The Role of Ocean Tides on Groundwater-Surface Water Exchange in a Mangrove-Dominated Estuary: Shark River Slough,Florida Coastal Everglades,USA     

Christopher G. Smith  René M. Price  Peter W. Swarzenski  Jeremy C. Stalker 《Estuaries and Coasts》2016,39(6):1600-1616

Low-relief environments like the Florida Coastal Everglades (FCE) have complicated hydrologic systems where surface water and groundwater processes are intimately linked yet hard to separate. Fluid exchange within these low-hydraulic-gradient systems can occur across broad spatial and temporal scales, with variable contributions to material transport and transformation. Identifying and assessing the scales at which these processes operate is essential for accurate evaluations of how these systems contribute to global biogeochemical cycles. The distribution of ²²²Rn and ^223,224,226Ra have complex spatial patterns along the Shark River Slough estuary (SRSE), Everglades, FL. High-resolution time-series measurements of ²²²Rn activity, salinity, and water level were used to quantify processes affecting radon fluxes out of the mangrove forest over a tidal cycle. Based on field data, tidal pumping through an extensive network of crab burrows in the lower FCE provides the best explanation for the high radon and fluid fluxes. Burrows are irrigated during rising tides when radon and other dissolved constituents are released from the mangrove soil. Flushing efficiency of the burrows—defined as the tidal volume divided by the volume of burrows—estimated for the creek drainage area vary seasonally from 25 (wet season) to 100 % (dry season) in this study. The tidal pumping of the mangrove forest soil acts as a significant vector for exchange between the forest and the estuary. Processes that enhance exchange of O₂ and other materials across the sediment-water interface could have a profound impact on the environmental response to larger scale processes such as sea level rise and climate change. Compounding the material budgets of the SRSE are additional inputs from groundwater from the Biscayne Aquifer, which were identified using radium isotopes. Quantification of the deep groundwater component is not obtainable, but isotopic data suggest a more prevalent signal in the dry season. These findings highlight the important role that both tidal- and seasonal-scale forcings play on groundwater movement in low-gradient hydrologic systems.  相似文献   

A simple predator-prey model of exploited marine fish populations incorporating alternative prey     

Spencer  Paul D.; Collie  Jeremy S. 《ICES Journal of Marine Science》1996,53(3):615-628

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Using AMOEBAs to display multispecies, multifleet fisheries advice     

Collie  Jeremy S.; Gislason  Henrik; Vinther  Morten 《ICES Journal of Marine Science》2003,60(4):709-720

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Alternative management systems for the UK fishing industry     

Jeremy Phillipson  Kevin Crean 《Ocean & Coastal Management》1997,35(2-3)

The paper considers opportunities for institutional development within the UK fishing industry that aim to engender a more meaningful incorporation of fishermen's organisations within the policy system. Special attention is given to the location of responsibility within the policy process. This involves an exploration of an alternative approach to consultation and the scope for delegation of management responsibilities to fishermen's organisations. Mechanisms to improve coordination among fishermen's organisations and to strengthen their internal architecture are also considered. The analysis raises important questions to inform the continuing debate over the development and structure of devolved management systems, in particular regarding the assumptions underlying user participation and the representativeness, capabilities and aspirations of fishermen's organisations.  相似文献   

Impact history of the Apollo 17 landing site revealed by U‐Pb SIMS ages          下载免费PDF全文

Fiona Thiessen  Alexander A. Nemchin  Joshua F. Snape  Martin J. Whitehouse  Jeremy J. Bellucci 《Meteoritics & planetary science》2017,52(4):584-611

Secondary ion mass spectrometry (SIMS) U‐Pb ages of Ca‐phosphates from four texturally distinct breccia samples (72255, 76055, 76015, 76215) collected at the Apollo 17 landing site were obtained in an attempt to identify whether they represent a single or several impact event(s). The determined ages, combined with inferences from petrologic relationships, may indicate two or possibly three different impact events at 3920 ± 3 Ma, 3922 ± 5 Ma, and 3930 ± 5 Ma (all errors 2σ). Searching for possible sources of the breccias by calculating the continuous ejecta radii of impact basins and large craters as well as their expected ejecta thicknesses, we conclude that Nectaris, Crisium, Serenitatis, and Imbrium are likely candidates. If the previous interpretation that the micropoikilitic breccias collected at the North Massif represent Serenitatis ejecta is correct, then the average ²⁰⁷Pb/²⁰⁶Pb age of 3930 ± 5 Ma (2σ) dates the formation of the Serenitatis basin. The occurrence of zircon in the breccias sampled at the South Massif, which contain Ca‐phosphates yielding an age of 3922 ± 5 Ma (2σ), may indicate that the breccia originated from within the Procellarum KREEP terrane (PKT) and the Imbrium basin appears to be the only basin that could have sourced them. However, this interpretation implies that all basins suggested to fall stratigraphically between Serenitatis and Imbrium formed within a short (<11 Ma) time interval, highlighting serious contradictions between global stratigraphic constraints, sample interpretation, and chronological data. Alternatively, the slightly older age of the two micropoikilitic breccias may be a result of incomplete resetting of the U‐Pb system preserved in some phosphate grains. Based on the currently available data set this possibility cannot be excluded.  相似文献   

