (MeHg), a neurotoxin which bioaccumulates through foodwebs, can reach levels in fish and wildlife that may pose health risks to human consumers. We used spring-time sampling of the accumulated snowpack at sites located varying distances from the major developments to estimate winter 2012 Hg loadings to a ∼20 000 km 2 area of the Athabasca oil sands region. Total Hg (THg; all forms of Hg in a sample) loads were predominantly particulate-bound (79 ± 12%) and increased with proximity to major developments, reaching up to 1000 ng m −2 . MeHg loads increased in a similar fashion, reaching up to 19 ng m −2 and suggesting that oil sands developments are a direct source of MeHg to local landscapes and water bodies. Deposition maps, created by interpolation of measured Hg loads using geostatistical software, demonstrated that deposition resembled a bullseye pattern on the landscape, with areas of maximum THg and MeHg loadings located primarily between the Muskeg and Steepbank rivers. Snowpack concentrations of THg and MeHg were significantly correlated (r = 0.45−0.88, p < 0.01) with numerous parameters, including total suspended solids (TSS), metals known to be emitted in high quantities from the upgraders (vanadium, nickel, and zinc), and crustal elements (aluminum, iron, and lanthanum), which were also elevated in this region. Our results suggest that at snowmelt, a complex mixture of chemicals enters aquatic ecosystems that could impact biological communities of the oil sands region.

Research paper thumbnail of Mercury in freshwater ecosystems of the Canadian Arctic: Recent advances on its cycling and fate

Science of The Total Environment, 2014

Research paper thumbnail of Methylated Mercury Species in Marine Waters of the Canadian High and Sub Arctic

Environmental Science & Technology, 2008

Distribution of total mercury (THg), gaseous elemental Hg(0) (GEM), monomethyl Hg (MMHg), and dim... more Distribution of total mercury (THg), gaseous elemental Hg(0) (GEM), monomethyl Hg (MMHg), and dimethyl Hg (DMHg) was examined in marine waters of the Canadian Arctic Archipelago (CAA), Hudson Strait, and Hudson Bay. Concentrations of THg were low throughout the water column in all regions sampled (mean ( standard deviation; 0.40 ( 0.47 ng L -1 ). Concentrations of MMHg were also generally low at the surface (23.8 ( 9.9 pg L -1 ); however at mid-and bottom depths, MMHg was present at concentrations sufficient to initiate bioaccumulation of MMHg through Arctic marine foodwebs (maximum 178 pg L -1 ; 70.3 ( 37.3 pg L -1 ). In addition, at midand bottom depths, the % of THg that was MMHg was high (maximum 66%; 28 ( 16%), suggesting that active methylation of inorganic Hg(II) occurs in deep Arctic marine waters. Interestingly, there was a constant, near 1:1, ratio between concentrations of MMHg and DMHg at all sites and depths, suggesting that methylated Hg species are in equilibrium with each other and/or are produced by similar processes throughout the water column. Our results also demonstrate that oceanographic processes, such as water regeneration and vertical mixing, affect Hg distribution in marine waters. Vertical mixing, for example, likely transported MMHg and DMHg upward from production zones at some sites, resulting in elevated concentrations of these species in surface waters (up to 68.0 pg L -1 ) where primary production and thus uptake of MMHg by biota is potentially highest. Finally, calculated instantaneous ocean-atmosphere fluxes of gaseous Hg species demonstrated that Arctic marine waters are a substantial source of DMHg and GEM to the atmosphere (27.3 ( 47.8 and 130 ( 138 ng m -2 day -1 , respectively) during the ice-free season.

Research paper thumbnail of Some Sources and Sinks of Monomethyl and Inorganic Mercury on Ellesmere Island in the Canadian High Arctic

Environmental Science & Technology, 2005

the increase in concentrations of Hg observed in certain Arctic marine mammals in recent decades.... more the increase in concentrations of Hg observed in certain Arctic marine mammals in recent decades. Concentrations of MMHg in warm and shallow freshwater ponds on Ellesmere Island were also quite high (up to 3.0 ng/L), leading us to conclude that there are very active regions of microbial Hg(II) methylation in freshwater systems during the short summer season in the High Arctic.

