Grey waters bright with Neolithic argonauts? Maritime connections and the Mesolithic-Neolithic transition within the 'western seaways' of Britain, c. 5000-3500 BC.

Careful examination of the probable natural conditions for travel in the North Sea and Irish Sea during the late Mesolithic are here combined with the latest radiocarbon dates to present a new picture of the transition to the Neolithic in the British Isles. The islands of the west were already connected by Mesolithic traffic and did not all go Neolithic at the same time. The introduction of the Neolithic package neither depended on seaborne incomers nor on proximity to the continent. More interesting forces were probably operating on an already busy seaway.

Glaciodynamics of the central sector of the last British–Irish ice sheet in Northern England

The central sector of the last British–Irish Ice Sheet (BIIS) was characterised by considerable complexity, both in terms of its glacial stratigraphy and geomorphological signature. This complexity is reflected by the large number and long history of papers that have attempted to decipher the glaciodynamic history of the region. Despite significant advances in our understanding, reconstructions remain hotly debated and relatively local, thereby hindering attempts to piece together BIIS dynamics. This paper seeks to address these issues by reviewing geomorphological mapping evidence of palimpsest flow signatures and providing an up-to-date stratigraphy of the region. Reconciling geomorphological and sedimentological evidence with relative and absolute dating constraints has allowed us to develop a new six-stage glacial model of ice-flow history and behaviour in the central sector of the last BIIS, with three major phases of glacial advance. This includes: I. Eastwards ice flow through prominent topographic corridors of the north Pennines; II. Cessation of the Stainmore ice flow pathway and northwards migration of the North Irish Sea Basin ice divide; III. Stagnation and retreat of the Tyne Gap Ice Stream; IV. Blackhall Wood–Gosforth Oscillation; V. Deglaciation of the Solway Lowlands; and VI. Scottish Re-advance and subsequent final retreat of ice out of the central sector of the last BIIS. The ice sheet was characterised by considerable dynamism, with flow switches, initiation (and termination) of ice streams, draw-down of ice into marine ice streams, repeated ice-marginal fluctuations and the production of large volumes of meltwater, locally impounded to form ice-dammed glacial lakes. Significantly, we tie this reconstruction to work carried out and models developed for the entire ice sheet. This therefore situates research in the central sector within contemporary understanding of how the last BIIS evolved over time.

Sensitivity of DF-ICP-MS, PERALS and alpha-spectrometry for the determination of actinides: A comparison

We applied three techniques (DF-ICP-MS, PERALS and alpha-spectrometry) for the determination of minor actinides at environmental levels. For each method the limit of detection and the resolution were estimated in order to study the content and isotopic composition of the actinides. Two international reference materials, IAEA-135 (Irish Sea Sediment) and IAEA-300 (Baltic Sea sediment) were analyzed for activity concentrations of 238Pu, 239Pu, 240Pu, 241Pu and 241Am. The sensitivities of the three determination techniques were compared.

(Table 1) Activity of strontium-90 in waters of the Northeast Atlantic at the end of 1965 and the beginning of 1966

In 1965-1966 R/V Mikhail Lomonosov conducted studies on concentrations of artificial radioactive products in the Northeast Atlantic. Concentration of strontium-90 at the end of 1965 and the beginning of 1966 was higher than the average level for the ocean and reached about 53 dpm/100 l in the surface layer. The most intense transport of artificial radioactive products out of the Irish Sea was detected in the northern and northeastern directions along the Hebrides and the Orkneys. In addition to radioactive fission products from nuclear weapons tests, radioactive wastes of atomic industrial facilities discharged into the ocean are an important source of radioactive contamination of some regions of the world ocean.

Consistent increase in dimethyl sulfide (DMS) in response to high CO2 in five shipboard bioassays from contrasting NW European waters

The ubiquitous marine trace gas dimethyl sulfide (DMS) comprises the greatest natural source of sulfur to the atmosphere and is a key player in atmospheric chemistry and climate. We explore the short-term response of DMS production and cycling and that of its algal precursor dimethyl sulfoniopropionate (DMSP) to elevated carbon dioxide (CO2) and ocean acidification (OA) in five 96 h shipboard bioassay experiments. Experiments were performed in June and July 2011, using water collected from contrasting sites in NW European waters (Outer Hebrides, Irish Sea, Bay of Biscay, North Sea). Concentrations of DMS and DMSP, alongside rates of DMSP synthesis and DMS production and consumption, were determined during all experiments for ambient CO2 and three high-CO2 treatments (550, 750, 1000 µatm). In general, the response to OA throughout this region showed little variation, despite encompassing a range of biological and biogeochemical conditions. We observed consistent and marked increases in DMS concentrations relative to ambient controls (110% (28-223%) at 550 µatm, 153% (56-295%) at 750 µatm and 225% (79-413%) at 1000 µatm), and decreases in DMSP concentrations (28% (18-40%) at 550 µatm, 44% (18-64%) at 750 µatm and 52% (24-72%) at 1000 µatm). Significant decreases in DMSP synthesis rate constants (µDMSP /d) and DMSP production rates (nmol/d) were observed in two experiments (7-90% decrease), whilst the response under high CO2 from the remaining experiments was generally indistinguishable from ambient controls. Rates of bacterial DMS gross consumption and production gave weak and inconsistent responses to high CO2. The variables and rates we report increase our understanding of the processes behind the response to OA. This could provide the opportunity to improve upon mesocosm-derived empirical modelling relationships and to move towards a mechanistic approach for predicting future DMS concentrations.

Age determination of sediments from Kilkeel and sediment core Y69-71P

Evidence from the Irish Sea basin supports the existence of an abrupt rise in sea level (meltwater pulse) at 19,000 years before the present (B.P.). Climate records indicate a large reduction in the strength of North Atlantic Deep Water formation and attendant cooling of the North Atlantic at this time, indicating a source of the meltwater pulse from one or more Northern Hemisphere ice sheets.Warming of the tropical Atlantic and Pacific oceans and the Southern Hemisphere also began at 19,000 years B.P. These responses identify mechanisms responsible for the propagation of deglacial climate signals to the Southern Hemisphere and tropics while maintaining a cold climate in the Northern Hemisphere.