biogeochemistry at the confluence of an ard stream with a pristine mountain stream by: austin...
TRANSCRIPT
Biogeochemistry at the confluence of an ARD stream with a pristine
mountain stream
By: Austin Kaliher and Brian Gross
Question at hand
How are the heavy metals, sulfates, and Dissolved Organic Carbons (DOC) in two streams
(Upper Deer Creek and the Snake River) mixing below the their confluence?
Are some of the dissolved heavy metals precipitating out onto the stream bed?
Are the concentrations of DOC and heavy metals changing over time?
How safe is the water in the stream to drink?
Hypothesis If ARD occurs in the Upper Snake River and the water is tested for iron, zinc, and other
heavy metals, and the concentrations on the metals are changing over time, then the
concentrations of these metals will be the highest above the confluence with Deer Creek, the
lowest below the confluence due to dilution and precipitation and the river as a whole will
have a lower concentration of iron than in years past.
Background on Acid Rock Drainage
• Acid Rock Drainage is a process that occurs naturally in streams. ARD occurs when
sulfide minerals react with surrounding oxygen and water to form Sulfuric Acid
• Pyrite is the sulfide mineral most commonly associated with ARD in the Colorado Rocky
Mountains
• This Acidic environment cause heavy metals to dissolve out of the surrounding rock.
Background on Acid Rock Drainage
ARD can be accelerated in areas with historic mining.
The abandoned mine shafts and tills (un-valuable part of ore that is thrown away) greatly
increase surface area which accelerates ARD to unnatural levels.
This is often refereed to as Acid Mine Drainage or AMD.
Background on Acid Rock Drainage
• When ARD is accelerated, the amounts of heavy
metals in the water is increased.
• Zinc is a good indicator of ecological health because
it can be transported over long distances
• Because of this, Zinc can be used to judge overall trends
of metals concentrations relating to ARD
Background on Acid Rock Drainage
• Our research site is at the Confluence of the Upper Snake
River and Deer Creek.
• The Upper Snake River has been affected by ARD over
time
• Deer Creek has remained a relatively pristine creek over
the years
Methods • All water samples were taken in plastic bottles.• Specific test sites were used such as site DC5 which is in
Deer Creek just above the confluence.• All water samples were filtered on site using a hand
pump
and plastic filter.• All discharge measurements were taken using a pigmy-
meter.• All testing of water samples were done at the University
of
Colorado at Boulder
DataZn
0
200
400
600
800
1000
1200
1400
SN2 SN3 DC5
PPB
Zinc measurements in parts per billion from the three test sites
DataTotal Metals
0.00200.00400.00600.00800.00
1000.001200.001400.001600.00
SN2 SN3 DC5
PPB
Total metal concentrations in parts per billion at the three test sites.
DataFe
0
0.2
0.4
0.6
0.8
1
1.2
1.4
SN2 SN3 DC5
PP
M
Concentration of iron in parts per million at the three test sites.
Data
Concentration of calcium and magnesium in parts per million at the three test
sites.
Ca & Mg (hardness)
0
5
10
15
20
25
30
SN2 SN3 DC5
PP
M Ca
Mg
DataDOC (NPOC & TN)
0.00
0.50
1.00
1.50
2.00
2.50
SN2 DC5 SN3
mg
/L
Concentration of dissolved organic carbons in mg/L at the three test
sites.
DataSO4 with Total metals
0
500
1000
1500
2000
2500
SN2 SN3 DC5
SO4 (PPM)
Total Metals (PPB)
Concentrations in parts per million of sulfur and parts per billion of total
metals at the test sites.
Discharge Conclusions• 10.86% precipitation out of total metals
• 12.39% precipitation out of Zinc
• 43.50% precpiation out of Iron
• 12.61% precipitation out of Sulfate
Discharge Conclusions• Different Metals precipitate out faster at different phs’.
• Makes sense because Iron can be seen precipitating out at and just below the confluence where data was taken.
Water Quality• Iron 0.3PPM Iron 1.2PPM
• Zinc 5 PPM Zinc 1.2PPM• pH 6.5-8.5 pH SN2 3.7, DC5 6.25, DC3 4.7• Sulfate 250 PPM Sulfate 2000PPM• From the EPA drinking water regulations
Final Conclusions• About10% precipitation out of most metals• About 40% precipitation out of iron• Water exceeds total allowed concentration of
Iron and sulfate• Water’s pH does no lie the acceptable range• Change over time is still a work in progress
BibliographyNiyogi, Dev K., Diane M. McKnight, and William M. Lewis Jr. Influences of Water and Substrate Quality for Periphyton in a Montane Stream Affected by . Rep. American Society of Limnology and
Oceanography. Print.
Farag, Ada M., David A. Nimick, Briant A. Kimball, Stanley E. Church, David D. Harper, and William G. Brumbaugh. Concentrations of Metals in Water, Sediment, Biofilm, Benthic. Rep. Arch.
Environ. Contam. Toxicol. Print.
Boyer, Elizabeth W., Diane M. McKnight, Kenneth E. Bencala, Paul D. Brooks, Michael W. Anthony, Gary W. Zellweger, and Richard E. Harnish. Streamflow and Water Quality Characteristics for
the Upper Snake River and Deer Creek Catchments in Summit County, Colorado: Water Years 1980 to 1990 . Rep. Boulder, Colorado: Institute of Arctic and Alpine Research, 1999. Print.
Todd, Andrew S., Diane M. McKnight, and Sabre M. Duren. Water Quality Characteristics for the Snake RIver, North Fork of the Snake RIver, Peru Creek, and Deer Creek in Summit County,
Colorado: 2001 to 2002. Rep. Boulder, Colorado: Institute of Arctic and Alpine Research, 2005. Print.
McNight, Diane M., and K. E. Bencala. Annual Maxima in Zn Concentrations during spring snowmelt in streams impacted by mine drainage . Rep. Print.
"Drinking Water Contaminants | Safewater| Water | US EPA." US Environmental Protection Agency. Web. 30 Apr. 2010. <http://www.epa.gov/safewater/contaminants/index.html>.
Special thanks to
Our mentor Caitlin Crouch of the University
of Colorado at Boulder
