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Microorganisms are useful indicators of alterations in the natural environment. As presently employed, however, “indicator organisms” such as fecal coliforms and total coliforms have severe limitations. Other organisms have been proposed in recent years as potential indicator organisms, viz. Streptococci, Clostridia, and pseudomonads. The indicator organism concept is reviewed and recommendations for future studies are made. In particular, detection, isolation, and identification of viruses, effects of pollutants on the natural microbial flora, and reevaluation of microbial indicators are critical areas requiring research.  相似文献   

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The ozone distribution observed for April to September, 1976 and 1977, have been categorized and analyzed according to episodes. The major characteristics of the 40 ozone episodes are discussed. The major features are: (1) most episodes were associated with high pressure systems that enter the United States of America through Minnesota, (2) they normally have a duration which averages seven days for both years, (3) transported ozone from the midwest affected the northeastern United States and (4) the highest ozone concentrations were usually found in Connecticut. A particular episode, 9–19 May 1977, is examined in detail and shows the production of ozone in the midwestern United States under stagnant conditions and its eventual eastward transport. The first two days of the subsequent episode are shown to demonstrate the local accumulation of ozone in the northeast. The distribution of ozone throughout the entire eastern half of the country is also illustrated.  相似文献   

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Projections for 20 years of economic growth and change in the structure of the Thai economy were made for 180 sectors using a computable general equilibrium (CGE) model to compare the following four scenarios: (1) standard growth with infinite supply of factors, (2) finite land supply, (3) fixed use of agricultural chemicals, and (4) combined finite land supply with fixed use of agricultural chemicals. The computable projections suggest that the economic cost of hypothetical environmental control in agriculture is small and further weakened by urbanization. The computed structural development points to efficiency improvements specific to sectors to return the economy to balanced growth.  相似文献   

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Animal studies showed that the developing brain is particularly sensitive to chemical exposure. Human studies carried out in areas with high exposures have proven neurodevelopmental disorders in relation to e.g. lead and PCBs. Whether these chemicals are associated with behavioural problems in childhood at current environmental levels is not well known. Therefore, we assessed the association between prenatal exposure to lead, cadmium, PCBs, dioxin-like compounds, HCB and p,p′-DDE and behavioural problems in 7–8 year old children. Prenatal exposure data were obtained from the Flemish mother–new-born cohort. Lead, cadmium, PCBs, dioxin-like compounds, HCB and p,p′-DDE were analysed in cord blood. When the child reached 7–8 years, 270 mothers completed the Strengths and Difficulties Questionnaire assessing their children's behavioural health. We found that doubling the prenatal lead exposure (cord blood lead levels) was associated with a 3.43 times higher risk for hyperactivity in both boys and girls. In addition, total difficulties were 5.08 times more likely in the highest tertile for prenatal lead exposure compared to the lowest tertile. In girls, total difficulties were 4.92 more likely when doubling cord blood p,p′-DDE, whereas no significant association was found in boys. Further, we noted in boys a 1.53 times higher risk for emotional problems when doubling cord blood cadmium, whereas no significant association was found in girls. These results indicate that the presence of environmental contaminants influences the mental health of the next generation.  相似文献   

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There is growing interest in the correlation between working time and environmental pressures, but prior empirical studies mostly focused on static methodologies. This article used dynamic panel regression approaches to examine and compare the relationship among western, southern, and northern European countries over the period 1970–2010, and proved the existence of strongly significant relationships in all models. Furthermore, this article detected the relationship between working hours and environmental indicators (carbon emission and energy use) at different phases. We contribute to a further understanding of the environmental effects of the working time reduction policy by comparing the differences among various periods and country groups in a system generalized method of moments (GMM) dynamic framework.  相似文献   

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The South American country Brazil is one of the richest countries in terms of natural resources, representing 14 percent of the world’s total biocapacity. However, the biocapacity (biosphere’s ability to generate resources and sequester waste) per capita in Brazil has shown a massive decline over the last five decades, while economic growth and urbanization have rapidly increased for the same period. Brazil is one of the largest creditors of biocapacity to the world, and biocapacity loss in Brazil can lead to devastating environmental consequences. Therefore, this work empirically investigates the influence of urbanization, economic growth, and industrialization on biocapacity controlling human capital from 1961 to 2016 in Brazil. The Bayer and Hack cointegration test, the Autoregressive Distributed Lag (ARDL) technique, and Hacker and Hatemi-J (J Econ Stud 39:144–160, 2012) causality tests are employed. The findings unfolded a U-shaped relationship between economic growth and biocapacity, evidencing that economic growth reduces biocapacity, but after achieving a threshold level, it promotes biocapacity. Urbanization has a negative relationship with biocapacity per capita, indicating that urbanization is a significant driver of the biocapacity loss in Brazil. Further, urbanization and economic growth Granger cause biocapacity. Lastly, relevant policy implications are proposed to overcome the reduction in biocapacity.

