To study the characteristics and the effects of biodegradation on the carbon isotopic composition of gaseous hydrocarbons of the natural gases in the Bamianhe oil field of the Jiyang Depression, five gas samples and three associated oil samples from the Bamianhe oil field of the Jiyang Depression, Eastern China, were collected and analyzed. The results present here an example of gas biodegradation. The main component of natural gas is methane, in the range of 94.8 to 99.2%. There are only small amounts of ethane and heavier wet hydrocarbon components in the gas, with methane/(ethane + propane) ratios (C₁/(C₂ + C₃)) ranging from 78 to 551. The carbon isotopic compositions of methane and ethane rang from -45.0 to -50.0‰ and from -34.2 to -39.8‰, respectively. The carbon isotopic compositions of propane, iso-butane and normal butane display significant variability, ranging from -2.6 to -31.1‰, -14.6 to -29.5‰, and -3.7 to -29.2‰, respectively. The δ¹³C of propane and normal butane are generally more enriched in ¹³C than that of iso-butane, and there exists a direct correlation between δ¹³C values of propane and normal butane of biodegraded gases. The carbon isotopic compositions of CO₂ tend to become depleted in ¹³C with the increasing δ¹³C values of propane and n-butane. This study reveals that δ¹³C values of methane and ethane basically have not been changed by the biodegradation; biodegradation of natural gas can lead to drier gas compositions; the effects of biodegradation on the δ¹³C of normal butane are greater than that on the δ¹³C of iso-butane; and that propane and normal butane are attacked by microorganisms in a synchronous process. Normal alkanes in the oil samples from the Bamianhe oil field are lost partially or totally with the increasing degree of biodegradation, resulting in the rising of the ratios of (Acyclic Isoprenoid Alkanes/(Normal Alkanes and the ratios of (pristane + phytane)/(nC₁₇ + nC₁₈). With the increasing of the above ratios, the carbon isotopic compositions of propane, iso-butane and normal butane become enriched in ¹³C and the C₁/(C₂ + C₃) ratios increase. It confirms that the abnormal gas components and carbon isotopic compositions of natural gases of the Bamianhe oil field are the result of biodegradation.

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I report here on a comprehensive ion microprobe study of Mn-Cr systematics of six pallasites. Four pallasites show excesses of radiogenic ⁵³Cr (⁵³Cr*), which correlate well with the Mn/Cr ratios. For these pallasites, the inferred initial (⁵³Mn/⁵⁵Mn)_o ratios are ~1 × 10^-5, which indicates that pallasites formed very early in the solar system. Eagle Station and Imilac show hints of ⁵³Cr*, but the excesses are not resolved from terrestrial standards. Comparisons of Mn-Cr results with those of Pd-Ag indicate that these two short-lived radionuclide chronometers are self-consistent in pallasites. Inferred (⁵³Mn/⁵⁵Mn)_o ratios in this study are generally higher than those previously observed by TIMS (1-3 × 10^-6). It is not clear what mechanism caused such a discrepancy. Nevertheless, it should be noted that ion probe depends on the zoning profiles to give high Mn/Cr ratios at the edges of the olivine crystals. Thus, it dates the closure time of diffusive fractionation of Mn and Cr in pallasite olivines.

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The uptake of Pb²⁺ and Sr²⁺ ions from aqueous solutions by calcite was studied at various initial concentrations and pH conditions using the batch method under ambient conditions. XRPD, SEM/EDS, AAS/AES, and DRIFT techniques were used in characterizing the sorption process. The results indicated that the retention mechanism of Pb²⁺ and Sr²⁺ ions ranged from ion incorporation to precipitate overgrowth (cerussite, hydrocerussite for Pb, strontianite for Sr) depending on the concentration and pH conditions. The calcite structure seemed to be entirely vanishing upon formation of cerussite and hydrocerussite while partial dissolution of calcite occurred upon strontianite formation. The formation of precipitates showed rapid kinetics, and equilibrium seemed to be reached within about an hour from the start of mixing. SEM analysis showed that cerussite, hydrocerussite, and strontianite had columnar prismatic-like, tabular hexagonal-like, and needle-like morphologies. Based on a nine-month observation period, dry samples of hydrocerussite seemed to show more morphological stability than cerussite. EDS analysis indicated that Pb²⁺ sorption is more favored than that of Sr²⁺, particularly in the phase of precipitate overgrowth. DRIFT analysis indicated a change in the symmetry of the carbonate groups in calcite matrix upon uptake of Pb²⁺ and Sr²⁺ cations.

