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31.
Olivier Maury Yunne-Jai Shin Blaise Faugeras Tamara Ben Ari Francis Marsac 《Progress in Oceanography》2007,74(4):500-514
Numerical simulations using a physiologically-based model of marine ecosystem size spectrum are conducted to study the influence of primary production and temperature on energy flux through marine ecosystems. In stable environmental conditions, the model converges toward a stationary linear log–log size-spectrum. In very productive ecosystems, the model predicts that small size classes are depleted by predation, leading to a curved size-spectrum.It is shown that the absolute level of primary production does not affect the slope of the stationary size-spectrum but has a nonlinear effect on its intercept and hence on the total biomass of consumer organisms (the carrying capacity). Three domains are distinguished: at low primary production, total biomass is independent from production changes because loss processes dominate dissipative processes (biological work); at high production, ecosystem biomass is proportional to primary production because dissipation dominates losses; an intermediate transition domain characterizes mid-production ecosystems. Our results enlighten the paradox of the very high ecosystem biomass/primary production ratios which are observed in poor oceanic regions. Thus, maximal dissipation (least action and low ecosystem biomass/primary production ratios) is reached at high primary production levels when the ecosystem is efficient in transferring energy from small sizes to large sizes. Conversely, least dissipation (most action and high ecosystem biomass/primary production ratios) characterizes the simulated ecosystem at low primary production levels when it is not efficient in dissipating energy.Increasing temperature causes enhanced predation mortality and decreases the intercept of the stationary size spectrum, i.e., the total ecosystem biomass. Total biomass varies as the inverse of the Arrhenius coefficient in the loss domain. This approximation is no longer true in the dissipation domain where nonlinear dissipation processes dominate over linear loss processes. Our results suggest that in a global warming context, at constant primary production, a 2–4 °C warming would lead to a 20–43% decrease of ecosystem biomass in oligotrophic regions and to a 15–32% decrease of biomass in eutrophic regions.Oscillations of primary production or temperature induce waves which propagate along the size-spectrum and which amplify until a “resonant range” which depends on the period of the environmental oscillations. Small organisms oscillate in phase with producers and are bottom-up controlled by primary production oscillations. In the “resonant range”, prey and predators oscillate out of phase with alternating periods of top-down and bottom-up controls. Large organisms are not influenced by bottom-up effects of high frequency phytoplankton variability or by oscillations of temperature. 相似文献
32.
A field study was carried out to investigate whether polyaromatic hydrocarbon (PAH) contamination in shore crabs (Carcinus maenas) could be measured using fluorescence spectrometry. Crabs were collected as part of an integrated study to assess PAH contamination in Southampton Water, UK. Urine was collected from crabs via a non-destructive technique and analysed using fixed wavelength fluorescence (FF) and synchronous fluorescence spectrophotometry (SFS) in order to determine the presence of PAH metabolites, indicative of PAH exposure. By scanning at wavelength pairs specific to a variety of PAH groups the fluorescence of metabolites was analysed and attributed to the following PAH groups; naphthalenes, pyrenes and benzo[a]pyrene (BAP). Naphthalene-type, pyrene-type and BAP-type metabolites were detected using FF and SFS techniques and two distinct parameters were measured; Peak Intensity and Peak Area. Results showed that crabs obtained near a petroleum refinery, a point source of PAH discharge, exhibited significantly higher PAH metabolites for all PAH groups, than at sites sampled along the estuary (ANOVA, p<0.05). This study highlights the effectiveness of using FF and SFS as a rapid and cost-effective biomonitoring tool for detecting PAH contamination. 相似文献
33.
Galloway TS Brown RJ Browne MA Dissanayake A Lowe D Jones MB Depledge MH 《Marine environmental research》2004,58(2-5):233-237
The ECOMAN project was initiated from an awareness of the complexity of the functioning of coastal marine systems and the clear need for more pragmatic environmental assessment techniques linking environmental degradation with its causes. The aim of the project is to develop a suite of easy to use, cost effective and environmentally valid biological responses (biomarkers) to assess the general health of coastal systems, including estuaries. To achieve this aim, various sublethal endpoints are being measured and evaluated from a range of common coastal organisms showing different feeding types (filter feeding, grazing and predation) and habitat requirements (estuary and rocky shore) and at different levels of biological response (cellular, physiological and behavioural). This holistic integrated approach is essential to identify the full impact of chemical contamination on organisms, and enables the sensitivity of organisms to be ranked and key sentinel species for specific habitats to be identified. 相似文献
34.
