Wave erosion of a massive artificial coastal landslide

The Lone Tree landslide is located on the coast north of San Francisco, California, and is unusual in that it is positioned within the San Andreas fault zone. Its material ranges from mud through to boulders, which makes the slide particularly susceptible to mass movement. Movement of its western half increased following the Loma Prieta earthquake in 1989, closing an important highway for over a year, at which time a large cut-and-fill operation was undertaken to remove the upper portion of the slide so it would create no future disruption. Material cut from the upper slide was dumped below the highway, with the debris extending into the ocean. This created an artificial debris fill that is equivalent to a massive natural landslide, and a unique opportunity to monitor its erosion. Rainfall quickly eroded a series of rills into the face of the artificially created landslide, but the concentration of gravel and cobbles armoured these small channels, greatly reducing the rate of subsequent erosion. Waves cut away the toe, and the focus of this paper is on the development of a model to analyse the frequency of wave attack in terms of tide levels and wave conditions. A beach consisting of cobbles and boulders formed at the toe of the debris, offering partial protection and reducing the rate of continued erosion. In the short term, armouring of the rills and the development of a fronting beach have reduced the overall erosion of the debris and the transfer of sediment to the ocean. In the longer term, the formation of secondary slumps can be expected to renew the erosion. Eventually the morphology of the debris fill should approach the configuration of the natural landslide, an unmodified portion of which remains adjacent to the artificial fill. © 1998 John Wiley & Sons, Ltd.     

Iron and Pyritization in Wetland Soils of the Florida Coastal Everglades

We explored environmental factors influencing soil pyrite formation within different wetland regions of Everglades National Park. Within the Shark River Slough (SRS) region, soils had higher organic matter (62.65 ± 1.88 %) and lower bulk density (0.19 ± 0.01 g cm^?3) than soils within Taylor Slough (TS; 14.35 ± 0.82 % and 0.45 ± 0.01 g cm^?3, respectively), Panhandle (Ph; 15.82 ± 1.37 % and 0.34 ± 0.009 g cm^?3, respectively), and Florida Bay (FB; 5.63 ± 0.19 % and 0.73 ± 0.02 g cm^?3, respectively) regions. Total reactive sulfide and extractable iron (Fe) generally were greatest in soils from the SRS region, and the degree of pyritization (DOP) was higher in soils from both SRS (0.62 ± 0.02) and FB (0.52 ± 0.03) regions relative to TS and Ph regions (0.30 ± 0.02 and 0.31 ± 0.02, respectively). Each region, however, had different potential limits to pyrite formation, with SRS being Fe and sulfide limited and FB being Fe and organic matter limited. Due to the calcium-rich soils of TS and Ph regions, DOP was relatively suppressed. Annual water flow volume was positively correlated with soil DOP. Soil DOP also varied in relation to distance from water management features and soil percent organic matter. We demonstrate the potential use of soil DOP as a proxy for soil oxidation state, thereby facilitating comparisons of wetland soils under different flooding regimes, e.g., spatially or between wet years versus dry years. Despite its low total abundance, Fe plays an important role in sulfur dynamics and other biogeochemical cycles that characterize wetland soils of the Florida coastal Everglades.     

New insights into rare earth element (REE) particulate generated by cigarette lighters: an electron microscopy and materials science investigation of a poorly understood indoor air pollutant and constraints for urban geochemistry

Cigarette smoking is a well-recognized cause of lung cancer and other diseases and is a major contributor to indoor air pollution in numerous settings worldwide. Most cigarette lighters use rare earth element (REE) mischmetal in their flints in order to aid ignition, and these lighters thus have pyrophoric properties. REE particulate emitted from these lighters presents a complexity in the role of health of smokers that has yet to be explored fully. Furthermore, these particles are likely present in numerous urban settings and contribute to the complexities of urban geochemistry. Details of the material properties of rare earth element (REE) particulate derived from smoking lighters are determined first the first time. Particulate was investigated using back-scatter detection scanning electron microscopy techniques and transmission electron microscopy techniques. Several particle types were observed and demonstrate a diverse range of size and textures, many of which are previously not documented and are much smaller than previous basic scanning electron microscopy investigations. These include irregularly shaped fragments of mischmetal, micrometer-scale spherules, aggregates of nanospherules, and platy sponge-like nanoparticles. All of these particles have significant REE content, and most are of a particle size that can be deposited deep in the lung. The available literature regarding toxicity of REEs and the material science data presented here argues very strongly for cause for concern.     

