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1.
Integrating toxicology and ecology: putting the "eco" into ecotoxicology   总被引：1，自引：0，他引：1  
Environmental toxicology has been and continues to be an important discipline (e.g., single-species testing for screening purposes). However, ecological toxicology (ecotoxicology--more realism in tests, test species and exposures) is required for predicting real world effects and for site-specific assessments. Ecotoxicology and ecology have shown similar developmental patterns over time; closer cooperation between ecologists and toxicologists would benefit both disciplines. Ecology can be incorporated into toxicology either extrinsically (separately, e.g., providing information on pre-selected test species) or intrinsically (e.g., as part of test species selection)--the latter is preferable. General guidelines for acute and chronic testing and criteria for species selection differ for ecotoxicology and environmental toxicology, and are outlined. An overall framework is proposed based on ecological risk assessment (ERA), for combining ecology and toxicology (environmental and ecological) for decision-making. Increased emphasis on ecotoxicology represents a shift from reductionist to holistic approaches.  相似文献   

2.
Intertidal harpacticoid copepods are commonly used in eco-toxicity tests worldwide. They predominately live in mid-high shore rock pools and often experience a wide range of temperature and salinity fluctuation. Most eco-toxicity tests are conducted at fixed temperature and salinity and thus the influence of these environmental factors on chemical toxicity is largely unknown. This study investigated the combined effect of temperature and salinity on the acute toxicity of the copepod Tigriopus japonicus against two common biocides, copper (Cu) and tributyltin (TBT) using a 2 × 3 × 4 factorial design (i.e. two temperatures: 25 and 35 °C; three salinities: 15.0‰, 34.5‰ and 45.0‰; three levels of the biocide plus a control). Copper sulphate and tributyltin chloride were used as the test chemicals while distilled water and acetone were utilised as solvents for Cu and TBT respectively. 96h-LC50s of Cu and TBT were 1024 and 0.149 μg l−1 respectively (at 25 °C; 34.5‰) and, based on these results, nominal biocide concentrations of LC0 (i.e. control), LC30, LC50 and LC70 were employed. Analysis of Covariance using ‘concentration’ as the covariate and both ‘temperature’ and ‘salinity’ as fixed factors, showed a significant interaction between temperature and salinity effects for Cu, mortality increasing with temperature but decreasing with elevated salinity. A similar result was revealed for TBT. Both temperature and salinity are, therefore, important factors affecting the results of acute eco-toxicity tests using these marine copepods. We recommend that such eco-toxicity tests should be conducted at a range of environmentally realistic temperature/salinity regimes, as this will enhance the sensitivity of the test and improve the safety margin in line with the precautionary principle.  相似文献   

3.
Urban Svensson   《Journal of Hydrology》2001,250(1-4):187-205
A method to represent fracture networks in a continuum model is evaluated by an application to the Äspö Hard Rock Laboratory (HRL). The basic approach of the method is to first generate a fracture network, based on data from field measurements and then represent the network as grid cell conductivities, using a staggered grid arrangement. It is argued that the resulting conductivity fields capture the correlation and anisotropy structures, as well as the mean conductivity, of the rock in a realistic way. The main objective is to evaluate if the suggested method can be used in an application to a real site. The objective is formulated in three questions: ‘Can the method utilize available field data?’, ‘Can the generated fields be calibrated and conditioned?’ and ‘Are realistic distributions of pressure, flow and density obtained?’. From the application to the Äspö HRL, it is concluded that the hydraulic conductivity fields, generated by the suggested method, can utilize field data and be calibrated. It is also demonstrated that realistic distributions of pressure, flow and density can be simulated.  相似文献   

4.
Correlation of cyclic preloading with the liquefaction resistance   总被引：1，自引：0，他引：1  
The compactivity of sand due to cyclic loading with a high number (N>103) of small cycles (εampl≤10−3) cannot be described by void ratio and stress alone. It depends strongly on the soil fabric usually described as ‘cyclic preloading’. The cyclic preloading cannot be measured directly in situ but correlates well with the liquefaction resistance. This paper demonstrates this correlation on the basis of laboratory tests. Practical applications can be derived from this work.  相似文献   

