A5005576881- Groundwater flow and contamination studies
- Soil and Water Nutrient Dynamics
- Hydrology and Watershed Management Studies
- Hydrology and Sediment Transport Processes
- Groundwater and Isotope Geochemistry
- Wastewater Treatment and Nitrogen Removal
- Fish Ecology and Management Studies
- Geophysical and Geoelectrical Methods
- NMR spectroscopy and applications
- Soil and Unsaturated Flow
- Hydraulic Fracturing and Reservoir Analysis
- Water Quality and Resources Studies
- Smart Materials for Construction
- Geophysical Methods and Applications
- Hydrological Forecasting Using AI
- Water Quality Monitoring Technologies
- Phosphorus and nutrient management
- Radioactive element chemistry and processing
- Hydrocarbon exploration and reservoir analysis
- Pharmaceutical and Antibiotic Environmental Impacts
- Analytical Chemistry and Sensors
- Geology and Paleoclimatology Research
- Freshwater macroinvertebrate diversity and ecology
- CO2 Sequestration and Geologic Interactions
- Peatlands and Wetlands Ecology
Oregon State University
2013-2024
Louisiana State University
2024
Waters (United States)
2013-2014
United States Department of Commerce
2010
Pacific Northwest National Laboratory
2010
Office of Scientific and Technical Information
2010
National Technical Information Service
2010
Massachusetts Institute of Technology
2004
Sandia National Laboratories
2004
Mass transfer between immobile and mobile zones is a consequence of simultaneous processes. We develop “multirate” model that allows modeling small‐scale variation in rates types mass by using series first‐order equations to represent each the The multirate incorporated into advective‐dispersive equation. First, we compare standard diffusion models transfer. spherical, cylindrical, layered are all shown be specific cases model. Mixtures from different geometries rate‐limited can combined...
Field studies in watershed hydrology continue to characterize and catalogue the enormous heterogeneity complexity of rainfall runoff processes more watersheds, different hydroclimatic regimes, at scales. Nevertheless, ability generalize these findings ungauged regions remains out reach. In spite their apparent physical basis complexity, current generation detailed models is process weak. Their representations internal states dynamics are still odds with many experimental findings. order make...
Abstract [1] Biogeochemical reactions associated with stream nitrogen cycling, such as nitrification and denitrification, can be strongly controlled by water solute residence times in the hyporheic zone (HZ). We used a whole-stream steady state 15N-labeled nitrate (15NO3−) conservative tracer (Cl−) addition to investigate spatial temporal physiochemical conditions controlling denitrification dynamics HZ of an upland agricultural stream. measured concentrations (15NO3−, 15N2 (g), well NO3−,...
We investigated the late‐time (asymptotic) behavior of tracer test breakthrough curves (BTCs) with rate‐limited mass transfer (e.g., in dual‐porosity or multiporosity systems) and found that concentration c is given by simple expression = t ad { 0 g − [ m (∂ /∂ )]}, for ≫ α , where advection time, initial medium, zeroth moment injection pulse, mean residence time immobile domain (i.e., characteristic time). The function proportional to distribution domain; we tabulate many geometries,...
The fate of biologically available nitrogen (N) and carbon (C) in stream ecosystems is controlled by the coupling physical transport biogeochemical reaction kinetics. However, determining relative role controls at different temporal spatial scales difficult. hyporheic zone (HZ), where groundwater–stream water mix, can be an important location controlling N C transformations because it creates strong gradients both conditions that control redox biogeochemistry. We evaluated reactions linking...
We measured the hyporheic residence time distribution in a 2nd‐order mountain stream at H. J. Andrews Experimental Forest, Oregon, and found it to be power‐law over least 1.5 orders of magnitude (1.5 hr 3.5 d). The has very long tail which scales as t −1.28 , is poorly characterized by an exponential model. Because small exponent, efforts characterize mean ( s ) this system result estimates that are scale invariant, increasing with characteristic advection within channel ad ). implies zone...
We investigated multiple‐rate diffusion as a possible explanation for observed behavior in suite of single‐well injection‐withdrawal (SWIW) tests conducted fractured dolomite. first the ability conventional double‐porosity model and multirate to explain data. This revealed that hypothesis/model is consistent with available data capable matching all recovery curves. Second, we studied sensitivity SWIW curves distribution rate coefficients other parameters. concluded test very sensitive but...
Studies of hyporheic exchange flows have identified physical features channels that control flow at the channel unit scale, namely slope breaks in longitudinal profile streams generate subsurface head distributions. We recently completed a field study suggested spacing stream profiles can be used to predict between zones upwelling (flux water into stream) and downwelling zone) beds mountain streams. Here, we use two-dimensional groundwater particle tracking models simulate vertical along...
[1] We used an in situ steady state 15N-labeled nitrate (15NO3−) and acetate (AcO−) well-to-wells injection experiment to determine how the availability of labile dissolved organic carbon (DOC) as AcO−influences microbial denitrification hyporheic zone upland (third-order) agricultural stream. The experimental wells receiving conservative (Cl− Br) reactive solute tracers had median residence times 7.0 13.1 h, nominal flowpath lengths 0.7 3.7 m, hypoxic conditions (<1.5 mg O2 L−1). All...
