Michelle Nerentorp - Academia.edu (original) (raw)
Papers by Michelle Nerentorp
Water, Air, & Soil Pollution
Mercury (Hg) in the form of highly toxic methyl mercury (MeHg) accumulates in aquatic food webs t... more Mercury (Hg) in the form of highly toxic methyl mercury (MeHg) accumulates in aquatic food webs to an extent where it may threaten fish health in many freshwaters. Selenium (Se) mitigates the toxicity of accumulated Hg by forming strong bonds with it, a drawback being diversion of Se from biosynthetic pathways of essential selenoenzymes. We measured Se and Hg in muscle tissue of Eurasian perch (Perca fluviatilis) and vendace (Coregonus albula). For the perch, Se and Hg correlated positively. For the vendace, a positive relationship was seen when the effect of fish size was accounted for. All fish displayed surplus Se (mol Se – mol Hg > 0). For both fish species, the Se molar surplus ((nmol Se – nmol Hg)/g ww) decreased with fish weight. It was higher in the perch than in the vendace and showed the least variation among the small perch (4–34 g). For the large perch (79–434 g), the Se molar surplus decreased with increasing Hg below 0.5 µg Hg but then increased with further Hg incr...
Metoden att använda mattbildande mossor som bioindikatorer är ett effektivt sätt att övervaka luf... more Metoden att använda mattbildande mossor som bioindikatorer är ett effektivt sätt att övervaka luftmiljön, både vad gäller metaller och kväve. Som en del av den nationella miljöövervakningen har Naturvårdsverket, vart femte år, sedan 1975 finansierat undersökningar av metallhalter i mossprover insamlade i bakgrundsmiljö i hela landet. Den långa mätserien är en styrka och visar på trender för belastningen av metaller över tid. Nedfallet av både metaller och kväve över Sverige uppvisar en tydlig gradient från söder till norr, med högst nedfall i sydväst som sedan avtar norröver, vilket återspeglar intransporten av utsläpp från kontinenten. På vissa platser bryts dock mönstret med förhöjda metallhalter som går att koppla till lokala och regionala utsläppskällor. Exempel på detta är förhöjda halter av koppar och krom utmed norrlandskusten samt förhöjda halter av järn i malmfälten i Norrbottens län. Även längre söderut i Sverige kan man se förhöjda halter, till exempel av kobolt i Mellans...
Sedan mitten av 1980-talet har IVL Svenska Miljöinstitutet AB utfört undersökningar av deposition... more Sedan mitten av 1980-talet har IVL Svenska Miljöinstitutet AB utfört undersökningar av deposition och avrinning av bland annat svavel, kväve samt metaller i ett granskogsområde vid Holmsvattnet, ca 15 km SSV om Rönnskärsverken. I denna rapport jämförs resultaten från mätningarna 2017/18 vid Holmsvattnet med tidigare mätningar i området samt med mätningar vid andra närliggande stationer inom Krondroppsnätet. Syftet med mätningarna är att kvantifiera det atmosfäriska nedfallet samt beskriva förändringar i kemin i det avrinnande vattnet
Organophosphate esters (OPEs) are widely used as flame retardants, plasticizers, anti-foaming age... more Organophosphate esters (OPEs) are widely used as flame retardants, plasticizers, anti-foaming agents and as additives in lubricants and hydraulic fluids. They can be found for example in air, deposition and snow, both near and far from emission sources. In this study, OPEs were analyzed in air samples from two stations in Sweden (Råö, Norunda) and one in Finland (Pallas) for one year (2018). For TCEP and EHDPP, a geographical variation could be distinguished with highest concentrations in the north and lowest in the south. Seasonal variations were observed for TCPP and TCEP at Råö, where higher levels were measured during the summer. TEP, which is reported to be produced in large quantities, was not detected in high concentrations in air at any of the stations. Results in this study were comparable with literature data. Based on the results of this study, we conclude that the existing network of measurement stations, monitoring frequency, sampling and analysis procedures used within the national environmental monitoring (EMEP), can be used to measure OPEs in air as well.Organofosfatestrar (OPEs) har i denna studie hittats i atmosfären på två stationer i södra Sverige och en i norra Finland. Vissa ämnen visade sig dominera i luft och geografiska- och säsongsvariationer kunde urskiljas. Uppmätta nivåer var jämförbara med resultat funna i litteraturen. Baserat på resultaten från denna studie drar vi slutsatsen att de befintliga procedurerna för att mäta organiska föroreningar i luft inom EMEP, även kan användas för att mäta OPEs i luft
Naturvårdsverket ansvarar för den nationella övervakningen av luftens och nederbördens kvalitet i... more Naturvårdsverket ansvarar för den nationella övervakningen av luftens och nederbördens kvalitet i bakgrundsmiljö. I rapporten redovisas resultat från verksamheten inom Programområde Luft avseende mätningar till och med 2017 och regionala modellberäkningar till och med 2016, respektive 2017 för marknära ozon
cumulation rates of Hg in the diverse set of tree species in the Gothenburg area were related to ... more cumulation rates of Hg in the diverse set of tree species in the Gothenburg area were related to the specific leaf area (SLA). Leaf-area-based [Hg] was negatively and non-linearly correlated with SLA, while mass-based [Hg] had a somewhat weaker positive relationship with SLA. An elaborated understanding of the relationship behind [Hg] and SLA may have the potential to support large-scale modelling of Hg uptake by vegetation and Hg circulation.
