Results 261 to 270 of about 248,597 (344)
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Science of the Total Environment, 2022
Cultural eutrophication is the leading cause of water quality degradation worldwide. The traditional monitoring of eutrophication is time-consuming and not integrative in space and time.
C. Heredia +9 more
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Cultural eutrophication is the leading cause of water quality degradation worldwide. The traditional monitoring of eutrophication is time-consuming and not integrative in space and time.
C. Heredia +9 more
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Journal of Forensic Sciences, 2009
Abstract: There remains significant uncertainty in illicit marijuana cultivation. We analyzed the δ13C and δ15N of 508 domestic samples from known U.S.A. counties, 31 seized from a single location, 5 samples grown in Mexico and Colombia, and 10 northwest border seizures. For a subset, inflorescences and leaves were analyzed separately.
J. West, Janet M Hurley, J. Ehleringer
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Abstract: There remains significant uncertainty in illicit marijuana cultivation. We analyzed the δ13C and δ15N of 508 domestic samples from known U.S.A. counties, 31 seized from a single location, 5 samples grown in Mexico and Colombia, and 10 northwest border seizures. For a subset, inflorescences and leaves were analyzed separately.
J. West, Janet M Hurley, J. Ehleringer
semanticscholar +3 more sources
Stable Carbon and Nitrogen Isotopic
Aquatic Geochemistry, 2004The perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica, are part of the coldest and driest ecosystem on earth. To understand lacustrine carbon and nitrogen cycling in this end-member ecosystem, and to define paleolimnological proxies for ice-covered lakes, we measured the stable carbon and nitrogen isotopic composition of particulate ...
Jennifer Lawson +4 more
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Stable isotope studies of soil nitrogen
2020Sound generalisations and predictions of soil processes are difficult to make with confidence because of the chemical, physical and biological variations that occur in soil at all scales in both space and time. Natural abundance studies have been used in a wide range of soil-nitrogen (N) investigations and have provided some insights to the complexity ...
D.W. Hopkins, R.E. Wheatley, D. Robinson
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Mercury and Stable Isotopes of Carbon and Nitrogen in Mink
Environmental Toxicology and Chemistry, 2007Abstract Total Hg concentrations and values of stable isotopes (δ15N, δ13C) in tissues of mink (Mustela vison) captured in Rhode Island (USA) during winters of 1999 to 2004 were statistically distinct based on location. Mink captured in salt marsh environments (salt marsh group mink [SMGM]) had significantly lower mean Hg concentrations ...
James L, Lake +4 more
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Stable Nitrogen Isotope Analysis by Optical Spectroscopy
Analytical Chemistry, 1958Optical spectroscopy with photo-electric detection provides a rapid and precise micromethod for determining the nitrogen isotopic concentration of nitrogen gas and of nitric oxide gas. This paper describes the effect of operating conditions on the precision and the accuracy of such measurements.
H. P. Broida, M. W. Chapman
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Stable nitrogen isotopes in Angola Basin surface sediments
Marine Geology, 1996Abstract Sedimentary δ15N contains a record of biogeochemical processes occurring in the water column. Stable nitrogen isotopes were measured in the bulk sedimentary matter of 18 surface sediment samples collected in three transects in the eastern Angola Basin, perpendicular to the coast, at 6 °S, 12 °S and 17 °S and two samples from the Zaire ...
M.Elizabeth Holmes +5 more
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STABLE NITROGEN AND SULFUR ISOTOPES IN ATMOSPHERIC CHEMISTRY
2021SO2 and NOx (NO+NO2) are important trace gases in the atmosphere as they adversely affect air quality and are precursors to sulfate and nitrate aerosols in the atmosphere. However, there are significant uncertainties in the emission inventories and the atmospheric chemistry processes of both gases.
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