About

Diane McKnight is a Distinguished Professor at the University of Colorado Boulder, affiliated with the Department of Environmental Studies and the Institute of Arctic and Alpine Research (INSTAAR). Her research interests include freshwater aquatic ecology and biogeochemistry, hydrology, and the study of alpine and polar regions, with a focus on climate change adaptation. She is also an Environmental Engineering Affiliate. Her work involves understanding the ecological and biogeochemical processes in freshwater systems, particularly in sensitive and changing environments such as alpine and polar regions.

Research topics

• Environmental science
• Ecology
• Environmental engineering
• Chemistry
• Geology
• Biology
• Geography
• Environmental chemistry
• Mathematics
• Geochemistry

Selected publications

• Spatial patterns of rare earth elements and trace metals in an acid mine drainage-impacted wetland ecosystem

  Figshare · 2026-04-06

  articleOpen accessSenior author

  Climate trends in the Colorado Mineral Belt have intensified acid rock drainage (ARD) and acid mine drainage (AMD), increasing the need to understand trace metal and rare earth element (REE) cycling in affected watersheds. This study investigated hydrologic and biogeochemical controls on metal and REE concentrations across an AMD-impacted wetland located below an abandoned mine. Wetland surface waters had higher conductivity, sulfate, trace metal, and REE concentrations than underlying groundwater. REE concentrations varied spatially, with highest levels in wetland surface waters where Ce, Nd, and Y concentrations reached ~100 to 200 μg/L, exceeding those of traditional AMD contaminants (e.g. Cd and Pb). Flow patterns and residence times influenced trace metal distributions, with Zn and Cu concentrations of 16.4 and 0.8 mg/L in wetland surface waters compared to 2.7 and 0.01 mg/L in groundwater. Cerium anomaly patterns revealed spatial gradients in oxidative processing, with values ranging from 0.96 in an adjacent stream, 0.51 to 0.97 in wetland surface water, and 0.70 to 0.85 in groundwater, reflecting the influence of extended groundwater–sediment contact allowing progressive REE transformation. These findings demonstrate that AMD-impacted wetlands are multizone ecosystems where hydrologic flow paths control biogeochemical processing of trace metals and REEs.

  PublisherDOI

• Acceleration of Weathering of Trace Metals and Rare Earth Elements in Alpine Watersheds in the Colorado Mineral Belt

  2026-03-14

  articleOpen access1st authorCorresponding

  Many mountain watersheds in the Rocky Mountains in Colorado, USA, are impacted by natural acid rock drainage (ARD) and acid mine drainage (AMD), which mobilize trace metals and rare earth elements (REEs) into surface waters. Analysis of long-term water quality records for alpine tributaries receiving ARD in the Colorado Mineral Belt indicates that warmer summer conditions have been driving increases in the concentrations of sulfate, trace metals and rare earth elements (REEs). One example of these climate-change impacts is the Lincoln Creek Watershed, where a highly mineralized tributary contributes a substantial ARD loading into the headwaters, with an additional AMD contribution from a nearby abandoned mine, the Ruby Mine. We evaluated the transport, mixing, and attenuation of major solutes, trace metals and REEs across the snowmelt to fall period. Water samples from six main sites along a 7-km reach of Lincoln Creek below the ARD and AMD inflows were analyzed by Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and Ion Chromatography (IC) methods. The results were explored through transport calculations employing sulfate as a conservative natural tracer. Water chemistry in Lincoln Creek reveals distinct geochemical fingerprints for the Ruby Mine (enriched in Ca, Mg, Mn, and Cd) and the Mineralized Tributary (enriched in SO4, Fe, Al, and Cu). REE fractionation patterns and Ce anomalies further distinguish source contributions and processes, with the Mineralized Tributary displaying MREE enrichment from natural pyrite weathering and the Ruby Mine exhibiting HREE enrichment tied to mine derived flows. Most solutes exhibited conservative transport during mid-summer when the pH values were low, in the range of pH 4-4.5. During the higher flows associated with snowmelt instream losses of some trace metals and REEs was observed, which was also the case in the fall. These results indicate that both source composition, instream pH-dependent reactivity and hydrologic processes interact to control the downstream water quality impacts associated with these high mountain sources of ARD and AMD.

