A5016158716- Soil and Water Nutrient Dynamics
- Hydrology and Watershed Management Studies
- Water Quality and Resources Studies
- Fish Ecology and Management Studies
- Groundwater and Isotope Geochemistry
- Wastewater Treatment and Nitrogen Removal
- Urban Stormwater Management Solutions
- Freshwater macroinvertebrate diversity and ecology
- Hydrology and Sediment Transport Processes
- Water Quality and Pollution Assessment
- Groundwater flow and contamination studies
- Smart Materials for Construction
- Aquatic Ecosystems and Phytoplankton Dynamics
- Diatoms and Algae Research
- Soil erosion and sediment transport
- Paleontology and Stratigraphy of Fossils
- Atmospheric and Environmental Gas Dynamics
- Microbial Community Ecology and Physiology
- Peatlands and Wetlands Ecology
- Geotechnical Engineering and Soil Stabilization
- Aquatic Invertebrate Ecology and Behavior
- Invertebrate Taxonomy and Ecology
- Water Quality Monitoring and Analysis
- Plant and fungal interactions
- Environmental and Agricultural Sciences
United States Geological Survey
2012-2024
Entertainment Industries Council
2019
Pennsylvania Academy of Science
2012
Arizona State University
2004-2010
University of New Mexico
2010
Washington Water Science Center
2009-2010
University of New Hampshire
2009
Washington State University Vancouver
2008
Edmonds Community College
2008
University of California, Davis
2003-2007
Nitrous oxide (N(2)O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Anthropogenic nitrogen (N) loading river networks potentially important source of N(2)O via microbial denitrification converts N dinitrogen (N(2)). The fraction denitrified escapes as rather than N(2) (i.e., the yield) an determinant how much produced by networks, but little known about yield in flowing waters. Here, we present results whole-stream (15)N-tracer additions...
Summary 1. Rates of whole‐system metabolism (production and respiration) are fundamental indicators ecosystem structure function. Although first‐order, proximal controls well understood, assessments the interactions between distal controls, such as land use geographic region, lacking. Thus, influence on stream across regions is unknown. Further, there limited understanding how may alter variability in regions. 2. Stream was measured nine streams each eight ( n = 72) United States Puerto...
We measured uptake length of 15 NO 3 − in 72 streams eight regions across the United States and Puerto Rico to develop quantitative predictive models on controls length. As part Lotic Intersite Nitrogen eXperiment II project, we chose nine each region corresponding natural (reference), suburban‐urban, agricultural land uses. Study spanned a range human use maximize variation concentration, geomorphology, metabolism. tested causal model predicting using structural equation modeling. The...
We measured denitrification rates using a field 15 NO 3 − tracer‐addition approach in large, cross‐site study of nitrate uptake reference, agricultural, and suburban‐urban streams. 49 72 streams studied. Uptake length due to ( S Wden n) ranged from 89 m 184 km (median 9050 m) there were no significant differences among regions or land‐use categories, likely because the wide range conditions within each region land use. N 2 production far exceeded O all The fraction total removal water 0.5%...
Nutrient spiraling in theory and application provides a framework for comparing nutrient retention efficiency of urban streams to relatively unaltered streams. Previous research indicated that the southwestern USA deserts are highly retentive N because limitation, high productivity, channel complexity (in particular, extensive transient storage associated with hyporheic zone). Most have extensively modified channels experience loading from runoff inputs NO3−-contaminated groundwater....
Key Points Flow across the sediment‐water interface exhibits large temporal variability Seepage varies in response to rainfall, ET, wind, and stage change changes markedly within minutes hours of common hydrological events
Nutrient dynamics in rivers are central to global biogeochemistry. We measured ammonium (NH 4 + ) uptake, metabolism, nitrification, and denitrification the thalweg, river region of greatest flow, Kansas River (discharge = 14,360 L/s). estimated gross net uptake with a depleted 15 N‐NH release, metabolism diel O 2 measurements, dissolved N measurements. Net ecosystem production was negative. NH length 2.1 km when concentrations were elevated, 1.9 at ambient concentrations. Gross rate...
Populations of several Psammothidium species were found in core sediments from nine remote, high elevation, ultraoligotrophic and oligotrophic, Olympic Cascade Mountain lakes. Three these species, P. lacustre, alpinum, nivale, are described here as new. The morphology the silica frustules was documented using light scanning electron microscopy. We discuss similarities differences with previously species.