Temperature is a fundamentally important driver of ecosystem processes in streams. Recent warming terrestrial climates around the globe has motivated concern about consequent increases stream temperature. More specifically, observed trends increasing air temperature and declining flow are widely believed to result corresponding Here, we examined evidence for this using long‐term data from minimally highly human‐impacted sites located across Pacific continental United States. Based on...
Abstract Surface and subsurface flow dynamics govern residence time or water age until discharge, which is a key metric of storage availability for human use ecosystem function. Although observations in small catchments have shown fractal distribution ages, times are difficult to directly quantify measure large basins. Here we simulation major watersheds across North America compute distributions times. This results peak ages from 1.5 10.5 years, agreement with isotopic bomb‐derived...
The use of smart tracers to study hydrologic systems is becoming more widespread. Smart are compounds that irreversibly react in the presence a process or condition under investigation. Resazurin (Raz) tracer undergoes an irreversible reduction resorufin (Rru) cellular metabolic activity. We quantified relationship between transformation Raz and aerobic bacterial respiration pure culture experiments using two obligate aerobes facultative anaerobes, colonized surface shallow (<10 cm)...
Abstract The hyporheic zone is the interface beneath and adjacent to streams rivers where surface water groundwater interact. presents unique conditions for reaction of solutes from both groundwater, including reactions which depend upon mixing source waters. Some models assume that zones are well‐mixed conceptualize as a water‐groundwater zone. But what controls on effects mixing? What specific mechanisms cause relatively large (>∼1 m) suggested by subsurface solute measurements? In this...
Abstract Simulations of stream temperatures showed a wide range future thermal regimes under warming climate — from 2.9°C warmer to 7.6°C cooler than current conditions depending primarily on shade riparian vegetation. We used the temperature model, Heat Source, analyze 37‐km study segment upper Middle Fork John Day River, located in northeast Oregon, USA. developed alternative scenarios based downscaled projections change models and composition structure native forests. examined 36...
Groundwater–surface-water (GW-SW) interactions in streams are difficult to quantify because of heterogeneity hydraulic and reactive processes across a range spatial temporal scales. The challenge quantifying these has led the development several techniques, from centimeter-scale probes whole-system tracers, including chemical, thermal, electrical methods. We co-applied conservative smart solute-tracer tests, measurement heads, distributed temperature sensing, vertical profiles solute tracer...
Positive correlations have been reported between wastewater SARS-CoV-2 concentrations and a community's burden of infection, disease or both. However, previous studies mostly compared to clinical case counts nonrepresentative convenience samples, limiting their quantitative potential.
Abstract The single‐well, “push‐pull” test method is useful for obtaining information on a wide variety of aquifer physical, chemical, and microbiological characteristics. A push‐pull consists the pulse‐type injection prepared solution into single monitoring well followed by extraction solution/ground water mixture from same well. contains conservative tracer one or more reactants selected to investigate particular process. During phase, concentrations tracer, reactants, possible reaction...
Estimates of mass transfer timescales from 316 solute transport experiments reported in 35 publications are compared to the pore‐water velocities and residence times, as well experimental durations. New tracer were also conducted columns different lengths so that velocity advective time could be varied independently. In both literature new experiments, estimated timescale (inverse mass‐transfer rate coefficient) is better correlated duration than velocity. Of measures considered, multiplied...
Current stream tracer techniques do not allow separation of in‐channel dead zone (e.g., eddies) and out‐of‐channel (hyporheic) transient storage, yet this is important to understanding biogeochemical processes. We characterize storage with a rhodamine WT solute experiment in 304 m cascade‐pool‐type bedrock reach no hyporheic zone. compare the breakthrough curve (BTC) from that an adjacent 367 alluvial significant exchange. In reach, has exponential residence time distribution mean 3.0 hours...
Abstract There is a need to identify measurable characteristics of stream channel morphology that vary predictably throughout networks and influence patterns hyporheic exchange flow in mountain streams. In this paper we characterize longitudinal profiles according unit spacing the concavity water surface profile. We demonstrate that: (1) between zones upwelling downwelling beds streams closely related spacing; (2) magnitude vertical hydraulic gradients (VHGs) driving increase with increasing...
We propose the experimental use of resazurin (Raz) and develop a metabolically active transient storage (MATS) model to include processes that may provide additional information on from biogeochemical perspective in stream ecosystems. Raz is phenoxazine compound reduces irreversibly resorufin (Rru) presence aerobic bacteria. was added as tracer 128‐m reach forested second‐order Riera de Santa Fe del Montseny (Catalonia, NE Spain), along with conservative tracer, NaCl. transformed Rru at rate...
The modeling of fluvial systems is constrained by a lack spatial information about the continuity and structure streambed sediments. There are few methods for noninvasive characterization streambeds. Invasive using wells cores fail to provide detailed on prevailing architecture its continuity. Geophysical techniques play pivotal role in providing subsurface properties processes across many other environments, we have applied use one those We demonstrate, through two examples, how electrical...
A “smart” tracer is a that provides, directly or through measurement of its concentration in combination with another compound, at least one “bit” more information about the environment which it travels than conservative tracer. In this study we propose and present chemical compound resazurin as smart to assess coupling between solute transport microbiological activity sediment‐water interfaces freshwaters. Resazurin weakly fluorescent redox‐sensitive dye undergoes an irreversible reduction...