Mercury is a globally distributed contaminant that exists in the atmosphere in its elemental form... more Mercury is a globally distributed contaminant that exists in the atmosphere in its elemental form as a stable monoatomic gas. Having a residence time of around one year in air allows it to be transported far from emission sources and end up in polar ecosystems. Gaseous elemental mercury (GEM) can in air be oxidized by photo-induced processes which produce water soluble oxidized forms of mercury which are more easily deposited. Deposited mercury can in the environment be transformed to organic and bio-accumulating compounds which are neurotoxic, making mercury a global concern. Deposited oxidized mercury into the sea can be reduced back to the elemental form (GEM) and be re-emitted to air. This re-evasion constitutes of around 30% of the total emissions of mercury to air and originates from both natural and anthropogenic sources. Models have estimated that the yearly mercury emission from global sea surfaces is between 2000 and 3000 tonnes. The mercury flux rate at the interphase bet...
Mercury is a globally distributed contaminant that exists in the atmosphere as a stable monoatomi... more Mercury is a globally distributed contaminant that exists in the atmosphere as a stable monoatomic gas. Having almost a year’s residence time in the air allows it to reach remote polar regions. Deposited airborne mercury can be transformed in the environment to the organic and bio-accumulating compound methyl mercury. Methyl mercury is neurotoxic and affects land living and marine animals all over the world. Springtime atmospheric mercury depletion events, first discovered in 1995 in the Arctic, occur when the return of sunlight induces the formation of halogen radicals that oxidize tropospheric elemental mercury. These spring events occurring in polar regions increase the net deposition of mercury into polar marine ecosystems. Some studies have been performed on the fate of mercury deposited onto snowpack but the transportation and transformation of mercury through and within snow and sea ice are still not fully understood. This thesis is based on data from three oceanographic expe...
Global Biogeochemical Cycles, 2021
On a global scale 3,800 Mg a −1 mercury (Hg) enter the ocean through atmospheric deposition and 3... more On a global scale 3,800 Mg a −1 mercury (Hg) enter the ocean through atmospheric deposition and 300 Mg a −1 through riverine input (UNEP, 2019). Atmospheric wet deposition of divalent mercury (Hg II) constitutes the main deposition pathway of total atmospheric Hg to the surface ocean (Zhang et al., 2014), while dry deposition of Hg II constitutes a minor fraction in the mid-latitude marine boundary layer (Holmes et al., 2009). Reduction of Hg II to gaseous elemental mercury (Hg 0) in the surface ocean leads to re-emission of Hg 0 from the ocean of approximately 2,900 Mg a −1 (Horowitz et al., 2017). However, these current air-sea Hg exchange estimates are associated with high uncertainty and a better constraint on the Hg 0 flux is crucial for two reasons: first, ocean emissions reduce the reservoir of Hg II available for methylation in the water column and subsequent bioaccumulation in marine biota (Lavoie et al., 2013). Second, ocean emissions increase the amount of Hg actively cycling between the atmosphere, marine and terrestrial ecosystems (Amos et al., 2013; Selin, 2009). Air-sea exchange of Hg 0 is a diffusion process driven by the concentration gradient between Hg 0 in the atmosphere (Hg 0 air) and dissolved gaseous elemental Hg in seawater (DGM, hereinafter referred to as Hg 0 aq). The two key factors that control the Hg 0 air-sea exchange are (a) the saturation of Hg 0 in surface water relative to equilibrium conditions expressed by Henry's law constant for Hg 0 and (b) the gas transfer velocity (k) (Qureshi et al., 2011). The Hg 0 flux is typically estimated based on a thin film gas exchange model (Liss & Merlivat, 1986; Wanninkhof, 1992) that uses in situ measurements of Hg 0 air and Hg 0 aq together with a wind speed dependent parameterization of k that was developed based on field experiments with volatile
Atmospheric Measurement Techniques, 2021
