Sediment transport on the Freiston Shore managed realignment site: An investigation using environmental magnetism     

Robin Rotman  Larissa Naylor  Rachael McDonnell  Conall MacNiocaill 《Geomorphology》2008,100(3-4):241-255

This paper presents the first attempt to use environmental magnetism to quantify sediment provenance on a managed realignment (MR) site. MR is one technique for creating/restoring intertidal habitats and improving the standard of coastal flood protection. Monitoring of MR sites is essential for determining how successful they are at achieving these aims, and normally includes measurement of sedimentation rates through the use of accretion plates and sediment erosion tables (SETs). One limitation of this technique is that the provenance of sediment accreting on realigned surfaces cannot readily be quantified. Our results demonstrate that magnetics-based fingerprinting can successfully apportion sediment source contributions to created/restored coastal saltmarshes with an efficiency similar to that of existing un-mixing models applied to other habitats (82.87%). Analysis of mineral magnetic properties (χ_FD, IRM_soft and SIRM) demonstrated that the majority of sediment accreting on the Freiston Shore MR Site (Lincolnshire, UK) is derived from established saltmarshes seaward of the breached embankment. This indicates that the MR site may be growing at the expense of neighbouring saltmarshes—thereby undermining the habitat-creation objectives used to justify MR. It is recommended that future MR monitoring programmes consider the provenance of post-breach deposits to help identify any adverse impacts that wetland creation/restoration may have on existing habitats. Further testing of environmental magnetism in coastal saltmarshes and MR sites is necessary to validate wider use of the technique.  相似文献   

Using δN values in algal tissue to map locations and potential sources of anthropogenic nutrient inputs on the island of Maui, Hawai‘i, USA     

Meghan L. Dailer  Robin S. Knox  Jennifer E. Smith 《Marine pollution bulletin》2010,60(5):655-671

Macroalgal blooms of Hypnea musciformis and Ulvafasciata in coastal waters of Maui only occur in areas of substantial anthropogenic nutrient input, sources of which include wastewater effluent via injection wells, leaking cesspools and agricultural fertilizers. Algal δ¹⁵N signatures were used to map anthropogenic nitrogen through coastal surveys (island-wide and fine-scale) and algal deployments along nearshore and offshore gradients. Algal δ¹⁵N values of 9.8‰ and 2.0-3.5‰ in Waiehu and across the north-central coast, respectively, suggest that cesspool and agricultural nitrogen reached the respective adjacent coastlines. Effluent was detected in areas proximal to the Wastewater Reclamation Facilities (WWRF) operating Class V injection wells in Lahaina, Kihei and Kahului through elevated algal δ¹⁵N values (17.8-50.1‰). From 1997 to 2008, the three WWRFs injected an estimated total volume of 193 million cubic meters (51 billion gallons) of effluent with a nitrogen mass of 1.74 million kilograms (3.84 million pounds).  相似文献   

Analytical study on vulnerability functions for casualty estimation in the collapse of adobe buildings induced by earthquake     

Aiko Furukawa  Robin Spence  Yutaka Ohta  Emily So 《Bulletin of Earthquake Engineering》2010,8(2):451-479

Collapse of adobe buildings during an earthquakes with various earthquake intensities is analyzed using the 3-dimensional distinct element method code developed by the first author. Firstly, we evaluate structural damage with damage index, interior-space damage with w score, and human casualties in the collapsing buildings with three casualty criteria. Secondly, we investigate relationships between the earthquake intensity, the structural damage, the interior-space damage, and the casualties. It is found that the casualties have stronger correlation with the interior-space damage than the structural damage, and three vulnerability functions, namely, structural, interior-space and casualty vulnerability functions, are proposed. Effects of reinforcing methods on these functions are also examined. Finally, a series of analytical procedures to develop vulnerability functions and to estimate casualties using the functions are described.  相似文献   

Temporal and Spatial Dynamics of Diel-Cycling Hypoxia in Estuarine Tributaries     

Robin M. Tyler  Damian C. Brady  Timothy E. Targett 《Estuaries and Coasts》2009,32(1):123-145

