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931.
Intergovernmental Panel on Climate Change (IPCC) Tier 1 key sources level 1 assessment was applied to the 1994–1994 National Greenhouse Gases (GHG) emission inventory for Mexico in order to identify and analyze the key sources within it. Top key sources were from land use change and energy combustion contributing to about 60% of total national emissions. In addition, a Tier 1 trend assessment revealed some changes with respect to Tier 1 level assessment: Top key sources according to this analysis are waste disposal and delayed emissions from land clearing. Important insight for cost effective preventive mitigation actions can be extracted from this analysis. A comparison with other countries was carried out to find similarities in the GHG national emissions inventories related to common features on economic development.  相似文献   
932.
This study provides information on the current status of contamination by organochlorines (DDTs, PCBs, PCDDs and PCDFs) in the declining red kite (Milvus milvus L.) population breeding in the Do?ana National Park (DNP), south-western Spain. Analyses were performed in addled eggs collected between 1999 and 2001. DDE concentrations ranged from 0.1 to 33.5 microg/g ww, representing more than 86% of the total DDTs. Of the samples studied, 50% showed DDE levels above those associated with reproductive impairment in other raptor species. Concentrations of ortho PCBs (average 36.8 microg/g ww+/-37.7) in 50% of the eggs were much higher than levels reported to cause reduced hatching success, embryo mortality, and deformities in birds (>20 microg/g ww). It is remarkable that average ortho PCB and DDE concentrations showed an increase of one order of magnitude compared to previous data for the species during the 80s. Total PCDD/Fs showed levels in the low pg/g range (7.2-42 pg/g ww), having PCDDs and PCDFs similar contributions in most samples. Total mean TEQs were 238 pg/g (ww), being the range 7.02-667 pg/g (ww). Spatial variation within DNP was observed for PCBs, DDTs, as well as for TEQs. Since some eggs exceeded the NOEL (67%) and LOEL (33%) reported for other raptor species, we would expect the red kite to experience detrimental effects to dioxin-like toxicity. Our results suggest that organochlorine contaminants should be regarded as an element of concern in the population under study, in addition to other conservation problems already reported. Further investigations should be undertaken to identify potential sources of these chemicals in DNP, and to find out if organochlorine contamination is present in other predator species in the area, as well as their potential health effects on individuals and/or populations.  相似文献   
933.
Cobalt is a naturally occurring element found in rocks, soil, water, plants, and animals and has diverse industrial importance. It is cycled in surface environments through many natural processes (e.g. volcanic eruptions, weathering) and can be introduced through numerous anthropogenic activities (e.g. burning of coal or oil, or the production of cobalt alloys). The environmental behaviour of cobalt in terrestrial environment is relatively poorly studied and in particular where Co is used in industrial processes, the baseline information to support wider and long-term environmental impacts is widely dispersed. To support the adoption of new EU regulations on the risk assessment of chemicals, we review here the various aspects of the environmental chemistry, fate and transport of Co across environmental interfaces and discuss the toxicology and potential for bio magnification and food chain accumulation. The soil-to-plant transfer of Co appears to be viable route to expose lower trophic levels to biologically significant concentrations and Co is potentially accumulated in biomass and top soil. Evidence for further accumulation through soil-invertebrate transfer and to higher trophic levels is suggested by some studies but this is obscured by the relatively high variability of published transfer data. This variation is not due to one particular aspect of the transfer of Co in terrestrial environments. Influences are from the variability of geological sources within soil systems; the sensitivity of Co mobility to environmental factors (e.g. pH) and the variety of life strategies for metal elimination/use within biological species. Toxic effects of Co have been suggested for some soil-plant animal studies however, uncertainty in the extrapolation from laboratory to field is a major limitation.  相似文献   
934.
The application of mathematical tools in initial steps of sediment quality assessment frameworks can be useful to provide an integrated interpretation of multiple measured variables. This study reveals that the Self-Organizing Map (SOM) artificial neural network can be an effective tool for the integration of multiple physical, chemical and ecotoxicological variables in order to classify different sites under study according to their similar sediment quality. Sediment samples from 40 sites of 3 estuaries of Cantabria (Spain) were classified with respect to 13 physical, chemical and toxicological variables using the SOM. Results obtained with the SOM, when compared to those of traditional multivariate statistical techniques commonly used in the field of sediment quality (principal component analysis (PCA) and hierarchical cluster analysis (HCA)), provided a more useful classification for further assessment steps. Especially, the powerful visualization tools of the SOM, which offer more information and in an easier way than HCA and PCA, facilitate the task of establishing an order of priority between the distinguished groups of sites depending on their need for further investigations or remediation actions in subsequent management steps.  相似文献   
935.
In the Harghita volcanic range (Romania) there are many occurrences of dry CO(2) emanations, called mofettes. The emanating gas with high carbon dioxide content has a proved curative effect. The gas also contains important quantities of radon. Since the mofettes are used in curative purposes in several illnesses, in most of the cases without medical supervising, has been proposed to determine the radon activity concentration in some of the most frequented mofettes from Romania. The seasonal variations have also been monitored and were calculated the effective doses received by the patients during a cure. The radon activity concentrations' levels above the mofettes indoor air range between 548 and 10 717Bq/m(3) while within the gas pools' values between 3210 and 32 781Bq/m(3) have been measured. The effective dose received by the patients during a cure is between 0.0086 and 0.16mSv. No major seasonal variations of the radon activity concentrations levels have been pointed out so far in the studied mofettes.  相似文献   
936.
