This study has determined the relationship and extent of mangrove reduced carbon flow and its contribution to the diet of higher consumers in a nearby seagrass bed using stable isotope techniques. In a seagrass bed approximately 80 m from a riverine mangrove community, detritus from seagrass or other marine sources of carbon such as epiphytes (Stilophora rhizodes) or phytoplankton the major con...

Vertebrate fossils and continental sediments provide a rich record of variations in the isotopic composition of surface environments. To interpret these records, a greater understanding of isotopic sources, as well as fractionations associated with animal physiology, soil geochemistry, and diagenesis, has been essential. Tooth enamel and fish otoliths yield subannual records of surface environm...

The rhodium-catalyzed intramolecular carboacylation of quinolinyl ketones serves as an ideal subject for the mechanistic study of carbon-carbon bond activation. Combined kinetic and NMR studies of this reaction allowed the identification of the catalytic resting state and determination of the rate law, (12)C/(13)C kinetic isotope effects, and activation parameters. These results have identified...

Land-use changes until the beginning of the 20(th) century made the terrestrial biosphere a net source of atmospheric carbon. Later, burning of fossil fuel surpassed land use changes as the major anthropogenic source of carbon. The terrestrial biosphere is at present suggested to be a carbon sink, but the distribution of excess anthropogenic carbon to the ocean and biosphere sinks is highly unc...

Isotope ratio analyses of atmospheric CO(2) at natural abundance have significant potential for contributing to our understanding of photosynthetic and respiration processes in forest ecosystems. Recent advances in isotope ratio mass spectrometry allow for rapid, on-line analysis of small volumes of CO(2) in air, and open new research opportunities at the ecophysiological, whole-organism, and a...

he efficiency of photosynthesis continues to interest biochemists, biologists, and plant physiologists. Scientists interested in CO2 uptake are concerned about the extent to which the uptake rate is limited by such factors as stomatal diffusion and the chemistry of the CO2 absorption process. The fractionation of carbon isotopes that occurs during photosynthesis is one of the most useful techni...

Stable isotope analysis of a novel combination of carbon and nitrogen pools traced inputs and processing of primary-treated (PE) and secondary-treated effluent (SE) from a paper and pulp mill (PPM) in a temperate Australian estuary. Distinct carbon stable isotope ratios of dissolved organic carbon (DOC) near the PPM outfall indicated large PE and reduced SE inputs of DOC. DOC was remineralized ...

A rise in atmospheric O(2) has been linked to the Cambrian explosion of life. For the plankton and animal radiation that began some 40 million yr later and continued through much of the Ordovician (Great Ordovician Biodiversification Event), the search for an environmental trigger(s) has remained elusive. Here we present a carbon and sulfur isotope mass balance model for the latest Cambrian tim...

We have measured the stable isotope ratios of carbon in a suite of recent cave deposits (< 200 years) from the San Saba County, Texas, USA. The methodology for dating these deposits using excess 210pb was recently established [Baskaran and Iliffe, 1993]. The carbon isotope ratios of these samples, spanning the thne period -• 1800-1990 AD, reflect the carbon isotope ratio of atmospheric CO2 for ...

Perennial species with the C(4) pathway hold promise for biomass-based energy sources. We have explored the extent that CO(2) uptake of such species may be limited by light in a temperate climate. One energetic cost of the C(4) pathway is the leakiness () of bundle sheath tissues, whereby a variable proportion of the CO(2), concentrated in bundle sheath cells, retrodiffuses back to the mesophyl...