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Special rapid-mixing isotopic experiments using (super 18)O/(super 13)C-labeled bicarbonate are employed to quantify the inherent carbonic anhydrase activity in photosystem II (PS II) samples and the potential flux of oxygen from bicarbonate into the photosynthetically produced O2. The results show that bicarbonate is not the substrate for O2 production in these contemporary oxygenic photoautotrophs when assayed under single turnover conditions.

Researchers from the University of Alberta examined the distribution of liquid contaminants in soil microstructure from samples taken in Edmonton, Alberta, Canada.

Results from the bioremediation of creosote-contaminated soil reveal that the partition coefficients of [14C]naphthalene, which are related to the mass of organic carbon in the soil, are unaltered even as the average molecular weight of the residual creosote is increased by 10% to 36%. The partition coefficients for the creosote contaminant yield about 3500 to 4040 mL/g of organic carbon from both bioremediated and nonbioremediated soil samples when partitioning is used to model the total contributions of the nonaqueous phase contaminant and the soil organic matter.

Thermal desorption was combined with gas chromatography (ThermEx-GC) in analyzing hydrocarbons in creosote- and petroleum-contaminated soil. A mixture of anthracene and phenanthrene loaded into clean soil was used to determine the detectability and reproducibility of the analysis. ThermEx-GC provides direct and rapid analysis of contaminated soils by volatilizing target compounds from the soil into the carrier gas of a gas chromatograph. However, ThermEx-GC must be calibrated to allow for nonlinear response to sample size and concentration of hydrocarbons on the soil.

An investigation of the interactions between polynuclear aromatic hydrocarbons and soils was conducted as a function of moisture content and time. The recovery of anthracene in dry soils was very low. It was unrecoverable in Ellerslie soil after about 6 d. Pyrene and phenanthrene exhibited similar behavior. Addition of water to the soil inhibited the reactions, indicating that water and anthracene compete for access to active sites on mineral surfaces.

A study of the range of volatile organic sulfur compounds produced by brassica plants has highlighted limitations to the use of Carboxen/PDMS fibers for their analysis by solid-phase microextraction (SPME). These fibers are sometimes advocated for the analysis of sulfur gases, but a quantitative comparison of analytical data derived by SPME and by direct gas sampling of standard mixtures of volatile low molecular weight sulfur compounds at 0.01-10 mg/L has identified potential errors associated with their use. Higher molecular compounds displace lower molecular weight compounds as a consequence of competition for active sites on the fiber, and the relative proportions of the components adsorbed onto the fiber depend on their ratio in the headspace. As their relative concentrations change from sample to sample, the varying interactions result in irregular analytical responses, reflected in erratic calibration curves. Standards containing single components are not valid; only a standard containing all components found in the sample to be analyzed, and at the same relative concentrations, is appropriate. In practice, this may preclude the use of the fibers for quantitative analysis of multicomponent mixtures.

Greenhouse gas emissions are likely to rise faster than growth in population and more than double for water supply and wastewater services over the next 50 years in South East Queensland (SEQ), Australia. New sources of water supply such as rainwater tanks, recycled water, and desalination currently have greater energy intensity than traditional sources. In addition, direct greenhouse gas emissions from reservoirs and wastewater treatment and handling have potentially the same magnitude as emissions from the use of energy. Centralized and decentralized water supply and wastewater systems are considered for a scenario based upon a government water supply strategy for the next 50 years. Many sources of data have large uncertainties which are estimated following the IPCC Good Practice Guidelines. Important sources of emissions with large uncertainties such as rainwater tanks and direct emissions were identified for further research and potential mitigation of greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

A simple, one-pot synthesis of a surface-tethered MADIX agent was established via the reaction of 1,1′-thiocarbonyl diimidazole (TCDI) with a thiol, followed by reaction with the hydroxyl groups of a Wang resin. The supported RAFT agent was used to control the polymerization of vinyl acetate in toluene. The amount of surface-bound polymer was found to greatly increase with increasing content of solid MADIX agent, reaching values of almost 80%. The grafted PVAc chains were cleaved from the Wang resin support via radical reaction with tert-amyl peroxy acetate (TAPA), and the molecular weight distributions exhibited the typical shape of polymers formed via a well-controlled living radical polymerization (LRP), with the free polymers showing a slightly higher molecular weight than the living fraction. The Mnvalues of both living polymer fraction (surface-bound polymer) and dead polymer (free polymer) increased steadily with monomer conversionas expected for a well controlled MADIX polymerizationand were in good agreement with the theoretical molecular weights. PDI values of both polymer fractions scatter around 1.5, with a slight tendency of narrower molecular weight distributions of the living polymer, which shows a minimum value of 1.43. Addition of free MADIX agent to the solution phase led to a decrease in PDI values of both free and bound polymer, and the experimental molar masses were in very good agreement with theoretical predictions. [ABSTRACT FROM AUTHOR]