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AŽdajić M, Yumvihoze E, Blais JM, Poulain AJ. The effect of legacy gold mining on methylmercury cycling and microbial community structure in northern freshwater lakes. Environ Sci Process Impacts 2021; 23:1220-1230. [PMID: 34318847 DOI: 10.1039/d1em00129a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Smelting activities at Giant Mine (Yellowknife, NWT, Canada) have resulted in high sulfate and arsenic concentrations in nearby lakes. Here we tested whether historic smelting affects current mercury (Hg) cycling in 35 freshwater lakes over a 2800 km2 area around the former gold mine. We sampled lake water and sediment over three consecutive years (2015-2017) using a factorial sampling design that accounted for different environmental variables known to affect the net methylmercury (MeHg) levels in water. Stable Hg(ii) and MeHg isotope tracers were used to quantify Hg methylation and demethylation rate constants in sediments, and 16S rRNA gene amplicon sequencing was used to characterize microbial community structure. This study reveals that the fraction of methylated total Hg (% MeHg) found in surface water is positively correlated to the sulfate gradient, while the rate at which Hg is methylated (Km) in sediments is negatively correlated with total arsenic, and positively correlated with dissolved organic carbon, total phosphorous, and % MeHg in the water. Furthermore, 6 of the 28 lakes that had detectable demethylation rate constants (Kd) also had significantly lower DOC concentrations than lakes with non-detectable Kd. Our results also show that legacy pollution from smelting activities is affecting the structure of microbial communities in lake sediments. This study reveals the complex dynamics of Hg cycling in this northern environment, highlighting the importance of large-scale studies in which the effect of multiple pollution gradients (e.g. arsenic and sulfate) must be taken into consideration.
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Affiliation(s)
- Mija AŽdajić
- Department of Biology, University of Ottawa, 30 Marie-Curie, Ottawa, Ontario K1N 6N5, Canada.
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Chan HM, Hu XF, Cheung JS, Parajuli RP, Rosol R, Yumvihoze E, Williams L, Mohapatra A. Cohort profile: health effects monitoring programme in Ndilǫ, Dettah and Yellowknife (YKHEMP). BMJ Open 2020; 10:e038507. [PMID: 32988947 PMCID: PMC7523220 DOI: 10.1136/bmjopen-2020-038507] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 08/25/2020] [Accepted: 09/03/2020] [Indexed: 11/03/2022] Open
Abstract
PURPOSE The Yellowknife Health Effects Monitoring Programme (YKHEMP) was established to examine the relationship of exposure to arsenic and other chemicals of potential concern such as antimony, cadmium, lead, manganese and vanadium and health outcomes. PARTICIPANTS A total of 2037 individuals were recruited, including children (age 3-19) and adults (age 20+), residing in Dettah, Ndilǫ and Yellowknife, in the Northwest Territories, Canada, in two waves in Fall 2017 and Spring 2018. In Yellowknife, there were 891 (675 adults, 216 children), randomly selected participants with a participation rate of 64%. In addition, we also recruited a total of 875 (669 adults, 206 children) volunteer participants. A total of 225 (137 adults, 88 children) of the Yellowknives Dene First Nation (YKDFN), and 46 (33 adults, 13 children) of the North Slave Métis Alliance participated in the study. Each participant answered a lifestyle questionnaire as well as provided toenail clippings and urine for contaminant testing and saliva samples for testing of genetic polymorphisms associated with arsenic metabolism. Participants also provided consent to have their medical records reviewed by the research team for the past 5 years to allow for the investigation between exposure and health outcomes. FINDINGS TO DATE The adult YKHEMP participants had lower urinary total arsenic but the children had higher inorganic arsenic than the general Canadian population. There was no difference in urinary total arsenic concentrations between adults and children, however, urinary inorganic arsenic concentrations were generally higher in children than in adults in all four YKHEMP sampling groups. The adult YKDFN participants had lower urinary total arsenic and inorganic arsenic concentrations compared with the random selected and volunteer participants. FUTURE PLANS YKHEMP is designed as a prospective cohort study; the children participants will be re-examined in 2022 and both adult and children participants in 2027.
