Distribution and significance of long-chain alkenones as salinity and temperature indicators in Spanish saline lake sediments     

Emma J. Pearson  Steve Juggins 《Geochimica et cosmochimica acta》2008,72(16):4035-4046

We investigated relationships between sedimentary solvent-extractable long-chain alkenone (LCA) concentration and composition and environmental factors in a suite of endorheic lakes from inland Spain. LCAs were found in 14 of the 54 lakes examined, with concentrations comparable with those from previously published lacustrine settings. The composition of LCAs in our sites, however, contrast from the majority of those previously reported from lake environments; in our study the tri-unsaturated component is the most abundant component at most sites where LCAs are detected, and C_38:3 is the most abundant LCA in the majority of sites. LCA occurrence appears to be restricted to brackish-hypersaline sites and C₃₇ LCAs are absent above a salinity of ∼40 g L⁻¹ suggesting a salinity control on LCA-producing organisms in these sites. Low concentrations of C₃₇ LCA components means and temperature indices are generally not applicable. Instead we find good relationships between C₃₈ components and (in particular mean autumn) temperature and the strongest LCA-temperature relationships are found when using a combination of all C₃₇ and C₃₈ compounds. We propose a new alkenone temperature index for lakes with elevated salinity and where the C₃₈ components dominate the LCA distributions. This is expressed as (r² = 0.80, n = 13). In this paper, we provide the first account of sedimentary LCA distributions from lakes in inland Spain, extending the range of environments within which these compounds have been found and highlighting their significance as indicators of both salinity and temperature in saline, endorheic lake environments. This has important implications for extending the potential role of LCAs as palaeoclimatic indicators in lacustrine environments.  相似文献   

Reconstituting nature conservation: Towards a careful political ecology   总被引：1，自引：0，他引：1  

Steve Hinchliffe 《Geoforum》2008,39(1):88-97

This paper is about the relationship between nature conservation in theory and nature conservation in practice. I argue that in theory nature conservation is concerned with revealing presence and rendering the present eternal. In practice, the spaces and times of conservation are less clear. Conservationists work with matters of concern that are neither self-evident nor unproblematically co-present. Presence has to be made and re-made. These matters of concern, like rare species, do not always announce themselves to political ecology and they do not always perform to type. Such difficulties are analysed through discussion of practical work conducted in a UK city with field ecologists and nonhuman inhabitants. It is argued that a careful political ecology is one that is intent on making spaces for others that are not simply about presence, inclusion or accumulation. It also involves uncertainties, precautionary measures and looser forms of assemblage.  相似文献   

Paleolimnological evidence of the consequences of recent increased dissolved organic carbon (DOC) in lakes of the northeastern USA     

Robert E. Brown  Sarah J. Nelson  Jasmine E. Saros 《Journal of Paleolimnology》2017,57(1):19-35

As a result of reductions in sulfate deposition and changing climate, dissolved organic carbon (DOC) concentrations have increased in many lakes situated in forests of northeastern North America and northern Europe since the 1990s. Although this increase is well documented, the associated ecological implications remain unclear. In particular, DOC strongly influences the vertical temperature structure of lakes, with increasing DOC often leading to a shallower epilimnion. We investigated the effect of increased DOC concentrations on lake thermal structure using fossil diatom records from six remote Maine lakes. Sedimentary diatom profiles from three pairs of small (<0.5 km²) lakes were compared, with each pair containing one lake with a documented significant increase in DOC and the other experiencing no change in DOC since the early 1990s. Lake thermal structure was inferred from changes in the relative abundance of Discostella stelligera and Aulacoseira species, two diatom taxa that are associated with changes in thermal stratification. The three lakes without increasing DOC showed no change in diatom-inferred mixing depth over the past few decades. Of the lakes with documented increases in DOC, two showed the highest turnover in diatom community structure over time. Profiles from both of these lakes also indicated directional change in diatom-inferred mixing depth over the past 20 years, but the direction of change differed. This study demonstrates that recent increases in DOC have the potential to alter the physical and biological structure of lakes, but that these responses may differ across lakes.  相似文献   

A Tribute to Rick and Debbie Jahnke: From Deep Sea Pore Water to Coastal Permeable Sediments-Contributions that Cover the Oceans     

Timothy J. Shaw  Steve Emerson  Herbert L. Windom 《Aquatic Geochemistry》2016,22(5-6):391-399

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Are human values and community participation key to climate adaptation? The case of community forest organisations in British Columbia     

Ella Furness  Harry Nelson 《Climatic change》2016,135(2):243-259

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The 10th Antarctic meteorological observation,modeling, and forecasting workshop     

Steve R. Colwell  Arthur M. Cayette  Matthew A. Lazzara  Jordan G. Powers  David H. Bromwich  John J. Cassano  Scott Carpentier 《大气科学进展》2016,33(5):656-658

正1.Overview The 10th Antarctic Meteorological Observation,Modeling,and Forecasting Workshop(hereinafter AMOMFW)took place June 17–19,2015 in the historic city of Cambridge,United Kingdom.The meeting followed its purpose of connecting Antarctic atmospheric science to weatherrelated operational issues and advances in observing,modeling,forecasting,and understanding the Antarctic environ-  相似文献   

Exploring national decarbonization pathways and global energy trade flows: a multi-scale analysis     

Steve Pye  Christophe McGlade  Chris Bataille  Gabrial Anandarajah  Amandine Denis-Ryan  Vladimir Potashnikov 《Climate Policy》2016,16(4):S92-S109

The role of fossils fuels in national economies will change radically over the next 40 years under a strong climate regime. However, capturing this changing role through national-based analyses is challenging due to the global nature of fossil fuel demand and resulting trade patterns. This article sets out the limitations of existing national-scale decarbonization analyses in adequately capturing global conditions and explores how the introduction of a global modelling framework could provide vital insights, particularly for those countries that are dependent on fossil fuel exports or imports.

