A5067941959- Soil and Water Nutrient Dynamics
- Hydrology and Watershed Management Studies
- Fish Ecology and Management Studies
- Coastal wetland ecosystem dynamics
- Peatlands and Wetlands Ecology
- Marine and coastal ecosystems
- Groundwater flow and contamination studies
- Freshwater macroinvertebrate diversity and ecology
- Wastewater Treatment and Nitrogen Removal
- Hydrology and Sediment Transport Processes
- Groundwater and Isotope Geochemistry
- Urban Stormwater Management Solutions
- Flood Risk Assessment and Management
- Artificial Intelligence in Healthcare and Education
- Radiomics and Machine Learning in Medical Imaging
- Geology and Paleoclimatology Research
- Advanced X-ray and CT Imaging
- Water Quality and Pollution Assessment
- Smart Materials for Construction
- Microbial Community Ecology and Physiology
- Geophysical and Geoelectrical Methods
- Atmospheric and Environmental Gas Dynamics
- Water-Energy-Food Nexus Studies
- Plant responses to water stress
- Arctic and Antarctic ice dynamics
University of Connecticut
2016-2025
Duke University
2011-2014
University of Georgia
2008-2012
Marine Biological Laboratory
2009
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...
Mountaintop mining is the dominant form of coal and largest driver land cover change in central Appalachians. The waste rock from these surface mines disposed adjacent river valleys, leading to a burial headwater streams dramatic increases salinity trace metal concentrations immediately downstream. In this synoptic study we document cumulative impact more than 100 discharge outlets approximately 28 km 2 active reclaimed on Upper Mud River West Virginia. We measured major elements within...
Surface coal mining is the dominant form of land cover change in Central Appalachia, yet extent to which surface mine runoff polluting regional rivers currently unknown. We mapped from 1976 2005 for a 19,581 km(2) area southern West Virginia and linked these maps with water quality biological data 223 streams. The within catchments highly correlated ionic strength sulfate concentrations receiving Generalized additive models were used estimate amount watershed mining, stream strength, or...
Abstract Groundwater discharge generates streamflow and influences stream thermal regimes. However, the water quality buffering capacity of groundwater depends on aquifer source-depth. Here, we pair multi-year air temperature signals to categorize 1729 sites across continental United States as having major dam influence, shallow or deep signatures, lack pronounced (atmospheric) signatures. Approximately 40% non-dam have substantial contributions indicated by characteristic paired signal...
Mean annual temperature and mean precipitation drive much of the variation in productivity across Earth's terrestrial ecosystems but do not explain gross primary (GPP) or ecosystem respiration (ER) flowing waters. We document substantial magnitude seasonality GPP ER 222 US rivers. In contrast to their counterparts, most river respire far more carbon than they fix have less pronounced consistent metabolic rates. find that solar energy inputs stability flows are drivers A classification schema...
The United States (U.S.) coastal plain is subject to rising sea levels, land subsidence, more severe storms, and intense droughts. These changes lead inputs of marine salts into freshwater-dependent systems, creating saltwater intrusion. penetration salinity the interior exacerbated by groundwater extraction high density agricultural canals ditches throughout much rural U.S. landscape. Together intrusion level rise (SWISLR) create substantial social-ecological systems situated along plain....
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%...
Abstract Hypoxia in coastal waters and lakes is widely recognized as a detrimental environmental issue, yet we lack comparable understanding of hypoxia rivers. We investigated controls on using 118 million paired observations dissolved oxygen (DO) concentration water temperature over 125,000 locations rivers from 93 countries. found (DO < 2 mg L −1 ) 12.6% all river sites across 53 countries, but no consistent trend prevalence since 1950. High‐frequency data reveal 3‐h median duration...
Abstract We develop and illustrate the concept of ‘hydrologic spiralling’ using a high‐resolution (2 × 2 m grid cell) simulation hyporheic hydrology across 1.7 km section sand, gravel cobble floodplain aquifer upper Umatilla River northeastern Oregon, USA. parameterized model continuous map surface water stage derived from LIDAR remote sensing data. Model results reveal presence complex spatial patterns exchange scales. use to describe streams as collection hierarchically organized,...
Abstract Carbon and nitrogen cycles are coupled through both stoichiometric requirements for microbial biomass dissimilatory metabolic processes in which microbes catalyse reduction‐oxidation reactions. Here, we integrate theory thermodynamic principles to explain the commonly observed trade‐off between high nitrate organic carbon concentrations, even stronger ammonium across a wide range of aquatic ecosystems. Our results suggest these relationships emergent properties stoichiometry...
Abstract Streams and rivers can be highly reactive sites for nitrogen (N) transformation removal. Empirical model‐based research show how location in a stream network affects rates of N Because the structure networks vary widely cycling headwater streams may affect downstream reaches, we hypothesised that whole processing N. We generated three with same catchment area but differing shapes, based on optimal channel theory. applied model nitrate ( ) transport denitrification, implemented...
Abstract High‐resolution data are improving our ability to resolve temporal patterns and controls on river productivity, but we still know little about the emergent of primary production at river‐network scales. Here, estimate daily annual gross (GPP) by applying characteristic GPP (i.e., regimes) representing distinct functional types simulated networks. A defined envelope possible productivity regimes emerges network‐scale, amount timing network can vary widely within this range depending...
Abstract Thermal refuges are thermally distinct riverscape features used by aquatic organisms during unfavourable thermal events, facilitating resilience in marginal environments. However, the refuge concept is nebulous, and often interchangeable use of term ‘thermal refugia’ creates additional ambiguity. We argue that lexical differences resulting from divergent scholarly trainings hinder holistic understanding refuges; thus, existing studies would benefit a structured framework for...