Water-use efficiency and stable isotope composition were studied in three tropical tree species. Seedlings of Tectona grandis, Swietenia macrophylla and Platymiscium pinnatum were grown at either high or low water supply, and with or without added fertilizer. These three species previously exhibited low, intermediate and high whole-plant water-use efficiency (TE) when grown at high water supply...

Rat epididymal fat pad segments were incubated with glucose labeled uniformly with W, and with tritium in position 2, and in positions 1,3, and 6. Under conditions of high lipogenesis, 70 to 80% of tritium (T) from position 2 was recovered in water, with the remainder in lipid glycerol, fatty acids, and lactate. The highest tritium retention, relative to carbon, was in glycerol, with T:W ratios...

Compound-specific carbon isotope ratio analysis is a promising tool to assess the origin and fate of organic contaminants in groundwater. The aim of this study was to develop and evaluate a reliable, fast method to determine carbon isotope ratios of chlorinated methanes, ethanes, and ethenes in aqueous samples. Direct solid-phase microextraction (dSPME) and headspace solid-phase microextraction...

Rat epididymal fat pad segments were incubated with glucose labeled uniformly with W, and with tritium in position 2, and in positions 1,3, and 6. Under conditions of high lipogenesis, 70 to 80% of tritium (T) from position 2 was recovered in water, with the remainder in lipid glycerol, fatty acids, and lactate. The highest tritium retention, relative to carbon, was in glycerol, with T:W ratios...

Moderate elevated vertical methane (CH4) flux is associated with sediment accretion and raised fluid expulsion at the Hikurangi subduction margin, located along the northeast coast of New Zealand. This focused CH4 flux contributes to the cycling of inorganic and organic carbon in solid phase sediment and pore water. Along a 7 km offshore transect across the Porangahau Ridge, vertical CH4 flux r...

[1] Two hypotheses have been proposed to explain simultaneous large negative excursions (up to 7% PeeDee belemnite) in bulk carbonate (dCcarb) and organic carbon isotope records (d Corg) from black shales marking the Toarcian oceanic anoxic event (T-OAE). The first explanation envisions recycling of dissolved inorganic carbon (DIC) with a light isotopic signature into the photic zone from the l...

The cycles of carbon and oxygen at the Earth surface are intimately linked, where the burial of organic carbon into sediments represents a source of oxygen to the surface environment. This coupling is typically quantified through the isotope records of organic and inorganic carbon. Yet, the late Neoproterozoic Eon, the time when animals first evolved, experienced wild isotope fluctuations which...

Despite the widespread use of carbon stable isotopes to distinguish among potential energy pathways in food webs, their usefulness is limited where potential basal carbon sources are numerous and diverse. We measured carbon isotope values of the major fisheries species, the mostly carnivorous Scylla serrata (giant mud crab), and potential basal, autotrophic sources supporting the food web. Conv...

Time-series stable carbon isotope monitoring of volatile organic compounds (VOCs) atthe Idaho National Engineering and Environmental Laboratory's (INEEL) field site Test Area North (TAN) was conducted during a pilot study to investigate the treatment potential of using lactate to stimulate in situ biologic reductive dechlorination of trichloroethene (TCE). The isotope ratios of TCE and its biod...

The Toarcian oceanic anoxic event (T-OAE; ∼ 183 million y ago) is possibly the most extreme episode of widespread ocean oxygen deficiency in the Phanerozoic, coinciding with rapid atmospheric pCO2 increase and significant loss of biodiversity in marine faunas. The event is a unique past tipping point in the Earth system, where rapid and massive release of isotopically light carbon led to a majo...