Earthworms as a Bioindicator of Mercury Pollution in an Artisanal Gold Mining Community: Cachoeira do Piriá, Brazil Jennifer J. Hinton B.A.Sc. Geological Engineering The University of British Columbia Dept. of Mining Engineering Marcello Veiga Professor of Mining Engineering
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Earthworms as a Bioindicator of Mercury Pollution in an Artisanal Gold Mining Community: Cachoeira do Piriá, Brazil Jennifer J. Hinton B.A.Sc. Geological.
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Earthworms as a Bioindicator of Mercury Pollutionin an Artisanal Gold Mining Community:
Cachoeira do Piriá, Brazil
Jennifer J. HintonB.A.Sc. Geological Engineering
The University of British ColumbiaDept. of Mining Engineering
Effluent from active mining area entering Barriquinha Creek
Cachoeira – Mercury Distribution (cont…)
1000
1000
0
Cachoeira – Mercury Distribution
Mercury Concentration (ppb)
Approx. 1 km
CurrutelaCreek
BarriquinhaCreek
Lake Cachoeira
Cachoeira
Cachoeira – Mercury in Fish
Traíra 925 ppb 68%
Jejú 1274 ppb 100%
Mãe Rosa 667 ppb 63%
Mandi* 108 ppb 0%
Acará 347 ppb 21%
Piaba 215 ppb 0%
FISH Hg (ppb) % > 500 ppb
Herbivorous
Carnivorous
* Mandi omnivorous
CachoeiraAdult Male 2Adult Female 4Child (1-4 yrs) 14
Bela VistaAdult Male 6Adult Female 17Child (1-4 yrs) 56
Exposure Times aboveGroup Safe Limit
A Comparative Methodology
How do materials influence bioavailability?
How to identify/prioritize “hot spots”?
Simple, Low-Cost Methodology Using Earthworms:• Accumulate Heavy Metals from soil and other media
• Ingest large quantities of soil and are in full contact with the substrate they consume
• Participate in many food chains
• Constitute up to 92% of Invertebrate Biomass in soils
• Eisenia foetida species recognized for toxicity testing by several international organizations (Including: European Economic Community, U.S. EPA, ASTM, etc.)
Can bioavailability be reduced?
Invertebrate Protocols
ASTM 1676-95 Standard Guide for conducting laboratory soil toxicity tests for the Earthworm Eisenia foetida
US EPA 600R94024 Methods for measuring the Toxicity and Bioaccumulation of Sediment-Associated Contaminants with Freshwater Invertebrates
ASTM 1383-93A Standard Guide for Conducting Sediment Toxicity Tests with Freshwater Invertebrates
Lockheed Martin Environmental Restoration Program: Development and Validation of Bioaccumulation Models for Earthworms
Goats and Edwards (1988) – Prediction of Field Toxicity of Chemicals to Earthworms by Laboratory Methods
Hazardous Materials Assessment Team (HMAT) – 14-Day Soil Test using Earthworms
{ }Jars
20 Worms 60g Soil/sand + 80 ml 20 g. cellulose #1
Distilled Water Organic Acids { }
Earthworm Methodology
28d Exposure
CVAADigested tissuesanalyzed#4
DepurationWorms removed, cleaned, weighedand starved for 24 hrs. #2
AcidDigestion
Worms cleaned, weighed andtissues dissolved in 0.7M HNO3#3
Experimental Program
Earthworm Protocol
Solutions Soils / Sediments / Tailings
1. Evaluate the efficacy of the methodology.
6 Series of Tests
2. Determine influence of specific variables.
3. Assess the bioavailability of Hg-organic complexes.
1. Evaluate the efficacy of the methodology.
7 Series of Tests
2. Compare the effectiveness of different soils in inhibiting Hg bioavailability.
3. Assess the influence of organic acids on Hg bioavailability.