Data from a combination of laboratory and fieldwork is presented to initiate testing of stable carbon and nitrogen isotope ratios to trace sources of TNT in contaminated soil and groundwater. Evaluation of these extraction methods resulted in 99.9 and 99.8% recovery of TNT with Soxhlet and solid-phase extraction (SPE), respectively. As a result of the high extraction efficiency, isotope fractio...

The Early Jurassic was marked by a progressive recovery from the end-Triassic mass extinction and punctuated by recurring episodes of anoxia. These changes, associated with fluctuations in carbon isotope composition of marine carbonates, remain incompletely understood. Here we present a highresolution carbon and oxygen isotope record for the Early Jurassic based on well-preserved marine mollusk...

Whether photosynthetic pathway differences exist in the amplitude of nighttime variations in the carbon isotope composition of leaf dark-respired CO2 (δ13Cl) and respiratory apparent isotope fractionation relative to biomass (ΔR,biomass) in response to drought stress is unclear. These differences, if present, would be important for the partitioning of C3-C4 mixed ecosystem C fluxes. We measured...

We present a framework for interpreting the carbon isotopic composition of sedimentary rocks, which in turn requires a fundamental reinterpretation of the carbon cycle and redox budgets over Earth's history. We propose that authigenic carbonate, produced in sediment pore fluids during early diagenesis, has played a major role in the carbon cycle in the past. This sink constitutes a minor compon...

When inorganic carbon is converted to living matter during photosynthesis, there is an isotope effect and the carbon-containing compounds of cells have a slightly lower C13 concentration than the carbonate and carbon dioxide of the environment.' Craig2 has reviewed the existing data on carbon isotope abundances in nature. Park and Epstein3 4 have recently reported on some carbon isotope fractio...

Water and gas samples were collected from (1) nine shallow groundwater aquifers overlying Marcellus Shale in north-central West Virginia before active shale gas drilling, (2) wells producing gas from Upper Devonian sands and Middle Devonian Marcellus Shale in southwestern Pennsylvania, (3) coal-mine water discharges in southwestern Pennsylvania, and (4) streams in southwestern Pennsylvania and ...

Oxygen and carbon isotope ratios of benthic foraminifers were measured on the continuous middle to lower bathyal sedimentary sequence dated from the upper Maestrichtian to lower Eocene which was recovered at Site 752 in the eastern Indian Ocean. The changes in the carbon isotope values can be correlated with the faunal changes of the benthic foraminifers.

Natural waters’ carbon isotopes content is an important parameter in many environmental studies, as it hints to the water’s origin and history. Atmospheric water contain a certain amount of dissolved carbon dioxide, in the form of oxygen, hydrogen and carbon through their various species (CO2, HCO3 & CO3), which are commonly used for isotopic characterization of natural water [1]. Carbon posses...

a factorial pot experiment based on randomized complete blocks design with fourreplications was carried out in order to evaluate salt tolerance of four sugar beet cultivarsincluding madison (british origin) and three iranian cultivars (7233-p12, 7233-p21 and7233-p29) using carbon isotope discrimination (δ). plants were grown in sand culturemedium in greenhouse conditions. sugar beet cultivars w...

A longstanding puzzle in isotope studies of C3 plant species is that heterotrophic plant organs (e.g., stems, roots, seeds, and fruits) tend to be enriched in C compared to the autotrophic organ (leaves) that provides them with photosynthate. Our inability to explain this puzzle suggests key deficiencies in understanding post-photosynthetic metabolic processes. It also limits the effectiveness ...