Passive air samplers (PASs), which provide time-averaged concentrations of gaseous mercury over t... more Passive air samplers (PASs), which provide time-averaged concentrations of gaseous mercury over the timescale of weeks to months, are promising for filling a gap in the monitoring of atmospheric mercury worldwide. Their usefulness will depend on their ease of use and robustness under field conditions, their availability and affordability, and most notably, their ability to provide results of acceptable precision and accuracy. Here we describe a comparative evaluation of three PASs with respect to their ability to precisely and accurately record atmospheric background mercury concentrations at sites in both southern Italy and southern Ontario, Canada. The study includes the CNR-PAS with gold nanoparticles as a sorbent, developed by the Italian National Research Council, the IVL-PAS using an activated carbon-coated disk, developed by the Swedish Environmental Research Institute, and the MerPAS ® using a sulfurimpregnated activated carbon sorbent, developed at the University of Toronto and commercialized by Tekran. Detection limits are deduced from the variability in the amount of mercury quantified in more than 20 field blank samples for each PAS. Analytical and sampling precision is quantified through 22 triplicate deployments for each PAS, ranging in duration from 2 to 12 weeks. Accuracy and bias are assessed through comparison with gaseous elemental mercury concentrations recorded by Tekran 2537 automated mercury analyzers operating alongside the PASs at both locations. The performance of the PASs was significantly better in Italy, with all of them providing concentrations that are not significantly different from the average concentrations of the Tekran 2537 instruments. In Canada, where weather conditions were much harsher and more variable during the February through April deployment period, there are differences amongst the PASs. At both sites, the MerPAS ® is currently the most sensitive, precise, and accurate among the three PASs. A key reason for this is the larger size and the radial configuration of the MerPAS ® , which results in lower blank levels relative to the sequestered amounts of mercury when compared to the other two PASs, which rely on axial diffusion geometries. Since blank correction becomes relatively smaller with longer deployments, performance tends to be closer amongst the PASs during deployments of 8 and 12 weeks.
E3S Web of Conferences, 2013
Mercury speciation measurements were performed at the Arctic measurement site, Pallas Matorova, i... more Mercury speciation measurements were performed at the Arctic measurement site, Pallas Matorova, in northern Finland during the period 12-04-02 to 12-04-26. For the first time Hg speciation measurements with high sensitivity and temporal resolution were performed at this site. The measurement allowed simultaneous determination of TGM, GEM, GOM and particulate bound mercury. Evidence for long range transport of air masses depleted in mercury is provided as well as a study of possible mercury sources determining the temporal variations in airborne mercury species at the site.
Marine Chemistry, 2017
Despite the distance from large anthropogenic emission sources, toxic mercury is transported via ... more Despite the distance from large anthropogenic emission sources, toxic mercury is transported via the atmosphere and oceans to the Southern Ocean. Seawater samples were collected at selected stations and were analysed for total mercury (HgT) (8 stations), dissolved gaseous mercury (DGM) (62 stations) and methylmercury (12 stations) during winter (Weddell Sea), spring (Weddell Sea) and summer (Amundsen and Ross Seas) in the Southern Ocean. The HgT distribution in water columns was found to not vary significantly with depth. In the Weddell Sea the average column concentration was higher in spring (2.6 ± 1.3 pM, 2 stations) than in winter (2.0 ± 1.0 pM, 6 stations). We hypothesize that the seasonal HgT increase is due to atmospheric deposition of particulate Hg(II) formed during atmospheric mercury depletion events (AMDEs), as well as the addition of inorganic mercury species from melting sea ice and snow. Furthermore, HgT concentrations found in this study were significantly higher than previously measured in the Southern Ocean (Cossa et al., 2011), which was hypothesized to be due to seasonal variations in atmospheric deposition. The average water column DGM concentration in the Weddell Sea was 454 ± 254 fM in winter and 384 ± 239 fM in spring. The lowest average DGM concentration was found in summer in the Amundsen and Ross Seas (299 ± 137 fM). The highest observed concentration in winter was hypothesized to be caused by the larger sea ice coverage, which is known to reduce the evasion of Hg(0) from the sea surface. The average monomethylmercury (MMHg) concentration in the Weddell Sea was 60 ± 30 fM in winter (6 stations) and 95 ± 85 fM in spring (2 stations), showing no significant seasonal difference. In the Amundsen and Ross Seas the summer average concentration of MeHg (MMHg and dimethylmercury ;DMHg) was 135 ± 189 fM (4 stations). The highest MeHg concentration was found in modified circumpolar deep water, which is known to have high primary production.
