Ian Staton

Mineral matter and trace elements in coals of the Gunnedah Basin, New South Wales, Australia

Abstract The concentrations of major and trace inorganic elements in a succession of Permian coals from the Gunnedah Basin, New South Wales, have been determined by X-ray fluorescence techniques applied to both whole-coal and high-temperature ash samples. The results have been evaluated in the light of quantitative data on the minerals in the same coals, determined from X-ray diffraction study of whole-coal samples using a Rietveld-based interpretation program ( Siroquant ™), to determine relationships of the trace elements in the coals to the mineral species present. Comparison of the chemical composition of the coal ash interpreted from the quantitative mineralogical study to the actual ash composition determined by XRF analysis shows a high degree of consistency, confirming the validity of the XRD interpretations for the Gunnedah Basin materials. Quartz, illite and other minerals of detrital origin dominate the coals in the upper part of the sequence, whereas authigenic kaolinite is abundant in coals from the lower part of the Permian succession. These minerals are all reduced in abundance, however, and pyrite is a dominant constituent, in coals formed under marine influence at several stratigraphic levels. Calcite and dolomite occur as cleat and fracture infillings, mostly in seams near the top and bottom of the sequence. The potassium-bearing minerals in the detrital fraction are associated with significant concentrations of rubidium, and the authigenic kaolinite with relatively high proportions of titanium. Zirconium is also abundant, with associated P and Hf, in the Gunnedah Basin coal seams. Relationships exhibited by Ti, Zr, Nd and Y are consistent with derivation of the original sediment admixed with the seams from an acid volcanic source. Pyrite in the coals is associated with high concentrations of arsenic and minor proportions of thallium; no other element commonly associated with sulphides in coals, however, appears to occur in significant proportions with the pyrite in the sample suite. Small concentrations of Cl present in the coal are inversely related to the pyrite content, and appear to represent ion-exchange components associated with the organic matter. Strontium and barium are strongly associated with the cleat-filling carbonate minerals. Ge and Ga appear to be related to each other and to the coals organic matter. Cr and V are also related to each other, as are Ce, La, Nd and Pr, but none of these show any relationship to the organic matter or a particular mineral component.

Asymmetric metal-catalysed epoxidation of electron-deficient olefins

Abstract The SYN diastereospecific epoxidation of acyclic β-hydroxyketones (β-hydroxyacrylates) and cyclic β-hydroxyketones using titanium and vanadium catalysts is reported. Some initial results on the asymmetric epoxidation of these systems using the Sharpless titanium-tartrate catalyst are also described.

Crystal Structure of Pyrococcus furiosus Phosphoglucose Isomerase IMPLICATIONS FOR SUBSTRATE BINDING AND CATALYSIS

Phosphoglucose isomerase (PGI) catalyzes the reversible isomerization between d-fructose 6-phosphate and d-glucose 6-phosphate as part of the glycolytic pathway. PGI from the Archaea Pyrococcus furiosus (Pfu) was crystallized, and its structure was determined by x-ray diffraction to a 2-Å resolution. Structural comparison of this archaeal PGI with the previously solved structures of bacterial and eukaryotic PGIs reveals a completely different structure. Each subunit of the homodimeric Pfu PGI consists of a cupin domain, for which the overall structure is similar to other cupin domain-containing proteins, and includes a conserved transition metal-binding site. Biochemical data on the recombinant enzyme suggests that Fe2+ is bound to Pfu PGI. However, as catalytic activity is not strongly influenced either by the replacement of Fe2+ by a range of transition metals or by the presence or absence of the bound metal ion, we suggest that the metal may not be directly involved in catalysis but rather may be implicated in substrate recognition.

Tandem pericyclic reactions. The first X-Ray structure of an initial pyrone-olefin adduct and an easy, stereocontrolled, entry into polyoxygenated cyclohexanes

Abstract Under high-pressure conditions, 2-pyrone undergoes Diels-Alder reaction with a variety of dienophiles, leading to isolable, bridged, bicyclic lactones. The first X-Ray structure of one of these lactones and its conversion into polyoxygenated cyclohexane derivatives is reported.

The Use of Tree Bark as a Passive Sampler for Polychlorinated Dibenzo- p -Dioxins and Furans

The potential of using tree bark as a passive sampling medium for detection of Polychlorinated dibenzo- p -dioxins and furans (PCDD/F) in an urban environment has been investigated. Bark samples (∼ 30 g) were extracted with toluene using accelerated solvent extraction. Extracts were then cleaned up via a multi-bed silica column and a Florisil column followed by GC-MS/MS analysis. It is shown that PCDD/F are present in tree bark collected from sites close to a municipal waste incinerator, a crematorium, a hospital and a chemical incinerator. Furthermore, characteristic patterns for dioxin congeners were observed for the suspected emission sources.

Rapid Multielement Analysis of Tree Bark by EDXRF

A rapid and simple method for multielement analysis of tree bark using energy dispersive X-ray fluorescence (EDXRF) spectrometry has been developed. Sample preparation consisted of crushing tree bark into a fine powder prior to the production of pressed pellets. Limits of detection for elements of interest (Pb, Hg, Zn, Cu, Ni, Al, Sn, Fe, Cr, Mn, Ti, As, Cd, Sb, and Ag) were at or below the µg/g level. Analysis of environmental certified reference materials (fly-ash, soil and tea-leaves) was used to check accuracy and precision. Survey analysis was performed at industrial, urban and rural sites in diverse locations throughout the world. The potential for source apportionation was demonstrated as reflected in elevated levels of Pb (up to 12,300 µg/g) and Sb (up to 86 µg/g) near a lead smelter site (UK) and high concentrations of Hg (up to 4.2 µg/g) in gold extraction regions of Brazil.