A service-based framework for the OAIS model for earth science data management

The Consultative Committee for Space Data Systems (CCSDS), in 2002, released their first version of a Reference Model for an Open Archival Information System (OAIS). In 2003, the model was adopted by the International Standards Organization (ISO) as ISO 14721:2003. The CCSDS document was updated in 2012 with additional focus on verifying the authenticity of data and developing concepts of access rights and a security model. The OAIS model is the basis of research data management systems across institutions and disciplines around the world. The Organization for the Advancement of Structured Information Standards (OASIS), in 2006, released their first version of a Reference Model for Service Oriented Architecture (SOA). OASIS defines the SOA as “a paradigm for organizing and utilizing distributed capabilities that may be under the control of different ownership domains.” Systems designed around the SOA model benefit from improved scalability, flexibility, and agility. This paper applies the SOA model to the OAIS repository to describe how repositories can be implemented and extended through the use of services that may be internal or external to the host institution, including the consumption of network- or cloud-based services and resources. We use the Service Oriented Architecture (SOA) design paradigm to describe a set of potential extensions to OAIS Reference Model: purpose and justification for each extension, where and how each extension connects to the model, and an example of a specific service that meets the purpose.     

Field spectroscopy and radiative transfer modelling to assess impacts of petroleum pollution on biophysical and biochemical parameters of the Amazon rainforest

Biophysical and biochemical plant foliage parameters play a key role in assessing vegetation health. Those plant parameters determine the spectral reflectance and transmittance properties of vegetation; therefore, hyperspectral remote sensing, particularly imaging spectroscopy, can provide estimates of leaf and canopy chemical properties. Based on the relationship between spectral response and biochemical/biophysical properties of the leaves and canopies, the PROSPECT radiative transfer model simulates the interaction of light with leaves. In this study, more than 1100 leaf samples from the Amazon forest of Ecuador were collected at several study sites, some of which are affected by petroleum pollution, and across the vertical profile of the forest. For every sample, field spectroscopy at leaf level was conducted with a spectroradiometer. The goal of this study was to assess leaf optical properties of polluted and unpolluted rainforest canopies across the vertical profile and identify vegetation stress expressed in changes of biophysical and biochemical properties of vegetation. An ANOVA followed by Holme’s multiple comparisons of means and a principal component analysis showed that photosynthetic pigments, chlorophyll and carotenoids have significantly lower levels across the vertical profile of the forest, particularly in sites affected by petroleum pollution. On the other hand, foliar water content showed significantly higher levels in the polluted site. Those findings are symptoms of vegetation stress caused by reduced photosynthetic activity and consequently decreased transpiration and water-use efficiency of the plants. Cross-comparison between SPAD-502 chlorophyll content meter index and chlorophyll content showed strong positive correlation coefficients (r = 0.71 and r ² = 0.51) which suggests that using the SPAD-502 chlorophyll index itself is sensitive enough to detect vegetation stress in a multispecies tropical forest. Therefore, the SPAD-502 can be used to assess chlorophyll content of vegetation across polluted and non-polluted sites at different canopy layers. The results presented in this paper contribute to the very limited literature on field spectroscopy and radiative transfer models applied to the vertical profile of the Amazon forest.     