5.
Pre-eruptive conditions and degassing processes of the AD 79 plinian eruption of Mt. Vesuvius are constrained by systematic F and Cl measurements in melt inclusions and matrix glass of pumice clasts from a complete sequence of the pumice-fallout deposits. The entire ‘white pumice’ (WP) magma and the upper part of the ‘grey pumice’ (GP) magma were saturated relative to sub-critical fluids (a Cl-rich H2O vapour phase and a brine), with a Cl melt content buffered at ~ 5300 ppm, and a mean H2O content of ~ 5%. The majority of the GP magma was not fluid-saturated. From these results it can be estimated that the WP magma chamber had a low vertical extent (< 500 m) and was located at a depth of ~ 7.5 km while the GP magma reservoir was located just beneath the WP one, but its vertical extent cannot be constrained. This is approximately two times deeper than previous estimates. H2O degassing during the WP eruption followed a typical closed-system evolution, whereas GP clasts followed a more complex degassing path. Contrary to H2O, Cl was not efficiently degassed during the plinian phase of the eruption.

This study shows that F and Cl behave as incompatible elements in fluid-undersaturated phonolitic melts. H2O saturation is necessary for a significant partitioning of Cl into the fluid phase. However, Cl cannot be extracted in significant quantity from phonolitic melts during rapid H2O degassing, e.g. during plinian eruptions, due to kinetics effects. Halogen contents are better preserved in volcanic glass (melt inclusions or matrix glass) than H2O, therefore the combined analysis of both volatile species is required for reliable determination of pre-eruptive conditions and syn-eruptive degassing processes in magmas stored at shallow depths.  相似文献   


6.
Intertidal harpacticoid copepods are commonly used in eco-toxicity tests worldwide. They predominately live in mid-high shore rock pools and often experience a wide range of temperature and salinity fluctuation. Most eco-toxicity tests are conducted at fixed temperature and salinity and thus the influence of these environmental factors on chemical toxicity is largely unknown. This study investigated the combined effect of temperature and salinity on the acute toxicity of the copepod Tigriopus japonicus against two common biocides, copper (Cu) and tributyltin (TBT) using a 2 × 3 × 4 factorial design (i.e. two temperatures: 25 and 35 °C; three salinities: 15.0‰, 34.5‰ and 45.0‰; three levels of the biocide plus a control). Copper sulphate and tributyltin chloride were used as the test chemicals while distilled water and acetone were utilised as solvents for Cu and TBT respectively. 96h-LC50s of Cu and TBT were 1024 and 0.149 μg l−1 respectively (at 25 °C; 34.5‰) and, based on these results, nominal biocide concentrations of LC0 (i.e. control), LC30, LC50 and LC70 were employed. Analysis of Covariance using ‘concentration’ as the covariate and both ‘temperature’ and ‘salinity’ as fixed factors, showed a significant interaction between temperature and salinity effects for Cu, mortality increasing with temperature but decreasing with elevated salinity. A similar result was revealed for TBT. Both temperature and salinity are, therefore, important factors affecting the results of acute eco-toxicity tests using these marine copepods. We recommend that such eco-toxicity tests should be conducted at a range of environmentally realistic temperature/salinity regimes, as this will enhance the sensitivity of the test and improve the safety margin in line with the precautionary principle.  相似文献   

7.
Based on benthic macroinvertebrate samples from 57 sites of streams in the European Central Highlands (Ecoregion 9; Illies (1978). Limnofauna Europaea, Stuttgart), the composition and the abundance of Simuliid species were analysed in relation to hydromorphological and land use parameters. Sampling sites were located at two stream types differing in catchment geology, stream morphology and channel width. Land use data were taken from the official German information system for cartography and topography (ATKIS) and the German River Habitat Survey. Land use categories suitable to describe the sampling sites were ‘agricultural land’, ‘urban’ and near-natural areas. Hydromorphological parameters of the sites were recorded using the AQEM site protocol (AQEM Consortium (2002). Manual for the application of the AQEM system. A comprehensive method to assess European streams using benthic macroinvertebrates, developed for the purpose of the Water Framework Directive. EVK1-CT1999-00027, Version 1.0. Available via the Internet from www.aqem.de). Relevant parameters controlling Simuliid distribution in streams were the mineral substrates and the biotic microhabitats. Blackfly larvae and pupae were sampled at each site for 15 min. Statistical analysis was performed by CANOCO® (Ter Braak & Smilauer (1997). CANOCO Version 4.5. Biometrics Plant Research International, Wageningen, The Netherlands) using redundancy analysis (RDA).

