Carbon stable isotope signatures can effectively trace food sources, elucidate trophic interactions, and presumably reflect food web structure. The present study conducted a dietswitch experiment using freshwater teleost grass carp Ctenopharyngodon idella cultured for 3 mo with artificial feed that had a distinct carbon stable isotope composition. Turnover and fractionation of carbon stable iso...

The assessment of provenance of heparin is becoming a major concern for the pharmaceutical industry and its regulatory bodies. Batch-specific [carbon (δ(13) C), nitrogen (δ(15) N), oxygen (δ(18) O), sulfur (δ(34) S), and hydrogen (δD)] stable isotopic compositions of five different animal-derived heparins were performed. Measurements readily allowed their differentiation into groups and/or subg...

Introduction According to Anbar & Knoll (2002), the Proterozoic ocean was in a transition stage from euxinic with oxygenated shallow water to the fully oxygenated water column of the present day. Though there is no direct proxy for the concentration of oxygen in the past, carbon and sulfur isotopes help constrain these concentrations. The carbon and sulfur cycles underwent vast transitions in t...

We report the first Ni and Cr stable isotope data for ureilite meteorites that are mantle residue of a carbon-rich differentiated planet. Ureilites have similar compositions as chondrites, suggesting core-mantle differentiation parent body (UPB) did not fractionate isotopes. Since size Earth is potentially larger than UPB; with diameter >690 km), resulting in higher temperatures at boundary Ear...

The Archean-Proterozoic transition is characterized by the widespread deposition of organic-rich shale, sedimentary iron formation, glacial diamictite, and marine carbonates recording profound carbon isotope anomalies, but notably lacks bedded evaporites. All deposits refl ect environmental changes in oceanic and atmospheric redox states, in part associated with Earth’s earliest ice ages. Time-...

Dietary adaptations of prehistoric hunter-gatherers from Neolithic and Early Bronze Age cemeteries in the Little Sea region of Cis-Baikal (the region to the west and north of Lake Baikal) are explored using stable isotopes of carbon and nitrogen. Stable isotope data, including stable carbon isotopes from bone carbonate, are presented for 22 individuals from the site of Kurma XI, dated to approx...

Title of Document: SULFUR ISOTOPE FRACTIONATIONS IN BIOLOGICAL SYSTEMS: INSIGHT INTO THE PROTEROZOIC BIOSPHERE David T. Johnston, Ph.D. 2007 Directed By: Professor J. Farquhar, Department of Geology and ESSIC This study focuses on developing a framework for interpreting isotopic fractionations in the four stable sulfur isotopes, with a special focus on microbial effects. Calculations of low tem...

Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Ubeda, 18-22 October 2009) hosted a symposium on the ecology of st...