The beneficial role of mycorrhizal association on plant nutrition and water supply is well-known, however, very little information exists with respect to the availability of radionuclides. We have measured the effect of controlled mycorrhizal association on the root uptake from soil and accumulation in leaves of three radionuclides. The radionuclides have contrasting chemical and biological properties: Cs is strongly adsorbed on soil, has no biological role and is a close analogue of potassium; Sr is less strongly adsorbed on soil and behaves very similarly to calcium; and Tc is very mobile in soil as pertechnetate, but immobilised when reduced to Tc(IV), it is also considered to be easily assimilated by biological systems. We found that mycorrhizal association had no effect on root-to-needle transfer of Cs, but increased root uptake and that this increase could not be explained by improved potassium nutrition. In contrast, the symbiotic relation decreased Tc soil-to-needle transfer, but this resulted from complex dynamics of root uptake and rapid immobilisation of Tc in soil. No effect of mycorrhizal association on Sr, like its stable analogue Ca, was observed. The addition of a phytotoxic metal, Cu, inhibited mycorrhizal association, thus eliminating the effects observed for non-contaminated plant-fungus couples, but had no additional effect on radionuclide dynamics.  相似文献   
937.
We examine the control of air pollution caused by households burning wood for heating and cooking in the developing world. Since the problem is one of controlling emissions from nonpoint sources, regulations are likely to be directed at household choices of wood consumption and combustion technologies. Moreover, these choices are subtractions from, or contributions to, the pure public good of air quality. Consequently, the efficient policy design is not independent of the distribution of household income. Since it is unrealistic to assume that environmental authorities can make lump sum income transfers part of control policies, efficient control of air pollution caused by wood consumption entails a higher tax on wood consumption and a higher subsidy for more efficient combustion technologies for higher income households. Among other difficulties, implementing a policy to promote the adoption of cleaner combustion technologies must overcome the seemingly paradoxical result that efficient control calls for higher technology subsidies for higher income households.  相似文献   
938.
As tensions among diverse forest‐use interests in Lithuania are on the rise, this study examines the actual resource availability, the underlying planning approaches and the pertinent policy arena. Two 5‐year cycles of sampling‐based forest inventory provide accurate data showing that the overall timber harvest/increment ratio (or utilization intensity) is 61%. Utilization intensity is similar in state and private forests. It could potentially be raised to 70‐80%, with due account for environmental values. Such an increase is inhibited by rigid routines of forest management planning, involving inflexible rotation ages and cutting norms. Age‐class analysis indicates that the current planning practice counters its underlying aim of achieving a long‐term even flow of timber. According to a survey of key forest stakeholders, those who directly benefit from forest utilization have a weak position in the policy arena, the dominant powers being vested in the national forestry authorities. State forest enterprises have to follow restrictive plans from above, private forest owners are constrained by stern regulations and suffer from the bad image caused by the persistent myth of overuse in private forests. More rational management of Lithuanian forests is hardly possible without major shifts in the institutional set‐up accompanied by transformation of the professional ideology.  相似文献   
939.
How does knowledge management (KM) by a government agency responsible for environmental impact assessment (EIA) potentially contribute to better environmental assessment and management practice? Staff members at government agencies in charge of the EIA process are knowledge workers who perform judgement-oriented tasks highly reliant on individual expertise, but also grounded on the agency’s knowledge accumulated over the years. Part of an agency’s knowledge can be codified and stored in an organizational memory, but is subject to decay or loss if not properly managed. The EIA agency operating in Western Australia was used as a case study. Its KM initiatives were reviewed, knowledge repositories were identified and staff surveyed to gauge the utilisation and effectiveness of such repositories in enabling them to perform EIA tasks.  相似文献   
940.
Three different systems of designating protected areas in a Mediterranean region in southeastern Spain were studied, referring to their effectiveness and efficiency for protecting both the breeding territories and the suitable habitat of a set of ten raptor species. Taking into consideration the varying degrees of endangerment of these species, a map of multispecies conservation values was also drawn up and superimposed on the three protected-area systems studied. In order to compare the levels of protection afforded by the three systems, we considered two indices that measured their relative effectiveness and efficiency. The effectiveness estimated the proportion of territories or optimal habitat protected by the networks while efficiency implicitly considered the area of each system (percentage of breeding territories or optimal habitat protected per 1% of land protected). Overall, our results showed that the most efficient system was that formed by the set of regional parks and reserves (17 protected breeding territories per 100 km2), although, given its small total area, it was by far the least effective (only protecting the 21% of the breeding territories of all species and 17% of the area of high conservation value). The systems formed by the Special Protection Areas (designated under the EU “Birds Directive”) and by the Special Conservation Areas (designated under the EU “Habitats Directive”) notably increased the percentages of protected territories of all species (61%) and area of high conservation value (57%), but their efficiency was not as high as expected in most cases. The overall level of protection was high for all species except for the Lesser Kestrel (Falco naumanni), an endangered falcon that inhabits pseudo-steppe and traditional agricultural habitats, which are clearly underrepresented in the protected-area network of the study region.  相似文献   
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