A5089464561- Soil and Water Nutrient Dynamics
- Groundwater and Isotope Geochemistry
- Atmospheric chemistry and aerosols
- Isotope Analysis in Ecology
- Hydrology and Watershed Management Studies
- Atmospheric and Environmental Gas Dynamics
- Urban Stormwater Management Solutions
- Geology and Paleoclimatology Research
- Wastewater Treatment and Nitrogen Removal
- Coastal wetland ecosystem dynamics
- Air Quality and Health Impacts
- Marine and coastal ecosystems
- Atmospheric Ozone and Climate
- Odor and Emission Control Technologies
- Vehicle emissions and performance
- Water Treatment and Disinfection
- Soil Carbon and Nitrogen Dynamics
- Water Quality and Pollution Assessment
- Smart Materials for Construction
- Flood Risk Assessment and Management
- Hydrocarbon exploration and reservoir analysis
- Peatlands and Wetlands Ecology
- Fish Ecology and Management Studies
- Hydrology and Sediment Transport Processes
- Air Quality Monitoring and Forecasting
University of Pittsburgh
2014-2023
Planetary Science Institute
2008-2015
United States Geological Survey
2007-2009
Institute of Arctic and Alpine Research
2008
Johns Hopkins University
2000-2006
Louisiana State University Agricultural Center
1975
Nonpoint source nitrogen (N) pollution is a leading contributor to U.S. water quality impairments. We combined watershed N mass balances and stable isotopes investigate fate transport of nonpoint in forest, agricultural, urbanized watersheds at the Baltimore Long-Term Ecological Research site. Annual retention was 55%, 68%, 82% for suburban, forest watersheds, respectively. Analysis δ(15)N-NO(3)(-), δ(18)O-NO(3)(-) indicated wastewater an important nitrate streams during baseflow. Negative...
Despite the potential use of δ15N as a tracer NOx source contributions, prior documentation various emission sources is exceedingly limited. This manuscript presents first measurements nitrogen isotopic composition (δ15N-NOx) emitted from coal-fired power plants in U.S. at typical operating conditions with and without presence selective catalytic reduction (SCR) noncatalytic (SNCR) technology. To accomplish this, novel method for collection analysis stack samples was developed based on...
RATIONALE Ammonia (NH 3 ) emissions are a substantial source of nitrogen pollution to sensitive terrestrial, aquatic, and marine ecosystems dependable quantification NH sources is growing importance due recently observed increases in ammonium 4 + deposition rates. While determination the isotopic composition (δ 15 N‐NH can aid emission sources, existing methods have precluded comprehensive assessment δ values from major sources. METHODS We report an approach for analysis low concentration...
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...
Knowledge of key sources and biogeochemical processes that affect the transport nitrate (NO 3 − ) in streams can inform watershed management strategies for controlling downstream eutrophication. We applied dual isotope analysis NO to determine dominant concentrations six stream/river watersheds different land uses. Samples were collected monthly at a range flow conditions 15 mo during 2004–05 analyzed concentrations, δ N NO3 , 18 O from two forested indicated derived nitrification was...
Human-engineered landscapes and subsequent altered hydrology affect the fate transport of reactive nitrogen, particularly in urban watersheds. In this study, we used dual-nitrate isotopes mixing model analysis (δ(15)N δ(18)O NO3(-)) to quantify nitrogen inputs from two sources concentrated systems, sewage atmospheric deposition. Analysis was conducted on samples collected Nine Mile Run (Pittsburgh, PA) including over years biweekly through hydrographs four storm events. Mixing models...
The global inventory of NOx (NOx = NO + NO2) emissions is poorly constrained, with a large portion the uncertainty attributed to soil that result from abiotic and microbial processes. While natural abundance stable N isotopes (δ15N) in various N-containing compounds have proven be robust tracer cycling, δ15N-NO rarely quantified due measurement difficulties. Here, we present new method collects soil-emitted through conversion NO2 excess ozone (O3) subsequent collection 20% triethanolamine...
Abstract Increased deposition of reactive atmospheric N has resulted in the nitrogen saturation many forested catchments worldwide. Isotope‐based studies from multiple forest sites report low proportions (mean = ∼10%) unprocessed nitrate streams during baseflow, regardless or export rates. Given similar baseflow across a variety and types, it is important to address postdepositional drivers processes that affect transport fate within catchments. In meta‐analysis stable isotope‐based studies,...
The advent and industrialization of the Haber Bosch process in early twentieth century ushered a new era reactive nitrogen distributions on Earth. Since appearance first commercial scale fertilizer plants, application rates have greatly increased U.S. While contributions runoff to eutrophication anoxic dead zones coastal regions been well‐documented, potential influences applications air quality precipitation chemistry are poorly constrained. Here we combine 255‐year record nitrate isotopes...
Nitrification is a crucial step in ecosystem nitrogen (N) cycling, but scaling up from plot-based measurements of gross nitrification to catchments difficult. Here, we employed newly developed method which the oxygen isotope anomaly (Δ17O) nitrate (NO3–) used as natural tracer quantify situ catchment-scale rate (GNR) for temperate forest 2014 2017 northeastern China. The annual GNR ranged 71 120 kg N ha–1 yr–1 (average 94 ± 10 yr–1) over 4 years this forest. This result and high stream NO3–...
Research Article| October 01, 2013 Stable Isotopes as Tracers of Anthropogenic Nitrogen Sources, Deposition, and Impacts Meredith G. Hastings; Hastings 1Department Geological Sciences Environmental Change Initiative, Brown University, Providence, RI 02912, USAE-mail: meredith_hastings@brown.edu Search for other works by this author on: GSW Google Scholar Karen L. Casciotti; Casciotti 2Department Earth System Science, Stanford Stanford, CA 94305, kcasciotti@stanford.edu Emily M. Elliott...
Legacy effects of past land use and disturbance are increasingly recognized, yet consistent definitions criteria for defining them do not exist. To address this gap in biological- ecosystem-assessment frameworks, we propose a general metric evaluating potential legacy effects, which computed by normalizing altered system function persistence with duration disturbance. We also two distinct legacy-effect categories: signal from lags transport structural physical landscape changes. Using flux...
Little is known about the regional extent and variability of nitrate from atmospheric deposition that transported to streams without biological processing in forests. We measured water chemistry isotopic tracers (δ18O δ15N) sources across Northern Forest Region U.S. Canada reanalyzed data other studies determine when, where, how unprocessed was catchments. These inputs were more widespread numerous than commonly recognized, but with high spatial temporal variability. Only 6 32 had fractions...
Abstract Those who conduct integrated assessments (IAs) are aware of the need to explicitly consider multiple criteria and uncertainties when evaluating policies for preventing global warming. MCDM methods potentially useful understanding tradeoffs risks associated with climate policy alternatives. A difficulty facing potential users is wide range different techniques that have been proposed, each distinct advantages. Methods differ in terms validity, ease use, appropriateness problem....