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The latest generation of quadrupole ICP-MS instruments coupled with a 193 nm ArF excimer laser system (LA-ICP-MS) allows quantitative analysis for ultra-trace elements (ppm ~ ppb) from the small amount of solid materials. Multiple trace element compositions (Li, Be, B, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Cs, Ba, REE, Hf, Ta, Tl, Pb, Th and U) were simultaneously determined from thin layer (<30 μm) BCR-2G basalt glass reference materials using LA-ICP-MS. The effects of differences in matrix compositions (matrix effect) and elemental fractionation on the calibration technique for quantitative analysis, which involves combinations of external reference materials and internal standardization, were examined by using NIST SRM 612 (soda-lime glass) and two different elements (⁴²Ca and ²⁹Si) as an external reference material and internal standard elements, respectively. The elemental fractionation was found for several elements (B, Si, V, Mn, Ni, Zn, Rb, Mo and Pb). The effects of elemental fractionation on quantitative analysis are, however, practically negligible when the compositions were determined from thin layer samples, i.e., low depth-to-diameter ratio of laser pit, when ablating >50 μm pit diameter. No apparent differences between the Ca-normalized measured values and the Si-normalized one were found for both BCR-2G and natural minerals (clinopyroxene and amphibole in mafic rock). The measured values of BCR-2G are in agreement (within 20%) with the previous values for most elements (within 10% for REE except for Tb), except for Zn, Ga and Pb, in spite of large differences in matrix compositions between external reference material (NIST SRM 612) and the unknown sample (BCR-2G).

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Noble gas, Nd and Sr isotopic ratios and major and trace element compositions were determined for ultramafic xenoliths and their host Cenozoic alkali basalts from Baegdusan, Baegryongdo, Jogokri, Jejudo in the Korean peninsula, and Long Quan, close to the Baegdusan in northeastern China, to characterize the lithospheric mantle and the source of alkali basaltic magmatism beneath the active continental margin of the southeastern part of the Eurasian plate. The xenolith samples yield significantly variable ³He/⁴He ratios ranging from <0.2 to 16.8 R_A, with most samples (3.5-7.9 R_A) lower than the MORB value (~8 R_A). Among them, high ³He/⁴He ratios obtained by melting the samples are considered to reflect cosmogenic contribution. The ⁴⁰Ar/³⁶Ar ratios are much lower than the MORB values. Enriched Nd-Sr isotopic compositions in xenoliths and host basalts from the Baegdusan and Baegryongdo areas suggest assimilation of EMII lithosphere and/or continental crust. Widely ranging trace element concentrations in the xenoliths and highly saturated incompatible elements in the host alkali basalts are observed. K-Ar age data show that Cenozoic alkali volcanism in the Korean peninsula occurred intermittently, ranging in age from 21 Ma through 11.5-5.0 Ma to 0.1 Ma, and becoming gradually younger toward the south of the peninsula. Our geochemical and isotopic data suggest the presence of heterogeneously metasomatized enriched lithospheric mantle generated at an ancient subduction zone within the continental margin of the southeastern end of the Eurasian plate. Degree of enrichments by the metasomatism is discussed based on the observed ³He/⁴He ratios in the xenolithic olivines.

