Measurements of the Temperature Structure-Function Parameters with a Small Unmanned Aerial System Compared with a Sodar     

Timothy A. Bonin  David C. Goines  Aaron K. Scott  Charlotte E. Wainwright  Jeremy A. Gibbs  Phillip B. Chilson 《Boundary-Layer Meteorology》2015,155(3):417-434

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Summer algal blooms in a coastal ecosystem: the role of atmospheric deposition versus entrainment fluxes   总被引：2，自引：1，他引：2  

Jacob Carstensen  Lise Marie Frohn  Charlotte Bay Hasager  Bo G. Gustafsson 《Estuarine, Coastal and Shelf Science》2005,62(4):595-608

The nitrogen inputs from atmospheric deposition and bottom water entrainment to the surface layer were modelled in the summer period (May–September) over a 11-year period (1989–1999) and compared to investigate the significance of these fluxes for generating blooms in the Kattegat. In the summer periods the average atmospheric deposition was 2.81 mg N m⁻² d⁻¹ compared to average entrainment fluxes of 5.42 mg N m⁻² d⁻¹, 1.21 mg N m⁻² d⁻¹ and 1.15 mg N m⁻² d⁻¹ for the northern, central and southern part of the Kattegat, respectively. Atmospheric nitrogen deposition alone could not sustain biomass increases associated with observed blooms and entrainment fluxes dominated the high nitrogen inputs to the surface layer. The potential for a bloom through growth was typically obtained after several days of high nitrogen inputs from entrainment in the frontal area of the northern Kattegat and to some extent from atmospheric deposition. The modelled nitrogen input in this area could account directly for 30% of the observed blooms in the Northern sub-basin, and through advective transport 24% and 19% of the observed blooms in the central and southern Kattegat. The direct nitrogen inputs through atmospheric deposition and entrainment to the central and southern sub-basins were small and could not be linked to any bloom observation.  相似文献   

Diel patterns in pelagic fish behaviour and distribution observed from a stationary, bottom-mounted, and upward-facing transducer   总被引：1，自引：1，他引：1  

Axenrot  Thomas; Didrikas  Tomas; Danielsson  Charlotte; Hansson  Sture 《ICES Journal of Marine Science》2004,61(7):1100-1104

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The Messinian salinity crisis in Cyprus: a further step towards a new stratigraphic framework for Eastern Mediterranean   总被引：1，自引：1，他引：0       下载免费PDF全文

Vinicio Manzi  Stefano Lugli  Marco Roveri  Francesco Dela Pierre  Rocco Gennari  Francesca Lozar  Marcello Natalicchio  B. Charlotte Schreiber  Marco Taviani  Elena Turco 《Basin Research》2016,28(2):207-236

A revised stratigraphic framework for the Messinian succession of Cyprus is proposed demonstrating that the three‐stage model for the Messinian salinity crisis recently established for the Western Mediterranean also applies to the Eastern Mediterranean, at least for its marginal basins. This analysis is based on a multidisciplinary study of the Messinian evaporites and associated deposits exposed in the Polemi, Pissouri, Maroni/Psematismenos and Mesaoria basins. Here, we document for the first time that the base of the unit usually referred to the ‘Lower Evaporites’ in Cyprus does not actually correspond to the onset of the Messinian salinity crisis. The basal surface of this unit rather corresponds to a regional‐scale unconformity, locally associated with an angular discordance, and is related to the erosion and resedimentation of primary evaporites deposited during the first stage of the Messinian salinity crisis. This evidence suggests that the ‘Lower Evaporites’ of the southern basins of Cyprus actually belong to the second stage of the Messinian salinity crisis; they can be thus ascribed to the Resedimented Lower Gypsum unit that was deposited between 5.6 and 5.5 Ma and is possibly coeval to the halite deposited in the northern Mesaoria basin. Primary, in situ evaporites of the first stage of the Messinian salinity crisis were not preserved in Cyprus basins. Conversely, shallow‐water primary evaporites deposited during the third stage of the Messinian salinity crisis are well preserved; these deposits can be regarded as the equivalent of the Upper Gypsum of Sicily. Our study documents that the Messinian stratigraphy shows many similarities between the Western and Eastern Mediterranean marginal basins, implying a common and likely coeval development of the Messinian salinity crisis. This could be reflected also in intermediate and deep‐water basins; we infer that the Lower Evaporites seismic unit in the deep Eastern Mediterranean basins could well be mainly composed of clastic evaporites and that its base could correspond to the Messinian erosional surface.  相似文献   