The distribution and intensity of hypoxia (low dissolved oxygen) in estuaries is increasing worldwide due to cultural eutrophication. This study quantifies the strength of associations between the duration of diel-cycling severe hypoxia (≤2 mg O₂ l⁻¹) in bottom water (∼15 cm above bottom) of a shallow (<2 m) coastal lagoon estuary (Delaware, USA) and abiotic environmental variables (water temperature, insolation, tide, streamflow, and wind) and predicts the duration of severe hypoxia given different combinations of these variables. The intensity and spatial extent and dynamics of diel-cycling severe hypoxia events were defined. Vertical variability in dissolved oxygen (DO) concentration during the daytime was also determined. During the summers of 2001–2005, bottom DO data were collected for periods of weeks to months at multiple sites using automated sondes. Multiple linear regression (MLR) and regression tree analysis (RTA) were used to determine the relative importance of the environmental variables in predicting the number of hours of severe hypoxia per day. Key findings of the study were that severe hypoxia events of minutes to hours in duration occurred frequently in all four tributaries sampled, primarily between 0200 and 1000 hours. Severe hypoxia duration and diel-cycling amplitudes of DO concentration increased in the up-tributary direction. Hierarchically, the duration of severe hypoxia was influenced mostly by the mean daily water temperature, then by preceding days’ total insolation, percentage of morning hours (02:00 to 10:00 a.m.) ebb tide, and daily streamflow. Collectively, the variables examined by the MLR and the RTA approaches accounted for 62% and 65% of the variability in the duration of severe hypoxia, respectively. RTA demonstrated that daily mean water temperature above 26.3°C and previous day’s total insolation below 13.6 kW m⁻² were associated with the longest lasting severe hypoxic events (9.56 h). The environmental variables and combinations of conditions that modulate or augment diel-cycling hypoxia presented in this paper enhance understanding of this widespread and growing phenomenon and provide additional insight regarding the extent to which it can impact food webs in very shallow estuarine waters that often serve as nursery habitat.  相似文献   

The Rhenohercynian passive margin of SW England: Development,inversion and extensional reactivation     

Robin K. Shail  Brian E. Leveridge 《Comptes Rendus Geoscience》2009,341(2-3):140-155

The SW England Rhenohercynian passive margin initiated with rift-related non-marine sedimentation and bimodal magmatism (Late Lockhovian). Continued lithospheric extension resulted in the exhumation of mantle peridotites and limited seafloor spreading (Emsian-Eifelian). Variscan convergence commenced during the Late Eifelian and was coeval with rifting further north. Collision was marked by the Early Carboniferous emergence of deep marine sedimentary/volcanic rocks from the distal continental margin, oceanic lithosphere, pre-rift basement and upper plate gneisses (correlated with the Mid-German Crystalline High of the Saxothuringian Zone). Progressive inversion of the passive margin was strongly influenced by rift basin geometry. Convergence ceased in the Late Carboniferous and was replaced by an extensional regime that reactivated basin controlling/thrust faults and reorientated earlier fabrics (Start-Perranporth Zone). The resultant exhumation of the lower plate was accompanied by emplacement of the Early Permian SW England granites and was contemporaneous with upper plate sedimentary basin formation above the reactivated Rhenohercynian suture. The Rhenohercynian passive margin probably developed in a marginal basin north of the Rheic Ocean or, possibly, a successor basin following its closure. The Lizard ophiolite is unlikely to represent Rheic Ocean floor or associated forearc (SSZ) crust. The Rheic and Rhenohercynian sutures may be coincident or the Rheic suture may be located further south in the Léon Domain.  相似文献   

Alcohol,drinking, drunkenness: (dis)orderly spaces by Mark Jayne,Gill Valentine and Sarah Holloway,Ashgate Press,Farnham, 2011. 158 pp. ISBN 9780754671602.     

Robin Kearns 《New Zealand geographer》2013,69(1):77-78

  相似文献   

Using GIS and large-scale digital data to implement hedonic pricing studies     

Iain R. Lake  Andrew A. Lovett  Ian J. Bateman  Brett Day 《International journal of geographical information science》2013,27(6):521-541

This paper describes how a standard GIS package can be used to convert large-scale vector digital data (point, line and annotation features) into polygons using standardised and replicable methods. Building area, garden and land use polygons are all derived from such data (Ordnance Survey LandLine.Plus). These entities are then combined with further sources of digital data to derive more refined information such as property types. Finally, complex DEMs are developed for use in visibility studies. The variables calculated are subsequently employed in a property valuation study where many are found to be significant determinants of property price. The main exception is variables relating to viewsheds, although it is argued that this does not invalidate the techniques used in their deviation but highlights the difficulties involved in modelling a large number of variables in a property price analysis.  相似文献   

Evaluating legacy contaminants and emerging chemicals in marine environments using adverse outcome pathways and biological effects-directed analysis     

Thomas H. Hutchinson  Brett P. Lyons  John E. Thain  Robin J. Law 《Marine pollution bulletin》2013

