Kris%n M. Mikkelson,  Dr. John E. McCray, Dr. Reed Maxwell, Dr. Jonathan O. Sharp 

Hydrologic Science and Engineering Program Colorado School of Mines 

Plausible Mechanisms that could alter metal loading •  DOC ligand effects •  Soil acidification: N biogeochemistry •  Alterations in metal redox •  Physical mechanisms

NOM/DOC in Forested Watersheds 

See figure 3 in Helie, J.F., Peters, D.L., Tattrie, K.R. and Gibson, J.J. Review and synthesis of potential hydrologic impacts of mountain pine beetle and related harvesting activities in British Columbia. Water and Climate Impacts Research Centre- National Water Research Institute – Environment Canada. Working Paper 2005-23.

*See figure 3 in Huber C., Baumgarten, M., Gottlein, A. and Rotter, V. Nitrogen Turnover and Nitrate Leaching after Bark Beetle Attack in Mountainous Spruce Stands of the Bavarian Forest National Park. Water, Air and Soil Pollution. 2004.

DOC increase following insect infestation

DOC Ligand Effect

*See figure 1 in Johnson R., Johnson G., Nurmi, J. and Tratnyek P. Natural Organic Matter Enhanced Mobility of Nano Zerovalent Iron. Environmental Science and Technology. 2009.

*www.thisland.illinois.edu/50ways/images/5b.jpg

NH3 + O2 → NO2- + 3H+ + 2e-

(1)

NO2- + H2O → NO3

- + 2H+ + 2e- (2)

Alterations in Metal Redox

U(IV) U(VI)

Fe(III) Fe(II)

Mn(IV) Mn(II) NO2

- NO3-

N2O NO N2

O2 H2O

U-oxidation by indirect biological and abiotic processes

UO2 UO2

2+

-Loss of vegetation = increase in the net precipitation

- Increase in snow melt = higher and earlier peak flows

- Less evapotranspiration = higher soil water / groundwater levels

MPB Effects on Hydrology

*See figure 2 in Helie, J.F., Peters, D.L., Tattrie, K.R. and Gibson, J.J. Review and synthesis of potential hydrologic impacts of mountain pine beetle and related harvesting activities in British Columbia. Water and Climate Impacts Research Centre- National Water Research Institute – Environment Canada. Working Paper 2005-23.

Physical Mechanisms

Increased Erosion of minerals

Hypothesis 

Static soil-water concentrations and stream mass fluxes of dissolved toxic metals will statistically increase due to:

• An increased influx of natural organic matter • Reductions in pH due to increased nitrification • Alterations in metal redox states • Increased runoff in MPB infected watersheds

Pennsylvania Creek, Blue River, CO  ‐Site CharacterizaCon 

*hEp://www.allsummitcounty.com/maps/breckenridge_map.php 

Pennsylvania Creek, Blue River, CO  ‐Site InstrumentaCon  

y = 0.0224x ‐ 1.2455 R² = 0.9994 

0 

0.2 

0.4 

0.6 

0.8 

1 

1.2 

60  70  80  90  100  110 

Stage (H) 

Discharge (L/sec) 

Stage‐Discharge RelaConship  

MW1  

Linear(MW1 ) 

Preliminary Data:  Flow Rates 

Preliminary Data: Metal Loading

(No MPB infestation)

Future Plans….

• Expand and continue to monitor Pennsylvania Gulch (control site)

• Gage/install apparatus and monitor Keystone Gulch (infected site)

• Access to additional sites through Collaboration with Brooks and Gochis et al.

• Data/samples from Niwot Ridge(CO) • Chimney Park (WY)

• Broader impacts of the MPB with Stednick

Message to Stakeholders: 1)  We need to evaluate the potential for increased fluxes of metals in

watersheds impacted by MPB. •  Perturbed vs. unpertubed sites (the Colorado mountains are

littered with old abandoned mines/tailings piles)

2) End point ramifications on ecological health and drinking water endpoints – we need to understand if this is an issue.

3) We need to understand if management strategies (clear cut, let stands stay, preventative thinning) as well as the increased potential for forest fires will impact water quality.

4) What is the time span of these impacts.