  PublisherDOI

• Spatial patterns of rare earth elements and trace metals in an acid mine drainage-impacted wetland ecosystem

  Figshare · 2026-04-06

  articleOpen accessSenior author

  Climate trends in the Colorado Mineral Belt have intensified acid rock drainage (ARD) and acid mine drainage (AMD), increasing the need to understand trace metal and rare earth element (REE) cycling in affected watersheds. This study investigated hydrologic and biogeochemical controls on metal and REE concentrations across an AMD-impacted wetland located below an abandoned mine. Wetland surface waters had higher conductivity, sulfate, trace metal, and REE concentrations than underlying groundwater. REE concentrations varied spatially, with highest levels in wetland surface waters where Ce, Nd, and Y concentrations reached ~100 to 200 μg/L, exceeding those of traditional AMD contaminants (e.g. Cd and Pb). Flow patterns and residence times influenced trace metal distributions, with Zn and Cu concentrations of 16.4 and 0.8 mg/L in wetland surface waters compared to 2.7 and 0.01 mg/L in groundwater. Cerium anomaly patterns revealed spatial gradients in oxidative processing, with values ranging from 0.96 in an adjacent stream, 0.51 to 0.97 in wetland surface water, and 0.70 to 0.85 in groundwater, reflecting the influence of extended groundwater–sediment contact allowing progressive REE transformation. These findings demonstrate that AMD-impacted wetlands are multizone ecosystems where hydrologic flow paths control biogeochemical processing of trace metals and REEs.

  PublisherDOI

• Geologic misfortune: Diel and tracer studies reveal surface flows, groundwater inputs, solute sources, rare earth element, and metal mobility in an undisturbed mineralized mountain catchment impacted by acid rock drainage

  Figshare · 2026-01-01

  articleOpen accessSenior author

  In mineralized regions of the Colorado Rockies, acid rock drainage (ARD) presents an ongoing challenge to water resources. Many watersheds are also experiencing shifts in climate, with linkages to decreasing water quality. Here we examined the Upper Snake River (USR), an ARD-impaired catchment abutting the Continental Divide where one small highly acidic tributary has been proven to be the dominant source of acidity, metals, and rare earth elements (REEs). Long-term research indicates that enhanced weathering and dissolution of metals and REEs is linked to warming summers, drought, and declining baseflows. To better understand these trends, we conducted diel and tracer studies at the confluence of this tributary with the USR. These revealed steady concentrations of ARD solutes over a 24-hour period, conservative solute behavior and substantial groundwater input near the confluence. The increased loadings below the confluence suggest strong hyporheic zone connectivity and contributions from an adjacent fen. Our findings underscore the importance of resolving streamflow and solute dynamics to reveal sources, sinks, and/or redox conditions driving downstream fluxes. Studies of the Snake River Watershed continue to offer insight into the hydrological and geochemical controls on ARD, exemplifying the connectivity of mountain hydrology and water quality in a changing world.

  PublisherDOI

• Climate-driven hydrological connectivity alters littoral and ice-covered ecosystems of Antarctic lake margins

  Frontiers in Freshwater Science · 2026-01-16

  articleOpen access

  Climate-driven glacial melt is altering polar ecosystems. Shifts in hydrological regimes have cascading effects on limno-terrestrial ecosystems. In the McMurdo Dry Valleys (Southern Victoria Land, Antarctica), year-round ice cover isolates lentic habitats, yet seasonal melt along the lake perimeter forms open-water “moats” during the short austral summer provide transient hydrological connectivity among soils, benthos, and the stratified water columns of the dry valley lakes. To investigate how connectivity influences biological communities, we tracked biodiversity, phytoplankton photosynthesis, and physicochemistry along lateral transects in two McMurdo Dry Valley lakes, Fryxell and Bonney. These lakes, shaped by distinct basin features (bathymetry, streams) and ecological legacies (nutrient status, chemistry), exhibited contrasting degrees of limno-terrestrial connectivity. Our data reveal that lake-specific hydrological linkages restructure microbial and invertebrate communities. We conclude that climate-induced hydrological changes destabilize previously stratified systems, altering ecological interactions and fundamental ecosystem processes across Antarctic limno-terrestrial ecosystems. Our findings provide critical insight into how polar freshwater ecosystems may reorganize under future climate scenarios, informing predictions of microbial community resilience in extreme environments.

