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Perrier F Richon P Crouzeix C Morat P Le Mouël JL 《Journal of environmental radioactivity》2004,71(1):17-32
Radon-222 activity concentration has been monitored since 1999 in an underground limestone quarry located in Vincennes, near Paris, France. It is homogeneous in summer, with an average value of 1700 Bq m(-3), and varies from 730 to 1450 Bq m(-3) in winter, indicating natural ventilation with a rate ranging from 0.5 to 2.4 x 10(-6) s(-1) (0.04-0.22 day(-1)). This hypothesis is supported by measurements in the vertical access pit where, in winter, a turbulent air current produces a stable radon profile, smoothly decreasing from 700 Bq m(-3) at 20 m depth to 300 Bq m(-3) at surface. In summer, a thermal stratification is maintained in the pit, but the radon-222 concentration jumps repeatedly between 100 and 2000 Bq m(-3). These jumps are due to atmospheric pressure pumping, which induces ventilation in the quarry at a rate of about 0.1 x 10(-6) s(-1) (0.009 day(-1)). Radon-222 monitoring thus provides a dynamical characterisation of ventilation regimes, which is important for the assessment of the long-term evolution of underground systems. 相似文献
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Tineke H. Jones Alain Houde Elyse Poitras Pierre Ward Michael W. Johns 《Food and environmental virology》2009,1(2):57-65
There are increasing concerns of zoonotic transmission of some animal enteric viruses, such as calicivirus, hepatitis E virus,
and rotavirus, which are closely related to human pathogenic strains. Most enteric viruses are detected by molecular techniques
because they cannot be cultured. Surrogates such as F-RNA coliphages are cultivable but few molecular methods exist. Individual
real-time TaqMan RT-PCR assays for the replicase gene of F-RNA coliphage genogroups I and IV were developed and multiplexed
with a real-time TaqMan RT-PCR assay for feline calicivirus as a sample process control for the simultaneous detection and
enumeration of genogroup I and IV F-RNA coliphages. Genogroup IV were successfully detected with the multiplexed assay in
80% of fecal samples that contained F-RNA coliphage levels ≥3.2 log plaque forming units (pfu). F-RNA coliphage were at or
below the limit of detection in most fecal samples when levels were ≤4 log pfu/g. 相似文献
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This note addresses the question of what policy the government should adopt when industrial pollution can be reduced partially by the imposition of effluent taxes and partially by a publicly operated waste treatment plant.In the case of increasing returns to public abatement, an effluent tax set at marginal user cost will not generate enough revenue to finance the facility. The key issue is that of finding additional revenue the most efficiently. Here, this question is dealt with in the framework of commodity taxation, with consideration given to the possibility that both effluent and commodity taxes derived on efficiency grounds might be quite regressive. 相似文献
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Christian Mougin Claude Jolivalt Pierre Briozzo Catherine Madzak 《Environmental Chemistry Letters》2003,1(2):145-148
Laccases are multicopper oxidases mainly secreted by filamentous fungi. Producing radical forms from organic substrates, they
are involved in numerous reactions leading to the degradation and polymerization of xenobiotics. Our studies have led to a
better knowledge of the structural, catalytic and genetic properties of laccases and allowed to develop a strategy for their
evolution through genetic engineering. Here, we show that fungal laccases, wild or engineered, may be potent tools to develop
bioremediation processes of soils polluted by organic compounds, and assays to assess the ecotoxicological impact of these
pollutants on soil fungi. 相似文献
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The spatial and temporal organization of ecological processes and features and the scales at which they occur are central topics to landscape ecology and metapopulation dynamics, and increasingly regarded as a cornerstone paradigm for understanding ecological processes. Hence, there is need for computational approaches which allow the identification of the proper spatial or temporal scales of ecological processes and the explicit integration of that information in models. For that purpose, we propose a new method (multiscale codependence analysis, MCA) to test the statistical significance of the correlations between two variables at particular spatial or temporal scales. Validation of the method (using Monte Carlo simulations) included the study of type I error rate, under five statistical significance thresholds, and of type II error rate and statistical power. The method was found to be valid, in terms of type I error rate, and to have sufficient statistical power to be useful in practice. MCA has assumptions that are met in a wide range of circumstances. When applied to model the river habitat of juvenile Atlantic salmon, MCA revealed that variables describing substrate composition of the river bed were the most influential predictors of parr abundance at 0.4-4.1 km scales whereas mean channel depth was more influential at 200-300 m scales. When properly assessed, the spatial structuring observed in nature may be used purposefully to refine our understanding of natural processes and enhance model representativeness. 相似文献
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