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Iván N. Pérez-Maldonado Antonio Trejo-Acevedo Lucia Guadalupe Pruneda-Alvarez Octavio Gaspar-Ramirez Selene Ruvalcaba-Aranda Francisco Javier Perez-Vazquez 《Environmental monitoring and assessment》2013,185(11):9287-9293
The aim of this study was to evaluate the DDT, DDE, and 1-hydroxypyrene exposure levels of children living in communities located in southeastern Mexico. The study communities were Lacanja and Victoria in Chiapas state and Ventanilla in Oaxaca state. Children living in Lacanja had total blood DDT levels (mean?±?SD, 29,039.6?±?11,261.4 ng/g lipid) that were significantly higher than those of children in Victoria (10,220.5?±?7,893.1 ng/g lipid) and Ventanilla (11,659.7?±?6,683.7 ng/g lipid). With respect to the 1-hydroxypyrene levels in urine samples, the levels in Lacanja (4.8?±?4.1 μg/L or 4.5?±?3.9 μmol/mol creatinine) and Victoria (4.6?±?3.8 μg/L or 3.9?±?3.0 μmol/mol Cr) were significantly higher than levels found in Ventanilla (3.6?±?1.4 μg/L or 2.5?±?0.5 μmol/mol Cr). In conclusion, our data indicate high levels of exposure in children living in the communities studied in this work. The evidence found in this study could be further used as a trigger to revisit local policies on environmental exposures. 相似文献
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Methods for collecting time/activity pattern information related to exposure to combustion products 总被引:4,自引:0,他引:4
Focus groups, surveys and questionnaires, diaries and observations can be used to gather information about people's exposure to a wide range of combustion products. Information about locations and durations of exposure, and sources of exposure can be obtained with these instruments. The types of instruments used must be fine tuned to meet the design characteristics of the community in which the study will be conducted. 相似文献
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Antioco López-Molina Richart Vázquez-Román M. Sam Mannan M. Guadalupe Félix-Flores 《Journal of Loss Prevention in the Process Industries》2013,26(5):887-894
An approach to reduce the probability of producing a domino effect in process industry is developed in this work. It is assumed that optimal layouts should include appropriate analysis to reduce risk during the process design stage. The model developed for this approach combines the estimation of probability of damage due to overpressure, proposed by Mingguang and Juncheng (2008), and escalation threshold values defined by Cozzani, Gubinelli, and Salzano (2006). These equations are combined with other typical layout constraints as well as bounding the probability constraint, which has resulted in a highly non-linear MINLP problem. Solving a case study used by other authors provides evidence for reliability of the developed approach. In this way, layouts are designed to reduce the escalation probability yielding safe distributions. 相似文献
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Jorge A. Achcar Eliane R. Rodrigues Guadalupe Tzintzun 《Environmental and Ecological Statistics》2011,18(2):271-290
In this paper we make use of some stochastic volatility models to analyse the behaviour of a weekly ozone average measurements
series. The models considered here have been used previously in problems related to financial time series. Two models are
considered and their parameters are estimated using a Bayesian approach based on Markov chain Monte Carlo (MCMC) methods.
Both models are applied to the data provided by the monitoring network of the Metropolitan Area of Mexico City. The selection
of the best model for that specific data set is performed using the Deviance Information Criterion and the Conditional Predictive
Ordinate method. 相似文献
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Celia A Harvey Arnulfo Medina Dalia Merlo Sánchez Sergio Vílchez Blas Hernández Joel C Saenz Jean Michel Maes Fernando Casanoves Fergus L Sinclair 《Ecological applications》2006,16(5):1986-1999
As tropical regions are converted to agriculture, conservation of biodiversity will depend not only on the maintenance of protected forest areas, but also on the scope for conservation within the agricultural matrix in which they are embedded. Tree cover typically retained in agricultural landscapes in the neotropics may provide resources and habitats for animals, but little is known about the extent to which it contributes to conservation of animal species. Here, we explore the animal diversity associated with different forms of tree cover for birds, bats, butterflies, and dung beetles in a pastoral landscape in Nicaragua. We measured species richness and abundance of these four animal taxa in riparian and secondary forest, forest fallows, live fences, and pastures with high and low tree cover. We recorded over 20,000 individuals of 189 species including 14 endangered bird species. Mean abundance and species richness of birds and bats, but not dung beetles or butterflies, were significantly different among forms of tree cover. Species richness of bats and birds was positively correlated with tree species richness. While the greatest numbers of bird species were associated with riparian and secondary forest, forest fallows, and pastures with >15% tree cover, the greatest numbers of bat species were found in live fences and riparian forest. Species assemblages of all animal taxa were different among tree cover types, so that maintaining a diversity of forms of tree cover led to conservation of more animal species in the landscape as a whole. Overall, the findings indicate that retaining tree cover within agricultural landscapes can help conserve animal diversity, but that conservation efforts need to target forms of tree cover that conserve the taxa that are of interest locally. Preventing the degradation of remaining forest fragments is a priority, but encouraging farmers to maintain tree cover in pastures and along boundaries may also make an important contribution to animal conservation. 相似文献
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Analysis of soil gases is a relatively rapid and inexpensive method to delineate and measure hydrocarbon contamination in the subsurface caused by diesel or gasoline. Techniques originally developed for petroleum exploration have been adapted to tracking hydrocarbons which have leaked or spilled at or below the earth's surface.Discriminant analysis (a multivariate statistical technique) is used to classify soil gas samples of C1 to C7 hydrocarbons as biogenic (natural soil gases) or thermogenic (contaminant hydrocarbons). Map plots of C1 to C7 total interstitial hydrocarbons, C2 to C7 interstitial hydrocarbons, and C1/C
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rations are used to further delineate and document the extent and migration of contamination.Three case studies of the technique are presented: each involves leakage of hydrocarbons from underground storage tanks. Soil gas analysis clearly defines the spread of contamination and can serve as the basis for the correct placement of monitoring wells. The method proved to be accurate, rapid, and cost-effective; it therefore has potential for widespread application to the identification of soil and groundwater contaminated by hydrocarbons. 相似文献