Atmospheric Nitrogen Flux from the Watersheds of Major Estuaries of the United States: An Application of the SPARROW Watershed Model

2013 ◽  
pp. 119-170 ◽  
Author(s):  
Richard B. Alexander ◽  
Richard A. Smith ◽  
Gregory E. Schwarz ◽  
Stephen D. Preston ◽  
John W. Brakebill ◽  
...  
Keyword(s):  
United States ◽  
The United States ◽  
Atmospheric Nitrogen ◽  
Watershed Model ◽  
Nitrogen Flux

scholarly journals Watershed-Scale Response to Climate Change through the Twenty-First Century for Selected Basins across the United States

2011 ◽  
Vol 15 (17) ◽  
pp. 1-37 ◽  
Author(s):  
Lauren E. Hay ◽  
Steven L. Markstrom ◽  
Christian Ward-Garrison
Keyword(s):  
Climate Change ◽  
United States ◽  
Coupled Model ◽  
The United States ◽  
Lessons Learned ◽  
First Century ◽  
Emission Scenarios ◽  
Watershed Model ◽  
Geographical Regions ◽  
Twenty First Century

Abstract The hydrologic response of different climate-change emission scenarios for the twenty-first century were evaluated in 14 basins from different hydroclimatic regions across the United States using the Precipitation-Runoff Modeling System (PRMS), a process-based, distributed-parameter watershed model. This study involves four major steps: 1) setup and calibration of the PRMS model in 14 basins across the United States by local U.S. Geological Survey personnel; 2) statistical downscaling of the World Climate Research Programme’s Coupled Model Intercomparison Project phase 3 climate-change emission scenarios to create PRMS input files that reflect these emission scenarios; 3) run PRMS for the climate-change emission scenarios for the 14 basins; and 4) evaluation of the PRMS output. This paper presents an overview of this project, details of the methodology, results from the 14 basin simulations, and interpretation of these results. A key finding is that the hydrological response of the different geographical regions of the United States to potential climate change may be very different, depending on the dominant physical processes of that particular region. Also considered is the tremendous amount of uncertainty present in the climate emission scenarios and how this uncertainty propagates through the hydrologic simulations. This paper concludes with a discussion of the lessons learned and potential for future work.

Estimates of diffuse phosphorus sources in surface waters of the United States using a spatially referenced watershed model

2004 ◽  
Vol 49 (3) ◽  
pp. 1-10 ◽  
Author(s):  
R.B. Alexander ◽  
R.A. Smith ◽  
G.E. Schwarz
Keyword(s):  
United States ◽  
Land Use ◽  
Surface Waters ◽  
Mississippi River ◽  
Spatial Data ◽  
Phosphorus Removal ◽  
The United States ◽  
Watershed Model ◽  
Phosphorus Sources ◽  
Mixed Land Use

The statistical watershed model SPARROW (SPAtially Referenced Regression On Watershed attributes) was used to estimate the sources and transport of total phosphorus (TP) in surface waters of the United States. We calibrated the model using stream measurements of TP from 336 watersheds of mixed land use and spatial data on topography, soils, stream hydrography, and land use (agriculture, forest, shrub/grass, urban). The model explained 87% of the spatial variability in log transformed stream TP flux (kg yr-1). Predictions of stream yield (kg ha-1 yr-1) were typically within 45% of the observed values at the monitoring sites. The model identified appreciable effects of soils, streams, and reservoirs on TP transport. The estimated aquatic rates of phosphorus removal declined with increasing stream size and rates of water flushing in reservoirs (i.e. areal hydraulic loads). A phosphorus budget for the 2.9 million km2 Mississippi River Basin provides a detailed accounting of TP delivery to streams, the removal of TP in surface waters, and the stream export of TP from major interior watersheds for sources associated with each land-use type.

scholarly journals Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States

2016 ◽  
Vol 113 (15) ◽  
pp. 4086-4091 ◽  
Author(s):  
Samuel M. Simkin ◽  
Edith B. Allen ◽  
William D. Bowman ◽  
Christopher M. Clark ◽  
Jayne Belnap ◽  
...  
Keyword(s):  
United States ◽  
Species Richness ◽  
Plant Species ◽  
Plant Species Richness ◽  
The United States ◽  
N Deposition ◽  
Soil Conditions ◽  
Atmospheric Nitrogen ◽  
General Response ◽  
Negative Relationships