E3S Web of Conferences, 2013
Dissolved gaseous mercury (DGM) concentrations and gaseous elemental mercury (GEM) concentrations... more Dissolved gaseous mercury (DGM) concentrations and gaseous elemental mercury (GEM) concentrations were measured during an oceanographic campaign in the Mediterranean Sea. The DGM concentrations were measured using two different methods, a manual-and an automated method. The manual method was used to obtain DGM depth profiles at several stations throughout the campaign. The automated device measured DGM concentrations continuously at a depth of 4 m. Gaseous elemental mercury (GEM) concentrations in air were measured continuously at the bridge deck. The objectives were to achieve DGM depth profiles, compare the manual-and automated DGM measurement methods, to calculate the supersaturation grades of the sea and the evasional fluxes from the sea surface. Depth profiles of the four measured stations show no diurnal variations. The manual-and the automated method show good compliance. Supersaturation grades are high due to high DGM values and low GEM concentrations. Fluxes of Hg from the sea surface are more dependent on the wind speed than on the supersaturation grade according to the flux models used.
Environmental Science & Technology, 2016
Limited studies have been conducted on mercury concentrations in the polar cryosphere and the fac... more Limited studies have been conducted on mercury concentrations in the polar cryosphere and the factors affecting the distribution of mercury within sea ice and snow are poorly understood. Here we present the first comprehensive seasonal study of elemental and total mercury concentrations in the Antarctic sea ice environment covering data from measurements in air, sea ice, sea water, snow, frost flowers and brine. The average concentration of total mercury in sea ice decreased from winter (9.7 ng L-1) to spring (4.7 ng L-1) while the average elemental mercury concentration increased from winter (0.07 ng L-1) to summer (0.105 ng L-1). The opposite trends suggest potential photo- or dark oxidation/reduction processes within the ice and an eventual loss of mercury via brine drainage or gas evasion of elemental mercury. Our results indicate a seasonal variation of mercury species in the polar sea ice environment probably due to varying factors such as solar radiation, temperature, brine volume and atmospheric deposition. This study shows that the sea ice environment is a significant interphase between the polar ocean and the atmosphere and should be accounted for when studying how climate change may affect the mercury cycle in polar regions.
We would like to thank our supervisor Rickard Arvidsson who has guided and supported us throughou... more We would like to thank our supervisor Rickard Arvidsson who has guided and supported us throughout our study. Our examiner Sverker Molander, who introduced us to the project and helped it evolve, deserves gratitude. Thank you Germund Wahlbeck, our field supervisor for introducing us to reality. A very special thank you to the Managing director of Chikweti, Åsa Tham, for her great hospitality. It was a pleasure to meet all senior staff of Chikweti, thank you all for an unforgettable time. We want to thank Johan Fredriksson and Josefin Åhman, for putting up with us.
Atmospheric Chemistry and Physics Discussions, 2016
Long-term monitoring data of ambient mercury (Hg) on a global scale to assess its emission, trans... more Long-term monitoring data of ambient mercury (Hg) on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg pollution on the environment. The Global Mer-1
Journal of Cleaner Production, 2013
Biofuels are advanced to replace fossil fuels in order to reduce emissions of greenhouse gases an... more Biofuels are advanced to replace fossil fuels in order to reduce emissions of greenhouse gases and other environmental impacts. Yet freshwater scarcity is another growing concern and increased production of biofuels may increase this problem. In order to assess whether biofuels truly have a higher water use than do fossil fuels, a life cycle assessment study of a low input jatropha plantation in northern Mozambique was conducted. In addition to different water use indicators, the fossil energy use and global warming potential were assessed for 1 MJ of jatropha oil. The analysis compares results for jatropha oil with fossil diesel, generally showing lower global warming potential and fossil energy use for jatropha oil. However, aspects related to land use may alter the global warming potential of jatropha oil. Regarding water use, the choice of the water use indicator strongly influences the results. Specifically the indication of (1) so-called green water flows, (2) formation of so-called blue water and (3) water scarcity show crucial influences on the comparison. Depending on these specific features, jatropha oil may have higher or lower water use than fossil diesel. A number of uncertainties, such as the jatropha oil yield, are also shown to have a considerable impact on the results.
Atmospheric Chemistry and Physics Discussions, 2016
Within the EU project, Global Mercury Observation System (GMOS) airborne mercury have been monito... more Within the EU project, Global Mercury Observation System (GMOS) airborne mercury have been monitored at the background Råö measurement site on the west coast of Sweden from mid May 2012 tot the beginning of July 2013 and from the beginning of February 2014 to the end of May 2015. The mercury concentrations measured at the Råö site was found to be low in comparison to other comparable European measurement sites. A back trajectory analysis to study the origin of air masses reaching the Råö site was performed. Due to the remotely location of the Råö measurement station it receives background air most of the time. However, elevated concentrations with air masses coming from especially the south east are noticeable. Evidence for formation of gaseous oxidised mercury (GOM) in background free tropospheric air is presented.