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This study shows that the role of various geochemical processes regulating groundwater chemistry can be effectively evaluated using a simple mass balance approach. The application of this approach was successful in a case study on a predominantly agricultural area (Namwon, Korea). For this study, a total of 279 groundwater samples were collected from 93 wells distributed over the study area and analyzed for pH, alkalinity, major cations (Ca²⁺, Mg²⁺, Na⁺, K⁺), major anions (NO₃^-, Cl^-, SO₄^2-), and silica. Nitrate, chloride, and sulfate concentrations point to the influence of anthropogenic activities on the groundwater composition. Increasing concentrations of major anions and cations toward the top of the aquifer suggests that they come mostly from surface sources. Mass balance analysis based on reaction stoichiometry reveals that the water chemistry is regulated primarily by the combination of three processes: (1) the weathering of minerals such as silicates, carbonates, and/or lime; (2) the input of Cl/SO₄ salts; and (3) the generation of nitrates (through nitrification and/or aerobic decomposition of organic matter). Based on this mass balance analysis, we could also quantify the contributions of each process to the observed water chemistry. The results show that mineral weathering is the predominant process affecting groundwater chemistry. Groundwaters more influenced by anthropogenic activities generally show the larger effect of mineral weathering, suggesting that (1) the weathering of silicates might be triggered by protons generated from nitrate generation and/or (2) the water chemistry is affected by lime (CaO) applied to cultivated land and/or carbonates (i.e., CaCO₃) in cement materials. However, the influence of protons, which can be co-produced with nitrate, on concentrations of major cations and alkalinity due to ion exchange were revealed to be negligible because the studied groundwater has sufficient alkalinity to neutralize those acids.

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We report concentrations of platinum group elements (PGE: Os, Ir, Ru, Rh, Pt and Pd) for picrite-basalt lavas of the Emeishan large igneous province, SW China. The absolute concentrations of Os in most of the Emeishan picrites are higher than in picrites from ocean islands and other continental flood basalt provinces, and in estimated primitive mantle. A roughly positive correlation between MgO and Cr and Ni, and no overall correlation of Os or Ir with MgO, show that no Cu-Ni sulfide fractionated during differentiation but rather that olivine and chromite fractionated, implying that the initial picritic magma was sulfide-undersaturated. In addition, Os/Ir ratios are unusually high, suggesting that the picritic magmas may have been contaminated by black shales. Modeling shows that a 7% partial melt of primitive mantle containing 0.01 wt% of sulfides can account for the observed Os, Ir and Ru concentrations in the most primitive picrite if the melt is contaminated by 10 wt% of black shale en route to the surface.

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We report here the first synchrotron radiation (SR)-based X-ray absorption fine structure (XAFS) spectra for Os at L_III-edge in geo- and cosmo-chemical materials. Samples were Negrillos meteorite, a II-A type iron meteorite, and a Pt ore specimen, aggregates of coarse grained Pt-Fe alloys, from the Chocó district, Colombia. X-ray absorption near-edge structure (XANES) spectra of Os are presented for Negrillos, which has an Os abundance of 65 ppm, as well as for the platinum-group mineral (PGM). The XANES spectra showed that Os in the iron meteorite and the PGM chiefly exist as a metallic species. The average interatomic distance of Os in the Pt ore from the Chocó district are calculated from the EXAFS spectra. The results suggest that the neighboring atoms of Os are not Pt. Instead, they are most likely Os and Ir. This is consistent with the common occurrence of fine lamellae of Os and iridosmine as exsolution products of Pt-Fe alloys. Furthermore, this confirms the limited solubility of Os in Pt-Fe alloys. EXAFS could thus be useful for identifying the host phases of Os in natural samples. This study has verified that the chemical state of Os in natural samples can be determined using XAFS. It is expected that further application of the XAFS technique to Os speciation in natural samples will help to elucidate Re/Os fractionation processes in the Re-Os isotopic system.

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A quick and inexpensive method of relative high iodine determination from coal samples was evaluated. Energy dispersive X-ray fluorescence (EDXRF) provided a detection limit of about 14 ppm (3 times of standard deviations of the blank sample), without any complex sample preparation. An analytical relative standard deviation of 16% was readily attainable for coal samples. Under optimum conditions, coal samples with iodine concentrations higher than 5 ppm can be determined using this EDXRF method. For the time being, due to the general iodine concentrations of coal samples lower than 5 ppm, except for some high iodine content coal, this method can not effectively been used for iodine determination. More work needed to meet the requirement of determination of iodine from coal samples for this method.

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