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731.
Assessment of organic contaminant fate in waste water treatment plants. I: Selected compounds and physicochemical properties 总被引:1,自引:0,他引:1
An extensive and comprehensive literature review has been conducted for compounds which we hypothesise could be present in sludge and maintain their integrity following application to agricultural land. The following compounds have been selected for review; chlorinated paraffins, quintozene, brominated diphenyl ethers, polychlorinated naphthalenes, polydimethylsiloxanes, chloronitrobenzenes, and a range of biologically active and pharmaceutical compounds. All have received interest as a result of their persistence and/or toxicity in environmental media. Physicochemical property information has also been compiled and/or calculated. In this way, an accompanying paper will attempt to predict compound fate in waste water treatment plants (WWTPs) and assess likely transfers from soil/plants to grazing livestock. These papers describe a first attempt to predict the fate of these classes of compounds in the environment and prioritise those of greatest concern. 相似文献
732.
The microbial role in hot spring silicification 总被引:8,自引:0,他引:8
Recent experimental studies indicate that microorganisms play a passive role in silicification. The organic functional groups that comprise the outer cell surfaces simply serve as heterogeneous nucleation sites for the adsorption of polymeric and/or colloidal silica, and because different microorganisms have different cell ultrastructural chemistry, species-specific patterns of silicification arise. Despite their templating role, they do not appear to increase the kinetics of silicification, and at the very most, they contribute only marginally to the magnitude of silicification. Instead, silicification is due to the polymerization of silica-supersaturated hydrothermal fluids upon discharge at the surface of the hot spring. Microorganisms do, however, impart an influence on the fabric of the siliceous sinters that form around hot spring vents. Different microorganisms have different growth patterns, that in turn, affect the style of laminations, the primary porosity of the sinter and the distribution of later-stage diagenetic cementation. 相似文献
733.
Jones JM Hogrefe C Henry RF Ku JY Sistla G 《Journal of the Air & Waste Management Association (1995)》2005,55(1):13-19
The updated regulatory framework for demonstrating that future 8-hr ozone (O3) design values will be at or below the National Ambient Air Quality Standards (NAAQS) provides guidelines for the development of a State Implementation Plan (SIP) that includes methods based on photochemical modeling and analytical techniques. One of the suggested approaches is the relative reduction factor (RRF) for estimating the efficacy of emission reductions. In this study, the sensitivity of model-predicted responses towards emission reductions to the choice of meteorology and chemical mechanisms was examined. While the different modeling simulations generally were found to be in agreement on whether predicted future-year design values would be above or below the NAAQS for 8-hr O3 at a majority of the monitoring locations in the eastern United States, differences existed for a small percentage of monitors (approximately 6.4%). Another issue investigated was the ability of the attainment demonstration procedure to predict changes in monitored O3 design values. A retrospective analysis was performed by comparing predicted O3 design values from model simulations using emission estimates for 1996 and 2001 with monitored O3 design values for 2001. Results indicated that an average gross error of approximately 5 ppb was present between modeled and observed design values and that, at approximately 27% of all sites, model-predicted and observed design values disagreed as to whether the design value was above or below the NAAQS. Retrospective analyses such as the one presented in this study can provide valuable insights into the strengths and limitations of modeling and analysis techniques used to predict future design values over time periods of a decade or more for the purpose of developing SIPs. Furthermore, such analyses could provide avenues for improvement and added confidence in the use of the RRF approach for addressing attainment of the NAAQS. 相似文献
734.
