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Sommar J, Osterwalder S, Zhu W. Recent advances in understanding and measurement of Hg in the environment: Surface-atmosphere exchange of gaseous elemental mercury (Hg 0). THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 721:137648. [PMID: 32182462 DOI: 10.1016/j.scitotenv.2020.137648] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 02/26/2020] [Accepted: 02/28/2020] [Indexed: 05/26/2023]
Abstract
The atmosphere is the major transport pathway for distribution of mercury (Hg) globally. Gaseous elemental mercury (GEM, hereafter Hg0) is the predominant form in both anthropogenic and natural emissions. Evaluation of the efficacy of reductions in emissions set by the UN's Minamata Convention (UN-MC) is critically dependent on the knowledge of the dynamics of the global Hg cycle. Of these dynamics including e.g. red-ox reactions, methylation-demethylation and dry-wet deposition, poorly constrained atmosphere-surface Hg0 fluxes especially limit predictability of the timescales of its global biogeochemical cycle. This review focuses on Hg0 flux field observational studies, namely the theory, applications, strengths, and limitations of the various experimental methodologies applied to gauge the exchange flux and decipher active sub-processes. We present an in-depth review, a comprehensive literature synthesis, and methodological and instrumentation advances for terrestrial and marine Hg0 flux studies in recent years. In particular, we outline the theory of a wide range of measurement techniques and detail the operational protocols. Today, the most frequently used measurement techniques to determine the net Hg0 flux (>95% of the published flux data) are dynamic flux chambers for small-scale and micrometeorological approaches for large-scale measurements. Furthermore, top-down approaches based on Hg0 concentration measurements have been applied as tools to better constrain Hg emissions as an independent way to e.g. challenge emission inventories. This review is an up-dated, thoroughly revised edition of Sommar et al. 2013 (DOI: 10.1080/10643389.2012.671733). To the tabulation of >100 cited flux studies 1988-2009 given in the former publication, we have here listed corresponding studies published during the last decade with a few exceptions (2008-2019). During that decade, Hg stable isotope ratios of samples involved in atmosphere-terrestrial interaction is at hand and provide in combination with concentration and/or flux measurements novel constraints to quantitatively and qualitatively assess the bi-directional Hg0 flux. Recent efforts in the development of relaxed eddy accumulation and eddy covariance Hg0 flux methods bear the potential to facilitate long-term, ecosystem-scale flux measurements to reduce the prevailing large uncertainties in Hg0 flux estimates. Standardization of methods for Hg0 flux measurements is crucial to investigate how land-use change and how climate warming impact ecosystem-specific Hg0 sink-source characteristics and to validate frequently applied model parameterizations describing the regional and global scale Hg cycle.
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Affiliation(s)
- Jonas Sommar
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China.
| | - Stefan Osterwalder
- Institut des Géosciences de l'Environnement, Université Grenoble Alpes, CNRS, IRD, Grenoble INP, Grenoble, France
| | - Wei Zhu
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
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Osterwalder S, Huang JH, Shetaya WH, Agnan Y, Frossard A, Frey B, Alewell C, Kretzschmar R, Biester H, Obrist D. Mercury emission from industrially contaminated soils in relation to chemical, microbial, and meteorological factors. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 250:944-952. [PMID: 31085481 DOI: 10.1016/j.envpol.2019.03.093] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 03/21/2019] [Accepted: 03/22/2019] [Indexed: 06/09/2023]
Abstract
The Minamata Convention entered into force in 2017 with the aim to phase-out the use of mercury (Hg) in manufacturing processes such as the chlor-alkali or vinyl chloride monomer production. However, past industrial use of Hg had already resulted in extensive soil pollution, which poses a potential environmental threat. We investigated the emission of gaseous elemental mercury (Hg0) from Hg polluted soils in settlement areas in the canton of Valais, Switzerland, and its impact on local air Hg concentrations. Most soil Hg was found as soil matrix-bound divalent Hg (HgII). Elemental mercury (Hg0) was undetectable in soils, yet we observed substantial Hg0 emission (20-1392 ng m-2 h-1) from 27 soil plots contaminated with Hg (0.2-390 mg Hg kg-1). The emissions of Hg0 were calculated for 1274 parcels covering an area of 8.6 km2 of which 12% exceeded the Swiss soil remediation threshold of 2 mg Hg kg-1. The annual Hg0 emission from this area was approximately 6 kg a-1, which is almost 1% of the total atmospheric Hg emissions in Switzerland based on emission inventory estimates. Our results show a higher abundance of Hg resistance genes (merA) in soil microbial communities with increasing soil Hg concentrations, indicating that biotic reduction of HgII is likely an important pathway to form volatile Hg0 in these soils. The total soil Hg pool in the top 20 cm of the investigated area was 4288 kg; hence, if not remediated, these contaminated soils remain a long-term source of atmospheric Hg, which is prone to long-range atmospheric transport.