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Affiliation(s)
- Hing Man Chan
- Biology, University of Ottawa Faculty of Science, Ottawa, Ontario, Canada
| | - Xue Feng Hu
- Biology, University of Ottawa Faculty of Science, Ottawa, Ontario, Canada
| | - Janet S Cheung
- Biology, University of Ottawa Faculty of Science, Ottawa, Ontario, Canada
| | | | - Renata Rosol
- Biology, University of Ottawa Faculty of Science, Ottawa, Ontario, Canada
| | - Emmanuel Yumvihoze
- Biology, University of Ottawa Faculty of Science, Ottawa, Ontario, Canada
| | - Linna Williams
- Health and Social Services, Government of the Northwest Territories, Yellowknife, Northwest Territories, Canada
| | - Asish Mohapatra
- Environmental Health Program, Health Canada, Ottawa, Ontario, Canada
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Murphy T, Irvine K, Phan K, Lean D, Yumvihoze E, Wilson K. Interactions of Dimethylarsinic Acid, Total Arsenic and Zinc Affecting Rice Crop Management and Human Health in Cambodia. J Health Pollut 2020; 10:200612. [PMID: 32509413 PMCID: PMC7269330 DOI: 10.5696/2156-9614-10.26.200612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 04/21/2020] [Indexed: 04/18/2023]
Abstract
BACKGROUND In parts of Cambodia and in many other parts of the world, irrigation of rice with groundwater results in arsenic (As) accumulation in soil and rice, leading to health concerns associated with rice consumption. At times, some As is present as relatively nontoxic, non-regulated, dimethylarsinic acid (DMA). Low levels of zinc (Zn) have been found in rice from Bangladesh, Cambodia, and China where As levels in rice are high. Furthermore, there have been claims that Zn deficiency is responsible for stunting the growth of children in Cambodia and elsewhere, however in rural Asia, rice is the major source of Zn. Current data are inadequate for both Zn and DMA in Cambodian rice. OBJECTIVES The present study aimed to provide a preliminary evaluation of the relationship between the content of Zn and DMA in rice grain in Preak Russey, an area with elevated levels of As in groundwater and to improve the management of Zn deficiency in rice. METHODS Rice agriculture was evaluated along the Mekong River in Cambodia. Analyses for metals, total As, and As species in rice and water were conducted by inductively coupled plasma mass spectrometry. Analysis of total Zn and As in soils and total Zn in rice were analyzed using X-ray fluorescence (XRF) spectrometry. RESULTS Rice in Preak Russey had Zn concentrations less than a third the level recommended by the United Nations World Food Programme. There was a significant (p < 0.05) negative correlation between the Zn content of rice and DMA in rice with the lowest Zn and highest DMA levels occurring near irrigation wells, the source of As. CONCLUSIONS The highest levels of DMA in rice were associated with Zn deficiency in rice. COMPETING INTERESTS The authors declare no competing financial interests.
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Affiliation(s)
- Tom Murphy
- International University, Phnom Penh, Cambodia
| | | | | | - David Lean
- Lean Environmental, Apsley, Ontario, Canada
| | | | - Ken Wilson
- Texas State University, San Marcos, Texas, USA
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Murphy T, Phan K, Yumvihoze E, Irvine K, Wilson K, Lean D, Ty B, Poulain A, Laird B, Chan LHM. Groundwater Irrigation and Arsenic Speciation in Rice in Cambodia. J Health Pollut 2018; 8:180911. [PMID: 30524870 PMCID: PMC6257176 DOI: 10.5696/2156-9614-8.19.180911] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 07/09/2018] [Indexed: 04/29/2023]
Abstract
BACKGROUND Arsenic bioaccumulation in rice is a global concern affecting food security and public health. OBJECTIVE The present study examined arsenic species in rice in Cambodia to characterize health risks with rice consumption and to clarify uncertainties with Codex guidelines. METHODS The present study collected 61 well water samples, 105 rice samples, 70 soil samples, and conducted interviews with 44 families in Preak Russey near the Bassac River and Kandal Province along the Mekong River in Cambodia. Analyses of metals, total arsenic and arsenic species were conducted in laboratories in Canada, Cambodia and Singapore. RESULTS Unlike in Bangladesh, rice with the highest total arsenic concentrations in Cambodia contains mostly organic arsenic, dimethylarsinic acid (DMA), which is unregulated and much less toxic than inorganic arsenic. The present study found that storing surface runoff in ditches prior to irrigation can significantly reduce the arsenic concentration in rice. It is possible to remove > 95% of arsenic from groundwater prior to irrigation with natural reactions. CONCLUSIONS The provision of high quality drinking water in 2015 to Preak Russey removed about 95% of the dietary inorganic arsenic exposure. The extremes in arsenic toxicity that are still obvious in these farmers should become less common. Rice from the site with the highest documented levels of arsenic in soils and water in Cambodia passes current Codex guidelines for arsenic. INFORMED CONSENT Obtained. COMPETING INTERESTS The authors declare no competing financial interests.
