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The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
Browse more than 5,500 book chapters authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.
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Preparation and analysis of nitrogen-bearing compounds in water for stable isotope ratio measurement Preparation and analysis of nitrogen-bearing compounds in water for stable isotope ratio measurement
This chapter reviews methods for analyzing "natural abundance" nitrogen-bearing compounds in water for δ15N, δ18O, and δ17O. The techniques that are reviewed are Kjeldahl distillation and digestion, diffusion, micro diffusion, ion exchange, and microbial denitrifier methods. It overlaps the contents of the preparation of ecological and biogeochemical samples for isotope analysis and also...
Authors
Cecily C.Y. Chang, Steven R. Silva, Carol Kendall, Greg Michalski, Karen L. Casciotti, Scott D. Wankel
Stable Isotope Analysis of Water and Aqueous Solutions by Conventional Dual-Inlet Mass Spectrometry Stable Isotope Analysis of Water and Aqueous Solutions by Conventional Dual-Inlet Mass Spectrometry
This chapter reviews the recent developments and refinements of analytical methods for preparing waters and other aqueous samples of different origins for the measurement of the oxygen and hydrogen isotopes by conventional dual-inlet, dynamic gas-source isotope-ratio mass spectrometry. The emerging techniques of continuous-flow mass-spectrometry are discussed as they are employed in both...
Authors
Juske Horita, Carol Kendall
Hydrology: Chapter D Hydrology: Chapter D
No abstract available.
Authors
Claudia C. Faunt, Frank A. D’Agnese, Grady M. O’Brien
Selenium, iron, and chromium stable isotope ratio measurements by the double isotope spike TIMS method Selenium, iron, and chromium stable isotope ratio measurements by the double isotope spike TIMS method
This chapter focuses on the double-spike calibrated thermal ionization mass spectrometry (TIMS) methods for measurement of mass dependent isotope fractionation in Se, Fe, and Cr. Current measurement precision is approximately ± 0.2 per mil on 80Se / 76Se, 56Fe / 54Fe, and 53Cr / 52Cr. Sample size requirements are 500ng, 1μg, and 250ng for Se, Fe, and Cr respectively. These measurements...
Authors
Thomas M. Johnson, Thomas D. Bullen
Molecular markers and their use in environmental organic geochemistry Molecular markers and their use in environmental organic geochemistry
Molecular markers are organic substances that carry information about sources of organic matter or contamination. The source/marker relation can be used to indicate the presence of a given source material (qualitative), or, under appropriate conditions, to estimate the amount of a source material (quantitative source apportionment) in the environment. Assemblages of markers can also be...
Authors
Robert P. Eganhouse
Modeling microbial enhancement of Zn (II) and Pb (II) transport in columns packed with geologic media Modeling microbial enhancement of Zn (II) and Pb (II) transport in columns packed with geologic media
No abstract available.
Authors
Lee L. Landkamer, R.W. Harvey, D. W. Metge, J. N. Ryan
Lessons learned about metals in the estuary: The importance of long-term clam accumulation data Lessons learned about metals in the estuary: The importance of long-term clam accumulation data
No abstract available.
Authors
C. L. Brown, Samuel N. Luoma, Francis Parchaso, Janet K. Thompson
Geochemistry of coastal tarbells in southern California: A tribute to I.R. Kaplan Geochemistry of coastal tarbells in southern California: A tribute to I.R. Kaplan
No abstract available.
Authors
Keith A. Kvenvolden, Frances D. Hostettler
Survival estimation in bats: historical overview, critical appraisal, and suggestions for new approaches Survival estimation in bats: historical overview, critical appraisal, and suggestions for new approaches
No abstract available.
Authors
T. J. O'Shea, L.E. Ellison, T.R. Stanley
Evaluating remedial alternatives for the Alamosa River and Wightman Fork, near Summitville Mine, Colorado: Application of a reactive transport model to low- and high-flow simulations Evaluating remedial alternatives for the Alamosa River and Wightman Fork, near Summitville Mine, Colorado: Application of a reactive transport model to low- and high-flow simulations
Reactive-transport processes in Wightman Fork and the Alamosa River downstream from the Summitville Mine, south-central Colorado, were simulated at low and high flow using the OTEQ reactive-transport model. The simulations were calibrated using data from synoptic studies conducted during October 1998 and June 1999. Discharge over the 30-km reach from just below the mine site to the...
Authors
J.W. Ball, R.L. Runkel, D. Kirk Nordstrom
U-Pb geochronology and evolution of Mesoproterozoic basement rocks, western Connecticut U-Pb geochronology and evolution of Mesoproterozoic basement rocks, western Connecticut
Geologic mapping and U-Pb geochronology by ion microprobe on zircon, titanite, and monazite in the New Milford quadrangle, western Connecticut indicate Meso-proterozoic events at ca. 1.3, 1.05, and 0.99 Ga in the Laurentian basement rocks. Pink granite gneiss (1311 ± 7 Ma) intruded a paragneiss sequence during the early stages of the Elzevirian orogeny. During the Ottawan orogeny, syn...
Authors
Gregory J. Walsh, John N. Aleinikoff, C. Mark Fanning