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Considering the role of radon in epidemiology, an attempt was made to make a nation-wide map of indoor 222Rn and 220Rn for India. More than 5000 measurements have been carried out in 1500 dwellings across the country comprising urban and nonurban locations. The solid state nuclear track detectors based twin cup 222Rn/220Rn discrimination dosimeters were deployed for the measurement of indoor 222Rn, 220Rn and their progeny levels. The geometric means of estimated annual inhalation dose rate due to indoor 222Rn, 220Rn and their progeny in the dwellings was 0.94 mSvy−1 (geometric standard deviation 2.5). It was observed that the major contribution to the indoor inhalation dose was due to indoor 222Rn and its progeny. However, the contribution due to indoor 220Rn and its progeny was not trivial as it was found to be about 20% of the total indoor inhalation dose rates. The indoor 222Rn levels in dwellings was significantly different depending on the nature of walls and floorings. 相似文献
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Identifying Determinants of Nations' Wetland Management Programs Using Structural Equation Modeling: An Exploratory Analysis 总被引:1,自引:0,他引:1
La Peyre MK Mendelssohn IA Reams MA Templet PH Grace JB 《Environmental management》2001,27(6):859-868
Integrated management and policy models suggest that solutions to environmental issues may be linked to the socioeconomic
and political characteristics of a nation. In this study, we empirically explore these suggestions by applying them to the
wetland management activities of nations. Structural equation modeling was used to evaluate a model of national wetland management
effort and one of national wetland protection. Using five predictor variables of social capital, economic capital, environmental
and political characteristics, and land-use pressure, the multivariate models were able to explain 60% of the variation in
nations' wetland protection efforts based on data from 90 nations, as defined by level of participation in the international
wetland convention. Social capital had the largest direct effect on wetland protection efforts, suggesting that increased
social development may eventually lead to better wetland protection. In contrast, increasing economic development had a negative
linear relationship with wetland protection efforts, suggesting the need for explicit wetland protection programs as nations
continue to focus on economic development. Government, environmental characteristics, and land-use pressure also had a positive
direct effect on wetland protection, and mediated the effect of social capital on wetland protection. Explicit wetland protection
policies, combined with a focus on social development, would lead to better wetland protection at the national level. 相似文献
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Nagappagari Lakshmana Reddy Vempuluru Navakoteswara Rao Murkinati Mamatha Kumari Raghava Reddy Kakarla Parnapalle Ravi Marappan Sathish Mani Karthik Shankar Muthukonda Venkatakrishnan Inamuddin 《Environmental Chemistry Letters》2018,16(3):765-796
Massive production of hydrogen by water decomposition triggered by a solar light active photocatalyst is a major objective in chemistry and a promising avenue to overcome the global energy crisis. The development of efficient, stable, economically viable and eco-friendly photocatalysts for hydrogen production is a challenging task. This article reviews the use of nanocomposite in three combinations: metal oxide–metal oxide semiconductor, metal–metal oxide semiconductor and metal chalcogenide–metal oxide core–shell nanostructures. These core–shell structures occur in two forms: a simple form where the photocatalyst is either in the core or the shell or in a more complex system where the core–shell structure comprises a co-catalyst deposited on a semiconducting material. We discuss the design, synthesis and development of semiconductor-based nanocomposite photocatalysts for hydrogen production. The major points are the role of catalytic active sites, the chemical nature of sacrificial agents, the effect of light sources, the variable light intensity and the energy efficiency calculation. For TiO2-based nanocomposites, the metal oxide or metal co-catalyst loading of 1.0–3.0 wt% was optimal. TiO2 nanotube–CuO hybrid nanocomposites produce 1,14,000 µmol h?1 \({\text{g}}^{ - 1}_{\text{cat}}\), whereas TiO2/Au nanocomposites display 1,60,000 µmol h?1 \({\text{g}}^{ - 1}_{\text{cat}}\). For core–shell catalysts, a shell thickness of 2–20 nm was found for the best activity, and its performance is as follows: (a) CdS–NiO system produces around 19,949 µmol h?1 \({\text{g}}^{ - 1}_{\text{cat}}\) and (b) CuO–Cr2O3 as co-catalyst immobilized on TiO2 system produces around 82,390 µmol h?1 \({\text{g}}^{ - 1}_{\text{cat}}\). 相似文献