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Affiliation(s)
- Tom Murphy
- International University, Phnom Penh, Cambodia
| | | | | | - Kim Irvine
- Nanyang Technological University, Singapore
| | - Ken Wilson
- Texas State University, San Marcos, Texas, USA
| | - David Lean
- Lean Environmental, Apsley, Ontario, Canada
| | - Borey Ty
- Institute of Technology Cambodia, Phnom Penh
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Murphy T, Phan K, Yumvihoze E, Irvine K, Wilson K, Lean D, Poulain A, Laird B, Chan LHM. Effects of Arsenic, Iron and Fertilizers in Soil on Rice in Cambodia. J Health Pollut 2018; 8:180910. [PMID: 30524869 PMCID: PMC6257173 DOI: 10.5696/2156-9614-8.19.180910] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 07/09/2018] [Indexed: 04/29/2023]
Abstract
BACKGROUND In parts of Cambodia, irrigation with groundwater results in arsenic accumulation in soils and rice, leading to health concerns associated with rice consumption. A high concentration of iron in groundwater can precipitate arsenic and reduce its bioavailability, however high concentrations of arsenic and iron can also reduce rice production. Furthermore, concerns have been raised about chemical contamination from inorganic fertilizers used to grow rice. The relationship between soil geochemistry and arsenic concentrations in rice is not yet fully understood. OBJECTIVES The primary objective of this project was to investigate the relationship between arsenic concentrations in irrigation water, soil and rice collected from different sites in Cambodia. A secondary objective was to explore arsenic and phosphorus levels in fertilizer samples obtained from the study area in Cambodia. METHODS The present study collected 61 well water samples, 105 rice samples, 70 soil samples, 11 inorganic fertilizer samples and conducted interviews with 44 families along the Mekong River in Cambodia. Analyses for metals, total arsenic, and arsenic species in the water and rice were conducted in Canada by inductively coupled plasma mass spectrometry. Analyses for metals, total arsenic and phosphorus in soils and inorganic fertilizers were conducted in Cambodia and Singapore by X-ray fluorescence. RESULTS The concentration of arsenic in rice paddy soils was highly variable and as much as 20 times higher near the irrigation wells than in more distal areas of the paddy. Two farmers in Preak Russey had integrated soil samples with arsenic levels above the concentration associated with toxicity to rice in Taiwan (40 mg/kg) and above the Dutch concentration requiring intervention or remediation (55 mg/kg). The highest total arsenic measured in soil was 95 mg/kg. In Preak Russey, the loading of arsenic from irrigation water was 3710 times greater than the loading of arsenic from inorganic fertilizers. Half of the commercial inorganic fertilizers had less than 50% of the labelled content of phosphorus. CONCLUSIONS Emphasis should be placed on improving the management of irrigation water, not on inactivation of arsenic in soil. The high levels of iron in groundwater mitigate arsenic toxicity, but the accumulation of iron could later result in lower rice productivity. Irrigation of rice with groundwater is not likely sustainable. To improve rice productivity, the content of phosphorus in local inorganic fertilizers must be improved to world standards. X-ray fluorescence analysis can quickly identify poor quality fertilizers. INFORMED CONSENT Obtained. COMPETING INTERESTS The authors declare no competing financial interests.
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Affiliation(s)
- Tom Murphy
- International University, Phnom Penh, Cambodia
| | | | | | - Kim Irvine
- Nanyang Technological University, Singapore
| | - Ken Wilson
- Texas State University, San Marcos, Texas, USA
| | - David Lean
- Lean Environmental, Apsley, Ontario, Canada
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Chételat J, Hickey MBC, Poulain AJ, Dastoor A, Ryjkov A, McAlpine D, Vanderwolf K, Jung TS, Hale L, Cooke ELL, Hobson D, Jonasson K, Kaupas L, McCarthy S, McClelland C, Morningstar D, Norquay KJO, Novy R, Player D, Redford T, Simard A, Stamler S, Webber QMR, Yumvihoze E, Zanuttig M. Spatial variation of mercury bioaccumulation in bats of Canada linked to atmospheric mercury deposition. Sci Total Environ 2018; 626:668-677. [PMID: 29396333 DOI: 10.1016/j.scitotenv.2018.01.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/05/2018] [Accepted: 01/06/2018] [Indexed: 06/07/2023]
Abstract
Wildlife are exposed to neurotoxic mercury at locations distant from anthropogenic emission sources because of long-range atmospheric transport of this metal. In this study, mercury bioaccumulation in insectivorous bat species (Mammalia: Chiroptera) was investigated on a broad geographic scale in Canada. Fur was analyzed (n=1178) for total mercury from 43 locations spanning 20° latitude and 77° longitude. Total mercury and methylmercury concentrations in fur were positively correlated with concentrations in internal tissues (brain, liver, kidney) for a small subset (n=21) of little brown bats (Myotis lucifugus) and big brown bats (Eptesicus fuscus), validating the use of fur to indicate internal mercury exposure. Brain methylmercury concentrations were approximately 10% of total mercury concentrations in fur. Three bat species were mainly collected (little brown bats, big brown bats, and northern long-eared bats [M. septentrionalis]), with little brown bats having lower total mercury concentrations in their fur than the other two species at sites where both species were sampled. On average, juvenile bats had lower total mercury concentrations than adults but no differences were found between males and females of a species. Combining our dataset with previously published data for eastern Canada, median total mercury concentrations in fur of little brown bats ranged from 0.88-12.78μg/g among 11 provinces and territories. Highest concentrations were found in eastern Canada where bats are most endangered from introduced disease. Model estimates of atmospheric mercury deposition indicated that eastern Canada was exposed to greater mercury deposition than central and western sites. Further, mean total mercury concentrations in fur of adult little brown bats were positively correlated with site-specific estimates of atmospheric mercury deposition. This study provides the largest geographic coverage of mercury measurements in bats to date and indicates that atmospheric mercury deposition is important in determining spatial patterns of mercury accumulation in a mammalian species.