Hopane,sterane and n-alkane distributions in shallow sediments hosting high arsenic groundwaters in Cambodia     

Bart E. van Dongen  Helen A.L. Rowland  Andrew G. Gault  David A. Polya  Charlotte Bryant  Richard D. Pancost 《Applied Geochemistry》2008

The presence of elevated As in ground waters exploited for drinking water and irrigation in South-East Asia is causing serious impacts on human health. A key mechanism that causes the mobilization of As in these waters is microbially mediated reductive transformation of As-bearing Fe(III) hydrated oxides and the role of degradable organic matter (OM) in this process is widely recognized. A number of different types of OM that drive As release in these aquifers have been suggested, including petroleum derived hydrocarbons naturally seeping into shallow sediments from deeper thermally mature source rocks. However, the amount of information on the characteristics of the OM in South-East Asian aquifers is limited. Here the organic geochemical analyses of the saturated hydrocarbon fractions and radiocarbon analysis, of two additional sites in SE Asia are reported. The results show that the OM in a given sedimentary horizon likely derives from multiple sources including naturally occurring petroleum. The importance of naturally occurring petroleum as one of the sources was clearly indicated by the n-alkane CPI of approximately 1, the presence of an unresolved complex mixture, and hopane (dominated by 17α(H),21β(H) hopanes) and sterane distribution patterns. The results also indicate that the OM in these aquifers varies tremendously in content, character and potential bioavailability. Furthermore, the presence of petroleum derived OM in sediments at both sites doubles the number of locations where their presence has been observed in association with As-rich, shallow aquifers, suggesting that the role of petroleum derived OM in microbially mediated As release might occur over a wider range of geographical locations than previously thought.  相似文献   

Arsenic mobilisation in a new well field for drinking water production along the Red River,Nam Du,Hanoi     

Jenny Norrman  Charlotte J. Sparrenbom  Michael Berg  Dang Duc Nhan  Pham Quy Nhan  Håkan Rosqvist  Gunnar Jacks  Emma Sigvardsson  David Baric  Johanna Moreskog  Peter Harms-Ringdahl  Nguyen Van Hoan 《Applied Geochemistry》2008

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Contaminant fluxes from point and diffuse sources from abandoned mines in the River Tamar catchment, UK     

Krongkaew Mighanetara  Charlotte B. Braungardt  John S. Rieuwerts  Fethi Azizi   《Journal of Geochemical Exploration》2009,100(2-3):116-124

Acid mine waters have the potential to seriously impair the environmental quality of aquatic systems long after mining activities have ceased. This detailed study of dissolved and particulate metal fluxes from adits, drains and streams in the River Tamar catchment, southwest England, showed that seven specific sources, of the 25 adits and streams surveyed, accounted for more than 75% each of the 13 t a^− 1 Fe, 4.3 t a^− 1 Mn, 4.2 t a^− 1 Cu, 3.6 t a^− 1 Zn and 1.4 t a^− 1 As that we estimated to be discharged annually from the abandoned metalliferous mining area centred around Calstock and Gunnislake. Upstream of this study area, widespread multi-metallic mineralisation contributed to the flux of Fe, Mn, As, Co, Cu and Zn within the River Tamar. Simple mass balance calculations indicated that a large proportion (≥ 50% for most dissolved and particulate metals) of the metal flux in the River Tamar was unaccounted for by our survey, and therefore is likely to have an important diffuse component, which is subject to ongoing investigations. Potential impacts of mine contamination on the estuarine environment are discussed. The study provided information necessary to prioritise monitoring and remediation efforts in the context of sustainable catchment management.  相似文献   

Impact of earthquakes on agriculture during the Roman-Byzantine period from pollen records of the Dead Sea laminated sediment     

Suzanne A.G. Leroy  Shmuel Marco  Charlotte S. Miller 《Quaternary Research》2010,73(2):191-5248