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Affiliation(s)
- Stefan Osterwalder
- Environmental Geosciences, University of Basel, 4056 Basel, Switzerland; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden.
| | - Jen-How Huang
- Environmental Geosciences, University of Basel, 4056 Basel, Switzerland
| | - Waleed H Shetaya
- Environmental Geosciences, University of Basel, 4056 Basel, Switzerland; Air Pollution Research Department, Environmental Research Division, National Research Centre, Dokki, Giza 12622, Egypt
| | - Yannick Agnan
- Sorbonne Université, CNRS, EPHE, UMR Metis, 75252 Paris, France
| | - Aline Frossard
- Federal Research Institute WSL, 8903 Birmensdorf, Switzerland
| | - Beat Frey
- Federal Research Institute WSL, 8903 Birmensdorf, Switzerland
| | - Christine Alewell
- Environmental Geosciences, University of Basel, 4056 Basel, Switzerland
| | - Ruben Kretzschmar
- Institute of Biogeochemistry and Pollutant Dynamics, CHN, ETH Zürich, Zürich, Switzerland
| | - Harald Biester
- Institut für Geökologie, AG Umweltgeochemie, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Daniel Obrist
- Department of Environmental, Earth and Atmospheric Sciences, University of Massachusetts, Lowell, MA 01854, USA
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Agnan Y, Le Dantec T, Moore CW, Edwards GC, Obrist D. New Constraints on Terrestrial Surface-Atmosphere Fluxes of Gaseous Elemental Mercury Using a Global Database. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:507-24. [PMID: 26599393 DOI: 10.1021/acs.est.5b04013] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Despite 30 years of study, gaseous elemental mercury (Hg(0)) exchange magnitude and controls between terrestrial surfaces and the atmosphere still remain uncertain. We compiled data from 132 studies, including 1290 reported fluxes from more than 200,000 individual measurements, into a database to statistically examine flux magnitudes and controls. We found that fluxes were unevenly distributed, both spatially and temporally, with strong biases toward Hg-enriched sites, daytime and summertime measurements. Fluxes at Hg-enriched sites were positively correlated with substrate concentrations, but this was absent at background sites. Median fluxes over litter- and snow-covered soils were lower than over bare soils, and chamber measurements showed higher emission compared to micrometeorological measurements. Due to low spatial extent, estimated emissions from Hg-enriched areas (217 Mg·a(-1)) were lower than previous estimates. Globally, areas with enhanced atmospheric Hg(0) levels (particularly East Asia) showed an emerging importance of Hg(0) emissions accounting for half of the total global emissions estimated at 607 Mg·a(-1), although with a large uncertainty range (-513 to 1353 Mg·a(-1) [range of 37.5th and 62.5th percentiles]). The largest uncertainties in Hg(0) fluxes stem from forests (-513 to 1353 Mg·a(-1) [range of 37.5th and 62.5th percentiles]), largely driven by a shortage of whole-ecosystem fluxes and uncertain contributions of leaf-atmosphere exchanges, questioning to what degree ecosystems are net sinks or sources of atmospheric Hg(0).
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Affiliation(s)
- Yannick Agnan
- Division of Atmospheric Sciences, Desert Research Institute , Reno, Nevada 89523, United States
| | - Théo Le Dantec
- Université de Toulouse ; INP, UPS; EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement); ENSAT, Avenue de l'Agrobiopole, F-31326 Castanet-Tolosan, France
- CNRS; EcoLab; F-31326 Castanet-Tolosan, France
| | - Christopher W Moore
- Division of Atmospheric Sciences, Desert Research Institute , Reno, Nevada 89523, United States
| | - Grant C Edwards
- Department of Environmental Sciences, Faculty of Science and Engineering, Macquarie University , Sydney, New South Wales, Australia
| | - Daniel Obrist
- Division of Atmospheric Sciences, Desert Research Institute , Reno, Nevada 89523, United States
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Moore CW, Castro MS. Investigation of factors affecting gaseous mercury concentrations in soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 419:136-43. [PMID: 22281042 DOI: 10.1016/j.scitotenv.2011.12.068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 12/29/2011] [Accepted: 12/30/2011] [Indexed: 05/04/2023]
Abstract
The purpose of this study was to determine the effects of soil temperature, soil moisture, redox potential (Eh) and soil organic matter (SOM) on the total gaseous mercury (TGM) concentrations in background soils. Our measurements were made in a grass field and deciduous forest at the Piney Reservoir Ambient Air Monitoring Station (PRAAMS) in Garrett County, Maryland. Three plots in each area were sampled every third week from July 2009 to June 2010 at the Oe-A soil horizon interface, the A-E soil horizon interface, and 5 and 10 cm into the E soil horizon. The mean soil TGM concentration for all depths in the forest (2.3 ± 2.2 ng m(-3)) was significantly higher than the mean soil TGM concentration in the grass field (1.5 ± 1.9 ng m(-3)). Soil TGM at all depths was most strongly and consistently correlated to soil temperature. The soil TGM concentrations were highest and most variable at the forest Oe-A soil horizon interface (4.1 ± 2.0 ng m(-3)), ranging from 1.5 to 8.4 ng m(-3). This soil horizon interface had 11 to 26% more SOM and the soil Eh was 100 to 400 mV lower than the other soil depths. Our results suggest that soil temperature, soil Eh and SOM are significant factors affecting TGM concentrations in forest soils. Future studies of TGM dynamics in background soils may benefit from closely monitoring the organic soil horizon.