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Affiliation(s)
- John Chételat
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada.
| | | | - Alexandre J Poulain
- Biology Department, Faculty of Science, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Ashu Dastoor
- Air Quality Research Division, Environment and Climate Change Canada, Dorval, Quebec H9P 1J3, Canada
| | - Andrei Ryjkov
- Air Quality Research Division, Environment and Climate Change Canada, Dorval, Quebec H9P 1J3, Canada
| | - Donald McAlpine
- New Brunswick Museum, Saint John, New Brunswick E2K 1E5, Canada
| | - Karen Vanderwolf
- New Brunswick Museum, Saint John, New Brunswick E2K 1E5, Canada; Canadian Wildlife Federation, Kanata, Ontario K2M 2W1, Canada
| | - Thomas S Jung
- Yukon Department of Environment, Whitehorse, Yukon Territory Y1A 2C6, Canada
| | - Lesley Hale
- Ontario Ministry of Natural Resources & Forestry, Peterborough, Ontario K9J 8M5, Canada
| | - Emma L L Cooke
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
| | - Dave Hobson
- Alberta Environment and Parks, Edson, Alberta T7E 1T2, Canada
| | - Kristin Jonasson
- Department of Biology, Western University, London, Ontario N6A 5B7, Canada
| | - Laura Kaupas
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Sara McCarthy
- Wildlife Division, Fisheries and Land Resources, Goose Bay, Newfoundland and Labrador A0P 1E0, Canada
| | - Christine McClelland
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
| | | | - Kaleigh J O Norquay
- Department of Biology, University of Winnipeg, Winnipeg, Manitoba R3B 2G3, Canada
| | - Richard Novy
- Golder Associates Ltd., Calgary, Alberta T2A 7W5, Canada
| | | | - Tony Redford
- Animal Health Centre, BC Ministry of Agriculture, Abbotsford, British Columbia V3G 2M3, Canada
| | - Anouk Simard
- Direction de l'expertise sur la faune terrestre, l'herpétofaune et l'avifaune, Ministère des Forêts, de la Faune et des Parcs, Québec, Quebec G1S 4X4, Canada
| | - Samantha Stamler
- Alberta Environment and Parks, Edmonton, Alberta T6H 4P2, Canada
| | - Quinn M R Webber
- Department of Biology, University of Winnipeg, Winnipeg, Manitoba R3B 2G3, Canada
| | - Emmanuel Yumvihoze
- Biology Department, Faculty of Science, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Michelle Zanuttig
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
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Guo G, Yumvihoze E, Poulain AJ, Man Chan H. Monomethylmercury degradation by the human gut microbiota is stimulated by protein amendments. J Toxicol Sci 2018; 43:717-725. [DOI: 10.2131/jts.43.717] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Galen Guo
- Department of Biology, Faculty of Science, University of Ottawa, Ottawa, Canada K1N 9B4
| | - Emmanuel Yumvihoze
- Department of Biology, Faculty of Science, University of Ottawa, Ottawa, Canada K1N 9B4
| | - Alexandre J. Poulain
- Department of Biology, Faculty of Science, University of Ottawa, Ottawa, Canada K1N 9B4
| | - Hing Man Chan
- Department of Biology, Faculty of Science, University of Ottawa, Ottawa, Canada K1N 9B4
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Mailloux RJ, Yumvihoze E, Chan HM. Superoxide produced in the matrix of mitochondria enhances methylmercury toxicity in human neuroblastoma cells. Toxicol Appl Pharmacol 2015; 289:371-80. [DOI: 10.1016/j.taap.2015.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 10/28/2015] [Accepted: 11/02/2015] [Indexed: 01/08/2023]
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Mailloux RJ, Yumvihoze E, Chan HM. Superoxide anion radical (O2(-)) degrades methylmercury to inorganic mercury in human astrocytoma cell line (CCF-STTG1). Chem Biol Interact 2015; 239:46-55. [PMID: 26111762 DOI: 10.1016/j.cbi.2015.06.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 06/11/2015] [Accepted: 06/19/2015] [Indexed: 10/23/2022]
Abstract
Methylmercury (MeHg) is a global pollutant that is affecting the health of millions of people worldwide. However, the mechanism of MeHg toxicity still remains somewhat elusive and there is no treatment. It has been known for some time that MeHg can be progressively converted to inorganic mercury (iHg) in various tissues including the brain. Recent work has suggested that cleavage of the carbon-metal bond in MeHg in a biological environment is facilitated by reactive oxygen species (ROS). However, the oxyradical species that actually mediates this process has not been identified. Here, we provide evidence that superoxide anion radical (O2(-)) can convert MeHg to iHg. The calculated second-order rate constant for the degradation of 1μM MeHg by O2(-) generated by xanthine/xanthine oxidase was calculated to be 2×10(5)M(-1)s(-1). We were also able to show that this bioconversion can proceed in intact CCF-STTG1 human astrocytoma cells exposed to paraquat (PQ), a O2(-) generating viologen. Notably, exposure of cells to increasing amounts of PQ led to a dose dependent increase in both MeHg and iHg. Indeed, a 24h exposure to 500μM PQ induced a ∼13-fold and ∼18-fold increase in intracellular MeHg and iHg respectively. These effects were inhibited by superoxide dismutase mimetic MnTBAP. In addition, we also observed that a 24h exposure to a biologically relevant concentration of MeHg (1μM) did not induce cell death, oxidative stress, or even changes in cellular O2(-) and H2O2. However, co-exposure to PQ enhanced MeHg toxicity which was associated with a robust increase in cell death and oxidative stress. Collectively our results show that O2(-) can bioconvert MeHg to iHg in vitro and in intact cells exposed to conditions that simulate high intracellular O2(-) production. In addition, we show for the first time that O2(-) mediated degradation of MeHg to iHg enhances the toxicity of MeHg by facilitating an accumulation of both MeHg and iHg in the intracellular environment.
