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We present 10 in situ cosmogenic exposure ages from two moraines on the Isle of Skye. The Strollamus medial moraine was deposited during deglaciation of the Devensian ice sheet and yields a mean exposure age from five samples of 14.3 ± 0.9 ka. The moraine age indicates that a significant ice mass existed on Skye at the time of a regional readvance recorded in Wester Ross, northwest Scotland. Taken at face value the ages suggest that deglaciation did not occur until well into Greenland Interstade 1. The Slapin moraine represents the local limit of the Loch Lomond Readvance (LLR) and yields a mean exposure age from five samples of 11.5 ± 0.7 ka, which is consistent with deposition relating to the LLR. These ages suggest that the maximum extent may have been reached late in the stadial and that some glaciers may have remained active until after the climatic amelioration that marks its end. This scenario is considered unlikely given the nature of the climate during this period, which leads us to call for a locally calibrated production rate. Copyright © 2011 John Wiley & Sons, Ltd.

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The development of analytical techniques suitable for providing structural information on a wide range of elemental species is a growing necessity. For arsenic speciation a variety of mass spectrometric techniques, mainly inductively coupled plasma mass spectrometry (ICP-MS) and electrospray tandem mass spectrometry (ES-MS/MS) coupled on-line with high-performance liquid chromatography (HPLC), are in use. In this paper we report the identification of arsenic species present in samples of marine origin (seaweed extracts) using ES ion trap mass spectrometry (IT) multistage mass spectrometry (MS n ). Both reversed-phase and anion-exchange HPLC have been coupled on-line to ES-ITMS. Product ion scans with multiple stages of tandem MS (MS n ; n = 2±4)were used to acquire diagnostic data for each arsenosugar. The spectra contain structurally characteristic fragment ions for each of the arsenosugars examined. In addition it was observed that upon successive stages of collision-induced dissociation (CID) a common product ion (m/z 237) was formed from all four arsenosugars examined. This product ion has the potential to be used as an indicator for the presence of dimethylated arsenosugars (dimethylarsinoylribosides). The HPLC/ES-ITMS n method developed allows the sensitive identification of arsenosugars present in crude seaweed extracts without the need for extended sample preparation. In fact, sample preparation requirements are identical to those typically employed for HPLC/ICP-MS analysis. Additionally, the resulting product ions are structurally diagnostic of the arsenosugars examined, and tandem mass spectra are reproducible and correspond well to those obtained using other low-energy CID techniques. As a result, the HPLC/ES-ITMS n approach minimises the potential for arsenic species misidentification and has great potential as a means of overcoming the need for characterised standards. Copyright # 2002 John Wiley & Sons, Ltd.Arsenic occurs in the environment and biological systems in a number of different organic and inorganic forms, most of which exhibit wide variations in their toxicity, bioavailability and transport properties. As a result, total arsenic determinations do not yield sufficient information for accurate risk assessments and speciation data are therefore required. In most cases, speciation of organometallic compounds has been carried out by using a separation technique such as high-performance liquid chromatography (HPLC) coupled on-line to an element-specific detector. A major breakthrough in arsenic speciation analysis came when inductively coupled plasma mass spectrometry (ICP-MS) was used as an arsenic-specific detector for high-performance liquid chromatography (HPLC) ICP-MS. 1 In addition to the advantages of high selectivity and sensitivity, HPLC/ICP-MS offers on-line real time detection. This approach, however, has some key drawbacks, mainly because arsenic species identification is based on matching chromatographic retention times with those of standard arsenic compounds. Consequently, chroma...

The 'Parallel Roads' of Glen Roy, Scotland, are the shorelines of former ice-dammed lakes created by the last glaciers to occupy the area. We use surface exposure dating with cosmic rayproduced 10 Be in quartz to provide the first numerical age control on the timing of formation of one of one of these shorelines and depositional features in Glen Roy. Four bedrock samples from the surface of the 325 m 'Parallel Road' yielded a mean formation age of ca. 11.5-11.9 ka. This age range confirms the long-held view that the 'Parallel Roads' are Loch Lomond Stadial (ca. 12.9-11.5 ka) features. The age range reflects variation in currently available cosmogenic nuclide scaling schemes and the related 10 Be production rates. Two samples from the surface of the Turret fan indicate that the 260 m lake drained before ca. 10.7-11.0 ka, while two samples from the Brunachan fan suggest that subaerial sedimentation occurred after ca. 9.7-9.9 ka.