Polychlorinated biphenyls (PCBs) in the British environment: sinks, sources and temporal trends 总被引:17,自引:0,他引:17
Harrad SJ Sewart AP Alcock R Boumphrey R Burnett V Duarte-Davidson R Halsall C Sanders G Waterhouse K Wild SR Jones KC 《Environmental pollution (Barking, Essex : 1987)》1994,85(2):131-146
This paper estimates the present UK environmental loading of polychlorinated biphenyls (PCBs). Of the estimated approximately 40,000 t SigmaPCB sold in the UK since 1954, only an estimated 1% (400 t) are now present in the UK environment. Comparisons of estimated production and current environmental loadings of congeners 28, 52, 101, 138, 153 and 180 suggest that PCB persistence broadly increases with increasing chlorination. Those PCBs that are not now present in the UK environment are considered to have been destroyed--by natural or anthropogenic mechanisms, to be still in use, to reside in landfills or to have undergone atmospheric and/or pelagic transport from the UK. The dramatic fall in PCB levels in archived UK soils and vegetation between the mid-1960s and the present is evidence that the latter mechanism is the most important and that a significant proportion of PCBs released into the UK environment in the 1960s have subsequently undergone environmental transport away from the UK. The bulk (93.1%) of the estimated contemporary UK environmental burden of SigmaPCBs is associated with soils, with the rest found in seawater (3.5%) and marine sediments (2.1%). Freshwater sediments, vegetation, humans and sewage sludge combined account for 1.4% of the present burden, whilst PCB loadings in air and freshwater are insignificant. Although consideration of individual congeners does not reveal any major deviations from the relative partitioning of Sigma PCBs, the importance of sinks other than soils is enhanced for individual congeners, particularly 138 and 180. In particular, around 2% of the total UK burden of congener 180 is present in humans, implying that biodata as a whole may constitute an important sink for the higher chlorinated congeners. The contemporary flux of SigmaPCBs to the UK surface is estimated at 19 t yr(-1), compared with an estimated annual flux to the atmosphere of 44-46 t. This implies that the major sources of PCBs to the UK atmosphere have been identified and that there is currently a net loss of these compounds from the UK. These sources are: volatilisation from soils (88.1%), leaks from large capacitors (8.5%), the production of refuse-derived fuel (RDF) (2.2%), leaks from transformers (0.6%), the recovery of contaminated scrap metal (0.5%) and volatilisation from sewage sludge-amended land (0.2%). Interestingly, whilst large excesses of estimated annual fluxes to the atmosphere over deposition fluxes for individual congeners exist for congeners 28, 52 and 101, estimates of fluxes in both directions across the soil-atmosphere interface agree closely for congeners 138, 153 and 180. This suggests that lower chlorinated congeners are more susceptible to both long-range environmental transport beyond the UK and to atmospheric degradation. Retrospective analysis of dated sediment cores, vegetation and soils indicates that environmental transport from North America and continental Europe introduced PCBs into the British environment well before the onset of their commercial production in the UK in 1954. Since that time, the input of PCBs to the UK environment has essentially reflected temporal trends in UK use. After peaking in the 1960s they declined rapidly through the 1970s following restrictions on PCB use. Recent evidence, however, is that the rate of decrease has diminished and that further significant reductions in fresh environmental input will take some time to occur. Such reductions will be especially slow for humans and other biota with long life-spans. This stems partly from cross-generational transfer from parents to offspring and also because the persistence of PCBs in biota means that present body burdens will reflect past as well as current exposure. 相似文献
735.
M. B. Jones 《Marine Biology》1975,30(1):13-20
The effects of cadmium (3CdSO4·8H2O), zinc (ZnSO4·7H2O) and lead [Pb (NO3)2] on mortality, and cadmium, zinc and mercury (HgCl2) on osmoregulation, have been recorded for marine and estuarine species of isopods (Crustacea). The marine species studied were Idotea baltica, I. neglecta, I. emarginata and Eurydice pulchra, which were adapted to 100, 80, 60 and 40% sea water (SW) (100% SW э 34‰ S). The estuarine species used were Jaera albifrons sensu stricto and J. nordmanni, which were adapted to 100, 50, 10 and 1% SW. Both groups of isopods have low mortalities in 100% SW with 10 and 20 ppm of cadmium, zinc and lead, but a decrease in salinity caused an increase in the toxicities of these metals and reduced the LT50 values (time, in hours, to 50% mortality). Mortalities at 10°C were generally higher than those recorded at 5°C. Cadmium had no significant effect on the osmoregulation of I. baltica and I. emarginata in 100 and 80% SW at 5°C, but this metal significantly lowered the blood osmotic concentration of I. neglecta in 80% SW. Zinc did not alter the haemolymph osmotic concentration of I. neglecta in 100 and 80% SW, but significantly lowered the blood osmotic concentration of I. baltica in 100% SW. Cadmium, zinc and mercury also significantly altered the osmoregulatory ability of J. albifrons in dilute saline. 相似文献
736.
