Isotope Ratio Determination in the Earth and Environmental Sciences: Developments and Applications in 2004/2005

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 2004 and 2005. The emphasis is largely one on applications, reflecting the enormous diversity of problems to which isotopic analysis is now applied, but seen against a background of rapid change in the uptake of new analytical technologies.     

Hurricane effects on seagrasses along Alabama's Gulf Coast

In November 2004, we evaluated the effect of Hurricane Ivan on seagrass meadows in Alabama by surveying all coastal locations known to support seagrass prior to Hurricane Ivan's Iandfall in September 2004. We found that 82% of the sites containing seagrass in 2002 still supported seagrass, and that, as in 2002, the most abundant species wasHalodule wrightii (shoalgrass). We also found more sites containingRuppia maritima (widgeongrass) than previously recorded. We confirmed the existence ofThalassia testudinum (turtlegrass) in Little Lagoon, Alabama, whose first record in the state had been noted in 2002. A resurvey of the western half of Alabama's coastal waters in October 2005 after Hurricane Katrina found no loss of seagrass, with all sites that supported seagrass in 2004 still containing seagrass in 2005. There was no major loss of Alabama's seagrass resources due to Hurricanes Ivan or Katrina, even though both category 3 hurricanes severely affected the northern Gulf Coast.     

Concentrations of Artificial Sweeteners and Their Ratios with Nutrients in Septic System Wastewater

This study reports the first comprehensive data set of characteristic concentrations of four artificial sweeteners: acesulfame (ACE), sucralose (SUC), saccharin (SAC), and cyclamate (CYC), and their ratios with nutrients, for untreated septic system wastewater. Samples were collected from the tanks of 19 different septic systems from across Ontario, Canada; these had a variety of usages, from single‐family cottages to multiple‐dwelling (campground or resort) facilities and had no additional treatment systems. The artificial sweetener concentrations and their relative proportions were highly variable in some cases, both temporally for several individual tanks and from site‐to‐site. Variability tended to be lower for multiple‐dwelling compared to single‐dwelling systems. This variability likely reflects differing use of artificial sweetener‐containing products. The median concentrations for the complete data set of all four artificial sweeteners (in a range of 10 to 60 μg/L) were of a similar order of magnitude, but slightly higher, than has generally been reported for wastewater treatment plant influent (though these vary substantially globally). Both SUC and ACE provided adequate positive linear relationships for dissolved nitrogen and phosphorus in the septic tanks, while a summation of ACE and SUC concentrations also gave a strong correlation. In contrast, CYC and SAC showed poor linear correlation with these nutrients. These reported ranges for artificial sweetener concentrations and ratios with nutrients may be used in future studies to estimate the contributions of nutrients or other wastewater constituents (e.g., pharmaceuticals, bacteria, and viruses) from domestic septic systems to groundwater, including water supply or irrigation wells, and nearby surface water bodies.     

A non-linear numerical model of the tuned liquid damper

The Tuned Liquid Damper (TLD) is modelled numerically as an equivalent tuned mass damper with non-linear stiffness and damping. These parameters are derived from extensive experimental results described in References 1 and 2. This Non-linear Stiffness and Damping (NSD) model captures the behaviour of the TLD system adequately under a variety of loading conditions. In particular, the NSD model incorporates the stiffness hardening property of the TLD under large amplitude excitation. Copyright © 1999 John Wiley & Sons, Ltd.     

Electron Microprobe/SIMS Determinations of Al in Olivine: Applications to Solar Wind,Pallasites and Trace Element Measurements

Electron probe microanalyser measurements of trace elements with high accuracy are challenging. Accurate Al measurements in olivine are required to calibrate SIMS implant reference materials for measurement of Al in the solar wind. We adopt a combined EPMA/SIMS approach that is useful for producing SIMS reference materials as well as for EPMA at the ~ 100 µg g^?1 level. Even for mounts not polished with alumina photoelectron spectroscopy shows high levels of Al surface contamination. In order to minimise electron beam current density, a rastered 50 × 100 µm electron beam was adequate and minimised sensitivity to small Al‐rich contaminants. Reproducible analyses of eleven SIMS‐cleaned spots on San Carlos olivine agreed at 69.3 ± 1.0 µg g^?1. The known Al mass fraction was used to calibrate an Al implant into San Carlos. Accurate measurements of Al were made for olivines in the pallasites: Imilac, Eagle Station and Springwater. Our focus was on Al in olivine, but our technique could be refined to give accurate electron probe measurements for other contamination‐sensitive trace elements. For solar wind, it is projected that the Al/Mg abundance ratio can be determined to 6%, a factor of 2 more precise than the solar spectroscopic ratio.     

GGR Biennial Review: Isotope Ratio Determination in the Earth and Environmental Sciences 2008–2009

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 2008 and 2009. 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 development of new analytical methodologies as significant new drivers of research output.     