  PublisherDOI

• Geologic misfortune: Diel and tracer studies reveal surface flows, groundwater inputs, solute sources, rare earth element, and metal mobility in an undisturbed mineralized mountain catchment impacted by acid rock drainage

  Figshare · 2026-01-01

  articleOpen accessSenior author

  In mineralized regions of the Colorado Rockies, acid rock drainage (ARD) presents an ongoing challenge to water resources. Many watersheds are also experiencing shifts in climate, with linkages to decreasing water quality. Here we examined the Upper Snake River (USR), an ARD-impaired catchment abutting the Continental Divide where one small highly acidic tributary has been proven to be the dominant source of acidity, metals, and rare earth elements (REEs). Long-term research indicates that enhanced weathering and dissolution of metals and REEs is linked to warming summers, drought, and declining baseflows. To better understand these trends, we conducted diel and tracer studies at the confluence of this tributary with the USR. These revealed steady concentrations of ARD solutes over a 24-hour period, conservative solute behavior and substantial groundwater input near the confluence. The increased loadings below the confluence suggest strong hyporheic zone connectivity and contributions from an adjacent fen. Our findings underscore the importance of resolving streamflow and solute dynamics to reveal sources, sinks, and/or redox conditions driving downstream fluxes. Studies of the Snake River Watershed continue to offer insight into the hydrological and geochemical controls on ARD, exemplifying the connectivity of mountain hydrology and water quality in a changing world.

  PublisherDOI

• Aquatic Community Responses and Water Quality Drivers Following Wildland-Urban Interface Fire in Colorado

  2026-03-09

  articleOpen access

  The Marshall Fire, which occurred on December 30, 2021, destroyed more than 1,000 structures and impacted the Coal Creek watershed in Boulder County, Colorado. We report results of benthic macroinvertebrate and water quality monitoring conducted for one year following this urban wildfire. Benthic macroinvertebrates and stream water were sampled monthly from January-November 2022 at four sites during baseflow. Water quality was also monitored after snowfall and rainstorms. The impacts of water quality and land use parameters on the Hilsenhoff Biotic Index characteristics and scraper abundance were evaluated using random forest analysis. The Marshall Fire altered ecological dynamics of Coal Creek at fire-impacted sites. At the wildland burned site, periphyton abundance remained low. At the site with the combined influences of urbanization and fire, the expected relationship between periphyton and scraper abundance was not observed, with scraper response to periphyton availability reduced 8-fold compared to the two other sites with abundant periphyton. At the burned urban site, shifts in water chemistry occurred, with elevated metal concentrations. The random forest analysis identified filtered manganese and fire parameters including burned structures as predictors of shifts toward pollution-tolerant scraper taxa. The analyses indicated that manganese may be a proxy for fire-derived contaminants affecting the tolerance of scraper taxa, particularly mayflies, which rely on the physical structure of streambeds and the availability of periphyton. These findings demonstrate the value of stream-scale monitoring for observing the cumulative ecosystem effects of urban and wildland fire-related contaminants.

  PublisherOA PDFDOI

• Geologic misfortune: Diel and tracer studies reveal surface flows, groundwater inputs, solute sources, rare earth element, and metal mobility in an undisturbed mineralized mountain catchment impacted by acid rock drainage

  Arctic Antarctic and Alpine Research · 2026-01-20 · 1 citations

  articleOpen accessSenior author

  In mineralized regions of the Colorado Rockies, acid rock drainage (ARD) presents an ongoing challenge to water resources. Many watersheds are also experiencing shifts in climate, with linkages to decreasing water quality. Here we examined the Upper Snake River (USR), an ARD-impaired catchment abutting the Continental Divide where one small highly acidic tributary has been proven to be the dominant source of acidity, metals, and rare earth elements (REEs). Long-term research indicates that enhanced weathering and dissolution of metals and REEs is linked to warming summers, drought, and declining baseflows. To better understand these trends, we conducted diel and tracer studies at the confluence of this tributary with the USR. These revealed steady concentrations of ARD solutes over a 24-hour period, conservative solute behavior and substantial groundwater input near the confluence. The increased loadings below the confluence suggest strong hyporheic zone connectivity and contributions from an adjacent fen. Our findings underscore the importance of resolving streamflow and solute dynamics to reveal sources, sinks, and/or redox conditions driving downstream fluxes. Studies of the Snake River Watershed continue to offer insight into the hydrological and geochemical controls on ARD, exemplifying the connectivity of mountain hydrology and water quality in a changing world.

