A new method for the recovery of ammonium from natural waters for measurement of 15N composition in isotope dilution experiments

Abstract. We describe a new method for the measurement of U/Pb ratios by isotope dilution multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for the dating of geologically young clean carbonates, particularly speleothems. The method is intended for materials containing little or no initial 232Th. We illustrate and validate the method with four examples ranging from 0.57 Ma to 20 Ma old. The new method is capable of applying the 235U-207 and 238U-234U-206Pb chronometers, common Pb and quantifiable residual 234U/238U disequilibrium permitting. These provide an alternative to the more widely used 238U-206Pb chronometer, which can be highly inaccurate for samples a few million years old, owing to uncertainties in the excess initial 234U (hence, excess radiogenic 206Pb) commonly observed in speleothems.

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A dynamic gas extraction-assisted paper-based method for colorimetric determination of bromides

Analytical Methods ◽

10.1039/c9ay02640a ◽

2020 ◽

Vol 12 (4) ◽

pp. 587-594 ◽

Cited By ~ 1

Author(s):

Marina O. Gorbunova ◽

Maria S. Garshina ◽

Margarita S. Kulyaginova ◽

Vladimir V. Apyari ◽

Aleksei A. Furletov ◽

...

Keyword(s):

Natural Waters ◽

New Method ◽

Colorimetric Determination ◽

Gas Extraction ◽

Selective Determination

A new method for selective determination of bromides in natural waters, foodstuffs and pharmaceuticals has been developed.

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The use of the 15N isotope dilution technique to estimate the contribution of associated biological nitrogen fixation to the nitrogen nutrition of Paspalum notatum cv. batatais

Canadian Journal of Microbiology ◽

10.1139/m83-161 ◽

1983 ◽

Vol 29 (8) ◽

pp. 1036-1045 ◽

Cited By ~ 44

Author(s):

Robert M. Boddey ◽

Phillip M. Chalk ◽

Reynaldo L. Victoria ◽

Eiichi Matsui ◽

Johanna Döbereiner

Keyword(s):

Isotope Dilution ◽

Nitrogen Nutrition ◽

Control Plant ◽

Paspalum Notatum ◽

Dilution Technique ◽

N Nutrition ◽

Advantages And Disadvantages ◽

Reduction Activity ◽

Dilution Experiments ◽

Biological Nitrogen

This paper reports the results of a field experiment to investigate the use of the 15N-dilution technique to measure the contribution of biological N2 fixation to the N nutrition of the batatais cultivar of Paspalum notatum. The pensacola cultivar of this grass supports little associated N2 fixation as evidenced by the low associated C2H2 reduction activity and was thus used as a nonfixing control plant. The grasses were grown in 60-cm diameter concrete cylinders sunk into the soil, and the effects of four different addition rates of labelled nitrogen (NH4)2SO4, were investigated. The data from seven harvests clearly demonstrated that there was a significant input of plant associated N2 fixation to the nutrition of the batatais cultivar amounting to approximately 20 kg N∙ha−1∙year−1. Problems associated with the conduct of such isotope dilution experiments are discussed including the importance of using nonfixing control plants of similar growth habit, the advantages and disadvantages of growing the plants in cylinders as opposed to field plots, and the various methods of application of labelled N fertilizer.

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