A5036070265- Geological and Geochemical Analysis
- Astro and Planetary Science
- Geology and Paleoclimatology Research
- Isotope Analysis in Ecology
- Planetary Science and Exploration
- earthquake and tectonic studies
- Groundwater and Isotope Geochemistry
- Hydrocarbon exploration and reservoir analysis
- Paleontology and Stratigraphy of Fossils
- Geochemistry and Geologic Mapping
- Space Exploration and Technology
- Methane Hydrates and Related Phenomena
- High-pressure geophysics and materials
- Atmospheric and Environmental Gas Dynamics
- Geological and Geophysical Studies Worldwide
- Geochemistry and Elemental Analysis
- Atmospheric Ozone and Climate
- Nuclear Physics and Applications
- Geological and Tectonic Studies in Latin America
- Geological Formations and Processes Exploration
- Climate variability and models
- Geological and Geophysical Studies
- Radioactive element chemistry and processing
- Spacecraft and Cryogenic Technologies
- Marine and environmental studies
University of New Mexico
2015-2024
Planetary Science Institute
2004-2019
Trinity University
2012
Western Carolina University
2011
University of Lausanne
1992-2005
The University of Texas at San Antonio
2003
Centre Alpien de Phytogéographie
1997
Carnegie Institution for Science
1989-1991
Geophysical Laboratory
1989-1990
University of Michigan
1985-1988
Ultrafine particles (UFP, <100 nm) are ubiquitous in ambient urban and indoor air from multiple sources may contribute to adverse respiratory cardiovascular effects of particulate matter (PM). Depending on their particle size, inhaled UFP efficiently deposited nasal, tracheobronchial, alveolar regions due diffusion. Our previous rat studies have shown that can translocate interstitial sites the tract as well extrapulmonary organs such liver within 4 24 h postexposure. There were also...
Studies with intravenously injected ultrafine particles have shown that the liver is major organ of their uptake from blood circulation. Measuring translocation inhaled to extrapulmonary organs via compartment hampered by methodological difficulties (i.e., label may come off, partial solubilization) and analytical limitations (measurement very small amounts). The objective our pilot study was determine whether elemental carbon translocate other following inhalation as singlet rats. We...
Research Article| March 01, 2009 Seasonal bias in the formation and stable isotopic composition of pedogenic carbonate modern soils from central New Mexico, USA D.O. Breecker; Breecker † 1Department Earth Planetary Sciences, University Albuquerque, Mexico 87131, †E-mail: breecker@email.arizona.edu; Now at Arizona Search for other works by this author on: GSW Google Scholar Z.D. Sharp; Sharp L.D. McFadden Author Article Information Publisher: Geological Society America Received: 04 Feb 2008...
So Different and Similar Most known meteorites from Mars fit into one class. Agee et al. (p. 780 , published online 3 January; see the Perspective by Humayun ) describe a meteorite, NWA 7034, which shares some characteristics with other martian but does not within usual classification. 7034 matches composition of Mars' surface is also richer in water than meteorites, has different oxygen isotope composition, suggests existence multiple isotopic reservoirs Mars. Its radiometric age 2.1...
Abstract Groundwater recharged by meteoric water supports human life providing two billion people with drinking and supplying 40% of cropland irrigation. While annual groundwater recharge rates are reported in many studies, fewer studies have explicitly quantified intra‐annual (i.e., seasonal) differences recharge. Understanding seasonal the fraction precipitation that recharges aquifers is important for predicting under changing evapotranspiration regimes a warming climate, accurately...
Arguably, the most striking geochemical distinction between Earth and Moon has been virtual lack of water (hydrogen) in latter. This conclusion was recently challenged on basis data from lunar materials that suggest Moon's content might be far higher than previously believed. We measured chlorine isotope composition Apollo basalts glasses found range isotopic values [from -1 to +24 per mil (per thousand) versus standard mean ocean chloride] is 25 times for Earth. The huge spread explained by...
The destruction wrought by North Atlantic hurricanes in 2004 and 2005 dramatically emphasizes the need for better understanding of tropical cyclone activity apart from records provided meteorological data historical documentation. We present a 220-year record oxygen isotope values alpha-cellulose longleaf pine tree rings that preserves anomalously low latewood portion ring years corresponding with known 19th 20th century landfalling/near-coastal storms hurricanes. Our results suggest...
We report N and He isotopic relative abundance characteristics of volatiles emitted from two segments the Central American volcanic arc. In Guatemala, delta15N values are positive (i.e., greater than air) N2/He ratios high (up to 25,000). contrast, Costa Rican low (maximum 1483) negative (minimum -3.0 per mil). The results identify shallow hemipelagic sediments, subducted into Guatemalan mantle, as transport medium for heavy N. Mass balance arguments indicate that is efficiently cycled...
Quantifying atmospheric CO 2 concentrations ([CO ] atm ) during Earth’s ancient greenhouse episodes is essential for accurately predicting the response of future climate to elevated levels. Empirical estimates [CO Paleozoic and Mesozoic climates are based primarily on carbon isotope composition calcium carbonate in fossil soils. We report that have been significantly overestimated because previously assumed soil formation too high. More accurate , resulting from better constraints indicate...
[1] Water vapor in the subtropical troposphere plays an important role radiative balance, distribution of precipitation, and chemistry Earth's atmosphere. Measurements water mixing ratio paired with stable isotope ratios provide unique information on transport processes moisture sources that is not available data alone. D/H from Mauna Loa Observatory over 4 weeks October–November 2008 were used to identify components regional hydrological cycle. A model exploits fluxes time series data....
We investigate the relationship between sulfur and oxygen fugacity at Erta Ale Masaya volcanoes. Oxygen was assessed utilizing Fe 3+ /∑Fe major element compositions measured in olivine‐hosted melt inclusions matrix glasses. melts have of 0.15–0.16, reflecting f O 2 ΔQFM 0.0 ± 0.3, which is indistinguishable from calculated CO /CO ratios high‐temperature gases. more oxidized +1.7 0.4, typical arc settings. Sulfur isotope gases scoria (δ 34 S gas − 0.5‰; δ + 0.9‰) 4.8‰; 7.4‰) reflect distinct...