Photo: Raymondskill Creek, Poconos Mt, PA (M.J. Kurz)
My research broadly addresses the transport and transformation of chemical constituents in freshwater ecosystems. Of particular interest are the interactions between chemical constituents, hydrologic processes and the functioning of aquatic ecosystems and resulting spatio-temporal patterns in stream chemistry and ecosystem functioning at various scales. Current project themes include:
- Improving our predictive understanding of metabolism and reactive solute transport in stream networks, including the role of stream transient storage zones.
- Evaluating the fate and risks of PFAS contaminants on aquatic environments.
- Assessing the effect of human activities on water quality and ecosystem integrity.
Ongoing Research Projects
Understanding hydro-biogeochemical function in watersheds with heterogeneous land cover
The freshwater provisioning and regulating services provided by mid-order watersheds are under increasing stress driven by accelerating changes in land use and land cover (LULC) and an intensifying hydrologic cycle. Predicting the long-term consequences of such hydrologic intensification and LULC change (watershed evolution) at regional scales requires an improved, transferable understanding of how watershed function depends on environmental conditions (watershed dynamics). The Watershed Dynamics and Evolution (WaDE) Science Focus Area at ORNL is an integrated experimental, observational, and modeling program with the 9-year objective to advance predictive understanding of how dominant processes controlling watershed hydro-biogeochemical function operate under a range of hydrologic regimes and vary along stream networks that drain heterogeneous land covers.
Lead PI: Eric Pierce, Research Theme Leads: Elizabeth Herndon, Alexander Johs, Scott Brooks, Marie Kurz, Natalie Griffiths & Scott Painter. Funding: DOE Office of Science's Environmental System Science (ESS) Program |
|
** Interested in a postdoc or student internship position at ORNL or collaboration and funding opportunities? Get in touch! **
PFAS contamination in aquatic habitats
Per- and polyfluoroalkyl substances (PFAS) are a class of widely-used chemical compounds that have been linked to a growing list of negative human health outcomes. The manufacture, use and disposal of PFAS-containing products has resulted in significant environmental PFAS contamination. It is critical to understand the ecological and human health risks associated with the presence of PFASs in aquatic environments. We are investigating the extent, pathways and rates by which PFAS are taken up by aquatic organisms and transferred through stream food webs. Our results will support the quantitative prediction and assessment of the risks of PFAS to aquatic wildlife and humans as well as regulatory efforts by providing, for example, bioacummulation factors and relative exposure mechanisms for fishes that may be consumed by humans. Read more: Yun et al. (2023), Lewis et al. (2022)
Lead PI: Marie Kurz, Co-PIs: Chris Sales (Drexel U.), Erica McKenzie (Temple U.), Daniel Spooner (Lock Haven U.) & Carrie Blakeslee (USGS). Funding: Strategic Environmental Research and Development Program (SERDP) grant # ER19-1032.
Lead PI: Marie Kurz, Co-PIs: Chris Sales (Drexel U.), Erica McKenzie (Temple U.), Daniel Spooner (Lock Haven U.) & Carrie Blakeslee (USGS). Funding: Strategic Environmental Research and Development Program (SERDP) grant # ER19-1032.
Past Research Projects
Advancing coordinated, science-driven conservation across the Delaware River Watershed
The Delaware River Watershed Initiative (DRWI) unites >50 nonprofits in a collaborative program of coordinated, large-scale watershed conservation projects with the aim of protecting and restoring water quality and ecological health locally and in the larger Delaware River watershed, the source of drinking water for over 15 million people. DRWI focuses on 8 sub -watershed “clusters” of ecological significance comprising roughly one-quarter of the Delaware Basin. These clusters encompass the continuum of catchment landscapes, from pristine headwaters to urban centers, and impacts from a range of key stressors including loss of forested headwaters, agricultural run-off and polluted stormwater.
As the lead scientific partner, the Academy provides guidance to accelerate science-driven conservation and improve the effectiveness of the DRWI activities. This includes:
A Watershed Moment is a great short film summarizing the problems at hand and what we're doing to solve them.
Key ANS Personnel: Roland Wall, Stefanie Kroll, Marie Kurz, Lin Perez, David Keller & Carol Collier. Funding: William Penn Foundation
As the lead scientific partner, the Academy provides guidance to accelerate science-driven conservation and improve the effectiveness of the DRWI activities. This includes:
- Developing tools to assess stressor impacts (ex. the interactive Stream Reach Assessment Tool) and identifying priority working areas.