Bulk organic δC and C/N as indicators for sediment sources in the Pearl River delta and estuary,southern China     

Fengling Yu  Yongqiang Zong  Jeremy M. Lloyd  Guangqing Huang  Melanie J. Leng  Christopher Kendrick  Angela L. Lamb  Wyss W.-S. Yim 《Estuarine, Coastal and Shelf Science》2010

Preservation of organic matter in estuarine and coastal areas is an important process in the global carbon cycle. This paper presents bulk δ¹³C and C/N of organic matter from source to sink in the Pearl River catchment, delta and estuary, and discusses the applicability of δ¹³C and C/N as indicators for sources of organic matter in deltaic and estuarine sediments. In addition to the 91 surface sediment samples, other materials collected in this study cover the main sources of organic material to estuarine sediment. These are: terrestrial organic matter (TOM), including plants and soil samples from the catchment; estuarine and marine suspended particulate organic carbon (POC) from both summer and winter. Results show that the average δ¹³C of estuarine surface sediment increases from −25.0 ± 1.3‰ in the freshwater environment to −21.0 ± 0.2‰ in the marine environment, with C/N decreasing from 15.2 ± 3.3 to 6.8 ± 0.2. In the source areas, C₃ plants have lower δ¹³C than C₄ plants (−29.0 ± 1.8‰ and −13.1 ± 0.5‰ respectively). δ¹³C increases from −28.3 ± 0.8‰ in the forest soil to around −24.1‰ in both riverbank soil and mangrove soil due to increasing proportion of C₄ grasses. The δ¹³C_POC increases from −27.6 ± 0.8‰ in the freshwater areas to −22.4 ± 0.5‰ in the marine-brackish-water areas in winter, and ranges between −24.0‰ in freshwater areas and −25.4‰ in brackish-water areas in summer. Comparison of the δ¹³C and C/N between the sources and sink indicates a weakening TOM and freshwater POC input in the surface sedimentary organic matter seawards, and a strengthening contribution from the marine organic matter. Thus we suggest that bulk organic δ¹³C and C/N analysis can be used to indicate sources of sedimentary organic matter in estuarine environments. Organic carbon in surface sediments derived from anthropogenic sources such as human waste and organic pollutants from industrial and agricultural activities accounts for less than 10% of the total organic carbon (TOC). Although results also indicate elevated δ¹³C of sedimentary organic matter due to some agricultural products such as sugarcane, C₃ plants are still the dominant vegetation type in this area, and the bulk organic δ¹³C and C/N is still an effective indicator for sources of organic matter in estuarine sediments.  相似文献   

The Phase A study of the ESA M4 mission candidate ARIEL     

Ludovic Puig  Göran Pilbratt  Astrid Heske  Isabel Escudero  Pierre-Elie Crouzet  Bram de Vogeleer  Kate Symonds  Ralf Kohley  Pierre Drossart  Paul Eccleston  Paul Hartogh  Jeremy Leconte  Giusi Micela  Marc Ollivier  Giovanna Tinetti  Diego Turrini  Bart Vandenbussche  Paulina Wolkenberg 《Experimental Astronomy》2018,46(1):211-239

ARIEL, the Atmospheric Remote sensing Infrared Exoplanet Large survey, is one of the three M-class mission candidates competing for the M4 launch slot within the Cosmic Vision science programme of the European Space Agency (ESA). As such, ARIEL has been the subject of a Phase A study that involved European industry, research institutes and universities from ESA member states. This study is now completed and the M4 down-selection is expected to be concluded in November 2017. ARIEL is a concept for a dedicated mission to measure the chemical composition and structure of hundreds of exoplanet atmospheres using the technique of transit spectroscopy. ARIEL targets extend from gas giants (Jupiter or Neptune-like) to super-Earths in the very hot to warm zones of F to M-type host stars, opening up the way to large-scale, comparative planetology that would place our own Solar System in the context of other planetary systems in the Milky Way. A technical and programmatic review of the ARIEL mission was performed between February and May 2017, with the objective of assessing the readiness of the mission to progress to the Phase B1 study. No critical issues were identified and the mission was deemed technically feasible within the M4 programmatic boundary conditions. In this paper we give an overview of the final mission concept for ARIEL as of the end of the Phase A study, from scientific, technical and operational perspectives.  相似文献   

Regolith breccia Northwest Africa 7533: Mineralogy and petrology with implications for early Mars          下载免费PDF全文

Roger H. Hewins  Brigitte Zanda  Munir Humayun  Alexander Nemchin  Jean‐Pierre Lorand  Sylvain Pont  Damien Deldicque  Jeremy J. Bellucci  Pierre Beck  Hugues Leroux  Maya Marinova  Laurent Remusat  Christa Göpel  Eric Lewin  Marion Grange  Allen Kennedy  Martin J. Whitehouse 《Meteoritics & planetary science》2017,52(1):89-124