Tamara S. Galloway Rebecca J. Brown Mark A. Browne Awantha Dissanayake David Lowe Malcolm B. Jones Michael H. Depledge 《Marine environmental research》2004,58(2-5):233
The ECOMAN project was initiated from an awareness of the complexity of the functioning of coastal marine systems and the clear need for more pragmatic environmental assessment techniques linking environmental degradation with its causes. The aim of the project is to develop a suite of easy to use, cost effective and environmentally valid biological responses (biomarkers) to assess the general health of coastal systems, including estuaries. To achieve this aim, various sublethal endpoints are being measured and evaluated from a range of common coastal organisms showing different feeding types (filter feeding, grazing and predation) and habitat requirements (estuary and rocky shore) and at different levels of biological response (cellular, physiological and behavioural). This holistic integrated approach is essential to identify the full impact of chemical contamination on organisms, and enables the sensitivity of organisms to be ranked and key sentinel species for specific habitats to be identified. 相似文献
35.
Alexey A. Krylov Oleg M. Khlystov Akihiro Hachikubo Hirotsugu Minami Yutaka Nunokawa Hitoshi Shoji Tamara I. Zemskaya Lieven Naudts Tatyana V. Pogodaeva Masato Kida Gennady V. Kalmychkov Jeffrey Poort 《Geo-Marine Letters》2010,30(3-4):427-437
We report on the isotopic composition of dissolved inorganic carbon (DIC) in pore-water samples recovered by gravity coring from near-bottom sediments at gas hydrate-bearing mud volcanoes/gas flares (Malenky, Peschanka, Peschanka 2, Goloustnoe, and Irkutsk) in the Southern Basin of Lake Baikal. The δ13C values of DIC become heavier with increasing subbottom depth, and vary between ?9.5 and +21.4‰ PDB. Enrichment of DIC in 13C indicates active methane generation in anaerobic environments near the lake bottom. These data confirm our previous assumption that crystallization of carbonates (siderites) in subsurface sediments is a result of methane generation. Types of methanogenesis (microbial methyl-type fermentation versus CO2-reduction) were revealed by determining the offset of δ13C between dissolved CH4 and CO2, and also by using δ13C and δD values of dissolved methane present in the pore waters. Results show that both mechanisms are most likely responsible for methane generation at the investigated locations. 相似文献
36.
Namık Aysal Marcel Guillong Tamara Bayanova Mayuko Fukuyama Nicole Leonard İsak Yılmaz Elif Varol Fatma Şişman Tükel Yusuf Kaan Kadıoğlu Nurullah Hanilçi Fulya Uzun Ersin Kaygısız 《Geostandards and Geoanalytical Research》2023,47(2):297-310
Gem quality andradite-rich garnet (IUC-1), obtained from the Miocene trachyte dome near Ankara city (Turkey), has been identified as a potential natural secondary reference material for U-Pb dating. In this study, U-Pb dating was performed in five different laboratories using isotope dilution TIMS and laser ablation ICP-MS to determine the homogeneity of euhedral garnet crystals. The U-Pb ID-TIMS data for IUC-1 yielded 207Pb/235U and 206Pb/238U ages of 20.9 ± 0.4 and 20.6 ± 0.8 Ma respectively, and these values are consistent with U-Pb LA-ICP-MS analyses, in which different garnet crystals yielded ages of 20.8 ± 0.1, 20.7 ± 0.1, 20.7 ± 0.2 and 20.2 ± 0.1 Ma. An andradite (IUC-2) from the Serçeören wollastonite skarn (Turkey) can be used as a secondary reference material provided detailed imaging of the crystals is undertaken. ID-TIMS data yielded 207Pb/235U and 206Pb/238U ages of 20.4 ± 0.4 and 20.9 ± 1.0 Ma respectively, and yielded U-Pb ages on different grains of 20.5 ± 0.1, 20.7 ± 1.0, 20.8 ± 1.7 and 20.9 ± 1.6 Ma. The assigned weighted mean age of IUC-1 (20.4 ± 0.5 Ma, 2s) is proposed as a 2023 reference value. IUC-1 garnet is expected to contribute significantly to rapidly developing garnet geochronology in the near future. 相似文献
37.