This study examines the effects of flow regulation on water quantity and quality by comparing an impounded system (Mokelumne River) with adjacent unimpounded (Cosumnes River). Between 1999 2002, Cosumnes River displayed a strong seasonal cycle for each constituent analysed (total suspended solids, NO3-N, total nitrogen, PO4-P, phosphorus, dissolved silicon, specific conductivity, flow), while reservoirs in lower Mokelumne buffered attenuated physical chemical fluctuations creating weak...
The goal of this study was to document if lakes in National Parks Washington have exceeded critical levels nitrogen (N) deposition, as observed other Western States. We measured atmospheric N lake water quality, and sediment diatoms at our lakes. Water chemistry showed that were ultra-oligotrophic with ammonia nitrate concentrations often or below detection limits low specific conductance (<100 μS/cm), acid neutralizing capacities (<400 μeq/L). Rates summer bulk inorganic deposition all...
We used mass load budgets, transient storage modeling, and nutrient spiraling metrics to characterize nitrate (NO), ammonium (NH), inorganic phosphorus (SRP) demand in seven agricultural streams across the United States identify in-stream services that may control these conditions. Retention of one or all nutrients was observed but stream, for low relative transport. Transient (/, , ) correlated with NO retention not NH SRP retention, suggesting associated stream water residence time could...
Inorganic N transformations were examined in streambed sediments from the Shingobee River using sediment perfusion cores. The experimental design simulated groundwater‐stream water mixing within cores, which provided a well‐defined one‐dimensional representation of situ hydrologic conditions. Two distinct and chemical settings preserved cores: lowermost sediments, perfused with groundwater, remained anaerobic during incubations, whereas uppermost oxic pumped overlying column, stream...
Abstract: Dissolved inorganic nitrogen (DIN) retention‐transport through a headwater catchment was synthesized from studies encompassing four distinct hydrologic zones of the Shingobee River Headwaters near origin Mississippi River. The included: (1) hillslope ground water (ridge to bankside riparian); (2) alluvial riparian water; (3) discharged subchannel sediments (hyporheic zone); and (4) channel surface water. During subsurface transport Zone 1, DIN, primarily nitrate, decreased ∼3...
First posted February 15, 2019 For additional information, contact: Director, New England Water Science CenterU.S. Geological Survey 10 Bearfoot Road Northborough, MA 01532 During 2016, as part of the National Water-Quality Assessment Project (NAWQA), U.S. conducted Northeast Stream Quality (NESQA) to investigate stream quality in northeastern United States. The goal NESQA was assess health wadeable streams region by characterizing multiple water-quality factors that are stressors aquatic...
First posted August 25, 2017 For additional information, contact: Director, Washington Water Science Center U.S. Geological Survey 934 Broadway, Suite 300 Tacoma, 98402 In 2015, the (USGS) National Water-Quality Assessment (NAWQA) project conducted Pacific Northwest Stream Quality (PNSQA) to investigate stream quality across western part of Northwest. The goal PNSQA was assess health streams in region by characterizing multiple water-quality factors that are stressors in-stream aquatic life...
First posted December 22, 2016 For additional information, contact: Director, Washington Water Science CenterU.S. Geological Survey934 Broadway, Suite 300Tacoma, 98402http://wa.water.usgs.gov Recent advances in suspended-sediment monitoring tools and surrogate technologies have greatly improved the ability to quantify concentrations estimate daily, seasonal, annual fluxes from rivers coastal waters. However, little is known about chemical composition of suspended sediment, how it may vary...
ABSTRACT The relationship between local ground water flows and NO 3 − transport to the channel was examined in three well transects from a natural, wooded riparian zone adjacent Shingobee River, MN. hillslope originated as recharge intermittently grazed pasture up slope of site. In transect perpendicular stream, concentrations decreased ∼3 mg N L −1 beneath ridge (80 m channel) 0.01 1.0 at wells 1 channel. Cl /Cl ratios toward indicating dilution biotic retention. bankside parallel two...
Nutrient spiraling in theory and application provides a framework for comparing nutrient retention efficiency of urban streams to relatively unaltered streams. Previous research indicated that the southwestern USA deserts are highly retentive N because limitation, high productivity, channel complexity (in particular, extensive transient storage associated with hyporheic zone). Most have extensively modified channels experience loading from runoff inputs NO3−-contaminated groundwater....
Biological assemblages are commonly used for assessing stream health, but there is increased interest among the freshwater research community in incorporating measures of function, such as metabolism, to strengthen stream-health assessments. Presently, limited information about relationships between metabolism and biological assemblages, along with measurement period required relate biota. Our study assessed which environmental factors explained what degree minimum dissolved oxygen (DOmin)...