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

pH Snake River above 3.7 Deer Creek above 6.25 Snake River Below 4.7

Data Zinc measurements in parts per billion from the three test sites

Data Total metal concentrations in parts per billion at the three test sites.

Data 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.

Data Concentration of dissolved organic carbons in mg/L at the three test sites.

Data 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 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

Bibliography Niyogi, 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 Rep. Boulder, Colorado: Institute of Arctic and Alpine Research, 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 Rep. Boulder, Colorado: Institute of Arctic and Alpine Research, 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

Special thanks to Our mentor Caitlin Crouch of the University of Colorado at Boulder