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Affiliation(s)
- Christopher W Moore
- Division of Atmospheric Science, Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, United States
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Stamenkovic J, Gustin MS, Arnone JA, Johnson DW, Larsen JD, Verburg PSJ. Atmospheric mercury exchange with a tallgrass prairie ecosystem housed in mesocosms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2008; 406:227-238. [PMID: 18775555 DOI: 10.1016/j.scitotenv.2008.07.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 07/27/2008] [Accepted: 07/28/2008] [Indexed: 05/26/2023]
Abstract
This study focused on characterizing air-surface mercury Hg exchange for individual surfaces (soil, litter-covered soil and plant shoots) and ecosystem-level flux associated with tallgrass prairie ecosystems housed inside large mesocosms over three years. The major objectives of this project were to determine if individual surface fluxes could be combined to predict ecosystem-level exchange and if this low-Hg containing ecosystem was a net source or sink for atmospheric Hg. Data collected in the field were used to validate fluxes obtained in the mesocosm setting. Because of the controlled experimental design and ease of access to the mesocosms, data collected allowed for assessment of factors controlling flux and comparison of models developed for soil Hg flux versus environmental conditions at different temporal resolution (hourly, daily and monthly). Evaluation of hourly data showed that relationships between soil Hg flux and environmental conditions changed over time, and that there were interactions between parameters controlling exchange. Data analyses demonstrated that to estimate soil flux over broad temporal scales (e.g. annual flux) coarse-resolution data (monthly averages) are needed. Plant foliage was a sink for atmospheric Hg with uptake influenced by plant functional type and age. Individual system component fluxes (bare soil and plant) could not be directly combined to predict the measured whole system flux (soil, litter and plant). Emissions of Hg from vegetated and litter-covered soil were lower than fluxes from adjacent bare soil and the difference between the two was seasonally dependent and greatest when canopy coverage was greatest. Thus, an index of plant canopy development (canopy greenness) was used to model Hg flux from vegetated soil. Accounting for ecosystem Hg inputs (precipitation, direct plant uptake of atmospheric Hg) and modeled net exchange between litter-and-plant covered soils, the tallgrass prairie was found to be a net annual sink of atmospheric Hg.
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Affiliation(s)
- Jelena Stamenkovic
- Department of Natural Resources and Environmental Science, University of Nevada, Reno, Nevada 89557, USA
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Edwards GC. Development and evaluation of a sampling system to determine gaseous Mercury fluxes using an aerodynamic micrometeorological gradient method. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004jd005187] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Schroeder WH. Gaseous mercury emissions from natural sources in Canadian landscapes. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004jd005699] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Gustin MS. Are mercury emissions from geologic sources significant? A status report. THE SCIENCE OF THE TOTAL ENVIRONMENT 2003; 304:153-167. [PMID: 12663180 DOI: 10.1016/s0048-9697(02)00565-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Geologic sources of atmospheric mercury include areas of fossil and current geothermal activity, recent volcanic activity, precious and base metal deposits, and organic rich sedimentary rocks. Early estimates of emissions from these sources were not based on measurements of mercury fluxes but implied based on the difference between emissions from anthropogenic point sources and wet/dry deposition estimates. In the past approximately 7 years significant progress has been made in development of methods for the measurement of mercury emissions, definition of those parameters most important in controlling emissions and scaling up emissions from natural source areas. This paper summarizes the work done on scaling of emissions from discrete areas of natural enrichment and from the State of Nevada, which is situated within a global belt of mercury enrichment. Preliminary data indicate that elemental mercury is the predominant (>95%) form of mercury being emitted from these sources. Scaling results suggest that the value used in early models to represent emissions from global mercuriferous belts is too low by at least three times.
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Affiliation(s)
- Mae Sexauer Gustin
- Department of Environmental and Resource Sciences, University of Nevada-Reno, Reno, NV 89557, USA.
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Kim KH. Effects of changes in environmental conditions on atmospheric mercury exchange: Comparative analysis from a rice paddy field during the two spring periods of 2001 and 2002. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2003jd003375] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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