Use of Phytoremediation to Mitigate Mercury Pollution

Caused by Artisanal Gold Mining

Daren Many & Natalie GordonBZ 572

The World’s Worst Pollution Problems – The Top Ten of the Toxic Twenty (2008)Indoor Air PollutionUrban Air QualityUntreated SewageGroundwater

ContaminationContaminated Surface

WaterArtisanal Gold

Mining

Industrial Mining Activities

Metals smelting and processing

Radioactive Waste and Uranium Mining

Used Lead Acid Battery Recycling

Source: BlacksmithInstitute.org

Artisanal Mining Process– Mercury Amalgamation

Photo credit: David Cleary

AmalgamationSeparationDecompositionGold Melting

Potential for Mercury PollutionAmalgamation Spillage

Separation Residual Hg Discharge

Decomposition Release of vapors

Gold Melting Release of vapors

What is Mercury (Hg)

Three forms:• Elemental mercury (Hg(0)) – liquid or

vapor form• Ionic Salts – mercurous (I) or mercuric (II)

states• Organometallic compound -

methylmercury

Why is Hg Dangerous?Elemental Hg converted to Methyl Mercury through oxidation and methylation.

Hg (0)

Hg (II)

Methyl Hg

Artisanal Mining PollutionBiggest challenge with small-scale mining: Mercury in the atmosphere and Mercury poisoning

Photo credit: Blacksmith Institute

Skin rash caused by handling inorganic mercury

Entire families can inhale the gaseous mercury

Map of World Gold Mining Activities – Artisanal Mining

Current Mercury Pollution Remediation Practices

Worldwide there are no real mercury pollution cleanups occurring due to a lack of funding and/or interest.

Phytoremediation of Mercury

Phytovolatization

Liriodendron tulipifera

Arabidopsis thaliana

Nicotiana tabacum

Phytovolatization

Mercury transformed into less toxic form

Genetic Engineering

Volatized mercury will eventually be recycled

Phytomining for Gold

Studies being done to phytomine gold and extract Hg simultaneously using Canola.

Adjuvants used to increase gold solubility and uptake

Phytomining

Offsets expense of remediation

Returns land to agriculture

Adjuvants may mobilize elements into groundwater

Will phytoremediation actually work?

In-S

itu

Tre

atm

en

t • Soil Vapour extraction

• Reactive Walls• In-Situ

Leaching• Chemical

Immobilization• Water

Interceptors• Phytoremediati

on• Wetlands

Con

tain

men

t &

C

ove

rin

g• Inert Covers• Reactive

Covers

Rem

ove

an

d T

reat • Physical

Separation• Hydrometallurgi

cal• Thermal

Responses to Point Source Mercury Contamination

Hinton et al., 2001

What’s The Best Solution?A hybrid approach:• Phytoremediation to volatilize mercury

already in soil/water• Introduction of cleaner gold mining

methods, including use of retorts• Education of miners on the proper use

and handling of mercury and on better extraction options

Citations:Anderson, Chris, Meech, John A.. (2002). Growing Gold: Using Metal Accumulating Plants to Produce Gold. Available: http://www.mining.ubc.ca/cerm3/growing%20metals.html.

Blacksmith Institute. http://www.blacksmithinstitute.org/artisanal-gold-mining.html

Blue, Lisa Y., Van Aelstyn, Mike A., Matlock, Matthew and Atwood, David A. 2008. Low-level mercury removal from groundwater using a synthetic chelating ligand. Water Research 42(8- 9):2025-2028.

Davila, J. 2009. Mercury reduction by bacteria isolated from informal mining zones. Advanced Materials Research 71-73():637-640.

Ebbs, Stephen D., Kolev, Spas D., Piccinin, Robert C.R., Woodrow, Ian E., Baker, Alan J.M.. (2010). Solubilization of heavy metals from gold ore by adjuvants used during gold phytomining. Minerals Engineering. 23 , p. 819-822.

Elena Rodrigueza; Jason G. Parsonsb; Jose R. Peralta-Videab; Gustavo Cruz-Jimenezc; Jaime Romero-Gonzalezc; Blanca E. Sanchez-Salcidob; Geoffrey B. Saupeb; Maria Duarte-Gardead; Jorge L. Gardea-Torres. (2007). Potential of Chilopsis Linearis for Gold Phytomining: Using Xas to Determine Gold Reduction and Nanoparticle Formation Within Plant Tissues . International Journal of Phytoremediation. 9 (2), p.133-147.

Henry, Jeanna R.. (2000). An Overview of the Phytoremediation of Lead and Mercury. National Network of Environmental Management Studies, p. 1-55.

Jadia, Chhotu D., Fulekar, M.H. 2008. Phytoremediation of heavy metals: Recent techniques. African Journal of Biotechnology 8(6):921-928.

Citations cont’d:Lone,Mohammad Iqbal, He, Zhen-li, Stoffella, Peter J., Yang, Xiao-e. (2008). Phytoremediation of heavy metal polluted soils and water: Progresses and perspectives. Journal of Zhejiang University. 9 (3), p. 210-220.

Moreno, Fabio N., Anderson, Christopher W.N., Stewart, Robert B., Robinson, Brett H. 2007. Phytofiltration of mercury-contaminated water: volatilzation and plant-accumulation aspects. Environmental and Experimental Biology 62:78-85.

Mulligan, C.N., Yong, R.N. and Gibbs, B.F. 2001. Remediation technologies for metal-contaminated soils and groundwater: an evaluation. Engineering Geology 60(1-4):193-207.

Padmavathiamma, P. 2007. Phytoremediation technology: hyper-accumulation metals in plants. Water, Air and Soil Pollution 184(1-4):105-126.

Renault, S., Szczerski, C., Sailerova, E., Fedikow, M.A.F.. (2004). Phytoremediation and revegetation of mine tailings and bio-ore production: progress report on plant growth in amended tailings and metal accumulation in seedlings planted at Central Manitoba minesite.. Report of Activities. 1 (1), p257-261.

Rugh, C., Meagher, R.B.. (2003). Phytoremediation Technologies. Available: http://rydberg.biology.colostate.edu/Phytoremediation/2003/Amy/phytoremediationtechnologies.html.

Speigel, S. 2010. International guidelines on mercury management in small-scale gold mining. Journal of Cleaner Production 18(4):375-385.

Veiga, Marcello M. and Hinton, Jennifer J. 2002. Abandoned artisanal gold mines in the Brazilian Amazon: a legacy of mercurypollution. Natural Resources Forum 26:15-26.