  PublisherDOI

• Spatial patterns of rare earth elements and trace metals in an acid mine drainage-impacted wetland ecosystem

  Arctic Antarctic and Alpine Research · 2026-04-06

  articleOpen accessSenior author

  Climate trends in the Colorado Mineral Belt have intensified acid rock drainage (ARD) and acid mine drainage (AMD), increasing the need to understand trace metal and rare earth element (REE) cycling in affected watersheds. This study investigated hydrologic and biogeochemical controls on metal and REE concentrations across an AMD-impacted wetland located below an abandoned mine. Wetland surface waters had higher conductivity, sulfate, trace metal, and REE concentrations than underlying groundwater. REE concentrations varied spatially, with highest levels in wetland surface waters where Ce, Nd, and Y concentrations reached ~100 to 200 μg/L, exceeding those of traditional AMD contaminants (e.g. Cd and Pb). Flow patterns and residence times influenced trace metal distributions, with Zn and Cu concentrations of 16.4 and 0.8 mg/L in wetland surface waters compared to 2.7 and 0.01 mg/L in groundwater. Cerium anomaly patterns revealed spatial gradients in oxidative processing, with values ranging from 0.96 in an adjacent stream, 0.51 to 0.97 in wetland surface water, and 0.70 to 0.85 in groundwater, reflecting the influence of extended groundwater–sediment contact allowing progressive REE transformation. These findings demonstrate that AMD-impacted wetlands are multizone ecosystems where hydrologic flow paths control biogeochemical processing of trace metals and REEs.

  PublisherDOI

• Cold comfort for change: Stream mats as biological indicators of ecosystem processes in the <scp>McMurdo</scp> Dry Valleys, Antarctica

  Journal of Phycology · 2026-02-28

  articleOpen accessSenior author

  Glacier-fed streams (GFSs) make ideal systems for studying climate-related changes. Some of the best-studied GFSs are found in the McMurdo Dry Valleys (MDVs) of Antarctica, one of the Earth's coldest and driest deserts. Despite their harsh and isolated nature, MDV GFSs represent an oasis of life in a landscape visually devoid of it, with biomass dominated by photosynthetic microorganisms (including chlorophytes, cyanobacteria, and diatoms) and manifesting as benthic "mats." Mats form the basis of MDV GFS ecosystems, drive biogeochemical cycles, and harbor high proportions of the regional biodiversity. Furthermore, the biomass and composition of these mats respond to environmental fluctuations, making them ideal bioindicators for ecological monitoring. In this review, we have (1) distinguished the three major photosynthetic mat types by their taxonomic structure, habitat use, and elemental composition; (2) demonstrated how mat type distribution, coverage, and biomass are dictated by a combination of geomorphology, suspended sediment loads, and hydrology, among other factors; (3) introduced MDV diatoms as model organisms for investigating mat community assembly; and (4) speculated on how the biomass, community structure, and functional process rates of different mat types will change in a warmer and more connected world. Synthesizing this information, we suggest future opportunities for research, with the most promising avenues centering upon questions, methodologies, and scales that would have been inconceivable for the Heroic Age explorers that discovered them, ranging from studies of gene expression to cataloging changes in mat abundance by satellite.

  PublisherDOI

Recent grants

• Collaborative Research: Humics and Iron Redox Reactions in Bangladesh Aquifer

  NSF · $368k · 2008–2012

• Collaborative Research: Biogeochemistry of Dissolved Organic Matter in Pony Lake, Ross Island

  NSF · $285k · 2004–2007

• Stream Ecosystem "Harshness" and Microbial Endemism in the McMurdo Dry Valleys

  NSF · $495k · 2009–2013

• The Role of Resource Legacy on Contemporary Linkages Between Biodiversity and Ecosystem Processes in a Cold Desert Ecosystem: The McMurdo Dry Valley LTER Program

  NSF · $1.1M · 2010–2011

Frequent coauthors

• W. Berry Lyons

  The Ohio State University

  157 shared

• M. N. Gooseff

  Institute of Arctic and Alpine Research

  129 shared

• Peter T. Doran

  Louisiana State University

  113 shared

• John C. Priscu

  Montana State University

  113 shared

• Andrew G. Fountain

  108 shared

• Ross A. Virginia

  Dartmouth College

  98 shared

• Diana H. Wall

  97 shared

• Daryl Moorhead

  University of Toledo

  94 shared

Education

• Ph.D., Environmental Studies

  University of Colorado Boulder

  1990

• M.S., Environmental Studies

  University of Colorado Boulder

  1986

• B.S., Environmental Studies

  University of Colorado Boulder

  1983

Awards & honors

• INSTAAR Fellow