Biogeochemistry Biogeochemistry and Natural and Natural - - PowerPoint PPT Presentation

Biogeochemistry Biogeochemistry and Natural and Natural Attenuation of Attenuation of Acid Acid-

• Mine

Mine Drainage at Davis Drainage at Davis Pyrite Mine, Pyrite Mine, Rowe MA Rowe MA

Richard F. Yuretich David Ahlfeld Sarina Ergas Allan Feldman Klaus Nüsslein

UMass Amherst

Davis Mine

• Town of Rowe, MA
• Remains of an

abandoned pyrite mine

• Small area

– Ore body: 15 ha – AMD area: 3-4 ha

Davis Mine

Acidic Mine Effluent 100 m Shaft #1

Geology

• f Davis Mine
• Located in northwestern

Massachusetts.

• Sulfide mineralization

primarily (Fe)-Cu-Zn, low Pb and As.

• Scattered sulfide ore

bodies along NE-SW trend.

• Hydrothermal origin

related to arc volcanism

Davis Mine, Rowe, MA

• Pyrite extracted from 1886

until 1910.

• Collapsed because of poor

mining practices.

Shaft #1

Davis Mine, Rowe, MA

• Leaching acidity, iron, sulfate, and other metals into

nearby brook

Shaft #1

pH Cond Na Fe Zn Cl SO4 SiO2 Normal 5.7 20 2.2 0.27 0.08 2.61 8.12 5.14 Effluent 3.19 134 5.75 22.5 4.51 5.32 178.5 26.7

Pristine vs. Impacted Water

Initial Monitoring Network

• Mine effluent drains

from Shaft #1 into Davis Mine Brook.

• Three sampling points

along effluent stream.

Site 1 Mine Shaft Well #2

Site 2 Well #8

Well #13

pH, SO4 in Mine Effluent

50 100 150 200 250

SO4

Concentration (mg/l) 2.85

3.17 3.07 2.97

2.90 2.95 3.00 3.05 3.10 3.15 3.20

Site #1 Site #2 Site #3

pH

Trace Elements in Mine Effluent

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 Fe Mn Al Cu Zn Concentration (mg/l)

33.80 0.51 2.26 0.79 4.59

Site #1

14.36 0.59 2.88 0.65 4.07

Site #2

23.57 1.27 3.83 0.97 4.89

Site #3

Fe, Zn highest at mine entrance Precipitates via oxidation downstream Augmented by groundwater from tailings Mn, Al, (Cu) increase downstream

Present Study

• Impacts upon

Davis Mine Brook downstream from effluent

• Biogeochemistry
• f natural

attenuation

Davis Mine Brook: A4 to B4

Davis Mine Brook: Well 2 and Power Lines

pH, SO4 in Davis Mine Brook

Downstream 5 10 15 20 25 30

Concentration mg/l

Mine Effluent Input A4 B1 B2 B3 B4 W 2 P. L.

• S. X

3.50 4.00 4.50 5.00 5.50 6.00 pH

Mine Effluent Input

A4 B1 B2 B3 B4 W 2 P. L.S. X Downstream

Trace Elements: Davis Mine Brook

Zn, Al, most persistent trace elements Fe disappears more rapidly downstream Dilution by tributary has greatest effect Brook “macrobiota- free” for ~5 km

0.00 0.50 1.00 1.50 2.00 2.50 Fe Mn Zn Cu Al Concentration (mg/l) Stream Xing B1 B2 B3 B4 Near Well 2 Power Lines Stream Xing

Groundwater

• Hand-augur wells

1994-95

• Multi-level monitoring

wells installed April, 2003

• Geochemical and

hydrological modeling

• Assessment of rates and

mechanisms of natural remediation

• Documentation of

sulfate and iron- reducing bacteria

Groundwater Wells

Shallow wells 1994-95 Multilevel wells Installed April, 2003

• Acidification of

groundwater locally intense

• Extreme values found

in old tailings piles

• Ambient groundwater

from unimpacted areas helps restrict the AMD zone

• Iron “hot zone”

confined to small area

• f groundwater.
• Greater extension to S

down Davis Mine Brook.

• Reflects the more

complicated redox and solubility behavior of Fe.

• Sulfate shows

extensive area of elevated concentration.

• Reduction only

possible removal mechanism

Down Gradient Trends

• Three 1994-95

shallow wells ~1m deep

Trace Elements in Groundwater

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 Fe Mn Al Cu Zn Concentration (mg/l)

9.17 0.46 1.82 0.53 3.36

Well #2

32.44 2.14 6.55 1.76 12.35

Well #8

40.65 1.30 6.83 2.05 6.76

Well #13

Fe, Al, Cu increase down gradient Mn, Zn highest in Well #8, where hydraulic conductivity is lowest

Considerations

• Low pH limits ability of oxyhydroxides to

absorb Zn, Cu

• H2S odor noticeable is some areas = active

sulfate reduction by anaerobic microorganisms?

• CuS has lower solubility than ZnS, so Cu

would be scavenged preferentially on sulfide precipitates

Secular Variations in Groundwater

Zn in Groundwater

2 4 6 8 10 12 14 16 3/7/94 4/26/94 6/15/94 8/4/94 9/23/94 11/12/9 4 1/1/95 2/20/95 4/11/95 Concentration (mg/l)

Well #2 Well #8 Well #13

Secular Variations in Groundwater

Cu in Groundwater

1 2 3 4 5 6 7 8 9 10 3/7/94 4/26/94 6/15/94 8/4/94 9/23/94 11/12/94 1/1/95 2/20/95 4/11/95 Concentration (mg/l)

Well #2 Well #8 Well #13

Secular Variations in Groundwater

Zn/Cu Ratio in Groundwater

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 3/7/94 4/26/94 6/15/94 8/4/94 9/23/94 11/12/94 1/1/95 2/20/95 4/11/95 Concentration Ratio

Well #2 Well #8 Well #13

Natural Remediation?

• Active microbial sulfate reduction promotes

preferential removal of dissolved Cu on precipitated sulfides.

• High Zn/Cu ratios in groundwater point

towards this process.

• Seasonal patterns reflect variations in

microbial activity.

y = 0.6907x + 15.37 R2 = 0.2083 200 400 600 800 1000 100 200 300 400 500 600 ORP (mV) Sulfate (mg/ l)

Additional evidence of sulfate reduction

Cultivating Reducing Bacteria

Sulfate-reducing bacteria are present in this environment

Ongoing research supported by the National Science Foundation “Biocomplexity in the Environment” Program CHE-0221791

Ongoing Investigation Ongoing Investigation

• Continued field monitoring

Continued field monitoring

• Column studies to model geochemistry

Column studies to model geochemistry

• DNA identification

DNA identification

• Enrichment cultures and community ID

Enrichment cultures and community ID

• Benefits of research to K12 teachers

Benefits of research to K12 teachers

Ongoing research supported by the National Science Foundation “Biocomplexity in the Environment” Program CHE-0221791

Thanks to the Team! Thanks to the Team!

• Jessica Bloom

Jessica Bloom

• Liam

Liam Bevan Bevan

• Melissa Russell

Melissa Russell

• Mercedita

Mercedita Monserrate Monserrate

• Krissy

Krissy Forloney Forloney

• Phil Dixon

Phil Dixon

• Cristine

Cristine Barreto Barreto

• Jason Jean

Jason Jean

• Janice Wing

Janice Wing

• Jaime Harrison

Jaime Harrison

• Melinda Solomon

Melinda Solomon