Atmospheric nitrogen (N) deposition has been shown to decrease plant species richness along regional deposition gradients in Europe and in experimental manipulations. However, the general response of species richness to N deposition across different vegetation types, soil conditions, and climates remains largely unknown even though responses may be contingent on these environmental factors. We assessed the effect of N deposition on herbaceous richness for 15,136 forest, woodland, shrubland, and grassland sites across the continental United States, to address how edaphic and climatic conditions altered vulnerability to this stressor. In our dataset, with N deposition ranging from 1 to 19 kg N⋅ha−1⋅y−1, we found a unimodal relationship; richness increased at low deposition levels and decreased above 8.7 and 13.4 kg N⋅ha−1⋅y−1 in open and closed-canopy vegetation, respectively. N deposition exceeded critical loads for loss of plant species richness in 24% of 15,136 sites examined nationwide. There were negative relationships between species richness and N deposition in 36% of 44 community gradients. Vulnerability to N deposition was consistently higher in more acidic soils whereas the moderating roles of temperature and precipitation varied across scales. We demonstrate here that negative relationships between N deposition and species richness are common, albeit not universal, and that fine-scale processes can moderate vegetation responses to N deposition. Our results highlight the importance of contingent factors when estimating ecosystem vulnerability to N deposition and suggest that N deposition is affecting species richness in forested and nonforested systems across much of the continental United States.

scholarly journals Changes in Spring Snowpack for Selected Basins in the United States for Different Climate-Change Scenarios

2011 ◽  
Vol 15 (23) ◽  
pp. 1-18 ◽  
Author(s):  
Mark C. Mastin ◽  
Katherine J. Chase ◽  
R. W. Dudley
Keyword(s):  
Climate Change ◽  
United States ◽  
Snow Water Equivalent ◽  
The United States ◽  
Low Flow ◽  
Climate Change Scenarios ◽  
Emission Scenarios ◽  
Watershed Model ◽  
Snow Cover Area ◽  
The Future

Abstract Spring snowpack is an important water resource in many river basins in the United States in areas where snowmelt comprises a large part of the annual runoff. Increasing temperatures will likely reduce snowpacks in the future, resulting in more winter runoff and less available water during the summer low-flow season. As part of the National Climate Change Modeling Project by the U.S. Geological Survey, distributed watershed-model output was analyzed to characterize areal extent and water-equivalent volumes of spring snowpack for a warming climate. The output from seven selected watershed models from the mountainous western United States and one model from coastal Maine in the northeastern United States shows a future of declining spring snowpack. Snow-cover area (SCA) and snow-water equivalent (SWE) were used to compare the spring snowpack for current conditions (2006) with three time periods in the future (2030, 2060, and 2090) using three Intergovernmental Panel on Climate Change (IPCC) emission scenarios published in the 2007 Special Report on Emission Scenarios (SRES): A2, B1, and A1B. Distributed SWE and SCA values were sorted into elevation zones in each basin. The change in spring snowpack over time was greater than the change among different emission scenarios, suggesting that, even for a globally reduced carbon emission scenario, large decreases in SWE are likely to occur. The SRES A2 scenario resulted in the greatest decrease in SWE for six of the basins, and the SRES B1 and A1B scenarios resulted in the greatest decrease in one basin each.

Mycorrhizal associations of some actinomycete nodulated nitrogen-fixing plants

1980 ◽  
Vol 58 (13) ◽  
pp. 1449-1454 ◽  
Author(s):  
Sharon L. Rose
Keyword(s):  
United States ◽  
Mycorrhizal Fungi ◽  
The United States ◽  
Flowering Plants ◽  
Atmospheric Nitrogen ◽  
Nitrogen Fixing ◽  
Mycorrhizal Associations ◽  
Vesicular Arbuscular ◽  
Distributional Patterns ◽  
Va Mycorrhizal Fungi

Flowering plants that fix atmospheric nitrogen in actinomycete-induced nodules were sampled for mycorrhizal associates. Twenty-five species from seven families (Betulaceae, Casuarinaceae, Myricaceae, Rhamnaceae, Rosaceae, Elaeagnaceae, and Datiscaceae) were examined. Samples included were from the United States, Japan, and England.Both mycorrhizae and actinomycete-induced nitrogen-fixing nodules were present on: (i) four species of Alnus, (ii) two species of Casuarina, (iii) eight species of Ceanothus, (iv) four species of Myrica, (v) and one species each of Shepherdia, Hippophae, Cercocarpus, Dryas, Purshia, Comptonia, and Datisca. Soil sieving revealed species of the following genera of vesicular–arbuscular (VA) mycorrhizal fungi: Gigaspora, Glomus, Acaulospora, Entrophospora, and three undescribed taxa soon to be described. Spores of species in the first three genera of fungi were found most frequently from soil sievings. The VA mycorrhizal fungi exhibited distinct distributional patterns when associated with nonleguminous nitrogen-fixing hosts in different habitats. The ectomycorrhizae were not characterized.