The allocation of CO2 emissions to specific sources is a major policy issue for international aviation, especially for determining allocations for emissions trading schemes. This paper addresses the problem by recommending a possible methodology to allocate emissions to specific sources using detailed air traffic data. The basis for the calculations is an air traffic sample for one full-day of traffic from the UK. In order to analyse aircraft fuel burn use and hence CO2 emissions, the Reorganized Air Traffic Control Mathematical Simulator (RAMS Plus) and the Advanced Emission Model (AEM III) are used. The results from these detailed simulations are compared with two of the most widely-used aviation CO2 emission estimates to have been made for the UK: the SERAS study and NETCEN estimate. Their estimates for the year 2000 are 26.1 and 31.4 Mt, respectively. In addition, the most recent NETCEN estimate for the year 2003 is 34.1 Mt of CO2. Our estimate of total aviation CO2 emissions, using detailed simulations and real air traffic data, is 34.7 Mt for the year 2004. In addition, emission estimates are compared with two global aviation emission inventories: AERO2K and SAGE. Contributions of the highest-emitting flights and aircraft types are identified. International departures dominate; 6% of flights account for 50% of total emissions. The largest aircraft emit the most per flight-km, although not per passenger-km. Different methodologies and their implications are also discussed. 相似文献
38.
Hydrochemical properties of transition zone between fresh groundwater and seawater in karst environment of the Adriatic islands,Croatia 总被引:3,自引:3,他引:0
Eastern coast of the Adriatic Sea consists of karstified carbonates. It belongs to the well-known Dinaric karst region. The
coast is extremely indented and there are 718 islands with numerous rock crags and reefs. Some of the inhabited islands use
their own water resources for public water supply, or plan to do it in the future. Since karst rocks are extremely permeable,
the seawater intrudes into underground water resources, thereby forming the wedge. A wide transition zone occurs between this
seawater wedge and fresh water aquifers. Consequently, island groundwater reserves turn brackish to a certain extent. In this
study, 77 water samples were collected from a wide variety of water resources. Comprehensive statistical and mathematical
multivariate analysis of these data was performed. Simple statistical approach showed several useful correlations among some
parameters, and more complex multivariate techniques extracted three factors in connection with three natural processes: (1)
mixing with the seawater, (2) carbonate dissolution and (3) human influence (pollution) and nitrogen transformation processes.
The results of this study demonstrate that in situ measurement of electrical conductivity is adequate for the very rough field
estimation of numerous parameters. 相似文献
39.
Victorian farmers have experienced significant impact from climate change associated with drought and more recently flooding. These factors form a convergence with a complex of other factors to change production systems physically; and farmers’ decision making is variously described as adaptive or maladaptive to these drivers of change. Recently updated State Government policies on farming, climate and water have immediate and long term implications for food production systems but are not readily interpreted at a local scale. Further, peak oil and energy security are only partially integrated into either climate or water policy discourse. In effect, despite some far-sighted words about the meaning of climate change, uncertainty is largely met with a ‘business as usual’ mantra. Farmer narratives are used to demonstrate their systemic and increasing vulnerability and likelihood of perverse outcomes. The Future Farming strategy and Our Water Our Future are briefly analyzed, as are potential implications of the rhetoric of newly elected conservative government. Using ideas from Bourdieu and Bhabha we suggest that the reliance on farmers being able to innovate and take up opportunities associated with the uncertainty of large scale changes in climate and energy availability are misguided. It is more likely that current policy directions entrench the values of the global market and its elite, leaving farmers locked-in to historical structural responses that will not be successful in the long-term and will diminish their ability to imagine radical and diverse ways of avoiding the maladaptive structures currently surrounding their production systems. 相似文献
40.
Bonacci S Browne MA Dissanayake A Hagger JA Corsi I Focardi S Galloway TS 《Marine pollution bulletin》2004,49(5-6):445-455
Marine environments are continuously being threatened by a large number of xenobiotics from anthropogenic sources. Even in sparsely populated and relatively pristine areas, such as Antarctica, hazardous chemicals can pose a serious environmental problem. The main aims of the present study were to (1) validate and optimize an analytical technique utilizing a microtitre-plate photometer to ascertain background levels of esterase activities in the Antarctic bivalve Adamussium colbecki, (2) carry out in situ monitoring of esterase activities to assess any potential environmental impacts of the Italian Scientific Antarctic Base "Terra Nova Bay" on the surrounding marine area. Results showed the presence of organophosphorous-sensitive cholinesterase (ChE) and carboxylesterase (CbE) activities in the gills of A. colbecki and optimal assay conditions were comparable with those found for bivalve species from temperate areas. A higher sensitivity of ChE versus acetylthiocholine activity in A. colbecki to chlorpyrifos compared to species from temperate areas may also be inferred. The in situ study indicated no differences in the environmental quality of the three study sites located around the Italian Base. 相似文献