Water, Air, & Soil Pollution
Mercury (Hg) in the form of highly toxic methyl mercury (MeHg) accumulates in aquatic food webs t... more Mercury (Hg) in the form of highly toxic methyl mercury (MeHg) accumulates in aquatic food webs to an extent where it may threaten fish health in many freshwaters. Selenium (Se) mitigates the toxicity of accumulated Hg by forming strong bonds with it, a drawback being diversion of Se from biosynthetic pathways of essential selenoenzymes. We measured Se and Hg in muscle tissue of Eurasian perch (Perca fluviatilis) and vendace (Coregonus albula). For the perch, Se and Hg correlated positively. For the vendace, a positive relationship was seen when the effect of fish size was accounted for. All fish displayed surplus Se (mol Se – mol Hg > 0). For both fish species, the Se molar surplus ((nmol Se – nmol Hg)/g ww) decreased with fish weight. It was higher in the perch than in the vendace and showed the least variation among the small perch (4–34 g). For the large perch (79–434 g), the Se molar surplus decreased with increasing Hg below 0.5 µg Hg but then increased with further Hg incr...
Metoden att använda mattbildande mossor som bioindikatorer är ett effektivt sätt att övervaka luf... more Metoden att använda mattbildande mossor som bioindikatorer är ett effektivt sätt att övervaka luftmiljön, både vad gäller metaller och kväve. Som en del av den nationella miljöövervakningen har Naturvårdsverket, vart femte år, sedan 1975 finansierat undersökningar av metallhalter i mossprover insamlade i bakgrundsmiljö i hela landet. Den långa mätserien är en styrka och visar på trender för belastningen av metaller över tid. Nedfallet av både metaller och kväve över Sverige uppvisar en tydlig gradient från söder till norr, med högst nedfall i sydväst som sedan avtar norröver, vilket återspeglar intransporten av utsläpp från kontinenten. På vissa platser bryts dock mönstret med förhöjda metallhalter som går att koppla till lokala och regionala utsläppskällor. Exempel på detta är förhöjda halter av koppar och krom utmed norrlandskusten samt förhöjda halter av järn i malmfälten i Norrbottens län. Även längre söderut i Sverige kan man se förhöjda halter, till exempel av kobolt i Mellans...
Sedan mitten av 1980-talet har IVL Svenska Miljöinstitutet AB utfört undersökningar av deposition... more Sedan mitten av 1980-talet har IVL Svenska Miljöinstitutet AB utfört undersökningar av deposition och avrinning av bland annat svavel, kväve samt metaller i ett granskogsområde vid Holmsvattnet, ca 15 km SSV om Rönnskärsverken. I denna rapport jämförs resultaten från mätningarna 2017/18 vid Holmsvattnet med tidigare mätningar i området samt med mätningar vid andra närliggande stationer inom Krondroppsnätet. Syftet med mätningarna är att kvantifiera det atmosfäriska nedfallet samt beskriva förändringar i kemin i det avrinnande vattnet
Organophosphate esters (OPEs) are widely used as flame retardants, plasticizers, anti-foaming age... more Organophosphate esters (OPEs) are widely used as flame retardants, plasticizers, anti-foaming agents and as additives in lubricants and hydraulic fluids. They can be found for example in air, deposition and snow, both near and far from emission sources. In this study, OPEs were analyzed in air samples from two stations in Sweden (Råö, Norunda) and one in Finland (Pallas) for one year (2018). For TCEP and EHDPP, a geographical variation could be distinguished with highest concentrations in the north and lowest in the south. Seasonal variations were observed for TCPP and TCEP at Råö, where higher levels were measured during the summer. TEP, which is reported to be produced in large quantities, was not detected in high concentrations in air at any of the stations. Results in this study were comparable with literature data. Based on the results of this study, we conclude that the existing network of measurement stations, monitoring frequency, sampling and analysis procedures used within the national environmental monitoring (EMEP), can be used to measure OPEs in air as well.Organofosfatestrar (OPEs) har i denna studie hittats i atmosfären på två stationer i södra Sverige och en i norra Finland. Vissa ämnen visade sig dominera i luft och geografiska- och säsongsvariationer kunde urskiljas. Uppmätta nivåer var jämförbara med resultat funna i litteraturen. Baserat på resultaten från denna studie drar vi slutsatsen att de befintliga procedurerna för att mäta organiska föroreningar i luft inom EMEP, även kan användas för att mäta OPEs i luft
Naturvårdsverket ansvarar för den nationella övervakningen av luftens och nederbördens kvalitet i... more Naturvårdsverket ansvarar för den nationella övervakningen av luftens och nederbördens kvalitet i bakgrundsmiljö. I rapporten redovisas resultat från verksamheten inom Programområde Luft avseende mätningar till och med 2017 och regionala modellberäkningar till och med 2016, respektive 2017 för marknära ozon
cumulation rates of Hg in the diverse set of tree species in the Gothenburg area were related to ... more cumulation rates of Hg in the diverse set of tree species in the Gothenburg area were related to the specific leaf area (SLA). Leaf-area-based [Hg] was negatively and non-linearly correlated with SLA, while mass-based [Hg] had a somewhat weaker positive relationship with SLA. An elaborated understanding of the relationship behind [Hg] and SLA may have the potential to support large-scale modelling of Hg uptake by vegetation and Hg circulation.
