A Triple‐Stack Column Procedure for Rapid Separation of Cu and Zn from Geological Samples

We present a new procedure for the separation and purification of Cu and Zn from geological samples. Our procedure employed a single pass, triple‐stack column set‐up. The first column, filled with TRU resin (TrisKem International), quantitatively removed Fe and Ti from sample matrices. A second column, filled with pre‐filter resin (TrisKem International), removed organic compounds. Finally, a third column, filled with anion exchange resin (AG1‐X8, 200–400 mesh, Bio‐Rad), was used to separate Cu and Zn from the remaining matrix. Our procedure required about 50% less acid volume than previously reported methods for Cu and Zn separation, thereby minimising analytical blanks and column running times. Copper and Zn stable isotope ratios were determined by a Thermo Neptune Plus MC‐ICP‐MS using Zn and Cu external normalisation, respectively, in addition to sample‐standard bracketing to correct for instrumental mass bias. We explore the inter‐calibration of Cu and Zn isotope fractionation coefficients during analysis by measuring mixed Cu–Zn solutions with enhanced mass bias variation generated by varying sample gas flow rates. Our results demonstrate that this procedure is useful when variation in instrumental mass bias throughout analytical sequences is insufficient to inter‐calibrate Cu and Zn fractionation coefficients.     

Isotope Ratio Determination in the Earth and Environmental Sciences: Developments and Applications in 2003

This annual review documents developments and applications in the field of isotope ratio determination, as reflected in the literature for the Earth and environmental sciences for the year 2003. Particular emphasis is placed upon the relationship between the two dominant analytical techniques-thermal ionisation mass spectrometry (TIMS) and multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS)-and the rapidly changing nature of their roles in isotope analysis. Additionally, the review covers developments in single-collector ICP-MS and TOF technologies, new sample preparation procedures and the characterisation of isotopic reference materials, together with fundamental investigations of mass spectrometer performance.     

An Inter-Laboratory Assessment of the Thorium Isotopic Composition of Synthetic and Rock Reference Materials

We present a concerted international effort to cross-calibrate five synthetic Th isotope reference materials (UCSC Th "A", OU Th "U", WUN, IRMM-35 and IRMM-36), and six rock reference materials (UCSC TML, Icelandic ATHO, USGS BCR-2, USGS W-2, USGS BHVO-2, LV18) using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). We then compare our new values with a compilation of literature mass spectrometric data for these reference materials and derive recommended "consensus"²³⁰Th/²³²Th values for each. We also present isotope dilution U and Th concentration data for four rock reference materials (UCSC TML, Icelandic ATHO, USGS BCR-2, USGS W-2).     

Iron Isotopic Compositions of Geological Reference Materials and Chondrites

High‐precision iron isotopic compositions for Fe‐bearing geological reference materials and chondrites with a wide range of matrices (e.g., silicates, oxides, organic‐bearing materials) are reported. This comprehensive data set should serve as a reference for iron isotopic studies across a range of geological and biological disciplines for both quality assurance and inter‐laboratory calibration. Where comparison is available, the iron isotopic compositions of most geological reference materials measured in this study were in agreement with previously published data within quoted uncertainties. Recommendations for the reporting of future iron isotopic data and associated uncertainties are also presented. Long‐term repeat analyses of all samples indicate that highly reproducible iron isotopic measurements are now obtainable (± 0.03‰ and ± 0.05‰ for δ⁵⁶Fe and δ⁵⁷Fe, respectively).     

Preliminary analysis of the first digital recordings obtained in the Portuguese seismographic network — Attenuation studies

During experiments with digital stations in the period 1985–1987, twenty five earthquakes with magnitudes m _b in the range 2.9 to 4.8 and epicentres located within the area 36°–42.3° (N) and 4.5°–13.6° (W) were recorded at Montemor (MOE) and Montachique (MTH). The three-component recordings were obtained by Geotech S13 instruments with 1 second period. A preliminary analysis of the recordings consisted in the determination of amplitudes and spectral contents of P and S waves, and led to the following observations: (1) The attenuation of waves is expressed by the equation V = exp(C ₂).R ^C ₁. exp(C ₃.M), where V stands for acceleration, velocity or displacement; M-magnitude; R-focal distance; C ₁, C ₂ and C ₃ are constants to be obtained by least square fitting. The application of this equation led to C ₁ of the order 1.7 for displacement, 1.8 for velocity and 2.0 for acceleration, with an average mean square error 0.8. (2) The ratios L/T (longitudinal/transversal amplitudes), for velocity and displacement, showed a tendency to reduce with increasing focal distance, being 2 for short distances (<50 km) and 1 for long distances (400 km). (3) The ratios S/P (S-wave/P-wave amplitudes), although with a large dispersion, showed a slight tendency for increasing with focal distance. (4) The predominant frequencies also showed a slight tendency to decrease with increasing focal distance and with magnitude. (5) The dependence of C ₁ with frequency (3 to 12 Hz) is well behaved from 0.95 to 1.75 (for the velocity trace).     

