Supernova remnants, planetary nebulae and the distance to NGC 4214

We present narrow band, continuum subtracted Hα, [S ii], Hβ, [O iii] and [O ii] data taken with the Wide Field Camera 3 on the Hubble Space Telescope in the nearby dwarf starburst galaxy NGC 4214. From these images, we identify seventeen new planetary nebula candidates, and seven supernova remnant candidates. We use the observed emission line luminosity function of the planetary nebulae to establish a new velocity-independent distance to NGC 4214. We conclude that the PNLF technique gives a reddening independent distance to NGC 4214 of 3.19±0.36 Mpc, and that our current best-estimate of the distance to this galaxy ids 2.98±0.13 Mpc.     

Possible ice-rafted erratics in late Early to early Middle Pleistocene shallow marine and coastal deposits in northeast Norfolk, UK

Erratic clasts with a mass of up to 15 kg are described from preglacial shallow marine and coastal deposits (Wroxham Crag Formation) in northeast Norfolk. Detailed examination of their petrology has enabled them to be provenanced to northern Britain and southern Norway. Their clustered occurrence in coastal sediments in Norfolk is believed to be the product of ice-rafting from glacier incursions into the North Sea from eastern Scotland and southern Norway, and their subsequent grounding and melting within coastal areas of what is now north Norfolk. The precise timing of these restricted glaciations is difficult to determine. However, the relationship of the erratics to the biostratigraphic record and the first major expansion of ice into the North Sea suggest these events occurred during at least one glaciation between the late Early Pleistocene and early Middle Pleistocene (c. 1.1–0.6 Ma). In contrast to the late Middle (Anglian) and Late Pleistocene (Last Glacial Maximum) glaciations, where the North Sea was largely devoid of extensive marine conditions, the presence of far-travelled ice-rafted materials implies that earlier cold stage sea-levels were considerably higher.     

Prediction of bioconcentration and related lethal and sublethal effects with aquatic organisms

It is now well established that the octanol/water partition coefficient (K_0W) can be used to estimate bioconcentration of persistent organic compounds, such as the chlorohydrocarbons as well as PAHs and other hydrophobic substances. However, while these relationships are well established in the laboratory, use in the field often poses a number of problems. In recent studies of contaminants in fish from Australia, bioconcentration has been described using additional information on specimen size, lipid content and fish movement patterns.The use of internal biotic concentration provides an additional new and different perspective on toxicant behaviour as compared to the conventional ambient aqueous concentration-based toxicity measures. The internal lethal concentration for persistent organic compounds approaches a constant value for many compounds, and at these concentrations lethal effects are observed. This constant internal lethal concentration provides a basis for predicting toxicity and its relationship to exposure period. In addition, sublethal effects can be successfully related to the internal biotic concentration.     

Environmental Refugees? A tale of two resettlement projects in coastal Papua New Guinea

ABSTRACT

Environmental change in small islands may be associated with migration as a means of adaptation. Both Manam and the Carteret Islands in Papua New Guinea (PNG) have experienced rapid- and slow-onset changes, respectively. These have been accompanied by the forced migration and ‘temporary’ resettlement of the Manam population and attempts at resettlement by Carteret Islanders. Neither has proved successful, thwarted by ‘host’ landowners, the impossibility of gaining adequate access to land and land rights, and government inactivity. Settlers have been perceived as outsiders and rival claimants to valuable coastal resources. Inability to resettle in national contexts raises issues of ambiguity, identity and citizenship. The problems experienced by quite small population groups moving short distances in similar cultural contexts are indicative of the potential future problems facing environmental migrants in other contexts.     

Structural controls on sulphide deposition at the dyke–lava boundary, slow-spreading ocean crust, Macquarie Island

Ocean Drilling Program hole 504B revealed an ocean crust hydrothermal sulphur anomaly on the dyke–lava transition, with implications for global sulphur sinks. Here we confirm the presence of the anomaly sporadically along 7.5 km of dyke–basalt contact on the Macquarie Ridge at Macquarie Island, a 39–9.7 Ma slow‐spreading setting. Background contact‐zone pyrite S contents average 1845 p.p.m. across ～50 m. However, zones of small‐scale brittle faulting that commonly occur on and above the dyke–basalt contact average between 5000 and 11 000 p.p.m. S (20–30 m widths). These consist of steep ridge‐parallel faults and fault splays on the contact, overlain by up to 50 m of linked pyritic fault trellis. The contact zone faults are haloed by disseminated pyrite–chlorite, cross‐cut by quartz–chlorite–sphalerite and epidote‐cemented breccias, containing evidence of turbulent flow. The structural control on sulphur deposition is attributed to the active extensional slow spreading setting. With increasing extension, diffuse mixing across the contact was replaced by channellized flow and dynamic mixing in fault arrays. The magnitude of the dyke–lava transition sulphur sink must be reassessed to take account of this heterogeneity.