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Affiliation(s)
- Ryan J Mailloux
- University of Ottawa, Department of Biology, Center for Advanced Research in Environmental Genomics, Ottawa, ON K1N 6N5, Canada
| | - Emmanuel Yumvihoze
- University of Ottawa, Department of Biology, Center for Advanced Research in Environmental Genomics, Ottawa, ON K1N 6N5, Canada
| | - Hing Man Chan
- University of Ottawa, Department of Biology, Center for Advanced Research in Environmental Genomics, Ottawa, ON K1N 6N5, Canada.
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Zdanowicz C, Kruemmel E, Lean D, Poulain A, Kinnard C, Yumvihoze E, Chen J, Hintelmann H. Pre-industrial and recent (1970-2010) atmospheric deposition of sulfate and mercury in snow on southern Baffin Island, Arctic Canada. Sci Total Environ 2015; 509-510:104-114. [PMID: 24835341 DOI: 10.1016/j.scitotenv.2014.04.092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 04/16/2014] [Accepted: 04/22/2014] [Indexed: 06/03/2023]
Abstract
Sulfate (SO4(2-)) and mercury (Hg) are airborne pollutants transported to the Arctic where they can affect properties of the atmosphere and the health of marine or terrestrial ecosystems. Detecting trends in Arctic Hg pollution is challenging because of the short period of direct observations, particularly of actual deposition. Here, we present an updated proxy record of atmospheric SO4(2-) and a new 40-year record of total Hg (THg) and monomethyl Hg (MeHg) deposition developed from a firn core (P2010) drilled from Penny Ice Cap, Baffin Island, Canada. The updated P2010 record shows stable mean SO4(2-) levels over the past 40 years, which is inconsistent with observations of declining atmospheric SO4(2-) or snow acidity in the Arctic during the same period. A sharp THg enhancement in the P2010 core ca 1991 is tentatively attributed to the fallout from the eruption of the Icelandic volcano Hekla. Although MeHg accumulation on Penny Ice Cap had remained constant since 1970, THg accumulation increased after the 1980s. This increase is not easily explained by changes in snow accumulation, marine aerosol inputs or air mass trajectories; however, a causal link may exist with the declining sea-ice cover conditions in the Baffin Bay sector. The ratio of THg accumulation between pre-industrial times (reconstructed from archived ice cores) and the modern industrial era is estimated at between 4- and 16-fold, which is consistent with estimates from Arctic lake sediment cores. The new P2010 THg record is the first of its kind developed from the Baffin Island region of the eastern Canadian Arctic and one of very few such records presently available in the Arctic. As such, it may help to bridge the knowledge gap linking direct observation of gaseous Hg in the Arctic atmosphere and actual net deposition and accumulation in various terrestrial media.
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Affiliation(s)
- Christian Zdanowicz
- Department of Earth Sciences, Uppsala University, Villavägen 16, Uppsala 75646, Sweden.