Our results show a stream type-specific composition of the Blackfly fauna. The analyses reveal sensitivity of the Simuliid species to morphological degradation, which is indicated by the shift in the longitudinal zonation of the Simuliid communities. Especially, Prosimulium hirtipes (Fries, 1824) and Simulium argyreatum Meigen, 1838 are typical representatives of headwater streams. While they seem to indicate undisturbed conditions of this stream type and react sensitively to the degradation of stream habitats, Simulium ornatum Meigen, 1818 and Simulium equinum (Linnaeus, 1758) are more tolerant to stream degradation.

On catchment scale, ‘% natural forest’ and ‘% agricultural land use’ illustrate the degree of degradation of the two selected stream types. ‘Average stream depth’ and ‘relation riffles/pools’ account for hydromorphological degradation reflected by Simuliid species on the smaller reach scale. The analysis of habitat quality revealed that ‘% woody debris’ represents an important parameter of morphological degradation reflected by the Blackfly community.  相似文献   


8.
This paper provides a comprehensive overview of the merits and limitations of using an economics based approach to assess and implement initiatives for coastal habitat rehabilitation and creation. A review of the literature indicates that habitat rehabilitation/creation costs vary widely between and within ecosystems. For coral reefs, costs range from US$ 10,000 to 6.5 million/hectare (ha);1 for mangroves US$ 3000–510,000/ha; for seagrasses US$ 9000–680,000/ha and for saltmarshes US$ 2000–160,000/ha. A review of the economic benefits derived from various coastal habitats based on a ‘Total Economic Value’ approach (i.e. accounting for direct and indirect uses, and ‘non-uses’) reveals that many thousands of US$ per hectare could ultimately accrue from their rehabilitation/creation. The paper concludes that despite its limitations, the ‘benefit-cost analysis’ framework can play an important role both in assessing the justification of coastal habitat rehabilitation/creation initiatives, and by helping to improve the overall effectiveness of such initiatives.  相似文献   

9.
Soil moisture (SM) plays an important role in land surface and atmospheric interactions. It modifies energy balance at the surface and the rate of water cycling between the land and atmosphere. In this paper we provide a sensitivity assessment of SM and ET for heterogeneous soil physical properties and for three land uses including irrigated maize, rainfed maize, and grass at a climatological time-scale by using a water balance model. Not surprisingly, the study finds increased soil water content in the root zone throughout the year under irrigated farming. Soil water depletes to its lowest level under rainfed maize cultivation. We find a ‘land use’ effect as high as 36 percent of annual total evapotranspiration, under irrigated maize compared to rainfed maize and grass, respectively. Sensitivity analyses consisting of comparative simulations using the model show that soil characteristics, like water holding capacity, influence SM in the root zone and affect seasonal total ET estimates at the climatological time-scale. This ‘soils’ effect is smaller than the ‘land use’ effect associated with irrigation but, it is a source of consistent bias for both SM and ET estimates. The ‘climate’ effect basically masks the ‘soils’ effect under wet conditions. These results lead us to conclude that appropriate representation of land use, soils, and climate are necessary to accurately represent the water and energy balance in real landscapes.  相似文献   

