This article presents the use of natural abundance stable isotope (hydrogen, carbon, nitrogen, oxygen, chlorine) analysis data as a tool for providing important information about the origin of contaminants, the contribution of different sources to a multi-source plume, characterisation of their complex transport (rate and mechanisms) and for evaluating the success of contaminated site remediati...

Rapid responses of bacteria to sudden changes in their environment can have important implications for the structure and function of microbial communities. In this study, we used heavy-water stable isotope probing (H2(18)O-SIP) to identify bacteria that respond to soil rewetting. First, we conducted experiments to address uncertainties regarding the H2(18)O-SIP method. Using liquid chromatograp...

Silvicultural thinning usually improves the water status of remaining trees in water-limited forests. We evaluated the usefulness of a dual stable isotope approach (d 13C, d 18O) for comparing the physiological performance of remaining trees between forest stands subjected to two different thinning intensities (moderate versus heavy) in a 60-yearold Pinus halepensis Mill. plantation in semiarid...

Introduction: Methanogenic archaea, which consume CO2 and H2, have been considered models for possible life forms on Mars for a long time, even before the discovery of methane in the Martian atmosphere (1-8). Several intensive experimental studies have been conducted to investigate survivability of methanogens under conditions that approach those found on Mars (2, 3, 9). Various potential sourc...

We use the oxygen isotopic composition of tooth enamel from multiple mammalian taxa across eastern Africa to present a proxy for aridity. Here we report tooth enamel delta(18)O values of 14 species from 18 locations and classify them according to their isotopic sensitivity to environmental aridity. The species are placed into two groups, evaporation sensitive (ES) and evaporation insensitive (E...

Reconstructing Plio-Pleistocene African paleoenvironments is important for models of early hominin evolution, but is often hampered by low-resolution or discontinuous climatic data. Here, we present high-resolution stable oxygen and carbon isotope time series data from two flowstones (secondary cave deposits) from the South African hominin-bearing Makapansgat Valley. The age of the older of the...

Field studies analyzing the stable isotope composition of xylem water are providing important information on ecosystem water relations. However, the capacity of stable isotopes to characterize the functioning of plants in their environment has not been fully explored because of methodological constraints on the extent and resolution at which samples could be collected and analysed. Here, we int...

Stomatal conductance in trees is related to both foliar carbon-isotope abundance and stem hydraulic properties. By combining these relationships, I hypothesized that carbon-isotope abundance in foliage should vary with limitations to water movement through supporting branches. I sampled Douglas-fir branches (Pseudotsuga menziesii (Mirb.) Franco) from six sites across a climate gradient in Orego...

Isotope ratios of cellulose and cellulose nitrate from aquatic Crassulacean acid metabolism (CAM) and non-CAM plants were determined. Cellulose oxygen istope ratios for all plants that grew together were virtually identical, whereas large differences were observed for hydrogen isotope ratios of cellulose nitrate between CAM and non-CAM plants. Carbon isotope ratios of cellulose nitrate did not ...