| | - Eva Kruemmel
- Inuit Circumpolar Council of Canada, 75 Albert St., Suite 1001, Ottawa, ON K1P 5V5, Canada
| | - David Lean
- Lean Environmental, P.O. Box 309, Apsley, ON K0L 1A0, Canada
| | - Alexandre Poulain
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
| | - Christophe Kinnard
- Département des Sciences de l'Environnement, Université du Québec à Trois-Rivières, 3478, Léon-Provancher, Trois-Rivières, QC G9A 5H7, Canada
| | - Emmanuel Yumvihoze
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
| | - JiuBin Chen
- State Key Laboratory of Environmental Geochemistry, Chinese Academy of Sciences, 46 Guanshi Road, Guiyang 550002, China
| | - Holger Hintelmann
- Department of Chemistry, Trent University, 1600 West Bank Drive, Peterborough K9J 7B8, Canada
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Fillion M, Blais JM, Yumvihoze E, Nakajima M, Workman P, Osborne G, Chan HM. Identification of environmental sources of lead exposure in Nunavut (Canada) using stable isotope analyses. Environ Int 2014; 71:63-73. [PMID: 24973640 DOI: 10.1016/j.envint.2014.06.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 04/08/2014] [Accepted: 06/03/2014] [Indexed: 05/22/2023]
Abstract
BACKGROUND Blood lead levels (BLLs) were measured in the adult Inuit population of Nunavut, Northern Canada, during the Inuit Health Survey (IHS) in 2007-2008. Approximately 10% of the adult participants had BLL over the Health Canada's guidance of 100μg/L. OBJECTIVES 1) To repeat the measurement of BLL among the IHS participants with high BLL and household members including pregnant women and children under 10years of age; 2) to measure lead (Pb) concentrations in environmental samples to identify potential sources and 3) to explore how Pb from environmental samples contributes to BLL using Pb stable isotopic analyses. METHODS Blood samples were collected from 100 adults and 56 children in 2012. A total of 169 environmental samples (tap water, house dust, paint, country food, soil, and ammunition) were collected from 14 houses from three communities where the IHS participants had the highest BLL. Total Pb concentrations and Pb isotope mass balance were determined by inductively coupled plasma-mass spectrometry (ICP-MS). RESULTS The geometric mean of BLL was 43.1μg/L; BLL increased with age and was higher in adults than children (71.1 vs. 17.5μg/L). Median Pb concentrations in water (1.9μg/L) and dust (27.1μg/m(2) for wiped dust, 32.6mg/kg for vacuum dust coarse fraction, and 141.9mg/kg for vacuum dust fine fraction) were generally higher than in other parts of Canada. Median Pb concentrations of food and soil coarse and fine fractions were low (36.6μg/kg, 5.4mg/kg and 11.8mg/kg respectively); paint chips exceeded the Canadian guidelines in two houses (median: 3.8mg/kg). Discriminant analyses and isotope ratio analyses showed that ammunition and house dust are major sources of Pb in this study population. CONCLUSION Analyses of Pb stable isotopes are useful to identify the routes of exposure to Pb. This approach can contribute to develop targeted public health programmes to prevent Pb exposure.
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Affiliation(s)
- Myriam Fillion
- Centre for Advanced Research in Environmental Genomics, University of Ottawa, 30 Marie Curie, Gendron 160, Ottawa, Ontario K1N 6N5, Canada
| | - Jules M Blais
- Centre for Advanced Research in Environmental Genomics, University of Ottawa, 30 Marie Curie, Gendron 160, Ottawa, Ontario K1N 6N5, Canada
| | - Emmanuel Yumvihoze
- Centre for Advanced Research in Environmental Genomics, University of Ottawa, 30 Marie Curie, Gendron 160, Ottawa, Ontario K1N 6N5, Canada
| | - Maya Nakajima
- Department of Health, Government of Nunavut, Box 1000, Station 1000, Iqaluit, Nunavut X0A 0H0, Canada
| | - Peter Workman
- Department of Health, Government of Nunavut, Box 1000, Station 1000, Iqaluit, Nunavut X0A 0H0, Canada
| | - Geraldine Osborne
- Department of Health, Government of Nunavut, Box 1000, Station 1000, Iqaluit, Nunavut X0A 0H0, Canada
| | - Hing Man Chan
- Centre for Advanced Research in Environmental Genomics, University of Ottawa, 30 Marie Curie, Gendron 160, Ottawa, Ontario K1N 6N5, Canada.
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St Pierre KA, Chétélat J, Yumvihoze E, Poulain AJ. Temperature and the sulfur cycle control monomethylmercury cycling in high Arctic coastal marine sediments from Allen Bay, Nunavut, Canada. Environ Sci Technol 2014; 48:2680-2687. [PMID: 24555761 DOI: 10.1021/es405253g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Monomethylmercury (MMHg) is a neurotoxin of concern in the Canadian Arctic due to its tendency to bioaccumulate and the importance of fish and wildlife in the Inuit diet. In lakes and wetlands, microbial sediment communities are integral to the cycling of MMHg; however, the role of Arctic marine sediments is poorly understood. With projected warming, the effect of temperature on the production and degradation of MMHg in Arctic environments also remains unclear. We examined MMHg dynamics across a temperature gradient (4, 12, 24 °C) in marine sediments collected in Allen Bay, Nunavut. Slurries were spiked with stable mercury isotopes and amended with specific microbial stimulants and inhibitors, and subsampled over 12 days. Maximal methylation and demethylation potentials were low, ranging from below detection to 1.13 pmol g(-1) h(-1) and 0.02 pmol g(-1) h(-1), respectively, suggesting that sediments are likely not an important source of MMHg to overlying water. Our results suggest that warming may result in an increase in Hg methylation - controlled by temperature-dependent sulfate reduction, without a compensatory increase in demethylation. This study highlights the need for further research into the role of high Arctic marine sediments and climate on the Arctic marine MMHg budget.