- Monitoring stream water quality and ecosystem structure at a range of spatial and temporal scales in order to establish baselines in these parameters, track how they respond to restoration and protection activities in the clusters, and determine which indicators are the most effective for quantifying (changes in) stream integrity.
- Collaborating with conservation partners to refine and translate our tools and findings to both support their on-the-ground conservation and assessment work and the broader trajectory of the Initiative.
A Watershed Moment is a great short film summarizing the problems at hand and what we're doing to solve them.
Key ANS Personnel: Roland Wall, Stefanie Kroll, Marie Kurz, Lin Perez, David Keller & Carol Collier. Funding: William Penn Foundation
Biogeochemical transformations at critical interfaces in a mercury perturbed watershed
Mercury is a pervasive global pollutant that can be methylated to form toxic methylmercury, which bioaccumulates in aquatic food webs, endangering humans and other biota. The Oak Ridge National Lab (ORNL) Critical Interfaces Science Focus Area (SFA) aims to determine the fundamental mechanisms and environmental factors controlling Hg biogeochemical transformations at critical interfaces in terrestrial and aquatic ecosystems. A key research approach of the SFA is to improve stream reach-to-watershed reactive transport modeling of contaminant and nutrient export. Parameterization of the field-scale models being developed by ORNL requires robust observations of field-scale solute tracer datasets. A series of in-stream tracer experiments are planned at East Fork Poplar Creek, the SFA's intensive field site, to support these efforts.
Funded SFA Collaborators: Marie Kurz & Adam Ward (Indiana U.). Funding: ORNL Critical Interfaces Science Focus Area/DOE Subsurface Biogeochemical Research Program
Funded SFA Collaborators: Marie Kurz & Adam Ward (Indiana U.). Funding: ORNL Critical Interfaces Science Focus Area/DOE Subsurface Biogeochemical Research Program
Review of human health effects of PFAS in support of MCL development in Pennsylvania
PFAS have been found in the drinking water of over 16 million Americans across 33 states, and it is estimated that the water supplies of 110 million Americans may be contaminated with PFAS. We reviewed and evaluated the human health effects, toxicology data, and epidemiological studies of per- and polyfluoroalkyl substances (PFAS) and recommending toxicology values for these compounds using a risk assessment approach. Our recommendations were used to support the Pennsylvania Dept. of Environmental Protection's proposed regulation for a stricter, health-based Maximum Contaminant Levels (MCL) for two specific PFAS compounds, PFOA and PFOS, in drinking water. Read more: 2021 Report to PADEP.
PIs: Richard Hamilton, David Vearrier & Rita McKeever; Key Personnel: Esther Chernak, Charles Haas, Tom Hipper, Marie Kurz & Chris Sales. Funding: Pennsylvania Dept. of Environmental Protection
PIs: Richard Hamilton, David Vearrier & Rita McKeever; Key Personnel: Esther Chernak, Charles Haas, Tom Hipper, Marie Kurz & Chris Sales. Funding: Pennsylvania Dept. of Environmental Protection
Contrasting Raz-Rru stream metabolism and nutrient uptake downstream of urban wastewater effluent sites
Understanding how key ecosystem functions in streams respond to wastewater effluent is critical for assessing the ability of stream ecosystems to ameliorate anthropogenic nutrient loading. We evaluated in-stream metabolism, reactive solute transport, and nutrient uptake along two effluent-impacted stream reaches using plateau injections of the reactive tracer resazurin (Raz), diel oxygen patterns and longitudinal nutrient trends. Observed spatial and temporal variability in metabolic and nutrient uptake regimes were likely driven by differences in nutrient concentration, morphology, hydrologic regime, and canopy shading/light availability. Our ability to resolve sub-daily changes in ecosystem respiration exemplifies one of the key advantages of the Raz tracer system but the contrasting Raz results relative to other estimates of ecosystem function highlight the need for improved conceptual understanding of the differences between these methods.
Read more: Ledford, Kurz & Toran (2021) PIs: Marie Kurz & Sarah Ledford (Temple U./GSU); Key Personnel: Laura Toran (Temple U.). Funding: NSF grants # EAR 1750453 & EAR 1752016. |
|
Organizing principles of hyporheic processing (the Leverhulme Hyporheic Zone Network)
The hyporheic zone is the site of intensive biogeochemical cycling in streams. However, the controls on spatio-temporal variability in hyporheic processing, and the significance of hyporheic processing to reach-scale processing, are largely unknown. The Leverhulme Hyporheic Zone Network is an international collaboration designed to conceptualize the organizing principles of interdisciplinary process interactions in the hyporheic zone through joint, interdisciplinary experiments along biogeographical and catchment gradients.
