نتایج جستجو برای: nitrogen isotope
تعداد نتایج: 148851 فیلتر نتایج به سال:
OBJECTIVES: A “dip” in the stable nitrogen isotope ratios (dN) of subadults in the late weaning/early post-weaning phase of growth and development has been observed. Speculatively, this is the mechanism of positive nitrogen balance operating among rapidly growing subadults. An alternate hypothesis for dN dips is that during weaning, subadults eat lower-N foods than adults. METHODS: This study e...
Cahokia Mound 72 contains 272 human burials dating to the Lohmann and early Stirling phases (ca. 1050–1150 AD) of the Mississippian period. Substantial statusand gender-related differences in burial style are apparent. Some burials are associated with large quantities of prestigious grave goods, suggesting high status. Mass graves of young adult females with skeletal indicators of poor health s...
boron nitride semiconducting zigzag swcnt, $b_{cb}$$n_{cn}$$c_{1-cb-cn}$, as a potential candidate for making nanoelectronic devices was examined. in contrast to the previous dft calculations, wherein just one boron and nitrogen doping configuration have been considered, here for the average over all possible configurations, density of states (dos) was calculated in terms of boron and nitrogen ...
Diazotrophic inputs by Trichodesmium have been shown to support production in tropical and subtropical marine environments, but the importance of Trichodesmium in the Gulf of Mexico has not been widely investigated. Here, we use stable carbon (δ13C) and nitrogen (δ15N) isotopes to determine whether diazotrophy impacts the isotope baselines of pelagic food webs in the northern Gulf of Mexico. Ph...
The globalization of food production and distribution has homogenized human dietary patterns irrespective of geography, but it is uncertain how far this homogenization has progressed. This study investigated the carbon and nitrogen isotope ratios in the scalp hair of 1305 contemporary Japanese and found values of -19.4 ± 0.6‰ and 9.4 ± 0.6‰ (mean ± SD), respectively. Within Japan, the inter-reg...
In this study, we examined the nitrogen dynamics of a highly urbanized coastal area, focusing on the impacts of sewage-derived nitrogen. High levels of dissolved inorganic nitrogen were detected in seawater near treated sewage effluent (TSE) discharge points before decreasing in the offshore direction, suggesting that the impact zone of sewage effluent is about 1–2 km from the discharge point. ...
Bone Chemistry and Paleodiet: Reconstructing Prehistoric Subsistence-Settlement Systems in Australia
This article reviews the results of bone collagen stable carbon and nitrogen isotope paleodietary studies conducted in Australia. Stable isotopic analyses of prehistoric human and faunal bones and teeth provide a means to assess past Aboriginal dietary patterns and habitat use, palaeoclimate, and palaeoecology. In some cases, the relative consumption of marine versus terrestrial foods or use of...
We examine inherent variation in carbon and nitrogen stable isotope values of multiple soft tissues from a population of captive green turtles Chelonia mydas to determine the extent of isotopic variation due to individual differences in physiology. We compare the measured inherent variation in the captive population with the isotopic variation observed in a wild population of juvenile green tur...
Synthetic (e.g. urea) and organic fertilizers (e.g. compost) differed markedly in N isotope composition and the greater the difference between organic and synthetic fertilizer the more robust will be the differentiation of crops and vegetable grown under different farming systems. The objective of this study was to compare nitrogen and carbon isotope composition of organic fertilizers and manur...
Isotopic fractionations accompanying element transfer through terrestrial ecosystems have the potential to shed light on ecological interactions between primary producers and consumers, but with the exception of carbon and nitrogen this potential has barely been exploited. Here, the magnesium stable isotope composition of bones and teeth of extant mammals from Kruger National Park (KNP) and Wes...
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