Recent sediments of the southwestern Barents Sea

The paper is based on textural, mineralogical and chemical studies of surface and subsurface sediments from 80 stations in the southwestern Barents Sea. Dispersed phases are quantitatively insignificant in these oxic shelf sediments and it is argued that the deposits are predominantly terrigenous in origin. A combined analysis of the mineralogy and chemistry of the separated size fractions allows the recognition of petrographic provinces. The patterns of sediment dispersal are discussed. The coarsest components of the Barents Sea sediments are of local origin whereas long-distance transport of finer material is taking place.     

Evaluating the NOAA Coastal and Marine Ecological Classification Standard in estuarine systems: A Columbia River Estuary case study

A common first step in conservation planning and resource management is to identify and classify habitat types, and this has led to a proliferation of habitat classification systems. Ideally, classifications should be scientifically and conceptually rigorous, with broad applicability across spatial and temporal scales. Successful systems will also be flexible and adaptable, with a framework and supporting lexicon accessible to users from a variety of disciplines and locations. A new, continental-scale classification system for coastal and marine habitats—the Coastal and Marine Ecological Classification Standard (CMECS)—is currently being developed for North America by NatureServe and the National Oceanic and Atmospheric Administration (NOAA). CMECS is a nested, hierarchical framework that applies a uniform set of rules and terminology across multiple habitat scales using a combination of oceanographic (e.g. salinity, temperature), physiographic (e.g. depth, substratum), and biological (e.g. community type) criteria. Estuaries are arguably the most difficult marine environments to classify due to large spatio-temporal variability resulting in rapidly shifting benthic and water column conditions. We simultaneously collected data at eleven subtidal sites in the Columbia River Estuary (CRE) in fall 2004 to evaluate whether the estuarine component of CMECS could adequately classify habitats across several scales for representative sites within the estuary spanning a range of conditions. Using outputs from an acoustic Doppler current profiler (ADCP), CTD (conductivity, temperature, depth) sensor, and PONAR (benthic dredge) we concluded that the CMECS hierarchy provided a spatially explicit framework in which to integrate multiple parameters to define macro-habitats at the 100 m² to >1000 m² scales, or across several tiers of the CMECS system. The classification's strengths lie in its nested, hierarchical structure and in the development of a standardized, yet flexible classification lexicon. The application of the CMECS to other estuaries in North America should therefore identify similar habitat types at similar scales as we identified in the CRE. We also suggest that the CMECS could be improved by refining classification thresholds to better reflect ecological processes, by direct integration of temporal variability, and by more explicitly linking physical and biological processes with habitat patterns.     

The significance of needle-fibre calcite in a Lower Carboniferous palaeosol

Needle-fibre calcite occurs in association with root structures in a Lower Carboniferous calcrete crust. The origin of this form of calcite is discussed and the scattered literature from soil science, microbiology and geology is reviewed. It is concluded that while needle-fibre calcite is not diagnostic of any environment its origin is related to the activities of various micro-organisms, especially fungi. The use of needle-fibre calcite as a climatic indicator is reviewed and it is used, with other criteria, as evidence of fluctuating climates in the Lower Carboniferous.     

Peritidal carbonate facies models: A review

Existing facies models for peritidal carbonates are limited in number and do not reflect the wide spectrum of possible types. The major depositional processes in peritidal carbonate environments are reviewed in order to stress the complex nature of the systems. The tidal channel model is critically discussed and it is suggested that channel deposits may be of minor importance in typical shoaling-up sequences. The possible causes of multiple asymmetrical sequences are reviewed.     

Sedimentation within and among mangrove forests along a gradient of geomorphological settings

Coastal wetlands provide important ecological services to the coastal zone, one of which is sediment retention. In this study we investigated sediment retention across a range of geomorphological settings and across vegetation zones comprising coastal wetlands. We selected six coastal wetlands dominated by mangroves over a gradient from riverine to tidal settings in Southeast Queensland, Australia. Each site was comprised of three distinct vegetation communities distributed as parallel zones to the coast line: seaward fringe mangroves, landward scrub mangroves and saltmarsh/ cyanobacteria mat of the high intertidal zone. We measured suspended sediment retention and sedimentation rates. Additionally, in order to assess the origin of sediment transported and deposited in the mangroves, glomalin, a novel terrestrial soil carbon tracer, was used. Our results show a mean average sedimentation of 0.64 ± 0.01 mg cm⁻² spring tide⁻¹, which was variable within sites, regardless of geomorphological setting. However, geomorphological setting influenced spatial patterns of sediment deposition. Riverine mangroves had a more homogeneous distribution of sediments across the intertidal zone than tidal mangroves, where most sedimentation occurred in the fringe zone. Overall, the fringe zone retained the majority of sediment entering the coastal wetland during a tidal cycle with 0.90 ± 0.22 mg cm⁻² spring tide⁻¹, accounting for 52.5 ± 12.5% of the total sedimentation. The presence of glomalin in suspended sediments, and thus the relative importance of terrigenous sediment, was strongly influenced by geomorphological setting, with riverine mangroves receiving more glomalin in suspended solids than tidal mangroves. Glomalin was also differentially deposited within the vegetation zones at different geomorphological settings: primarily at the fringe zone of tidal mangroves and within the scrub zone of riverine mangroves. The differences we observed in the spatial distribution of sedimentation and the difference in the origin of the sediment deposited in riverine and tidal mangroves are likely to have an impact on ecological processes.     

High-latitude HF Doppler observations of ULF waves: 2. Waves with small spatial scale sizes

The DOPE (Doppler Pulsation Experiment) HF Doppler sounder located near Tromsø, Norway (geographic: 69.6°N 19.2°E; L = 6.3) is deployed to observe signatures, in the high-latitude ionosphere, of magnetospheric ULF waves. A type of wave has been identified which exhibits no simultaneous ground magnetic signature. They can be subdivided into two classes which occur in the dawn and dusk local time sectors respectively. They generally have frequencies greater than the resonance fundamentals of local field lines. It is suggested that these may be the signatures of high-m ULF waves where the ground magnetic signature has been strongly attenuated as a result of the scale size of the waves. The dawn population demonstrate similarities to a type of magnetospheric wave known as giant (Pg) pulsations which tend to be resonant at higher harmonics on magnetic field lines. In contrast, the waves occurring in the dusk sector are believed to be related to the storm-time Pc5s previously reported in VHF radar data. Dst measurements support these observations by indicating that the dawn and dusk classes of waves occur respectively during geomagnetically quiet and more active intervals.     

Mapping rates associated with polygons

Suppose that geographic data under investigation are rates associated with polygons. For example, disease incidence, mortality, and census undercount data may be displayed as rates. Spatial analysis of data of this sort can be handled very naturally through Bayesian hierarchical statistical modeling, where there is a measurement process at the first level, an explanatory process at the second level, and a prior probability distribution on unknowns at the third level. In our paper, we shall feature epidemiological data, specifically disease-incidence rates, and the “polygons” referred to in the title are typically states or counties.