Mercury is a globally distributed contaminant that exists in the atmosphere in its elemental form... more Mercury is a globally distributed contaminant that exists in the atmosphere in its elemental form as a stable monoatomic gas. Having a residence time of around one year in air allows it to be transported far from emission sources and end up in polar ecosystems. Gaseous elemental mercury (GEM) can in air be oxidized by photo-induced processes which produce water soluble oxidized forms of mercury which are more easily deposited. Deposited mercury can in the environment be transformed to organic and bio-accumulating compounds which are neurotoxic, making mercury a global concern. Deposited oxidized mercury into the sea can be reduced back to the elemental form (GEM) and be re-emitted to air. This re-evasion constitutes of around 30% of the total emissions of mercury to air and originates from both natural and anthropogenic sources. Models have estimated that the yearly mercury emission from global sea surfaces is between 2000 and 3000 tonnes. The mercury flux rate at the interphase bet...
Mercury is a globally distributed contaminant that exists in the atmosphere as a stable monoatomi... more Mercury is a globally distributed contaminant that exists in the atmosphere as a stable monoatomic gas. Having almost a year’s residence time in the air allows it to reach remote polar regions. Deposited airborne mercury can be transformed in the environment to the organic and bio-accumulating compound methyl mercury. Methyl mercury is neurotoxic and affects land living and marine animals all over the world. Springtime atmospheric mercury depletion events, first discovered in 1995 in the Arctic, occur when the return of sunlight induces the formation of halogen radicals that oxidize tropospheric elemental mercury. These spring events occurring in polar regions increase the net deposition of mercury into polar marine ecosystems. Some studies have been performed on the fate of mercury deposited onto snowpack but the transportation and transformation of mercury through and within snow and sea ice are still not fully understood. This thesis is based on data from three oceanographic expe...
Global Biogeochemical Cycles, 2021
On a global scale 3,800 Mg a −1 mercury (Hg) enter the ocean through atmospheric deposition and 3... more On a global scale 3,800 Mg a −1 mercury (Hg) enter the ocean through atmospheric deposition and 300 Mg a −1 through riverine input (UNEP, 2019). Atmospheric wet deposition of divalent mercury (Hg II) constitutes the main deposition pathway of total atmospheric Hg to the surface ocean (Zhang et al., 2014), while dry deposition of Hg II constitutes a minor fraction in the mid-latitude marine boundary layer (Holmes et al., 2009). Reduction of Hg II to gaseous elemental mercury (Hg 0) in the surface ocean leads to re-emission of Hg 0 from the ocean of approximately 2,900 Mg a −1 (Horowitz et al., 2017). However, these current air-sea Hg exchange estimates are associated with high uncertainty and a better constraint on the Hg 0 flux is crucial for two reasons: first, ocean emissions reduce the reservoir of Hg II available for methylation in the water column and subsequent bioaccumulation in marine biota (Lavoie et al., 2013). Second, ocean emissions increase the amount of Hg actively cycling between the atmosphere, marine and terrestrial ecosystems (Amos et al., 2013; Selin, 2009). Air-sea exchange of Hg 0 is a diffusion process driven by the concentration gradient between Hg 0 in the atmosphere (Hg 0 air) and dissolved gaseous elemental Hg in seawater (DGM, hereinafter referred to as Hg 0 aq). The two key factors that control the Hg 0 air-sea exchange are (a) the saturation of Hg 0 in surface water relative to equilibrium conditions expressed by Henry's law constant for Hg 0 and (b) the gas transfer velocity (k) (Qureshi et al., 2011). The Hg 0 flux is typically estimated based on a thin film gas exchange model (Liss & Merlivat, 1986; Wanninkhof, 1992) that uses in situ measurements of Hg 0 air and Hg 0 aq together with a wind speed dependent parameterization of k that was developed based on field experiments with volatile
Atmospheric Measurement Techniques, 2021
