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We examined the content and isotopic composition of nitrogen within soils of a juniper woodland and found that a cryptobiotic crust composed of cyanobacteria, lichens, and mosses was the predominant source of nitrogen for this ecosystem. Disturbance of the crust has resulted in considerable spatial variability in soil nitrogen content and isotopic composition; intercanopy soils were significantly depleted in nitrogen and had greater abundance of 15N compared to intra-canopy soils. Variations in the 15N\14N ratio for inter- and intracanopy locations followed similar Rayleigh distillation curves, indicating that the greater 15N/14N ratios for inter-canopy soils were due to relatively greater net nitrogen loss. Coverage...
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Nitrogen, phosphorus, and suspended-sediment loads, and changes in loads, in rivers across the Chesapeake Bay watershed have been calculated using monitoring data from the nine Chesapeake Bay River Input Monitoring (RIM) stations for the period 1985 through 2015. Nutrient and suspended-sediment loads and changes in loads were determined by applying a weighted regression approach called WRTDS (Weighted Regression on Time, Discharge, and Season). Yields (represents the mass of constituent transported from a unit area of a given watershed) are used to compare the export loads from one basin to another. Yield results are obtained by dividing the annual load (pounds) of a given constituent by the respective watershed...
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The following topics are currently covered by the MineralCommodity Summaries: domestic production and uses; U.S. salientstatistics; recycling; import sources; tariff; depletionallowance; government stockpile; events, trends, and issues;world production, reserves, and reserve base; world resources;and substitutes.
Tags: AY = Antarctica, Abrasives, Alumina, Aluminum, Antimony, All tags...
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This USGS Data Release represents the data used to develop multiple linear regression models for estimating the loads of total nitrogen in small streams. Recursive partitioning and random forest regression were used to assess 85 geospatial, environmental, and watershed variables across 636 small (less than 585 square kilometers) watersheds to determine which variables are fundamentally important to the estimation of annual loads of total nitrogen. These data support the following publication: Kronholm, S.C., Capel, P.D., and Terziotti, Silvia, 2016, Statistically extracted fundamental watershed variables for estimating the loads of total nitrogen in small streams: Environmental Modeling and Assessment, 10 p., http://dx.doi.org/10.1007/s10666-016-9525-3.
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This dataset shows the estimated delivered nitrogen load from all sources (livestock manure from confined operations, livestock manure from pasture feeding, livestock manure from feedlots, fertilizer applied to crops, runoff from urban land, combined municipal and wastewater discharge, and from atmospheric deposition)into the estuaries, bays, and sounds along the U.S. Gulf of Mexico coast in 2002.
Categories: Data; Tags: Alabama, Alabama, Apalachee Bay, Apalachee Bay, Apalachicola Bay, All tags...
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Mangrove restoration has a strong potential to enhance the services provided by coastal wetlands on a number of Department of the Interior (DOI) managed lands throughout the southeastern United States of America. Services include storm protection, water quality improvement, and biological carbon sequestration. Forest structural attributes including basal area, tree height, and stem density by species are used to calculate above ground biomass and above ground productivity. Percent cover is used to asses the forest canopy health. The data collected for the soils are: bulk density, percent total Nitrogen, percent total Carbon, and selected samples percent total Phosporus. The forest structure plots were placed in...
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This metadata record documents 11 comma delimited tables representing the amount of reported best management practice (BMP) implementation for the years from 1985 to 2014 at three geographic scales: county or land-river modeling segment, River Input Monitoring (RIM) station drainage areas, and the entire Chesapeake Bay Watershed (CBWS). Data originated from the Chesapeake Bay Watershed jurisdictions including Maryland, Pennsylvania, Virginia, Delaware, New York, West Virginia, and the District of Columbia. Data were reported to the Chesapeake Bay Program for an annual review of progress toward meeting nitrogen, phosphorus, and sediment reduction goals.
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This dataset provides aqueous nitrate+nitrite, aqueous manganese, aqueous iron, and total sulfate measurements in groundwater samples from 254 newly constructed private residential wells between 2014 and 2016. The study focuses on three geologically distinct regions of Minnesota: central, northwest, and northeast. These study regions were chosen due to their prevalent elevated As concentrations in drinking water. Each of the 254 wells were sampled in three rounds by the Minnesota Department of Health (MDH). The timing of the three sampling rounds was (1) immediately or shortly after well construction (round 1); (2) 3-6 months after initial sample collection (round 2); and (3) 12 months after initial sample collection...


map background search result map search result map A Break in the Nitrogen Cycle in Aridlands? Evidence from δ 15N of Soils Data on annual total nitrogen loads and watershed characteristics used to develop a method to estimate the total nitrogen loads in small streams Estimates of Total Nitrogen and Phosphorus Delivery to Estuaries, Bays, and Sounds Along the U.S. Gulf of Mexico Coast, 2002 Baseline data for a hydrological restoration of a mangrove forest near Goodland, Florida (2015 - 2017) Chesapeake Bay Nontidal Network 2005-2014: Average Yields 1) Best management practice implementation in the Chesapeake Bay watershed from 1985 to 2014 Aqueous nitrate+nitrite, aqueous manganese, aqueous iron, and total sulfate data Baseline data for a hydrological restoration of a mangrove forest near Goodland, Florida (2015 - 2017) A Break in the Nitrogen Cycle in Aridlands? Evidence from δ 15N of Soils 1) Best management practice implementation in the Chesapeake Bay watershed from 1985 to 2014 Aqueous nitrate+nitrite, aqueous manganese, aqueous iron, and total sulfate data Chesapeake Bay Nontidal Network 2005-2014: Average Yields Estimates of Total Nitrogen and Phosphorus Delivery to Estuaries, Bays, and Sounds Along the U.S. Gulf of Mexico Coast, 2002 Data on annual total nitrogen loads and watershed characteristics used to develop a method to estimate the total nitrogen loads in small streams