10.
New noble gas data of ultramafic xenoliths from Réunion Island, Indian Ocean, further constrain the characteristics of primordial and radiogenic noble gases in Earth’s mantle plume reservoirs. The mantle source excess of nucleogenic 21Ne is significantly higher than for the Hawaiian and Icelandic plume reservoirs, similar to excess of radiogenic 4He. 40Ar/36Ar of the Réunion mantle source can be constrained to range between 8000 and 12 000, significant 129Xe and fission Xe excess are present. Regarding the relative contribution of primordial and radiogenic rare gas nuclides, the Réunion mantle source is intermediate between Loihi- and MORB-type reservoirs. This confirms the compositional diversity of plume sources recognized in other radioisotope systematics. Another major result of this study is the identification of the same basic primordial component previously found for the Hawaiian and Icelandic mantle plumes and the MORB reservoir. It is a hybrid of solar-type He and Ne, and ‘atmosphere-like’ or ‘planetary’ Ar, Kr, Xe (Science 288 (2000) 1036). 20Ne/22Ne ratios extend to maximum values close to 12.5 (Ne-B), which is the typical signature of solar neon implanted as solar corpuscular radiation. This suggests that Earth’s solar-type noble gas inventory was acquired by small (less than km-sized) precursor planetesimals that were irradiated by an active early sun in the accretion disk after nebular gas dissipation, or, alternatively, that planetesimals incorporated constituents irradiated in transparent regions of the solar nebula. Previously, such an early irradiation scenario was suggested for carbonaceous chondrites which follow common volatile depletion trends in the sequence CI–CM–CV–Earth. In turn, CV chondrites closely match Earth’s mantle composition in 20Ne/22Ne, 36Ar/22Ne and 36Ar/38Ar. This indicates that mantle Ar could well be a planetary component inherited from precursor planetesimals. However, a corresponding conclusion for mantle Kr and Xe is less convincing yet, but this may be just due to the lack of appropriate ‘meteoritic’ building blocks matching terrestrial composition. Alternatively, heavy noble gases in Earth’s mantle could be due to admixing of severely fractionated air, but this effect must have affected all mantle sources to a very similar extent, e.g. by global subduction before the last homogenization of the mantle reservoirs.  相似文献   

11.
The changing concepts and challenges that the process industry has to face in relation to environmental protection are discussed. The original requirements on industry to reduce emissions of contaminants through the installation of filters and waste water treatment facilities or through process modification and introduction of ‘clean production’ strategies were mainly based on economic and technical considerations rather than on an effort to avoid environmental impacts. The introduction of concepts such as ‘assimilative capacity of the environment’ and ‘critical load’ provided useful instruments for setting effect-related emission standards, resulting in acceptable environmental protection. However, the actual requirement for ‘sustainability’ has forced industry to focus not only on controlling emissions of contaminants and pollutants, but to take a global environmental approach, including the choice of raw materials and energy sources, recycling and re-utilization of wastes and to take responsibility for the fate of their products, during their whole lifecycle.  相似文献   

12.
The priorities for the protection of the seas have been discussed extensively. Many consider that the problem of marine pollution can only be solved on the basis of joint international actions. This is particularly true for the various countries bordering on the North Sea. To implement such ‘Joint Actions’, a new understanding of safety, namely ‘global maritime safety’ should be discussed with all those involved.  相似文献   

13.
Environmental impacts occur at all stages of oil and gas production. They are the result of prospecting activities, of the physical impact due to the installation of rigs, of the operational discharges when production starts and of accidental spills. The input of oil to the North Sea due to the offshore industry has been estimated at 29% of the total input of oil. The operational discharges consist of production water and drilling cuttings. An overview of statistics collected over the last 10 years shows that although the amount of oil discharged via production water is increasing as platforms are getting older, cuttings still account for 75% of the oil entering the sea as a result of normal operations. Spills represent a relatively small source of oil. The effects on the marine environment of discharges of production water and of discarded oily cuttings have been extensively studied, by national authorities as well as by the industry. Although it has not always been possible to reach consensus about the significance of the observed effects, a number of ‘agreed facts’ have led to establishment of regulations in the framework of the Paris Commission. The ‘decisions’ and ‘recommendations’ adopted by the Commission are regularly reviewed in the light of new developments.  相似文献   