Passive air samplers (PASs), which provide time-averaged concentrations of gaseous mercury over t... more Passive air samplers (PASs), which provide time-averaged concentrations of gaseous mercury over the timescale of weeks to months, are promising for filling a gap in the monitoring of atmospheric mercury worldwide. Their usefulness will depend on their ease of use and robustness under field conditions, their availability and affordability, and most notably, their ability to provide results of acceptable precision and accuracy. Here we describe a comparative evaluation of three PASs with respect to their ability to precisely and accurately record atmospheric background mercury concentrations at sites in both southern Italy and southern Ontario, Canada. The study includes the CNR-PAS with gold nanoparticles as a sorbent, developed by the Italian National Research Council, the IVL-PAS using an activated carbon-coated disk, developed by the Swedish Environmental Research Institute, and the MerPAS ® using a sulfurimpregnated activated carbon sorbent, developed at the University of Toronto and commercialized by Tekran. Detection limits are deduced from the variability in the amount of mercury quantified in more than 20 field blank samples for each PAS. Analytical and sampling precision is quantified through 22 triplicate deployments for each PAS, ranging in duration from 2 to 12 weeks. Accuracy and bias are assessed through comparison with gaseous elemental mercury concentrations recorded by Tekran 2537 automated mercury analyzers operating alongside the PASs at both locations. The performance of the PASs was significantly better in Italy, with all of them providing concentrations that are not significantly different from the average concentrations of the Tekran 2537 instruments. In Canada, where weather conditions were much harsher and more variable during the February through April deployment period, there are differences amongst the PASs. At both sites, the MerPAS ® is currently the most sensitive, precise, and accurate among the three PASs. A key reason for this is the larger size and the radial configuration of the MerPAS ® , which results in lower blank levels relative to the sequestered amounts of mercury when compared to the other two PASs, which rely on axial diffusion geometries. Since blank correction becomes relatively smaller with longer deployments, performance tends to be closer amongst the PASs during deployments of 8 and 12 weeks.
E3S Web of Conferences, 2013
Mercury speciation measurements were performed at the Arctic measurement site, Pallas Matorova, i... more Mercury speciation measurements were performed at the Arctic measurement site, Pallas Matorova, in northern Finland during the period 12-04-02 to 12-04-26. For the first time Hg speciation measurements with high sensitivity and temporal resolution were performed at this site. The measurement allowed simultaneous determination of TGM, GEM, GOM and particulate bound mercury. Evidence for long range transport of air masses depleted in mercury is provided as well as a study of possible mercury sources determining the temporal variations in airborne mercury species at the site.
Marine Chemistry, 2017
Despite the distance from large anthropogenic emission sources, toxic mercury is transported via ... more Despite the distance from large anthropogenic emission sources, toxic mercury is transported via the atmosphere and oceans to the Southern Ocean. Seawater samples were collected at selected stations and were analysed for total mercury (HgT) (8 stations), dissolved gaseous mercury (DGM) (62 stations) and methylmercury (12 stations) during winter (Weddell Sea), spring (Weddell Sea) and summer (Amundsen and Ross Seas) in the Southern Ocean. The HgT distribution in water columns was found to not vary significantly with depth. In the Weddell Sea the average column concentration was higher in spring (2.6 ± 1.3 pM, 2 stations) than in winter (2.0 ± 1.0 pM, 6 stations). We hypothesize that the seasonal HgT increase is due to atmospheric deposition of particulate Hg(II) formed during atmospheric mercury depletion events (AMDEs), as well as the addition of inorganic mercury species from melting sea ice and snow. Furthermore, HgT concentrations found in this study were significantly higher than previously measured in the Southern Ocean (Cossa et al., 2011), which was hypothesized to be due to seasonal variations in atmospheric deposition. The average water column DGM concentration in the Weddell Sea was 454 ± 254 fM in winter and 384 ± 239 fM in spring. The lowest average DGM concentration was found in summer in the Amundsen and Ross Seas (299 ± 137 fM). The highest observed concentration in winter was hypothesized to be caused by the larger sea ice coverage, which is known to reduce the evasion of Hg(0) from the sea surface. The average monomethylmercury (MMHg) concentration in the Weddell Sea was 60 ± 30 fM in winter (6 stations) and 95 ± 85 fM in spring (2 stations), showing no significant seasonal difference. In the Amundsen and Ross Seas the summer average concentration of MeHg (MMHg and dimethylmercury ;DMHg) was 135 ± 189 fM (4 stations). The highest MeHg concentration was found in modified circumpolar deep water, which is known to have high primary production.