Five joint experiments took place from 2014-2016 at: the DRI-STREAM mesocosm facility in Hampshire UK, the upland Selke River in the German Harz Mountains, the Urban River Lab outside of Barcelona Spain, the lowland Hammer Stream in Sussex UK, and a range of headwater streams within the H.J. Andrews Experimental Forest in Oregon, USA. Among other methodologies, we employed the reactive stream tracer resazurin (Raz), a weakly fluorescent dye which irreversibly transforms under mildly reducing conditions, providing a proxy for aerobic respiration in streams. We used Raz to evaluate hyporheic respiration in relation to water depth & vegetation dynamics, discharge events, and variable channel morphology. |
|
Read more: Ward et al. (2022), Krause et al. (2022), Comer-Warner et al. (2019), Ward et al. (2019a), Ward et al. (2019b), Ward et al. (2019c), Kelleher et al. (2019), Blaen et al. (2018) , Folegot et al. (2017), Baranov et al. (2017), Kurz et al. (2017), Schmadel et al. (2016). Collaborators & PIs*: 46+ participants from 11 institutions, incl. Stefan Krause*, Philip Blaen & David Hannah (U. Birmingham), Adam Ward* & Noah Schmadel (U. Indiana), Jay Zarnetske* (Michigan State U.), Eugènia Martí* & Jennifer Drummond (CEAB-CSIC), Jan Fleckenstein* (Helmholtz-UFZ), Julia Knapp (U. Tubingen), Scott Larned* (NIWA) & Thibault Datry* (IRSTEA). Funding: Leverhulme Trust, UK (*to S. Krause et al.).
Influence of channel morphology on stream metabolism, solute transport and nutrient cycling
Only 10% of German water bodies have achieved 'good ecological status' under the EU Water Framework Directive. Achieving and maintaining good ecological status in streams will require improved conceptual understanding of ecosystem processes, identification of key indicators of ecosystem functioning, and the derivation of diagnostic tools. Transient storage zones can be locations of intensive biogeochemical processing in streams, enhancing functions such as reach-scale nutrient uptake and metabolism. Despite this, the relationships between ecosystem functioning, stream morphology, and solute transport remain largely unresolved. We conducted a series of pulse injections of reactive (Raz) and conservative (uranine + NaCl) tracers across multiple months and coupled with continuous injections of isotopically labeled 15N-NH4 and 15N-/13C-DOM in four upland streams to investigate: (1) What is the influence of stream channel morphology (ex. riffles and pools) and sediment characteristics on reach and sub-reach scale solute transport, respiration, and nutrient uptake? (2) Is the reactive tracer Raz a useful predictor of the relationship between transient storage and nutrient retention? (3) What is the significance of biofilms for nutrient uptake processes? Read more: 2017 AGU abstract, 2015 Goldschmidt abstract
Collaborators: Christian Schmidt, Mario Brauns, Ute Risse-Buhl & Christine Anlanger (Helmholtz-UFZ). Funding: Helmholtz-UFZ.
Collaborators: Christian Schmidt, Mario Brauns, Ute Risse-Buhl & Christine Anlanger (Helmholtz-UFZ). Funding: Helmholtz-UFZ.
|
Hydrologic & biogeochemical controls on trace metal sources & cycling in karst rivers (PhD Dissertation)
Multiple, coupled physical, chemical and biologic processes control the sources and cycling of solutes in streams; however, the relative magnitude and temporal variability of individual processes can be difficult to differentiate in large rivers. Understanding the timing and magnitude of these processes is critical to preserving the water quality and ecological health of stream systems and predicting their responses to environmental change. North Florida's springs are characterized by stable chemistry, temperature and discharge, providing an ideal setting to study fine-scale spatial and temporal variations in solute dynamics resulting from diffuse & point inputs and in-stream cycling. Dense, highly productive communities of aquatic vegetation further enhance the effect of reciprocal feedbacks between aquatic vegetation and in-stream hydro-geochemical processes. We combined high-frequency river and synoptic pore-water sampling, with measurements of submerged vegetation stoichiometry, and long-term records of river and pore-water hydrology in the Ichetucknee River, FL to investigate how diffuse groundwater discharge and in-stream diel (24-hr) cycling mediate the environmental availability of solutes and the composition and function of aquatic vegetation. Read more: Kurz et al. (2015), Kurz et al. (2013) & 2013 AGU abstract; Related studies: Khadka et al. (2017), Cohen et al. (2013) & de Montety et al. (2011).