Estimation of the Change in Storage Capacity above Mined Longwall Panels

Accurate estimation of the change in groundwater storage capacity (S) above mined longwall panels is vital for analysis of postmining void water level recovery in coal mines, and assessment of water quality impacts. At present, there is no generalized representation of the spatial distribution of changes in S around a panel. Current estimates are generally bulk averages with high uncertainty, precluding calculation of groundwater velocities in various parts of the subsurface. In this work, a recently published hydrogeological conceptual model of longwall caving is used in conjunction with observations from borehole extensometers, goaf height measurements, and pumping/drawdown records for mine pools to develop a subsurface spatial distribution of changes in S following longwall caving, with reduced uncertainty in their magnitudes. The assumption of saturation in the disturbed zone proved critical for obtaining accurate results and in reconciling widely varying published estimates of S. Results indicate that the goaf and collapsed zones each absorb over 30% of the mined volume, and about 20% is absorbed by the surface subsidence trough. The increase in S in the collapsed zone is inversely proportional to the amount of surface subsidence. The conceptual model is updated with these results to present the spatial distribution of S after caving. The results allow calculation of water velocities in various zones, and may provide greater accuracy in estimation of water level rebound and water quality processes. Most of the S participating in groundwater flows is provided by defects rather than the matrix.     

Image‐warping waveform tomography

Imaging the change in physical parameters in the subsurface requires an estimate of the long wavelength components of the same parameters in order to reconstruct the kinematics of the waves propagating in the subsurface. One can reconstruct the model by matching the recorded data with modeled waveforms extrapolated in a trial model of the medium. Alternatively, assuming a trial model, one can obtain a set of images of the reflectors from a number of seismic experiments and match the locations of the imaged interfaces. Apparent displacements between migrated images contain information about the velocity model and can be used for velocity analysis. A number of methods are available to characterize the displacement between images; in this paper, we compare shot‐domain differential semblance (image difference), penalized local correlations, and image‐warping. We show that the image‐warping vector field is a more reliable tool for estimating displacements between migrated images and leads to a more robust velocity analysis procedure. By using image‐warping, we can redefine the differential semblance optimization problem with an objective function that is more robust against cycle‐skipping than the direct image difference. We propose an approach that has straightforward implementation and reduced computational cost compared with the conventional adjoint‐state method calculations. We also discuss the weakness of migration velocity analysis in the migrated‐shot domain in the case of highly refractive media, when the Born modelling operator is far from being unitary and thus its adjoint (migration) operator poorly approximates the inverse.     

Estimation of the Change in Hydraulic Conductivity Above Mined Longwall Panels

The change in hydraulic conductivity (K) above subsided longwall panels at underground coal mines is determined using a data base of pre‐mining and post‐mining K measurements made at multiple locations down the depth profile at each of a number of sites worldwide. Results show that, following caving of roof strata, there is a clear difference in the magnitude of changes in K above and below the top of the collapsed zone. Within the collapsed zone, relative increases in K are larger, even when taking account of measurements made in potentially unsaturated strata. A generalized conceptual model is presented for K change above subsided longwall panels. These results form a third independent database supporting the height of desaturation reported in an earlier study.     

Optical dating and soil micromorphology at MacCauley's Beach,New South Wales,Australia

The ability to position landscapes in a context of time and space is a particular goal of Quaternary science research. The lack of context for dating samples published previously for MacCauley's Beach, an important site for the reconstruction of Australian sea levels, warranted a re‐evaluation of both the site stratigraphy and chronology. In this study, we combined optically stimulated luminescence (OSL) dating of sedimentary quartz grains and soil micromorphology of the same samples to improve our understanding of the depositional history and chronology of the sediments. This combination allowed the contextualization of samples not only in time and space, but also in terms of their depositional histories. The latter is important in OSL dating, where pre‐, syn‐ and post‐depositional processes can all influence the accuracy and precision of the final age estimates. The sediment profile at MacCauley's Beach is made up of three major units. The basal mottled mud layer has undergone extensive pedogenesis since deposition, and only a minimum age of 14.7 ± 2.7 ka could be calculated. The overlying grey mud, with OSL ages from the bottom and top of the unit of 10.0 ± 0.7 and 7.7 ± 0.5 ka, respectively, shows evidence of soil structure collapse. This unit correspond to the onset of the mid‐Holocene sea‐level high stand for this region. The overlying sand layer was first deposited at 7.5 ± 0.4 ka, with deposition continuing beyond 6.6 ± 0.4 ka. Not only does the chronology presented constrain the timing of deposition (and the extent of post‐depositional processes) at MacCauley's Beach, but the methodological approach used here can be applied to any site to aid in the interpretation of formation processes and assess their influence on OSL age determination. Copyright © 2014 John Wiley & Sons, Ltd.