E3S Web of Conferences, 2013
Dissolved gaseous mercury (DGM) concentrations and gaseous elemental mercury (GEM) concentrations... more Dissolved gaseous mercury (DGM) concentrations and gaseous elemental mercury (GEM) concentrations were measured during an oceanographic campaign in the Mediterranean Sea. The DGM concentrations were measured using two different methods, a manual-and an automated method. The manual method was used to obtain DGM depth profiles at several stations throughout the campaign. The automated device measured DGM concentrations continuously at a depth of 4 m. Gaseous elemental mercury (GEM) concentrations in air were measured continuously at the bridge deck. The objectives were to achieve DGM depth profiles, compare the manual-and automated DGM measurement methods, to calculate the supersaturation grades of the sea and the evasional fluxes from the sea surface. Depth profiles of the four measured stations show no diurnal variations. The manual-and the automated method show good compliance. Supersaturation grades are high due to high DGM values and low GEM concentrations. Fluxes of Hg from the sea surface are more dependent on the wind speed than on the supersaturation grade according to the flux models used.
Environmental Science & Technology, 2016
Limited studies have been conducted on mercury concentrations in the polar cryosphere and the fac... more Limited studies have been conducted on mercury concentrations in the polar cryosphere and the factors affecting the distribution of mercury within sea ice and snow are poorly understood. Here we present the first comprehensive seasonal study of elemental and total mercury concentrations in the Antarctic sea ice environment covering data from measurements in air, sea ice, sea water, snow, frost flowers and brine. The average concentration of total mercury in sea ice decreased from winter (9.7 ng L-1) to spring (4.7 ng L-1) while the average elemental mercury concentration increased from winter (0.07 ng L-1) to summer (0.105 ng L-1). The opposite trends suggest potential photo- or dark oxidation/reduction processes within the ice and an eventual loss of mercury via brine drainage or gas evasion of elemental mercury. Our results indicate a seasonal variation of mercury species in the polar sea ice environment probably due to varying factors such as solar radiation, temperature, brine volume and atmospheric deposition. This study shows that the sea ice environment is a significant interphase between the polar ocean and the atmosphere and should be accounted for when studying how climate change may affect the mercury cycle in polar regions.
We would like to thank our supervisor Rickard Arvidsson who has guided and supported us throughou... more We would like to thank our supervisor Rickard Arvidsson who has guided and supported us throughout our study. Our examiner Sverker Molander, who introduced us to the project and helped it evolve, deserves gratitude. Thank you Germund Wahlbeck, our field supervisor for introducing us to reality. A very special thank you to the Managing director of Chikweti, Åsa Tham, for her great hospitality. It was a pleasure to meet all senior staff of Chikweti, thank you all for an unforgettable time. We want to thank Johan Fredriksson and Josefin Åhman, for putting up with us.
Atmospheric Chemistry and Physics Discussions, 2016
Long-term monitoring data of ambient mercury (Hg) on a global scale to assess its emission, trans... more Long-term monitoring data of ambient mercury (Hg) on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg pollution on the environment. The Global Mer-1
Journal of Cleaner Production, 2013
Biofuels are advanced to replace fossil fuels in order to reduce emissions of greenhouse gases an... more Biofuels are advanced to replace fossil fuels in order to reduce emissions of greenhouse gases and other environmental impacts. Yet freshwater scarcity is another growing concern and increased production of biofuels may increase this problem. In order to assess whether biofuels truly have a higher water use than do fossil fuels, a life cycle assessment study of a low input jatropha plantation in northern Mozambique was conducted. In addition to different water use indicators, the fossil energy use and global warming potential were assessed for 1 MJ of jatropha oil. The analysis compares results for jatropha oil with fossil diesel, generally showing lower global warming potential and fossil energy use for jatropha oil. However, aspects related to land use may alter the global warming potential of jatropha oil. Regarding water use, the choice of the water use indicator strongly influences the results. Specifically the indication of (1) so-called green water flows, (2) formation of so-called blue water and (3) water scarcity show crucial influences on the comparison. Depending on these specific features, jatropha oil may have higher or lower water use than fossil diesel. A number of uncertainties, such as the jatropha oil yield, are also shown to have a considerable impact on the results.
Atmospheric Chemistry and Physics Discussions, 2016
Within the EU project, Global Mercury Observation System (GMOS) airborne mercury have been monito... more Within the EU project, Global Mercury Observation System (GMOS) airborne mercury have been monitored at the background Råö measurement site on the west coast of Sweden from mid May 2012 tot the beginning of July 2013 and from the beginning of February 2014 to the end of May 2015. The mercury concentrations measured at the Råö site was found to be low in comparison to other comparable European measurement sites. A back trajectory analysis to study the origin of air masses reaching the Råö site was performed. Due to the remotely location of the Råö measurement station it receives background air most of the time. However, elevated concentrations with air masses coming from especially the south east are noticeable. Evidence for formation of gaseous oxidised mercury (GOM) in background free tropospheric air is presented.