Research paper thumbnail of Rapid Reduction and Reemission of Mercury Deposited into Snowpacks during Atmospheric Mercury Depletion Events at Churchill, Manitoba, Canada

Environmental Science & Technology, 2006

Mercury (Hg) in some Arctic marine mammals has increased to levels that may be toxic to Northern ... more Mercury (Hg) in some Arctic marine mammals has increased to levels that may be toxic to Northern peoples consuming them as traditional food. It has been suggested that sunlight-induced atmospheric reactions called springtime atmospheric Hg depletion events (AMDEs) result in the loading of -150-300 tons of Hg to the Canadian Arctic archipelago each spring and that AMDEs are the ultimate source of Hg to Arctic foodwebs. AMDEs result from the oxidation of gaseous elemental Hg0 (GEM) in Arctic atmospheres to reactive gaseous Hg (RGM) and particulate Hg (pHg), both of which fall out of the atmosphere to snowpacks. We studied the springtime cycling of Hg between air and snowpacks near Churchill, Manitoba, for 2 years to determine the net input of Hg to Hudson Bay from AMDEs. In 2004, we monitored atmospheric concentrations of GEM, pHg, and RGM while simultaneously measuring concentrations of total Hg (THg) in surface snow collected over the sea ice on Hudson Bay. During numerous springtime AMDEs, concentrations of THg in surface snow increased, often to over 60 ng/L, demonstrating that AMDEs resulted in deposition of oxidized Hg (Hg(II)) to snowpacks. However, immediatelyfollowing AMDEs, average concentrations of THg in snow declined drastically from between 67.8+/-7.7 ng/L during AMDEs to only 4.25+/-1.85 ng/L four or more days following them. In 2003, we measured THg in surface snow collected daily over the sea ice and total gaseous Hg (TGM) concentrations in the interstitial airspaces of snowpacks. When concentrations of THg in the surface snow decreased, concentrations of TGM in interstitial airspaces of the snowpack increased sharply from between approximately 1.4-3.4 ng/m(3) to between approximately 20-150 ng/m(3), suggesting thatthere was a reduction of deposited Hg(II) to GEM, which then diffused out of snowpacks. At snowmelt in both 2003 and 2004, average concentrations of THg in meltwater collected over Hudson Bay were only 4.04+/-2.01 ng/L. Using concentrations of THg in meltwater and snow water equivalent, we estimated a net springtime loading of only 2.1+/-1.7 mg/ha of Hg to Hudson Bay from AMDEs, indicating that only a small portion of the Hg(II) deposited during AMDEs enters Hudosn Bay each spring.

Research paper thumbnail of A realistic approach towards hand hygiene for long-term care residents and health care personnel

American Journal of Infection Control, 2011

The Centers for Disease Control and Prevention and The World Health Organization's hand hygiene r... more The Centers for Disease Control and Prevention and The World Health Organization's hand hygiene recommendations focus on health care personnel in all health care settings. In the long-term care facility (LTCF) environment, where, for many residents, the LTCF is also their home, the recommendations may not be applicable to commonly encountered LTCF situations. The recommendations also do not address the importance of resident hand hygiene program to promote health and prevent infection.

Research paper thumbnail of Effectiveness of a comprehensive hand hygiene program for reduction of infection rates in a long-term care facility

American Journal of Infection Control, 2013

Research paper thumbnail of Methylated Mercury Species in Canadian High Arctic Marine Surface Waters and Snowpacks

Environmental Science & Technology, 2007

We sampled seawater and snowpacks in the Canadian high Arctic for methylated species of mercury (... more We sampled seawater and snowpacks in the Canadian high Arctic for methylated species of mercury (Hg). We discovered that, although seawater sampled under the sea ice had very low concentrations of total Hg (THg, all forms of Hg in a sample; on average 0.14-0.24 ng L -1 ), 30-45% of the THg was in the monomethyl Hg (MMHg) form (on average 0.057-0.095 ng L -1 ), making seawater itself a direct source of MMHg for biomagnification through marine food webs. Seawater under the ice also contained high concentrations of gaseous elemental Hg (GEM; 129 ( 36 pg L -1 ), suggesting that open water regions such as polynyas and ice leads were a net source of ∼130 ( 30 ng Hg m -2 day -1 to the atmosphere. We also found 11.1 ( 4.1 pg L -1 of dimethyl Hg (DMHg) in seawater and calculated that there could be a significant flux of DMHg to the atmosphere from open water regions. This flux could then result in MMHg deposition into nearby snowpacks via oxidation of DMHg to MMHg in the atmosphere. In fact, we found high concentrations of MMHg in a few snowpacks near regions of open water. Interestingly, we discovered a significant log-log relationship between Clconcentrations in snowpacks and concentrations of THg. We hypothesize that as Clconcentrations in snowpacks increase, inorganic Hg(II) occurs principally as less reducible chloro complexes and, hence, remains in an oxidized state. As a result, snowpacks that receive both marine aerosol deposition of Cland deposition of Hg(II) via springtime atmospheric Hg depletion events, for example, may contain significant loads of Hg(II). Overall, though, the median wet/dry loads of Hg in the snowpacks we sampled in the high Arctic (5.2 mg THg ha -1 and 0.03 mg MMHg ha -1 ) were far below wet-only annual THg loadings throughout southern Canada and most of the U.S. (22-200 mg ha -1 ). Therefore, most Arctic snowpacks contribute relatively little to marine pools of both Hg(II) and MMHg at snowmelt.