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71.
Euro Chlor Risk Assessment for the Marine Environment Osparcom Region: North Sea - Chloroform 总被引:1,自引:0,他引:1
Sabine Zok Jean-Charles Boutonnet Christ De Rooij Veronique Garny Andre Lecloux Roger Papp Roy S Thompson Dolf van Wijk 《Environmental monitoring and assessment》1998,53(3):401-424
This risk assessment on chloroform was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the "predicted environmental concentrations" (PEC) and the "predicted no effect concentrations" (PNEC) for the marine aquatic environment. In total, 23 studies for fish, 17 studies for invertebrates and 10 studies for algae have been evaluated. Both acute and chronic toxicity studies have been taken into account and the appropriate assessment factors have been used to define a typical PNEC value of 72 µg/l. Due to limitations of the studies evaluated, a worst PNEC of 1 µg/l could also be used. Most of the available monitoring data apply to rivers and estuaries and were used to calculate PECs. The most recent data (1991-1995) support a typical PEC of 0.2 µg chloroform per litre of water and a worst case PEC of 5 to 11.5 µg chloroform per litre of water. The calculated PEC/PNEC ratios give a safety margin of 6 to 360 between the predicted no effect concentration and the exposure concentrations. A worst case ratio, however, points to a potential risk for sensitive species. Refinement of the assessment is necessary by looking for more data. Additional evaluation of environmental fate and bioaccumulation characteristics showed that no concern is expected for food chain accumulation. 相似文献
72.
Christ De Rooij Jean Charles Boutonnet Veronique Garny Andre Lecloux Roger Papp Roy S Thompson Dolf Van Wijk 《Environmental monitoring and assessment》1998,53(3):489-508
This risk assessment on tetrachloroethylene (PER) was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the "predicted environmental concentrations" (PEC) and the "predicted no effect concentrations" (PNEC) for the marine aquatic environment. In total, 18 studies for fish, 13 studies for invertebrates and 8 studies for algae have been evaluated. Both acute and chronic toxicity studies have been taken into account and the appropriate assessment factors have been used to define a PNEC value of 51 µg/l. Most of the available monitoring data apply to rivers and estuary waters and were used to calculate PECs. The most recent data (1991-1995) support a typical PEC of 0.2 µg PER/l water and a worst case PEC of 2.5 µg PER/l water. The calculated PEC/PNEC ratios give a safety margin of 20 to 250 between the predicted no effect concentration and the exposure concentration. Additional evaluation of environmental fate and bioaccumulation characteristics showed that no concern is expected for food chain accumulation. 相似文献
73.
Joris Koornneef Tim van Keulen Andr Faaij Wim Turkenburg 《International Journal of Greenhouse Gas Control》2008,2(4):448
In this study the methodology of life cycle assessment has been used to assess the environmental impacts of three pulverized coal fired electricity supply chains with and without carbon capture and storage (CCS) on a cradle to grave basis. The chain with CCS comprises post-combustion CO2 capture with monoethanolamine, compression, transport by pipeline and storage in a geological reservoir. The two reference chains represent sub-critical and state-of-the-art ultra supercritical pulverized coal fired electricity generation. For the three chains we have constructed a detailed greenhouse gas (GHG) balance, and disclosed environmental trade-offs and co-benefits due to CO2 capture, transport and storage. Results show that, due to CCS, the GHG emissions per kWh are reduced substantially to 243 g/kWh. This is a reduction of 78 and 71% compared to the sub-critical and state-of-the-art power plant, respectively. The removal of CO2 is partially offset by increased GHG emissions in up- and downstream processes, to a small extent (0.7 g/kWh) caused by the CCS infrastructure. An environmental co-benefit is expected following from the deeper reduction of hydrogen fluoride and hydrogen chloride emissions. Most notable environmental trade-offs are the increase in human toxicity, ozone layer depletion and fresh water ecotoxicity potential for which the CCS chain is outperformed by both other chains. The state-of-the-art power plant without CCS also shows a better score for the eutrophication, acidification and photochemical oxidation potential despite the deeper reduction of SOx and NOx in the CCS power plant. These reductions are offset by increased emissions in the life cycle due to the energy penalty and a factor five increase in NH3 emissions. 相似文献
74.
