No abstract

We present a new fully automated instrument for the measurement of acid gases and soluble anionic constituents of atmospheric particulate matter. The instrument operates in two independent parallel channels. In one channel, a wet denuder collects soluble acid gases; these are analyzed by anion chromatography (IC). In a second channel, a cyclone removes large particles and the aerosol stream is then processed by another wet denuder to remove potentially interfering gases. The particles are then collected by one of two glass fiber filters which are alternately sampled, washed, and dried. The washings are preconcentrated and analyzed by IC. Detection limits of low to subnanogram per cubic meter concentrations of most gaseous and particulate constituents can be readily attained. The instrument has been extensively field-tested; some field data are presented. Results of attempts to decipher the total anionic constitution of urban ambient aerosol by IC-MS analysis are also presented.

The Ion spray liquid chromatography/mass spectrometry (LC/MS) Interface Is coupled via a postsuppressor split with an Ion chromatography (IC) system. The micromembrane suppressor selectively removes over 99.9% of the ion-pair agents required for Ion chromatography from the eluent. The resulting solution consists of analyte, organic modifier, and water, which Is compatible with Ion evaporation mass spectrometry. A flow rate of 0.8 or 1.0 mL/min from the column was split after suppression such that approximately 10-20 /zL/mln was directed to the Ion spray LC/MS Interface, which was coupled to an atmospheric pressure Ionization (API) mass spectrometer. This system provided a convenient way to effect Isocratic and gradient separations of organic Ions under chromatographic conditions Incompatible with most forms of mass spectrometrlc Ionization. This work describes the separation and positive ion detection of quaternary ammonium drugs and tetraalkylammonlum compounds of Industrial Importance using both single and tandem mass spectrometrlc detection (e.g., IC/MS and IC/MS/MS). The former easily provided the molecular weights of these compounds while the latter gave some structural Information. The limit of detection (LCD) of 40 pg Injected on-column for tetrapropylammonlum cation Is a factor of 10 better than that obtained with the conventional IC conductivity detector. The separation, detection, and Identification of some alkyl sulfates and sulfonates are also shown with negative Ion detection.Again, IC/MS readily produced the molecular weights of these compounds while IC/MS/MS provided some structural Information.

Changes in subsurface temperature distribution resulting from the injection of fluids into aquifers may impact physiochemical and microbial processes as well as basin resource management strategies. We have completed a 2 year field trial in a hydrogeologically and geochemically heterogeneous aquifer below Perth, Western Australia in which highly treated wastewater was injected for large-scale groundwater replenishment. During the trial, chloride and temperature data were collected from conventional monitoring wells and by time-lapse temperature logging. We used a joint inversion of these solute tracer and temperature data to parameterize a numerical flow and multispecies transport model and to analyze the solute and heat propagation characteristics that prevailed during the trial. The simulation results illustrate that while solute transport is largely confined to the most permeable lithological units, heat transport was also affected by heat exchange with lithological units that have a much lower hydraulic conductivity. Heat transfer by heat conduction was found to significantly influence the complex temporal and spatial temperature distribution, especially with growing radial distance and in aquifer sequences with a heterogeneous hydraulic conductivity distribution. We attempted to estimate spatially varying thermal transport parameters during the data inversion to illustrate the anticipated correlations of these parameters with lithological heterogeneities, but estimates could not be uniquely determined on the basis of the collected data.

No abstract