To better prioritize and plan remediation of streams affected by acid mine drainage, better understanding of the importance of stream-sediment bed exchange of colloids and colloid-associated metals is needed. Only recently has the hyporheic zone been included in modeling of the transport of colloids and suspended sediments in surface water. To better understand the role of the hyporheic zone, we will examine some of the key processes in colloid and colloid-associated metal transport in an acid mine drainage-affected stream in the Colorado Rocky Mountains. The objectives of this research are to (1) characterize the nature, size, surface chemistry, and aggregation kinetics of colloids in acid mine drainage-affected streams, (2) evaluate the importance of hyporheic zone exchange for colloids and colloid-associated metals, (3) examine the mechanisms of colloid removal in hyporheic zone sediments, and (4) advance and adapt the current model for colloid-associated contaminant transport to improve assessment of the fate and transport of metals in acid mine drainage-affected streams. The results of this research will promote better understanding and allow better prediction of the effects of acid mine drainage on water quality in alpine streams. With this knowledge, environmental scientists and engineers and environmental regulators will be better equipped to assess the risks of metal contamination to humans and aquatic life, and to design remediation strategies. To foster use of the products of this research, we will disseminate our results in widely-read journals. We will also continue our service as technical advisors for watershed stakeholder groups and develop this activity into an outreach center to engage undergraduate and graduate students in research and learning in service to communities. We will also integrate the research into regular academic courses taught at our institutions and into a short course for environmental professionals.