The Dead Sea region holds the archives of a complex relationship between an ever-changing nature and ancient civilisations. Regional pollen diagrams show a Roman-Byzantine period standing out in the recent millennia by its wetter climate that allowed intensive arboriculture. During that period, the Dead Sea formed laminites that display mostly a seasonal character. A multidisciplinary study focused on two earthquakes, 31 BC and AD 363, recorded as seismites in the Ze’elim gully A unit III which has been well dated by radiocarbon in a previous study. The sampling of the sediment was done at an annual resolution starting from a few years before and finishing a decade after each earthquake. A clear drop in agricultural indicators (especially Olea and cereals) is shown. These pollen indicators mostly reflect human activities in the Judean Hills and coastal oases. Agriculture was disturbed in large part of the rift valley where earthquake damage affected irrigation and access to the fields. It took 4 to 5 yr to resume agriculture to previous conditions. Earthquakes must be seen as contributors to factors damaging societies. If combined with other factors such as climatic aridification, disease epidemics and political upheaval, they may lead to civilisation collapse.  相似文献   

Palaeoecological,archaeological and historical data and the making of Devon landscapes. I. The Blackdown Hills     

Antony G. Brown  Charlotte Hawkins  Lucy Ryder  Sean Hawken  Frances Griffith  Jackie Hatton 《Boreas: An International Journal of Quaternary Research》2014,43(4):834-855

This paper presents the first systematic study of the vegetation history of a range of low hills in SW England, UK, lying between more researched fenlands and uplands. After the palaeoecological sites were located bespoke archaeological, historical and documentary studies of the surrounding landscape were undertaken specifically to inform palynological interpretation at each site. The region has a distinctive archaeology with late Mesolithic tool scatters, some evidence of early Neolithic agriculture, many Bronze Age funerary monuments and Romano‐British iron‐working. Historical studies have suggested that the present landscape pattern is largely early Medieval. However, the pollen evidence suggests a significantly different Holocene vegetation history in comparison with other areas in lowland England, with evidence of incomplete forest clearance in later‐Prehistory (Bronze?Iron Age). Woodland persistence on steep, but poorly drained, slopes, was probably due to the unsuitability of these areas for mixed farming. Instead they may have been under woodland management (e.g. coppicing) associated with the iron‐working industry. Data from two of the sites also suggest that later Iron Age and Romano‐British impact may have been geographically restricted. The documented Medieval land management that maintained the patchwork of small fields, woods and heathlands had its origins in later Prehistory, but there is also evidence of landscape change in the 6th–9th centuries AD. We conclude that the Blackdown Hills area was one of many ‘distinctive subregions’, which due to a combination of edaphic, topographic and cultural factors could qualify as an eco‐cultural region or ‘pays’. It is argued that the use of such eco‐culturally distinctive regions or pays can provide a spatial and archaeological framework for palaeoecology, which has implications for landscape research, designation and heritage management.  相似文献   

Creek enlargement in a low‐energy degrading saltmarsh in southern England     

Yining Chen  Michael B. Collins  Charlotte E.L. Thompson 《地球表面变化过程与地形》2011,36(6):767-778

A low‐energy saltmarsh in the Beaulieu River Estuary, southern England was investigated. A geomorphological survey revealed that the creek bank geometry was characterized by the presence of cantilevers, a result of the protection provided by roots over the upper part of the bank. The saltmarsh deposits, consisting mainly of clay and organic matter, have a high resistance to flow‐induced erosion. Short‐term hydrographic deployments revealed that the tidal currents and waves recorded were insufficient to cause erosion of the bank surface. However, pin measurements over a 2‐year period revealed that the tidal creeks within the saltmarsh did experience bank erosion, particularly below the cantilevers, in spite of this low‐energy setting. Bank face erosion was therefore considered to be related to long‐term processes. The bases of the cantilevers were found to be located at a precise level, in relation to the tides. Water level data over a 2‐year period were examined against erosion measured below the cantilevers. The results suggest that the erosion on the bank faces, particularly below the cantilevers, is associated with the frequency of water level variations and long‐term submergence/emergence cycles, which can decrease the bonds between the particles and enable erosion by low tidal and wind‐wave currents within this low‐energy environment. This mechanism is probably responsible for tidal creek enlargement via erosion of the bank face and subsequent bank failure, a process which acts over a long temporal scale (1–10 years). Copyright © 2010 John Wiley & Sons, Ltd.  相似文献