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Affiliation(s)
- K A St Pierre
- Department of Biology, University of Ottawa , 30 Marie-Curie, Ottawa, Ontario, K1N 6N5, Canada
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Abstract
Despite the alarming trends of declining base cation concentrations in boreal lakes, no studies have attempted to predict the consequences of this decline on the geochemical cycle of mercury, a top priority contaminant worldwide. In this study, we used a whole-cell gram-negative bioreporter to evaluate the direction and magnitude of changes in net accumulation of Hg(II) by bacteria in response to changing base cation concentrations. We show that regardless of the speciation of Hg(II) in solution, increasing divalent base cation concentrations decrease net Hg(II) accumulation by the bioreporter, suggesting a protective effect of these cations. Our work suggests that the complexity of the cell wall of gram-negative bacteria must be considered when modeling Hg uptake pathways; we propose that base divalent cations contribute to hamper net Hg(II) accumulation by decreasing outer membrane permeability and, therefore, the passive diffusion of Hg(II) species to the periplasmic space. This work points to an unsuspected and likely harmful consequence of a delay in recovering from acidification in boreal lakes, in that uptake of Hg(II) by bacteria is not only enhanced by the reduced pH but can also be enhanced by a decline in base cation levels.
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Affiliation(s)
- Valérie Daguené
- Department of Biology, University of Ottawa, 30 rue Marie Curie, Ottawa, ON K1N 6N5, Canada
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14
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Marusczak N, Larose C, Dommergue A, Yumvihoze E, Lean D, Nedjai R, Ferrari C. Total mercury and methylmercury in high altitude surface snow from the French Alps. Sci Total Environ 2011; 409:3949-3954. [PMID: 21752427 DOI: 10.1016/j.scitotenv.2011.06.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 06/11/2011] [Accepted: 06/16/2011] [Indexed: 05/31/2023]
Abstract
Surface snow samples were collected weekly from the 31st of December 2008 to the 21st of June 2009 from Lake Bramant in the French Alps. Total mercury (THg), total dissolved mercury (THgD), methylmercury (MeHg) and particle distributions in surface snow were analyzed. Results showed that THg concentrations, MeHg concentrations and particle load increased with snow surface temperature, which is an indicator of rising temperatures as the season progresses. Significant correlations between MeHg and snow surface temperature and MeHg and total particles greater than 10 μm were observed. This suggests that the MeHg found in the snow originates from atmospheric deposition processes rather than in situ snowpack sources. This study suggests that an important post-winter atmospheric deposition of MeHg and THg occurs on summital zones of the French Alps and it is likely that this contamination originates from the surrounding valleys.
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Affiliation(s)
- Nicolas Marusczak
- Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE) CNRS UMR 5183, 54, rue Molière, Domaine Universitaire, B.P. 96, 38402 Saint Martin d'Hères, France
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15
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Avramescu ML, Yumvihoze E, Hintelmann H, Ridal J, Fortin D, Lean DRS. Biogeochemical factors influencing net mercury methylation in contaminated freshwater sediments from the St. Lawrence River in Cornwall, Ontario, Canada. Sci Total Environ 2011; 409:968-978. [PMID: 21176945 DOI: 10.1016/j.scitotenv.2010.11.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 11/14/2010] [Accepted: 11/16/2010] [Indexed: 05/28/2023]
Abstract
The activity of various anaerobic microbes, including sulfate reducers (SRB), iron reducers (FeRP) and methanogens (MPA) has been linked to mercury methylation in aquatic systems, although the relative importance of each microbial group in the overall process is poorly understood in natural sediments. The present study focused on the biogeochemical factors (i.e. the relative importance of various groups of anaerobic microbes (FeRP, SRB, and MPA) that affect net monomethylmercury (MMHg) formation in contaminated sediments of the St. Lawrence River (SRL) near Cornwall (Zone 1), Ontario, Canada. Methylation and demethylation potentials were measured separately by using isotope-enriched mercury species ((200)Hg(2+) and MM(199)Hg(+)) in sediment microcosms treated with specific microbial inhibitors. Sediments were sampled and incubated in the dark at room temperature in an anaerobic chamber for 96h. The potential methylation rate constants (K(m)) and demethylation rates (K(d)) were found to differ significantly between microcosms. The MPA-inhibited microcosm had the highest potential methylation rate constant (0.016d(-1)), whereas the two SRB-inhibited microcosms had comparable potential methylation rate constants (0.003d(-1) and 0.002d(-1), respectively). The inhibition of methanogens stimulated net methylation by inhibiting demethylationand by stimulating methylation along with SRB activity. The inhibition of both methanogens and SRB was found to enhance the iron reduction rates but did not completely stop MMHg production. The strong positive correlation between K(m) and Sulfate Reduction Rates (SRR) and between K(d) and Methane Production Rates (MPR) supports the involvement of SRB in Hg methylation and MPA in MMHg demethylation in the sediments. In contrast, the strong negative correlation between K(d) and Iron Reduction Rates (FeRR) shows that the increase in FeRR corresponds to a decrease in demethylation, indicating that iron reduction may influence net methylation in the SLR sediments by decreasing demethylation rather than favouring methylation.