14.
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15.
Liquid metal-liquid silicate partitioning of Fe, Ni, Co, P, Ge, W and Mo among a carbon-saturated metal and a variety of silicate melts (magnesian-tholeiitic-siliceous-aluminous-aluminosiliceous basalts) depends modestly to strongly upon silicate melt structure and composition. Low valency siderophile elements, Fe, Ni and Co, show a modest influence of silicate melt composition on partitioning. Germanium shows a moderate but consistent preference for the depolymerized magnesian melt. High valency siderophile elements, P, Mo, and W, show more than an order of magnitude decrease in metal-silicate partition coefficients as the silicate melt becomes more depolymerized. Detailed inspection of our and other published W data shows that polymerization state, temperature and pressure are more important controls on W partitioning than oxidation state. For this to be true for a high and variable valence element implies a secondary role in general for oxidation state, even though some role must be present. Equilibrium core segregation through a magma ocean of ‘ultrabasic’ composition can provide a resolution to the ‘excess’ abundances of Ge, P, W and Mo in the mantle, but the mantle composition alone cannot explain the excess abundances of nickel and cobalt in chondritic proportions.  相似文献   

16.
During the first cruise of R/V ‘Philia’ in July 1997 within the framework of the TALOS programme supported by the Greek Ministry of Physical Planning and Public Works, the sampling of floating tar, litter and sea water for dissolved/dispersed petroleum hydrocarbons (DDPH) was carried out in the Cretan Sea. Analysis of these data has allowed a first assessment of the status of floating marine pollution in the region. DDPH measurements showed a mean concentration of 0.145 μg/l of chrysene equivalents (n = 24). Tar and plastics concentrations were in the range of 1–4280 and 0–1160 μg/m2, respectively. Mean pelagic tar concentration was 318 μg/m2, more than two times higher than what was reported for the area in previous studies. Based on in situ hydrographic observations there is strong evidence that most of the floating tar enters the Cretan Sea through the Ionian Sea.  相似文献   

17.
Many simplifications are used in modeling surface runoff over a uniform slope. A very common simplification is to determine the infiltration rate independent of the overland flow depth and to combine it afterward with the kinematic-wave equation to determine the overland flow depth. Another simplication is to replace the spatially variable infiltration rates along the slope i(x, t) due to the water depth variations h(x,t) with an infiltration rate that is determined at a certain location along the slope. The aim of this study is to evaluate the errors induced by these simplications on predicted infiltration rates, overland flow depths, and total runoff volume. The error analysis is accomplished by comparing a simplified model with a model where the interaction between the overland flow depth and infiltration rate is counted. In this model, the infiltration rate is assumed to vary along the slope with the overland flow depth, even for homogeneous soil profiles. The kinematic-wave equation with interactive infiltration rate, calculated along the slopy by Richard's equation, are then solved by a finite difference scheme for a 100-m-long uniform slope. In the first error analysis, we study the effect of combining an ‘exact’ and ‘approximate’ one-dimensional infiltration rate with the kinematic-wave equation for three different soil surface roughness coefficients. The terms ‘exact’ and ‘approximate’ stand for the solution of Richard's equation with and without using the overland flow depth in the boundary condition, respectively. The simulations showed that higher infiltration rates and lower overland flow depths are obtained during the rising stage of the hydrograph when overland flow depth is used in the upper boundary condition of the one-dimensional Richard's equation. During the recession period, the simplified model predicts lower infiltration rates and higher overland flow depths. The absolute relative errors between the ‘exact’ and ‘approximate’ solutions are positively correlated to the overland flow depths which increase with the soil surface roughness coefficient. For this error analysis, the relative errors in surface runoff volume per unit slope width throughout the storm are much smaller than the relative errors in momentary overland flow depths and discharges due to the alternate signs of the deviations along the rising and falling stages. In the second error analysis, when the spatially variable infiltration rate along the slope i(x, t) is replaced in the kinematic-wave equation by i(t), calculated at the slope outlet, the overland flow depth is underestimated during the rising stage of the hydrograph and overestimated during the falling stage. The deviations during the rising stage are much smaller than the deviations during the falling stage, but they are of a longer duration. This occurs because the solution with i(x, t) recognizes that part of the slope becomes dry after rainfall stops, while overland flow still exists with i(t) determined at the slope outlet. As obtained for the first error analysis, the relative errors in surface runoff volume per unit slope width are also much smaller than the relative errors in momentary overland flow depths and discharges. The relation between the errors in overland flow depth and discharge to different mathematical simplifications enables to evaluate whether certain simplifications are justified or more computational efforts should be used.  相似文献   