GGR Critical Review of Analytical Developments in 2008–2009: An Introduction

This collection of articles represents the fourth in a series of reviews in which authors have aimed at capturing the key advances in a range of analytical fields ( Hergt et al. 2005, 2006, 2008 ). The publication period under review is 2008–2009 and the intention here is to provide readers with a summary of the most influential developments published during this period, across a broad range of topics appropriate to the Earth and environmental sciences. Most authors comment on the ways in which the emphases of research in their specific fields of examination have changed over time. All note an increase in rigour and focus on data quality. Whether advances have taken place in instrumentation, sample manipulation or data deconvolution, there are a large number of dedicated scientists out there contributing to the high quality of geochemical data employed in geological and environmental research.     

NanoSIMS: Insights to biogenicity and syngeneity of Archaean carbonaceous structures

NanoSIMS is a relatively new technology that is being applied to ancient carbonaceous structures to gain insight into their biogenicity and syngeneity. NanoSIMS studies of well preserved organic microfossils from the Neoproterozoic (0.8 Ga) Bitter Springs Formation have established elemental distributions in undisputedly biogenic structures. Results demonstrate that sub-micron scale maps of metabolically important elements (carbon [C], nitrogen [measured as CN ion], and sulfur [S]) can be correlated with kerogenous structures identified by optical microscopy. Spatial distributions of C, CN, and S in individual microfossils are nearly identical, and variations in concentrations of these elements parallel one another. In elemental maps, C, CN, and S appear as globules, aligned to form remnant walls or sheaths of fossiliferous structures. The aligned character and parallel variation of C and CN are the strongest indicators of biogenicity.Nitrogen/carbon atomic ratios (N/C) of spheroids, filaments, and remnants of a microbial mat suggest that N/C may reflect original biochemical differences, within samples of the same age and degree of alteration. Silicon (Si) and oxygen (O) maps illustrate that silica is intimately interspersed with organic carbon of the microfossils. This relationship is likely to reflect the process of silica permineralization of biological remains and thus may be an indicator of syngeneity of the fossilized material with the mineral matrix.The NanoSIMS characterization of Bitter Springs microfossils can be used as a baseline for interpreting less well preserved carbonaceous structures that might occur in older or even extraterrestrial materials. An example of such an application is provided by comparison of Bitter Springs results with NanoSIMS of Archaean carbonaceous structures from Western Australia, including a spheroid in the 3 Ga Farrel Quartzite and material in a secondary vein in the 3.43 Ga Strelley Pool Chert. Results reinforce a biogenic, syngenetic interpretation for the Archaean spheroid.NanoSIMS has several advantages in the study of ancient organic materials: the technique allows characterization of extremely small structures that are present in low concentrations; organic matter does not have to be isolated by acid treatment but can be analyzed in polished thin section; preparation is simple; samples are minimally altered during analysis; results provide sub-micron scale spatial distribution coupled with concentration information for at least five elements; the biologically important elements of carbon and nitrogen can be assessed; and the ability to study organic remains in situ permits petrographic assessment of spatial relationships between organic matter and mineral constituents. These advantages could be of significant benefit for interpretation of poorly preserved and fragmentary carbonaceous remains that might occur in some of Earth's oldest samples as well as in meteorites or extraterrestrial material brought to Earth in future planetary missions.     

Pb,Sr and 10Be isotopic studies of volcanic rocks from the Northern Mariana Islands. Implications for magma genesis and crustal recycling in the Western Pacific

We report Sr and Pb isotope analyses for an extensive suite of volcanic rocks from the N. Mariana arc together with Sr and Pb isotope analyses of sediments from the nearby Mariana and Nauru basins. In addition ten of the most recent volcanic samples were analysed for ¹⁰Be.The Sr isotope compositions cluster tightly around ${}^{87}\text{Sr}{}^{86}\text{Sr}$ = 0.7035 being slightly but significantly higher than the Pacific ocean floor basalts on either side of the arc and agreeing well with previous data. In contrast, the large number of new Pb isotopic data presented significantly extends the observed range of Pb isotope compositions for volcanic rocks from the Mariana arc to more radiogenic compositions. The concentrations of ¹⁰Be were very low (< 0.5 × 10⁶ atom g^?1).These new data require either that the Pb and Sr isotopic compositions of the Mariana sub-arc mantle be substantially different from those of the mantle source of ocean floor basalts on either side of the arc, or that the enrichment in radiogenic Pb and Sr relative to the values observed in Pacific ocean floor basalts be related to the subduction process. We prefer the latter hypothesis in which radiogenic Sr and Pb in ocean floor sediments are added to M.O.R.B. type mantle either by direct assimilation of the sediments in partial melts or, more probably, by transfer in a fluid phase into the zone of magma production. The low ¹⁰Be concentrations observed suggest the removal of at least the top few metres of sediment during subduction.