中国若干海域溶解态铀同位素的研究

本文测定了南沙海域，南海东北部海域，厦门湾塔角附近海域与九龙江口水体中溶解态＾２３８Ｕ含量及其同位素组成。南沙，南海东北部海域溶解态＾２３８Ｕ比度及２３４Ｕ／＾２３８Ｕ）Ａ．Ｒ呈均匀分布状态，进一步证实开阔大洋水中铀同位素分布的均匀性。厦门湾塔角附近海域＾２３８Ｕ含量较南海水来得高，且其变化与盐度的变化不要协调，表明海域也许存在＾２３８Ｕ的附加来源。     

近8kaBP来云南洱海地区气候演化的有机碳稳定同位素记录

根据洱海湖泊沉积有机碳稳定同位素记录,结合硅藻分析资料,恢复了近８ｋａ来云南洱海地区的气候演化序列。结果表明：８．１ｋａＢ．Ｐ．来的气候演化分为９个阶段,伴随湖泊水位波动变化。     

Laboratory study of nitrogen and phosphorus remineralization during the decomposition of coastal plankton and seston

The decomposition of cultured marine phytoplankton (Skeletonema costatum) and natural estuarine seston from Narragansett Bay, RI, was studied at two temperatures (8°C and 18°C) in bottles containing sterile bay-water (30‰) and in bay-water with micro-organisms small enough to pass through a glass fibre filter (nominally < 1μ). About 50% of the particulate organic nitrogen (PON) and particulate phosphorus (PP) was immediately released to the water in dissolved organic forms from both types of organic matter. Comparison of changes in the dissolved organic nitrogen (DON) fraction in the sterile and non-sterile systems indicated that nearly all of the DON initially released was subsequently remineralized. Ammonification proceeded only in non-sterile bay-water. 20–25% of the PP was converted to dissolved inorganic-P (DIP) fraction after only 7 h in both sterile and non-sterile bay-water. Following autolytic releases of DON, DOP and DIP the initial rates of N and P remineralization were temperature dependent: Q₁₀ values for PON and PP decay during first phase of microbially mediated decomposition ranged from 1·3 to 6·4. Rates of remineralization then slowed so that about equal amounts of nutrients were remineralized (45–50% of the N and 57–60% of the P in the phytoplankton and 60–63% of the N and 36–60% of the P in the natural seston) after 30 days storage at either temperature. During 30 days of decomposition in non-sterile seawater the N/P ratios in the dissolved inorganic fractions converged on the ratios of total-N/total-P initially present in the bottles. Kinetic analysis of the decay of total organic-N (TON) and total organic-P (TOP) in the non-sterile systems and analysis of similar sets found in the literature showed that the initial stages of the decomposition of N and P from planktonic POM in vitro could be modelled as the sequential decay, at first-order rates, of two particulate fractions. The first, more labile, fraction comprised about 60% of the particulate N and P. First-order rate constants (−k, base e) for decomposition during the 1st and 2nd phases were 0·02 to 0·2 day⁻¹ and 0·003 to 0·02 day⁻¹, respectively. The decay rates are far too slow to account for the ‘rapid in situ recycling’ of nutrients needed to support phytoplankton production when other means of nutrient resupply (by advection, fixation, rainfall, etc.) are very low.     

Assessment of USGS BCR-2 as a Reference Material for Silicate Rock U-Pa Disequilibrium Measurements

The accuracy of ²³¹Pa-²³⁵U measurements can be readily assessed using a secular equilibrium reference material (RM), but a secular equilibrium RM is also required to calibrate the ²³³Pa spike used in ²³¹Pa determinations. The only silicate RM commonly accepted to be in secular equilibrium is Table Mountain Latite (TML) and so an additional reference is required. Our measurements on the widely available USGS BCR-2 (Basalt Columbia River) rock powder yielded (²³¹Pa/²³⁵U) = 0.997 ± 0.013 2s (n = 10), indicating its value as a secondary reference to test the fidelity of U-Pa determinations. Such a reference material additionally provides a useful check on data reduction, which our literature survey highlights can lead to discrepancies of up to 53% between reported (²³¹Pa/²³⁵U) activity ratios and corresponding U and Pa concentration data.     

Isotope Ratio Determination in the Earth and Environmental Sciences: Developments and Applications in 2006–2007

This review documents developments and applications in the field of isotope ratio determination, as reflected in the literature for the Earth and Environmental Sciences for the years 2006 and 2007. The emphasis is predominantly on applications, reflecting the enormous diversity of problems to which isotopic analysis can now be applied, but viewed in the context of rapid uptake of new analytical technologies and significant new drivers of research output.