18.
This paper presents a calibration model for CE-QUAL-W2. CE-QUAL-W2 is a two-dimensional (2D) longitudinal/vertical hydrodynamic and water quality model for surface water bodies, modeling eutrophication processes such as temperature–nutrient–algae–dissolved oxygen–organic matter and sediment relationships. The proposed methodology is a combination of a ‘hurdle-race’ and a hybrid Genetic-k-Nearest Neighbor algorithm (GA-kNN). The ‘hurdle race’ is formulated for accepting–rejecting a proposed set of parameters during a CE-QUAL-W2 simulation; the k-Nearest Neighbor algorithm (kNN)—for approximating the objective function response surface; and the Genetic Algorithm (GA)—for linking both. The proposed methodology overcomes the high, non-applicable, computational efforts required if a conventional calibration search technique was used, while retaining the quality of the final calibration results. Base runs and sensitivity analysis are demonstrated on two example applications: a synthetic hypothetical example calibrated for temperature, serving for tuning the GA-kNN parameters; and the Lower Columbia Slough case study in Oregon US calibrated for temperature and dissolved oxygen. The GA-kNN algorithm was found to be robust and reliable, producing similar results to those of a pure GA, while reducing running times and computational efforts significantly, and adding additional insights and flexibilities to the calibration process.  相似文献   

19.
L.J. Bren   《Journal of Hydrology》1993,150(2-4):277-299
In the last two decades, the effects of forest management on streams, riparian zones, and floodplains have become of much interest. In general, there is agreement that such areas should be maintained in a state approximating naturalness, although it is recognised that definition of this state is usually difficult or impossible. A diversity of management effects has been recognised and, in some cases quantified. For upland catchments, issues particularly relate to direct disturbance of the zone, changes in the flow of woody debris into the stream, or disturbance to the environment by effects generated upstream or downstream. For many areas, a particularly important commercial aspect is the definition of a ‘stream’, as this can impose many expensive and severe restrictions on management of the land. For large rivers, a common issue is the effect of river management on flooding forests. In each case, the issues are complex, information is difficult to collect, and there are fundamental difficulties in going from anecdotal observation to data. Currently, most information appears to be at a relatively local level, and there is a very inadequate knowledge base to give a more holistic overview, although the concept of ‘cumulative effects’, with the effects accumulated over both space and time, has much potential value. There are many opportunities for work in this field.  相似文献   

20.
Most lead brought to the Mediterranean Sea has an anthropogenic origin and is mainly transported through the atmosphere. Atmospheric Pb was continuously collected at Cap Ferrat in 1986 and 1987. From this study, the estimation of the anthropogenic Pb flux on the whole Western Mediterranean was, averaged on 1986 and 1987 data, 4080 t. Assuming that the atmospheric anthropogenic Pb input varied in this course of time similarly to the consumption of Pb added to gasolines in France, the mean annual flux could be calculated: 3.95 kg km−2 yr−1, that is an annual input of 3360 t yr−1. Reaching the sea, this metal seems to become rapidly bound to phytoplankton. Grazing by zooplankton leads to the production of faecal pellets which frequently contain rather high metal concentrations. The sinking rate of pellets of various zooplankton species is high; within a few days pellets may reach deep-sea sediments. After deposition, Pb is released from this organic-rich material during early diagenesis. In most cases, it, therefore, returns to the overlaying water body by ascending diffusion. But, in a deep-sea area of approximately 80 000 km2 where Mn oxide precipitation occurs in surficial sediments, Pb seems to remain stored by coprecipitation processes. By considering the lead stored in ‘excess’ in the surficial sediment of the deep-sea area, we estimate that a mean annual anthropogenic Pb amount ranging from 800 up to 1080 t was stored every year from 1950. On the same area, taking into account the Pb loss at the straits, the ‘direct’ atmospheric input to the sea bottom is, on average, 184 t yr−1. The remaining part, that is (800–1080)−184=(616–896) t yr−1, corresponds to an additional ‘indirect’ Pb flux in water due to Pb released from sediments of the surrounding areas where it does not remain stored.  相似文献   

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