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.

0

1

2

3

4

5

6

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

Thank you for your attentionc.merly@brgm.frv.guerin@brgm.fr