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Lavoie RA, Hebert CE, Rail JF, Braune BM, Yumvihoze E, Hill LG, Lean DRS. Trophic structure and mercury distribution in a Gulf of St. Lawrence (Canada) food web using stable isotope analysis. Sci Total Environ 2010; 408:5529-5539. [PMID: 20810146 DOI: 10.1016/j.scitotenv.2010.07.053] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 07/19/2010] [Accepted: 07/21/2010] [Indexed: 05/29/2023]
Abstract
Even at low concentrations in the environment, mercury has the potential to biomagnify in food chains and reaches levels of concern in apex predators. The aim of this study was to relate the transfer of total mercury (THg) and methylmercury (MeHg) in a Gulf of St. Lawrence food web to the trophic structure, from primary consumers to seabirds, using stable nitrogen (δ(15)N) and carbon (δ(13)C) isotope analysis and physical environmental parameters. The energy reaching upper trophic level species was principally derived from pelagic primary production, with particulate organic matter (POM) at the base of the food chain. We developed a biomagnification factor (BMF) taking into account the various prey items consumed by a given predator using stable isotope mixing models. This BMF provides a more realistic estimation than when using a single prey. Lipid content, body weight, trophic level and benthic connection explained 77.4 and 80.7% of the variation in THg and MeHg concentrations, respectively in this food web. When other values were held constant, relationships with lipid and benthic connection were negative whereas relationships with trophic level and body weight were positive. Total Hg and MeHg biomagnified in this food web with biomagnification power values (slope of the relationship with δ(15)N) of 0.170 and 0.235, respectively on wet weight and 0.134 and 0.201, respectively on dry weight. Values of biomagnification power were greater for pelagic and benthopelagic species compared to benthic species whereas the opposite trend was observed for levels at the base of the food chain. This suggests that Hg would be readily bioavailable to organisms at the base of the benthic food chain, but trophic transfer would be more efficient in each trophic level of pelagic and benthopelagic food chains.
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Affiliation(s)
- Raphael A Lavoie
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada K1N 6N5.
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Avramescu ML, Zhu J, Yumvihoze E, Hintelmann H, Fortin D, Lean DRS. Simplified sample preparation procedure for measuring isotope-enriched methylmercury by gas chromatography and inductively coupled plasma mass spectrometry. Environ Toxicol Chem 2010; 29:1256-1262. [PMID: 20821567 DOI: 10.1002/etc.158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Many procedures have been developed to measure the concentration of monomethylmercury (MeHg) from different sample matrices, and the use of stable isotopes of mercury now provides opportunities to determine its formation and degradation rates. Here, a modified procedure for measuring mercury isotopes in sediment samples that uses acid leaching-ion exchange-thiosulfate extraction (TSE) to isolate and purify the methylated mercury from the matrix is proposed. The latter is followed by aqueous-phase ethylation, purge and trap on Tenax, gas chromatography separation of ethylated mercury compounds, and inductively coupled plasma mass spectrometry detection. The new TSE procedure bridges together two well-known methods, the acid-leaching and distillation-derivatization procedures, offering the advantages of artifact-free formation of the first, and low detection limits and the possibility of quantification of individual isotopes of mercury of the second. The modified procedure retains the derivatization, purge and trap, and gas chromatography and inductively coupled plasma mass spectrometry (GC-ICP-MS) detection steps from the distillation-derivatization procedure, and eliminates the distillation step, which is not only laborious but also expensive, due to the high cost of installation and time-consuming cleaning process. Major advantages of the TSE procedure proposed include the extraction and analysis of a large number of samples in a short time, excellent analyte recoveries, and the lack of artifact formation. Sediment certified reference materials (CRMs), BCR 580 and IAEA 405, were used to test the TSE procedure accuracy. Recoveries between 94 to 106% and 95 to 96% were obtained for CRMs and spiked samples (Milli-Q(R) water), respectively. Comparisons among thiosulfate extraction, distillation, and acid-leaching procedures have shown good agreement of methylmercury values.
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Poissant L, Pilote M, Yumvihoze E, Lean D. Mercury concentrations and foliage/atmosphere fluxes in a maple forest ecosystem in Québec, Canada. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jd009510] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Constant P, Poissant L, Villemur R, Yumvihoze E, Lean D. Fate of inorganic mercury and methyl mercury within the snow cover in the low arctic tundra on the shore of Hudson Bay (Québec, Canada). ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jd007961] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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