Northwest Africa 7533, a polymict Martian breccia, consists of fine‐grained clast‐laden melt particles and microcrystalline matrix. While both melt and matrix contain medium‐grained noritic‐monzonitic material and crystal clasts, the matrix also contains lithic clasts with zoned pigeonite and augite plus two feldspars, microbasaltic clasts, vitrophyric and microcrystalline spherules, and shards. The clast‐laden melt rocks contain clump‐like aggregates of orthopyroxene surrounded by aureoles of plagioclase. Some shards of vesicular melt rocks resemble the pyroxene‐plagioclase clump‐aureole structures. Submicron size matrix grains show some triple junctions, but most are irregular with high intergranular porosity. The noritic‐monzonitic rocks contain exsolved pyroxenes and perthitic intergrowths, and cooled more slowly than rocks with zoned‐pyroxene or fine grain size. Noritic material contains orthopyroxene or inverted pigeonite, augite, calcic to intermediate plagioclase, and chromite to Cr‐bearing magnetite; monzonitic clasts contain augite, sodic plagioclase, K feldspar, Ti‐bearing magnetite, ilmenite, chlorapatite, and zircon. These feldspathic rocks show similarities to some rocks at Gale Crater like Black Trout, Mara, and Jake M. The most magnesian orthopyroxene clasts are close to ALH 84001 orthopyroxene in composition. All these materials are enriched in siderophile elements, indicating impact melting and incorporation of a projectile component, except for Ni‐poor pyroxene clasts which are from pristine rocks. Clast‐laden melt rocks, spherules, shards, and siderophile element contents indicate formation of NWA 7533 as a regolith breccia. The zircons, mainly derived from monzonitic (melt) rocks, crystallized at 4.43 ± 0.03 Ga (Humayun et al. 2013 ) and a ¹⁴⁷Sm‐¹⁴³Nd isochron for NWA 7034 yielding 4.42 ± 0.07 Ga (Nyquist et al. 2016 ) defines the crystallization age of all its igneous portions. The zircon from the monzonitic rocks has a higher Δ¹⁷O than other Martian meteorites explained in part by assimilation of regolith materials enriched during surface alteration (Nemchin et al. 2014 ). This record of protolith interaction with atmosphere‐hydrosphere during regolith formation before melting demonstrates a thin atmosphere, a wet early surface environment on Mars, and an evolved crust likely to have contaminated younger extrusive rocks. The latest events recorded when the breccia was on Mars are resetting of apatite, much feldspar and some zircons at 1.35–1.4 Ga (Bellucci et al. 2015 ), and formation of Ni‐bearing pyrite veins during or shortly after this disturbance (Lorand et al. 2015 ).  相似文献   

Late-Quaternary biogeographic scenarios for the brown bear (Ursus arctos), a wild mammal model species     

John Davison  Simon Y.W. Ho  Sarah C. Bray  Marju Korsten  Egle Tammeleht  Maris Hindrikson  Kjartan Østbye  Eivind Østbye  Stein-Erik Lauritzen  Jeremy Austin  Alan Cooper  Urmas Saarma 《Quaternary Science Reviews》2011,30(3-4):418-430

This review provides an up-to-date synthesis of the matrilineal phylogeography of a uniquely well-studied Holarctic mammal, the brown bear. We extend current knowledge by presenting a DNA sequence derived from one of the earliest known fossils of a polar bear (dated to 115 000 years before present), a species that shares a paraphyletic mitochondrial association with brown bears. A molecular clock analysis of 140 mitochondrial DNA sequences, including our new polar bear sequence, provides novel insights into the times of origin for different brown bear clades. We propose a number of regional biogeographic scenarios based on genetic data, divergence time estimates and paleontological records. The case of the brown bear provides an example for researchers working with less well-studied taxa: it shows clearly that phylogeographic models based on patterns of modern genetic variation alone can be substantially improved by including data on historical patterns of genetic diversity in the form of ancient DNA sequences derived from accurately dated samples and by using an approach to divergence-time estimation that suits the data under analysis. Using such approaches it has been possible to (i) establish that the processes shaping modern genetic diversity in brown bears acted recently, within the last three glacial cycles; (ii) distinguish among hypotheses concerning species’ responses to climatic oscillations in accordance with the lack of phylogeographic structure that existed in brown bears prior to the last glacial maximum (LGM); (iii) reassess theories linking monophyletic brown bear populations to particular LGM refuge areas; and (iv) identify vicariance events and track analogous patterns of migration by brown bears out of Eurasia to North America and Japan.  相似文献   

Using long-term transit timing to detect terrestrial planets     

Jeremy S. Heyl †  Brett J. Gladman † 《Monthly notices of the Royal Astronomical Society》2007,377(4):1511-1519

We propose that the presence of additional planets in extrasolar planetary systems can be detected by long-term transit timing studies. If a transiting planet is on an eccentric orbit then the presence of another planet causes a secular advance of the transiting planet's pericentre over and above the effect of general relativity. Although this secular effect is impractical to detect over a small number of orbits, it causes long-term differences when future transits occur, much like the long-term decay observed in pulsars. Measuring this transit-timing delay would thus allow the detection of either one or more additional planets in the system or the first measurements of non-zero oblateness ( J ₂) of the central stars.  相似文献