Collaborators: Jon Martin (UF), Matt Cohen (UF), Veronique de Montety (Université de Montpellier), Rachel Nifong (U. Maryland), Robert Hensley (UF), & Chad Foster (UF/NEON). Funding: NSF EAR 0838360 & IGERT 0504422 (to J. Martin)
Collaborators: Jon Martin (UF), Matt Cohen (UF), Veronique de Montety (Université de Montpellier), Rachel Nifong (U. Maryland), Robert Hensley (UF), & Chad Foster (UF/NEON). Funding: NSF EAR 0838360 & IGERT 0504422 (to J. Martin)
|
Age-Discharge-Geochemistry relationships in karst springs
One of the hallmarks of karst aquifers is rapid mixing between surface water and groundwater, which results in changes in flow and water chemistry at springs. Aquifers with little matrix porosity (telogenetic karst) tend to respond to storm events within days to weeks (e.g., are flashy) while aquifers characterized by elevated matrix porosity (eogenetic karst) may take months or years to respond. This response time is an important control on remediation of storm-derived contaminants as well as the magnitude of water-rock reactions that may result from mixing of surface water and groundwater with different compositions. Responses of flashy springs may be observed through time-series measurements of various solute compositions of the discharge, but response at springs discharging from eogenetic aquifers are difficult to observe because the chemical composition of the recharged storm water may be altered during its residence in the subsurface. For these aquifers, conservative tracers such as chlorofluorocarbon and 3H/3He ratios may provide useful information on the mixing, residence time, and variation in the average age of discharged water. We are testing this hypothesis at six springs discharging from the Floridan Aquifer to the Ichetucknee River in north Florida. Read more: Martin et al. (2016)
Collaborators: Jon Martin & Mitra Khadka (UF). Funding: Three Rivers FNPC & NSF IGERT 0504422 (to J. Martin)
Collaborators: Jon Martin & Mitra Khadka (UF). Funding: Three Rivers FNPC & NSF IGERT 0504422 (to J. Martin)
Comparing watershed geomorphology over a range of spatial resolutions (NSF REU)
Understanding and deriving the geomorphometry of watersheds is an important task in understanding and modeling various watershed processes and also allows for a more valid comparison between watersheds. Increasingly, Geographic Information System software is utilized to derive and analyze watershed morphometrics. To evaluate the sensitivity and robustness of morphometric parameters derived from digital elevation data of differing resolution, we analyzed and compared 7 geomorphic parameters (ex. total relief, slope distribution, stream density, etc.) in three sub-watersheds of Beaver Reservoir, northwest Arkansas. The study was part of a larger EPA study relating lake sedimentation to land-use in the same three watersheds. Read more: 2006 GSA abstract.
Advisors: Stephen Boss (U. Arkansas) & Jason Patton (Arkansas Tech U.). Funding: NSF REU program.
Advisors: Stephen Boss (U. Arkansas) & Jason Patton (Arkansas Tech U.). Funding: NSF REU program.
Looking for 'landscape knickzones' (B.S. Senior Thesis)
Concordant topographic highs within the central Virginia Piedmont suggest recent dissection of a once more continuous, low-relief surface. This interpretation is supported by documentation of rapid river incision and recognition of migrating kickzones along trunk rivers in the Virginia Piedmont. Taken together, these observations suggest a landscape in disequilibrium, with some portions of the landscape that have not yet responded to accelerated rates of fluvial incision. As fluvial knickzones migrate upstream incision lowers the boundaries for the adjacent hillslopes translating the wave of erosion to the surrounding landscape, the signature of which we termed the "landscape knickzone". We attempted to identify the position of fluvial and landscape knickzones in the James River watershed through evaluation of landscape metrics such as drainage density and channel longitudinal profiles, identification of concordant summits, and statistical assessment of variations in relief and landscape roughness. Read more: 2007 SE Section GSA abstract.
Advisor: Greg Hancock (W&M)
Advisor: Greg Hancock (W&M)
Dr. Marie J. Kurz
Oak Ridge National Laboratory Oak Ridge, TN |
Email. kurzmj<at>ornl.gov
Tel. +1 (865) 341-1731 Web. https://www.ornl.gov/ |