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Ecological processes of low-productivity ecosystems have long been considered to be driven by abiotic controls with biotic interactions playing an insignificant role. However, existing studies present conflicting evidence concerning the roles of these factors, in part due to the short temporal extent of most data sets and inability to test indirect effects of environmental variables modulated by biotic interactions. Using structural equation modeling to analyze 65 years of perennial vegetation change in the Sonoran Desert, we found that precipitation had a stronger positive effect on recruitment beneath existing canopies than in open microsites due to reduced evaporation rates. Variation in perennial canopy cover...
Categories: Publication;
Types: Citation;
Tags: SEM,
Tumamoc Hill,
arid,
density dependence,
modeling,
Samples of the crater lake water were filtered in the field with a 0.45 micron filter. Subsequently, additional precipitates formed in the solute-rich samples (secondary precipitates) which were subsequently filtered in the lab with a 0.45 micron filter. Resulting residues were analyzed both in situ on the filter and after scraping. Samples were sputter coated with 10 nm Au, then imaged in a Tescan VEGA3 scanning electron microscope (SEM) equipped with an Oxford 150 mm2 X-MaxN large area energy dispersive spectrometer at the U.S. Geological Survey, Menlo Park, CA. Elemental backscatter (BSE) images were collected with an accelerating voltage (HV) of 30 kV and a working distance (WD) of ~15 mm. Magnification is indicated...
This study is an evaluation of the potential environmentalimpacts of contaminated groundwater from the ASARCO metals refiningfacility adjacent to the Missouri River in Omaha, Nebraska. Surfacewaters, sediments, and sediment pore waters were collected from theBurt-Izard drain, which transects the facility, and from the Missouri Riveradjacent to the facility. Groundwater was also collected from thefacility. Waters and sediments were analyzed for inorganic contaminants,and the toxicity of the waters was evaluated with the Ceriodaphnia dubia7-day test. Concentrations of several elemental contaminants were highlyelevated in the groundwater, but not in river sediment pore waters. Leadconcentrations were moderately elevated...
Ecological processes of low-productivity ecosystems have long been considered to be driven by abiotic controls with biotic interactions playing an insignificant role. However, existing studies present conflicting evidence concerning the roles of these factors, in part due to the short temporal extent of most data sets and inability to test indirect effects of environmental variables modulated by biotic interactions. Using structural equation modeling to analyze 65 years of perennial vegetation change in the Sonoran Desert, we found that precipitation had a stronger positive effect on recruitment beneath existing canopies than in open microsites due to reduced evaporation rates. Variation in perennial canopy cover...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Ecology,
SEM,
Tumamoc Hill,
arid,
density dependence,
This data release presents geochemical analyses of silicate melt inclusions, host quartz phenocrysts, and biotite phenocrysts in samples collected by the U.S. Geological Survey (USGS) from mid-Cenozoic rhyolitic rocks from northern Nevada. Igneous intrusions and volcanic rocks in this study encompass nineteen rhyolitic samples from five magmatic centers across northeastern Nevada. Rhyolites were emplaced throughout northeastern Nevada over about an 8 million year timespan (41–33 mega-annum) in a variety of eruptive styles and volumes, ranging from meter-wide dikes to caldera-forming ignimbrites, and were roughly contemporaneous with regional ore deposition. Samples were prepared for petrographic and scanning electron...
Categories: Data;
Tags: Bald Mountain,
Beast pit,
Blue Star Mine,
Caetano Caldera,
Carico Lake Valley,
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