best technologies versus current practices in mercury ... · best technologies versus current...
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Best technologies versus current practices in mercury contaminated land management:
Results of the IMaHg survey
Enhanced knowledge in mercury fate and transport for Improved Management of Hg soil contamination
C. Merly, V. Guérin, Y. Ohlsson, D. P.-E. Back, Berggren Kleja, D. Jacques, B. Leterme, R. Sweeney
Mercury Regulatory Context
Stringent regulatory framework for mercuryemissions and risk control
Negotiations at international level:UNEP GC/GMEF (2007 and on going)Minamata international convention (2013)Legally binding document in preparation (2013)
At EU levelBanned export of metallic mercury outside Europe(2008)End of industrial use of Hg (2020-2028)
No EU specific regulations for managingmercury present as “non pure phase” productin the various compartments of the soil.
=> Need for improving and sharing expertise inidentifying, assessing, managing andremediating mercury.
Mercury CL management issues and challenges
Multiple sources of emissions: industrial, mining & coalcombustionDiffuse and point source pollutionMultiple forms of mercury having very different fate andtransport
Leterne & Jacques 2012
Very variable toxicity
IMaHg Project objectives
Main objectivesImprove the understanding of mercury speciation(chemical forms) and partition (physical forms) in thevadose zoneGive recommendations for characterisation, assessmentand management of mercury contaminationStress gaps and future needs to improve managementof mercury contaminated land.
Specific objectivesTo compile physical, chemical and thermodynamicconstants of mercury forms & to improve mercurygeochemical modellingTo compare available and currently used practices incharacterisation, risk assessment and management ofmercuryTo draw some recommendations and identify furtherresearch needs for mercury management
IMaHg – Current management practices
EU wide consultation based on a questionnairedesigned in four sections
CharacterisationRisk assessmentRemediation
Regulatory aspects
Targeted audience: service providers, problem owners,regulators and researchersDissemination through national contacts points and CLnetworks such as SNOWMAN, Common Forum,Heracles, NICOLE Hg Working group and Eurodemo+,International Committee on Contaminated Land.
Methodology
• References of national technical guidance• Feedback on current practices –
“interesting” case study• Difficulties faced & needs for future R&D
• Implementation of Hg regulation • Development of guidelines for Hg
management
IMaHg – Current management practicesResults – overview on participation
39 answers18 countries: 13 EU countries, 5 non EU countries
Reported case studies: 1/3 Chloroalkali-plants, mining activities,“other” industrial activities, measurement equipment industry, electricindustry and wood treatment plant industry.
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1
2
3
4
5
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Austria
Belgium
Czech Re
public
France
Germany
Ireland
Lithuania
Nethe
rland
Poland
Spain
Swed
en
Swissland UK
USA
Australia
New
Zealand
South Africa
Brazil
University
Research Institute
Industry
Regulatory bodies
Service providers
0510152025
IMaHg – Current management practicesResults – Characterisation
24 answers
Sub-surface compartments
pH, EH
Clay contentSolid organic content
Other parameters
SoilSedimentGroundwater
IMaHg – Current management practicesResults – Soil Characterisation
Soil sampling technologiesIssue of volatilisationDownwards migration
Soil screening was performed in 30% of the casesAnalyses of speciation in 42% of the case
100% Hg0
75% Methylmercury38% Cinnabar
Four types of solid speciation metods: extraction,thermal desorption, spectroscopic and EXAFNeed for method standardisation and development toprovide reliable solid speciation at reasonable price
IMaHg – Current management practicesResults – Water & Gas Characterisation
Characterisation of Hg speciation - Water1/3 case reported speciation
Need for reliable analytical method HgCH3
Water Passive samplers and specific probes gave badreproducibility
-------------------------------------------------------------------Gas analysis were performed in 1/5 of the reportedcases in order to determine:
1. Ambient air (73%)2. Soil gas (36%)3. Indirect Source identification (45%)
Systematic characterisation of Hg0 and organic mercuryhalf of the reported case studyNeed for better qualified operators for better dataacquisition and interpretation
IMaHg – Current management practicesResults – Characterisation
Representativeness 2,1Knowledge of mercury species fate and transport 2,1Loss of mercury associated with sampling protocol 2,8Change of in‐situ conditions, while sampling 3,0Matrix effect 3,0