Correlative microscopy in distrubuted (client/server) computing environments: tools for catalyzing the rapid dissemination of information about the cell biology of the human prostate

1995 ◽  
Vol 53 ◽  
pp. 682-683
Author(s):  
A. Hakam ◽  
J.T. Gau ◽  
M.L. Grove ◽  
B.A. Evans ◽  
M. Shuman ◽  
...  
Keyword(s):  
United States ◽  
Cell Biology ◽  
Tissue Bank ◽  
The United States ◽  
Prostate Adenocarcinoma ◽  
Correlative Microscopy ◽  
Client Server ◽  
Critical Elements ◽  
Transplant Organ

Prostate adenocarcinoma is the most common malignant tumor of men in the United States and is the third leading cause of death in men. Despite attempts at early detection, there will be 244,000 new cases and 44,000 deaths from the disease in the United States in 1995. Therapeutic progress against this disease is hindered by an incomplete understanding of prostate epithelial cell biology, the availability of human tissues for in vitro experimentation, slow dissemination of information between prostate cancer research teams and the increasing pressure to “ stretch” research dollars at the same time staff reductions are occurring.To meet these challenges, we have used the correlative microscopy (CM) and client/server (C/S) computing to increase productivity while decreasing costs. Critical elements of our program are as follows:1) Establishing the Western Pennsylvania Genitourinary (GU) Tissue Bank which includes >100 prostates from patients with prostate adenocarcinoma as well as >20 normal prostates from transplant organ donors.

Digital image acquisition, processing, and analysis in a polymer microscopy laboratory

1994 ◽  
Vol 52 ◽  
pp. 454-455
Author(s):  
Vinod K. Berry ◽  
Xiao Zhang
Keyword(s):  
United States ◽  
Image Analysis ◽  
Digital Image ◽  
Image Acquisition ◽  
Image Transmission ◽  
The United States ◽  
Quantitative Image Analysis ◽  
Quantitative Image

In recent years it became apparent that we needed to improve productivity and efficiency in the Microscopy Laboratories in GE Plastics. It was realized that digital image acquisition, archiving, processing, analysis, and transmission over a network would be the best way to achieve this goal. Also, the capabilities of quantitative image analysis, image transmission etc. available with this approach would help us to increase our efficiency. Although the advantages of digital image acquisition, processing, archiving, etc. have been described and are being practiced in many SEM, laboratories, they have not been generally applied in microscopy laboratories (TEM, Optical, SEM and others) and impact on increased productivity has not been yet exploited as well.In order to attain our objective we have acquired a SEMICAPS imaging workstation for each of the GE Plastic sites in the United States. We have integrated the workstation with the microscopes and their peripherals as shown in Figure 1.

Silence of the Land: On the Historical Irrelevance of Territory to Congressional Districting and Political Representation in the United States

2001 ◽  
Vol 15 (01) ◽  
pp. 53-87 ◽  
Author(s):  
Andrew Rehfeld
Keyword(s):  
United States ◽  
House Of Representatives ◽  
Political Representation ◽  
The United States ◽  
Representative Government ◽  
Congressional District ◽  
Congressional Districts ◽  
Communities Of Interest

Every ten years, the United States “constructs” itself politically. On a decennial basis, U.S. Congressional districts are quite literally drawn, physically constructing political representation in the House of Representatives on the basis of where one lives. Why does the United States do it this way? What justifies domicile as the sole criteria of constituency construction? These are the questions raised in this article. Contrary to many contemporary understandings of representation at the founding, I argue that there were no principled reasons for using domicile as the method of organizing for political representation. Even in 1787, the Congressional district was expected to be far too large to map onto existing communities of interest. Instead, territory should be understood as forming a habit of mind for the founders, even while it was necessary to achieve other democratic aims of representative government.

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