Insect societies are important models for evolutionary biology and sociobiology. The complexity of some eusocial insect societies
appears to arise from self-organized task allocation and group cohesion. One of the best-supported models explaining self-organized
task allocation in social insects is the response threshold model, which predicts specialization due to inter-individual variability
in sensitivity to task-associated stimuli. The model explains foraging task specialization among honeybee workers, but the
factors underlying the differences in individual sensitivity remain elusive. Here, we propose that in honeybees, sensory sensitivity
correlates with individual differences in the number of sensory structures, as it does in solitary species. Examining European
and Africanized honeybees, we introduce and test the hypothesis that body size and/or sensory allometry is associated with
foraging task preferences and resource exploitation. We focus on common morphological measures and on the size and number
of structures associated with olfactory sensitivity. We show that the number of olfactory sensilla is greater in pollen and
water foragers, which are known to exhibit higher sensory sensitivity, compared to nectar foragers. These differences are
independent of the distribution of size within a colony. Our data also suggest that body mass and number of olfactory sensilla
correlate with the concentration of nectar gathered by workers, and with the size of pollen loads they carry. We conclude
that sensory allometry, but not necessarily body size, is associated with resource exploitation in honeybees and that the
differences in number of sensilla may underlie the observed differences in sensitivity between bees specialized on water,
pollen and nectar collection. 相似文献
75.
Effects of four decades of fire manipulation on woody vegetation structure in Savanna 总被引:2,自引:0,他引:2
Higgins SI Bond WJ February EC Bronn A Euston-Brown DI Enslin B Govender N Rademan L O'Regan S Potgieter AL Scheiter S Sowry R Trollope L Trollope WS 《Ecology》2007,88(5):1119-1125
The amount of carbon stored in savannas represents a significant uncertainty in global carbon budgets, primarily because fire causes actual biomass to differ from potential biomass. We analyzed the structural response of woody plants to long-term experimental burning in savannas. The experiment uses a randomized block design to examine fire exclusion and the season and frequency of burn in 192 7-ha experimental plots located in four different savanna ecosystems. Although previous studies would lead us to expect tree density to respond to the fire regime, our results, obtained from four different savanna ecosystems, suggest that the density of woody individuals was unresponsive to fire. The relative dominance of small trees was, however, highly responsive to fire regime. The observed shift in the structure of tree populations has potentially large impacts on the carbon balance. However, the response of tree biomass to fire of the different savannas studied were different, making it difficult to generalize about the extent to which fire can be used to manipulate carbon sequestration in savannas. This study provides evidence that savannas are demographically resilient to fire, but structurally responsive. 相似文献
76.
A sandwich enzyme-linked immunosorbent assay (ELISA) was developed to quantitatively detect Carassius auratus vitellogenin (VTG) levels. The protein levels in fish plasma are useful aquatic biomarkers of estrogenic compounds. This procedure involved an ELISA using monoclonal antibodies of CVmA2 and CVmA7 against Carassius auratus VTG, and CVmA7 conjugated to horseradish peroxidase as the detection antibody. The assay range was between 1 and 401.5 ng/ml and the recovery of the VTG added to Carassius auratus plasma was 92.5-109%. An in vitro assay was performed to measure low levels of the VTG, using primary hepatocytes of Carassius auratus induced by 17-beta estradiol (E2). The detection limit was 1 ng/ml and 137 ng/ml at the maximum. Within each sex of wild Carassius auratus, VTG levels from the river next to sewage treatment works (STWs) were much higher than those from the feeding stream. The Carassius auratus VTG bioassay could be a sensitive and useful tool for quantification of estrogenic principles in aquatic environments. 相似文献
77.