Yes No ImprovementFor solid 7 1 3For water 5 2For gas 4 1 1For fauna 2 1 1For flora 2 1 1Technologies exists but must be used more systemically
Solid: Speciation (Speciation analysis and Solid PhaseThermo Desorption), Standardization of sampling strategyWater: SpeciationFlora: Assessment of mercury deposition
Pitfalls (1 is very important and 5 is the least important)
Needs for new tools
IMaHg – Current management practicesResults – Risk assessment
21 answers
Protection targets for mercury contaminationMercury species:
Total mercury was usually considered in the RAOrganic mercury was considered in 10% of the cases
Human Health RA:40% comparison with generic guidelines values40% site specific RA20% combination of both generic and specific
29%
21%17%
14%
12%
5%
2%
Human health
Ecology/environment
Groundwater
Surface water
Fish
Crops/vegetables
Others
IMaHg – Current management practicesResults – Risk assessment
Exposure pathways depends on phase partitioningKd approachMeasurements of pore gas and pore water concentrationsGeochemical modelling
Improvement for risk assessmentComplex as it is site specificOral intake pathways – bioavailability testsVapor intrusion pathways - pore gas measurementsDevelopment of Hg-specific transfer model (vaporexposure in particular)Better understanding of the MeHg bioamplification andaccumulation in the foodchainFor ecosystems, measurements of methylmercury apartof total HgBy more systematic application and definition oftoxicological dose-effect-values (RfD, RfC, UR, etc.) forall Hg-Species
IMaHg – Current management practices
20 answersType of remediation thresholds
Did you look at mercury forms to select the remediationtechnology?
Yes: 42% No: 58%If Yes, in accordance with Regulatory bodies, pilottest, based on RA, available treatment
Results - Remediation
Type of remediation technologies used (in-situ vs ex-situ)
Results - Remediation
For contaminated water
For contaminated soil
For contaminated gas: captureon activated carbon
IMaHg – Current management practices
Main difficulties encountered
“Solutions”Only ex-situ method usedBy prior technical-economic feasibility study and field pilottestsGood and Enough sampling and quick measurement
Results – Remediation difficulties
Remobilisation of Hg during the remediation process 1,9Insufficient knowledge in Hg fate and transport 2Lack of Hg contamination characterisation 2,3Matrix effect 2,6Achievement of the remediation goal 2,6Lack of efficient remediation technologies 2,8Presence of cocktail of Hg species having very different fate in the environment 3,1Interaction of mercury with other contaminants 3,2
IMaHg – Current management practices
Technology development and implementationRe-inforce passive & in-situ treatments for costreductionMore cost effective techniques for element mercuryrecovery from soils as opposed to segregation,solidification and disposal
Management / GuidelinesSpread of mercury by earthmoving equipment duringexcavation work is a concern that must be managedDevelopment of a guideline for BAT selectionImportance of a very good characterisationFurther education and understanding on fate,transport and species of mercury
Results – RemediationIMaHg – Current management practices
IMaHg – Current management practicesResults – Regulatory aspects
13 responsesLevel of importance of mercury in CL managementdepends on the countriesMercury set as a priority compounds
In Spain, Czech Republic, Belgium, (Australia)Not in France, Switzerland, the Netherlands, and Lithunia(Brazil)
Risk from mercury contaminated sites in comparisonwith the risks from other means of exposure
“medium” for Czech Republic, Netherlands, (Australia &Brazil)“high” for Spain, France and Switzerland“low for Lithuania.
National Hg specific technical guidelines: Germany andFrance
IMaHg – Current management practicesConclusions
Assessment of current Hg management practicesComing IMaHg technical reports
Characterisation report: Synthetic information onadvantages, drawbacks, conditions of use and regulationacceptance of all the main analytical methods andcharacterisation tools.Risk assessment report: Strategy for improved sitespecific risk assessment of Hg contaminated sites. Thisinvolves for the most important exposure pathways thecurrent practice, potential for improvements and theestimated effect on the risk assessment outcome.Remediation report: Performance of remediationtechnologies, their applicability in EU context, theiracceptance regarding the risk associated with adverseeffects from the remediation works (remobilisation to theair and/or water) and their efficiency regarding thedifferent forms of mercury
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