Natural and synthetic chemicals are essential to our daily lives, food supplies, health care, industries and safe sanitation. At the same time protecting marine ecosystems and seafood resources from the adverse effects of chemical contaminants remains an important issue. Since the 1970s, monitoring of persistent, bioaccumulative and toxic (PBT) chemicals using analytical chemistry has provided important spatial and temporal trend data in three important contexts; relating to human health protection from seafood contamination, addressing threats to marine top predators and finally providing essential evidence to better protect the biodiversity of commercial and non-commercial marine species. A number of regional conventions have led to controls on certain PBT chemicals over several years (termed ‘legacy contaminants’; e.g. cadmium, lindane, polycyclic aromatic hydrocarbons [PAHs] and polychlorinated biphenyls [PCBs]). Analytical chemistry plays a key role in evaluating to what extent such regulatory steps have been effective in leading to reduced emissions of these legacy contaminants into marine environments. In parallel, the application of biomarkers (e.g. DNA adducts, CYP1A-EROD, vitellogenin) and bioassays integrated with analytical chemistry has strengthened the evidence base to support an ecosystem approach to manage marine pollution problems. In recent years, however, the increased sensitivity of analytical chemistry, toxicity alerts and wider environmental awareness has led to a focus on emerging chemical contaminants (defined as chemicals that have been detected in the environment, but which are currently not included in regulatory monitoring programmes and whose fate and biological impacts are poorly understood). It is also known that natural chemicals (e.g. algal biotoxins) may also pose a threat to marine species and seafood quality. Hence complex mixtures of legacy contaminants, emerging chemicals and natural biotoxins in marine ecosystems represent important scientific, economic and health challenges. In order to meet these challenges and pursue cost-effective scientific approaches that can provide evidence necessary to support policy needs (e.g. the European Marine Strategy Framework Directive), it is widely recognised that there is a need to (i) provide marine exposure assessments for priority contaminants using a range of validated models, passive samplers and biomarkers; (ii) integrate chemical monitoring data with biological effects data across spatial and temporal scales (including quality controls); and (iii) strengthen the evidence base to understand the relationship between exposure to complex chemical mixtures, biological and ecological impacts through integrated approaches and molecular data (e.g. genomics, proteomics and metabolomics). Additionally, we support the widely held view that (iv) that rather than increasing the analytical chemistry monitoring of large number of emerging contaminants, it will be important to target analytical chemistry towards key groups of chemicals of concern using effects-directed analysis. It is also important to evaluate to what extent existing biomarkers and bioassays can address various classes of emerging chemicals using the adverse outcome pathway (AOP) approach now being developed by the Organization for Economic Cooperation and Development (OECD) with respect to human toxicology and ecotoxicology.  相似文献   

Annual to decadal morphodynamics of the foredune system at Greenwich Dunes,Prince Edward Island,Canada     

Jeff Ollerhead  Robin Davidson‐Arnott  Ian J. Walker  Sojan Mathew 《地球表面变化过程与地形》2013,38(3):284-298

The purpose of this study was to quantify relationships between season, sediment availability, sediment transport pathways, and beach/foredune morphology at Greenwich Dunes, PEI. This was done for periods ranging from a few days to multiple decades using erosion pins, bedframe measurements, annual surveys, and digital photogrammetry using historical aerial photographs. The relative significance of seasonal/annual processes versus response of the foredune system to broader geomorphic controls (e.g. relative sea level rise, storms, etc.) was also assessed. The data show that there are clear seasonal differences in the patterns of sand supply from the beach to the foredune at Greenwich and that there are differences in sediment supply to the foredune between the east and west reaches of the study area, resulting in ongoing differences in foredune morphology. They also demonstrate that models that incorporate wind climate alone, or even models that include other factors like beach moisture, would not be able to predict the amount of sediment movement from the beach to the foredune in this environment unless there were some way to parameterize system morphology, especially the presence or absence of a dune ramp. Finally, the data suggest that the foredune can migrate landward while maintaining its form via transfers of sediment from the stoss slope, over the crest, and onto the lee slope. Although the rate of foredune development or recovery after disturbance changes over time due to morphological feedback, the overall decadal evolution of the foredune system at Greenwich is consistent with, and supports, the Davidson‐Arnott (2005) conceptual model of dune transgression under rising sea level. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Quantifying urban land cover change between 2001 and 2006 in the Gulf of Mexico region     

George Xian  Collin Homer  Brett Bunde  Patrick Danielson  Jon Dewitz  Joyce Fry 《国际地球制图》2013,28(6):479-497

We estimated urbanization rates (2001–2006) in the Gulf of Mexico region using the National Land Cover Database (NLCD) 2001 and 2006 impervious surface products. An improved method was used to update the NLCD impervious surface product in 2006 and associated land cover transition between 2001 and 2006. Our estimation reveals that impervious surface increased 416 km² with a growth rate of 5.8% between 2001 and 2006. Approximately 1110.1 km² of non-urban lands were converted into urban land, resulting in a 3.2% increase in the region. Hay/pasture, woody wetland, and evergreen forest represented the three most common land cover classes that transitioned to urban. Among these land cover transitions, more than 50% of the urbanization occurred within 50 km of the coast. Our analysis shows that the close-to-coast land cover transition trend, especially within 10 km off the coast, potentially imposes substantial long-term impacts on regional landscape and ecological conditions.  相似文献