The article shows that fossil fuel use will significantly decline by 2050, although gas will have an important transition role. This leaves large fossil fuel exporters exposed, the extent of which is determined by mitigation action in different regions and especially by the pathways adopted by the larger Asian economies. We find that global-scale models provide critical insights that complement the more detailed national analyses and should play a stronger role in informing deep decarbonization pathways (DDPs). They also provide an important basis for exploring key uncertainties around technology uptake, mitigation rates and how this plays out in the demand for fossil fuels. However, use of global models also calls for improved representation of country specifics in global models, which can oversimplify national economic and political realities. Using both model scales provides important insights that are complementary but that can challenge the other’s orthodoxy. However, neither can replace the other’s strengths.

Policy relevance:

In recent years, how global fossil fuel markets will evolve under different climate regimes has been subject to much debate and analysis. This debate includes whether investments in fossil fuel production still make sense or will be exposed in the future to liabilities associated with high carbon prices. This is important for governments who need to develop coherent policy in relation to fossil fuel sectors and their role as drivers of economic growth and in providing for domestic energy needs. This article argues that national analyses need to be fully cognizant of the global-scale transition, which can be informed by using a multi-scale modelling approach.  相似文献   

Hindcasting community-level building damage for the 2011 Joplin EF5 tornado     

Navid Attary  John W. van de Lindt  Hussam Mahmoud  Steve Smith  Christopher M. Navarro  Yong Wook Kim  Jong Sung Lee 《Natural Hazards》2018,93(3):1295-1316

Resiliency of communities prone to natural hazards can be enhanced through the use of risk-informed decision-making tools. These tools can provide community decision makers key information, thereby providing them the ability to consider an array of mitigation and/or recovery strategies. The Center for Risk-Based Community Resilience Planning, headquartered at Colorado State University in Fort Collins, Colorado, developed an Interdependent Networked Community Resilience (IN-CORE) computational environment. The purpose of developing this computational environment is to build a decision-support system, for professional risk planners and emergency responders, but even more focused on allowing researchers to explore community resilience science. The eventual goal was being to integrate a broad range of scientific, engineering and observational data to produce a detailed assessment of the potential impact of natural and man-made hazards for risk mitigation, planning and recovery purposes. The developing computational environment will be capable of simulating the effects from different natural hazards on the physical and socioeconomic sectors of a community, accounting for interdependencies between the sectors. However, in order to validate this computational tool, hindcasting of a real event was deemed necessary. Therefore, in this study, the community of Joplin, Missouri in the USA, which was hit by an EF-5 tornado on May 22, 2011, is modeled in the IN-CORE v1.0 computational environment. An explanation of the algorithm used within IN-CORE is also provided. This tornado was the costliest and deadliest single tornado in the USA in the last half century. Using IN-CORE, by uploading a detailed topological dataset of the community and the estimated tornado path combined with recently developed physics-based tornado fragilities, the damage caused by the tornado to all buildings in the city of Joplin was estimated. The results were compared with the damage reported from field studies following the event. This damage assessment was done using three hypothetical idealized tornado scenarios, and results show very good correlation with observed damage which will provide useful information to decision makers for community resilience planning.  相似文献   

Correction to: A Tribute to Rick and Debbie Jahnke: From Deep Sea Pore Water to Coastal Permeable Sediments-Contributions that Cover the Oceans     

Timothy J. Shaw  Steve Emerson  Herbert L. Windom 《Aquatic Geochemistry》2018,24(4):323-323

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Local Habitat Influences on Feeding and Respiration of the Intertidal Mussels <Emphasis Type="Italic">Perumytilus purpuratus</Emphasis> Exposed to Increased <Emphasis Type="Italic">p</Emphasis>CO<Subscript>2</Subscript> Levels     

Luisa M. Saavedra  Diego Parra  Valeska San Martin  Nelson A. Lagos  Cristian A. Vargas 《Estuaries and Coasts》2018,41(4):1118-1129

Coastal ecosystems are exposed to changes in physical-chemical properties, such as those occurring in upwelling and freshwater-influenced areas. In these areas, inorganic carbon can influence seawater properties that may affect organisms and populations inhabiting benthic habitats such as the intertidal mussel Perumytilus purpuratus. Feeding and metabolic responses were measured in adult mussels from two geographic regions (central and southern Chile) and two local habitats (river-influenced and non-river-influenced) and three pCO₂ levels (380, 750, and 1200 μatm pCO₂ in seawater). The feeding rates of mussels tend to increase at high pCO₂ levels in seawater; however this response was variable across regions and local habitats. In contrast, there was no difference in the respiratory rate of mussels between geographic areas, but there was a significant reduction of oxygen consumption at intermediate and high levels of pCO_2. The results indicate that river-influenced organisms compensate for reductions in metabolic cost at elevated pCO₂ levels by having their energy demands met, in contrast with non-river-influenced organisms. The lack of regional-scale variability in the physiological performance of mussels may indicate physiological homogeneity across populations and thus potential for local adaptation. However, the local-scale influences of river- and non-river-influenced habitats may counterbalance this regional response promoting intra-population variability and phenotypic plasticity in P. purpuratus. The plasticity may be an important mechanism that allows mussels to confront the challenges of projected ocean acidification scenarios.  相似文献