Humin, the most recalcitrant and abundant organic fraction of soils and of sediments, is a significant contributor to the
stable carbon pool in soils and is important for the global carbon budget. It has significant resistance to transformations
by microorganisms. Based on the classical operational definition, humin can include any humic-type substance that is not soluble
in water at any pH. We demonstrate in this study how sequential exhaustive extractions with 0.1 M sodium hydroxide (NaOH) + 6 M
urea, followed by dimethylsulphoxide (DMSO) + 6% (v/v) sulphuric acid (H2SO4) solvent systems, can extract 70–80% of the residual materials remaining after prior exhaustive extractions in neutral and
aqueous basic media. Solid-state 13C NMR spectra have shown that the components isolated in the base + urea system were compositionally similar to the humic
and fulvic acid fractions isolated at pH 12.6 in the aqueous media. The NMR spectra indicated that the major components isolated
in the DMSO + H2SO4 medium had aliphatic hydrocarbon associated with carboxyl functionalities and with lesser amounts of carbohydrate and peptide
and minor amounts of lignin-derived components. The major components will have significant contributions from long-chain fatty
acids, waxes, to cuticular materials. The isolates in the DMSO + H2SO4 medium were compositionally similar to the organic components that resisted solvation and remained associated with the soil
clays. It is concluded that the base + urea system released humic and fulvic acids held by hydrogen bonding or by entrapment
within the humin matrix. The recalcitrant humin materials extracted in DMSO + H2SO4 are largely biological molecules (from plants and the soil microbial population) that are likely to be protected from degradation
by their hydrophobic moieties and by sorption on the soil clays. Thus, the major components of humin do not satisfy the classical
definitions for humic substances which emphasise that these arise from microbial or chemical transformations in soils of the
components of organic debris. 相似文献
78.
Philippe Vidon Pierre‐Andre Jacinthe Xiaoqiang Liu Katelin Fisher Matthew Baker 《Journal of the American Water Resources Association》2014,50(3):639-652
Little is known about the impact of agricultural legacy on subsurface biogeochemical processes in the years following restoration of riparian wetlands (WLs). More knowledge is also needed on the relative importance of seasons, precipitation events, and inputs of water and nutrients driving nitrogen (N), phosphorus (P), sulfur (S), and greenhouse gas (GHG) (N2O, CO2, CH4) dynamics in these systems. This investigation of a riparian zone comprising a restored WL area and a nonrestored well‐drained alluvium (AL) area in the United States Midwest revealed that despite successful hydrological restoration a decade earlier, biogeochemical conditions in the WL area remained less anoxic than in natural WLs, and not significantly different from those in the AL area. No significant differences in N, P, S, and C compound concentrations or fluxes were observed between the AL and WL areas. Over the duration of the study, nitrate (NO3?) and soluble reactive phosphorus appeared to be primarily driven by hillslope contributions. Ammonium (NH4+), sulfate (SO42?), and CO2 responded strongly to seasonal changes in biogeochemical conditions in the riparian zone, while N2O and CH4 fluxes were most influenced by large rewetting events. Overall, our results challenge overly simplistic assumptions derived from direct interpretation of redox thermodynamics, and show complex patterns of solutes and GHGs at the riparian zone scale. 相似文献
79.
Simpson AJ Lam B Diamond ML Donaldson DJ Lefebvre BA Moser AQ Williams AJ Larin NI Kvasha MP 《Chemosphere》2006,63(1):142-152
Recently it has been shown that urban surfaces are covered with a thin film which mediates the fate, distribution and accumulation of semi-volatile organic compounds in the environment. In this study we apply a combination of solution, semi-solids, and solid state nuclear magnetic resonance (NMR) methods to provide a general overview of the organic constituents. In surface film collected from 30 m2 of outside windows over an area of 12 km2 in downtown Toronto, we roughly estimate that the organic carbon is approximately 35% carbohydrate, approximately 35% aliphatics, approximately 20% aromatics, and approximately 10% carbonyl groups. Various aliphatic groups can be identified including a number of acids, alcohols, alkanes, and alkenes. Also, numerous intact aliphatic esters are apparent that have not been observed before, as well as carbohydrates. The aromatic species include a small portion that appears to be derived from a polymer of styrene, in addition a larger fraction is consistent with polyhydroxylated PAH derived material, although this assignment is tentative and based solely on 1-D NMR data only. In addition, signals from polybutadiene are present and while accurate quantification is not possible, it appears that this polymer may be up to a few percents by weight of the total organic material. 相似文献