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The paper examines the role of environmental norms in Chinese overseas investment in hydropower dams, exemplified by Sinohydro’s involvement in the Bui Dam in Ghana. While the investment of Western companies in hydropower dams in the global South is decreasing owing to changing notions of sustainability in the West, the investment of Chinese companies in hydro dams in Africa, Southeast Asia and Latin America is accelerating at great speed. The emergence of Chinese companies in international markets in the context of China’s Going Abroad strategy has sparked a debate on whether China can be considered a norm-changer in international development. The paper considers this question in the context of the status of environmental norms in Sinohydro’s investment in Ghana’s Bui Dam. The paper argues that the role of international norms in Chinese investment is dependent on two factors: the contractual arrangements under which Chinese companies operate abroad and the political institutions of host countries.  相似文献   

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The selection of trace element tolerant species is a key factor to the success of remediation of degraded mine soils. Mining activities generate a large amount of waste rocks and tailings, which get deposited at the surface. The degraded soils, the waste rocks and tailings are often very unstable and will become sources of pollution. The direct effects will be the loss of cultivated land, forest or grazing land, and the overall loss of production. The indirect effects will include air and water pollution and siltation of rivers. These will eventually lead to the loss of biodiversity, amenity and economic wealth. Restoration of a vegetation cover can fulfil the objectives of stabilization, pollution control, visual improvement and removal of threats to human beings. Thus, remediation of mine spoils/tailings and biogeochemical prospecting would rely on the appropriate selection of plant species. Plant community responds differently on their ability to uptake or exclude a variety of metals. In this work, plant species were sampled from all populations established in an abandoned copper mine of S?o Domingos, SE Portugal. Plants belonging to 24 species, 16 genera and 13 families were collected from the degraded copper mine of S?o Domingos. Plant samples were analysed for total Ag, As, Cu, Ni, Pb, and Zn. The highest concentrations of metals in soils dry matter were 11217.5 mg Pb kg(-1), 1829 mg Cu kg(-1), 1291 mg As kg(-1), 713.7 mg Zn kg(-1), 84.6 mg Cr kg(-1), 54.3 mg Co kg(-1), 52.9 mg Ni kg(-1) and 16.6 mg Ag kg(-1). With respect to plants, the higher concentrations of Pb and As were recorded in the semi-aquatic species Juncus conglomeratus with 84.8 and 23.5 mg kg(-1) dry weight (DW), Juncus efusus with 22.4 and 8.5 mg kg(-1) DW, and Scirpus holoschoenus with 51.7 and 8.0 mg kg(-1) DW, respectively. Thymus mastichina also showed high content of As in the aboveground parts, 13.6 mg kg(-1) DW. Overall, the results indicate accumulation of various metals by different plant species, with some of these metals being partitioned to the shoots. Environmental implications of these observations are discussed.  相似文献   

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The significance of colloidal fractions regarding the transport of artificial radionuclides in natural water systems is underlined by using sequential ultrafiltration both in the Rh?ne freshwater and the marine area under and outside the influence of the river outflow. Indeed, the Rhodanian aquatic system represents an interesting test site as various artificial radionuclides are released into the Rh?ne river by several nuclear installations. We focused our study on (137)Cs, (106)Ru, (60)Co, (238)Pu and (239+240)Pu. Our results show that Fe, Al and Organic carbon (OC) are the main components of colloidal matter. Colloids represent about 15% of dissolved (<450 nm) OC and 25% of dissolved Fe and Al exported towards the sea. Within the dissolved (< 450 nm) phase, these colloidal compounds are shown to account for the transport of 40% for both Co and Ru, 60% for (238)Pu and (239+240)Pu and have no significance on (137)Cs flux.  相似文献   

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