J. W. Jones H. D. Bowen J. R. Bradley Jr R. E. Stinner R. S. Sowell 《Ecological modelling》1975,1(4):289-302
A model is presented for predicting boll weevil, Anthonomus grandis Boheman, feeding damage to cotton. The model uses appropriate probability theory based on behavioral components of male and nonreproducing female boll weevils and includes the effects of (1) differential feeding site preferences, (2) previous damage to the sites, and (3) individual insect behavior extended to feeding damage caused by a population of insects. The model is sensitive to both crop and insect parameters. An example of how this model can be used in an insect-crop ecosystem simulation is offered. 相似文献
737.
In the carnivorous isopod Eurydice pulchra
Leach the mid-gut caeca have a pH of 5.6 and produce a strong acid proteinase, a lipase and a carbohydrase. Electron microscope studies of the digestive caeca of starved and fed animals show that secretion is merocrine and may originate from a complex involving the basal cell membrane and associated mitochondria, producing lysosomes. Absorbed materials, in fed animals, appear to take the form of neutral lipid bodies, glycogen, and proteinaceous crystals, the latter forming within the golgi complex. Digestion of both lipid and protein inclusions was observed to occur intra-cellularly by fusion with free lysosomes. Secretion and absorption may occur in the same cell, and the scheme for the sequence of epithelial cell stages is proposed. 相似文献
738.
739.
Tony Jones 《Local Environment》1996,1(1):87-106
Local authorities are increasingly undertaking policy initiatives which aim to achieve local sustainability. Indeed, the rapid development in this area since its first tentative steps in the late 1980s is very impressive. However, it is legitimate to question whether any real progress has been made in improving local environmental conditions. This is almost impossible to determine as very few have translated policy rhetoric into measurable environmental achievement. Although the development of sustainability indicators will, in the long term, provide some means of measuring success, few authorities have the necessary precursor for its achievement in place: performance-based environmental programmes. This important stage of development has been all but missed in the rush for national and international credibility, often at the expense of local communities and their environment rather than for their benefit. This paper examines the activities of one local authority, the London Borough of Hackney, and its efforts to translate policy principals into practical Action for the Environment through the mechanism of performance review. It is concluded that performance review has a valuable role to play in achieving environmental improvements to help move society towards sustainability but, like any mechanism, there are limitations in its use which need to be acknowledged if it is to be used effectively. These are explored in detail in the paper in the hope that they assist others when developing similar performance-based environmental programmes. 相似文献
740.
Tim Jones 《Natural resources forum》1993,17(3):170-180
Large-scale exploitation of fossil fuels and nuclear power can have an adverse effect on the human and natural environment. That need not be the case, if the effect on the environment is carefully assessed to ensure the development of a sustainable approach. This paper examines the process of environmental impact assessment (EIA) for coal from an international perspective. The concept of EIA is not new. A formalized process of EIA was introduced in the USA in 1970, and more recently similar legislation has been implemented in other countries. The member states of the European Community are required to adopt EIA regulations, as set out in Directive 85/337/EEC. Elsewhere, in Japan and Australia, there are requirements for EIA and a growing need for the process can be seen in developing countries. A comparison is made of the EIA process for coal in the international arena, and exemplary procedures are highlighted. Potential problems such as delays, modifications and additional costs are analysed, and the benefits of EIA, both to industry and environment, are discussed. A database of coal-related EIA would facilitate an exchange of information on the subject. 相似文献