A5043419036- Soil and Water Nutrient Dynamics
- Hydrology and Watershed Management Studies
- Groundwater and Isotope Geochemistry
- Marine and coastal ecosystems
- Atmospheric chemistry and aerosols
- Fish Ecology and Management Studies
- Atmospheric and Environmental Gas Dynamics
- Water Quality and Pollution Assessment
- Wastewater Treatment and Nitrogen Removal
- Direction-of-Arrival Estimation Techniques
- Plant Water Relations and Carbon Dynamics
- Soil Moisture and Remote Sensing
- Peatlands and Wetlands Ecology
- Soil erosion and sediment transport
- Hydrological Forecasting Using AI
- Water Quality and Resources Studies
- Isotope Analysis in Ecology
- Cryospheric studies and observations
- Mercury impact and mitigation studies
- Groundwater flow and contamination studies
- Flood Risk Assessment and Management
- Fire effects on ecosystems
- Climate variability and models
- Water resources management and optimization
- Soil Carbon and Nitrogen Dynamics
Pennsylvania State University
2015-2024
University of Nebraska Medical Center
2024
Gillette Children's Specialty Healthcare
2020
Charles River Laboratories (Netherlands)
2015
Buffalo State University
2009
Syracuse University
2003-2009
Northern Research Station
2009
US Forest Service
2009
University of Maine
2009
University of California, Berkeley
2003-2008
We studied the fluorescence properties of fulvic acids isolated from streams and rivers receiving predominantly terrestrial sources organic material lakes with microbial material. Microbially derived have fluorophores a more sharply defined emission peak occurring at lower wavelengths than in terrestrially acids. show that ratio intensity wavelength 450 nm to 500 nm, obtained an excitation 370 can serve as simple index distinguish aquatic In our study, this has value ~1.9 for microbially...
Seasonal hypoxia in the northern Gulf of Mexico has been linked to increased nitrogen fluxes from Mississippi and Atchafalaya River Basins, though recent evidence shows that phosphorus also influences productivity Gulf. We developed a spatially explicit structurally detailed SPARROW water-quality model reveals important differences sources transport processes control (N) (P) delivery Our simulations indicate agricultural watersheds contribute more than 70% delivered N P. However, corn...
Knowledge of headwater influences on the water-quality and flow conditions downstream waters is essential to water-resource management at all governmental levels; this includes recent court decisions jurisdiction Federal Clean Water Act (CWA) over upland areas that contribute larger water bodies. We review current watershed research use a model investigate receiving waters. Our evaluations demonstrate intrinsic connections headwaters landscape processes through their influence supply,...
The northeastern United States receives elevated inputs of anthropogenic nitrogen (N) largely from net imports food and atmospheric deposition, with lesser fertilizer, feed imports, N fixation associated leguminous crops. Ecological consequences to the Northeast include tropospheric ozone formation, damage plants, alteration forest cycles, acidification surface waters, eutrophication in coastal waters. We used two models, PnET-BGC WATERSN, evaluate management strategies for reducing forests...
The spatial distribution of source areas and associated residence times water in the catchment are significant factors controlling annual cycles dissolved organic carbon (DOC) concentration Deer Creek (Summit County, Colorado). During spring snowmelt (April–August 1992), stream DOC concentrations increased with rising limb hydrograph, peaked before maximum discharge, then declined rapidly as melting continued. We investigated sources to streamflow, measuring tension lysimeters, groundwater...
Abstract Carbon cycling in the coastal zone affects global carbon budgets and is critical for understanding urgent issues of hypoxia, acidification, tidal wetland loss. However, there are no regional spanning three main ecosystems waters: wetlands, estuaries, shelf waters. Here we construct such a budget eastern North America using historical data, empirical models, remote sensing algorithms, process‐based models. Considering net fluxes total at domain boundaries, 59 ± 12% (± 2 standard...
We present an overview of riverine nitrogen flux calculations that were prepared for the International Nitrogen Initiative's current global assessment cycles: past, present, and future (Galloway et al., 2004). quantified anthropogenic natural inputs reactive (N) to terrestrial landscapes associated N fluxes. Anthropogenic include fossil‐fuel derived atmospheric deposition, fixation in cultivated croplands, fertilizer use, net import human food animal feedstuffs. Natural biological forests...
Abstract The stable isotopic composition of dissolved inorganic carbon (δ 13 C‐DIC) was investigated as a potential tracer streamflow generation processes at the Sleepers River Research Watershed, Vermont, USA. Downstream sampling showed δ C‐DIC increased between 3–5‰ from stream source to outlet weir approximately 0·5 km downstream, concomitant with increasing pH and decreasing P CO 2 . An increase in 2·4 ± 0·1‰ per log unit decrease excess (stream normalized atmospheric ) observed...
The importance of lotic systems as sinks for nitrogen inputs is well recognized. A fraction in streamflow removed to the atmosphere via denitrification with remainder exported loads. At watershed scale, there a keen interest understanding factors that control fate throughout stream channel network, particular attention processes deliver large loads sensitive coastal ecosystems. We use dynamic transport model assess biogeochemical (nitrate loadings, concentration, temperature) and...
We explored catchment processes that control stream nutrient concentrations at an upland forest in northeastern Vermont, USA, where inputs of nitrogen via atmospheric deposition are among the highest nation and affect ecosystem functioning. traced sources water, nitrate, dissolved organic matter (DOM) using water samples collected high frequency during spring snowmelt. Hydrochemistry, isotopic tracers, end‐member mixing analyses suggested timing, sources, source areas from which nutrients...
Dry deposition is a major component of total atmospheric nitrogen and thus an important source bioavailable to ecosystems. However, relative wet deposition, less known regarding the sources spatial variability dry deposition. This in part due difficulty measuring associated velocities. Passive sampling techniques offer potential for improving our understanding distribution gaseous aerosol N species, referred here as We report dual nitrate isotopic composition ( δ 15 18 O) actively collected...
Nearly all freshwaters and coastal zones of the US are degraded from inputs excess reactive nitrogen (Nr), sources which runoff, atmospheric N deposition, imported food feed. Some major adverse effects include harmful algal blooms, hypoxia fresh waters, ocean acidification, long-term harm to human health, increased emissions greenhouse gases. Nitrogen fluxes areas nitrous oxide waters have in response inputs. Denitrification sedimentation organic sediments important processes that divert...