282 research outputs found
CARLON, Emeterio y Erasmo LUQUE
No full textDocuments related to records of court hearing and fine levied by the subaltern director of the Fiscal Stamp against the Tomato Company in Los Mochis. Telegrams of Mr. Emeterio Carlon, Erasmo Luque, and Gen. Alvaro Obregón concerning a matter discussed with the President. File C-25. / Documentos relativos al acta judicial y a la multa que contra la Compañía Tomatera de Los Mochis levantó el administrador subalterno del Timbre. Telegramas entre los Srs. Emeterio Carlon, Erasmo Luque y el Gral. Alvaro Obregón, sobre asunto tratado con el Presidente de la República. Exp. C-2
Risk based characterization of a contaminated industrial site using multivariate and geostatistical tools
No full textHuman and ecological risk assessment requires the sources, distribution, mobility and environmental behaviour of contaminants
to be investigated on a site-speci®c basis. It often deals with data sets which are relatively small and a ected by sampling gaps. In
the case of a polycyclic aromatic hydrocarbon (PAH) contaminated industrial site, Kriging interpolation of spatial data and prin-
cipal component analysis (PCA) proved useful for extracting additional value from the data set. Kriging was adopted for assessing
the horizontal and vertical distribution and transport of PAHs in soil. PCA was applied to PAH concentration and relative abun-
dance in soil samples and interpreted on the basis of the PAH physico-chemical and bio-degradation properties. It revealed corre-
lation with the products of a neighbouring factory and the weathering of the lighter PAHs. The geo- and multivariate statistical
results were coupled with the previous hydrogeological characterisation of the site to develop a site-conceptual model for use in the exposure scenario modelling for risk assessment
Fractional Brownian motion and the critical dynamics of zipping polymers
No full textWe consider two complementary polymer strands of length L attached by a common-end monomer. The two strands bind through complementary monomers and at low temperatures form a double-stranded conformation (zipping), while at high temperature they dissociate (unzipping). This is a simple model of DNA (or RNA) hairpin formation. Here we investigate the dynamics of the strands at the equilibrium critical temperature T = T-c using Monte Carlo Rouse dynamics. We find that the dynamics is anomalous, with a characteristic time scaling as tau similar to L-2.26(2), exceeding the Rouse time similar to L-2.18. We investigate the probability distribution function, velocity autocorrelation function, survival probability, and boundary behavior of the underlying stochastic process. These quantities scale as expected from a fractional Brownian motion with a Hurst exponent H = 0.44(1). We discuss similarities to and differences from unbiased polymer translocation
Regression models to predict water-soil heavy metals partition coefficients in risk assessment studies
No full textRisk assessment studies apply fate and transport models to predict the behaviour of chemicals in the environment. The definition of physico-chemical properties is crucial to predict the mobility of pollutants and heavy metals in particular within the environmental compartments. The conservative approach normally adopted at a screening level in attributing a value to the K-d value, results in an extremely variable mobility in soil. In this paper a regression model to estimate rapidly the K-d for heavy metals is proposed and applied to Pb, allowing a considerable reduction (3-4 orders of magnitude) of the estimation uncertainty. The application of a stepwise forward multiple regression to literature data provided a pH-dependent regression equation of the soil-water distribution coefficient (K-d) for Pb: log K-d = 1.99 + 0.42 pH
Characterization of contaminated soil and groundwater surrounding an illegal landfill (S.Giuliano, Venice, Italy) by principal component analysis and kriging
No full textThe characterization of a hydrologically complex contaminated site bordering the lagoon of Venice (Italy) was undertaken by investigating soils and groundwaters affected by the chemical contaminants originated by the wastes dumped into an illegal landfill. Statistical tools such as principal components analysis and geostatistical techniques were applied to obtain the spatial distribution of chemical contaminants. Dissolved organic carbon (DOC), SO42- and Cl- were used to trace the migration of the contaminants from the top soil to the underlying groundwaters. The chemical and hydrogeological available information was assembled to obtain the schematic of the conceptual model of the contaminated site capable to support the formulation of major exposure scenarios, which are also provided
Screening ecological risk assessment for the benthic community in the Venice lagoon (Italy)
No full textAccording to the risk hypothesis: the sediment as source of potential risk for the benthic community, an Ecological Risk Assessment (ERA) based on the quotient method was undertaken. The exposure of the benthic community to different classes of pollutants (metals, chlorinated organic compounds and polynuclear aromatic hydrocarbons) was inferred by estimating the pollutant stocks in the top 15-cm sediment of the whole Venice lagoon, after application of geostatistic techniques. The risk was calculated by comparing the sediment exposure profiles with the ecotoxicological benchmarks for benthic organisms. Kriging based maps of the spatial distribution of the estimated risk for the benthic community over the whole lagoon were obtained. The highest risk, found in the areas nearest to the sources of contamination (e.g., the industrial district of Porto Marghera and the river mouths), was posed by mercury (40% of the sampling stations showed exposure levels higher than the Probable Effect Level), arsenic and nickel (75% of the sampling stations exceeded the Threshold Effect Level
Roles of stiffness and excluded volume in DNA denaturation
No full textThe nature and the universal properties of DNA thermal denaturation are
investigated by Monte Carlo simulations. For suitable lattice models we
determine the exponent c describing the decay of the probability
distribution of denaturated loops of length l , Psimilar tol(-c) . If
excluded volume effects are fully taken into account, c=2.10(4) is
consistent with a first order transition. The stiffness of the double
stranded chain has the effect of sharpening the transition, if it is
continuous, but not of changing its order and the value of the exponent
c, which is also robust with respect to inclusion of specific base-pair
sequence heterogeneities
Analytical and Environmental Chemistry in the Framework of Risk Assessment and Management: The Lagoon of Venice as a Case Study
No full textPrevention of toxic pollutant discharge and remediation of contaminated sediments and soils are topics increasingly addressed by the scientific community and the stakeholders. The research activity carried out on the lagoon of Venice highlights the crucial role played by analytical and environmental chemistry in assessing the environmental behavior of chemicals (i.e. occurrence level, transformation, ultimate fate) and exposure of human and environmental targets to pollutants. The extrapolation from analytical data to decisional steps was accomplished by data treatment (descriptive and multivariate statistics, spatial statistics), environmental modeling (e.g. partitioning bioaccumulation models and linear regression models), environmental risk assessment (ERA), and a GIS-based Decision Support System (DSS). Results obtained by this integrated approach supported analytical and environmental chemistry by improving the selection of priority pollutants, optimizing sampling design, and identifying critical environmental pathways. Both uncertainty minimization and cost saving of the overall decision process could be achieved. Selected results are presented here on the application of the proposed approach to the contaminated sediments of the lagoon of Venice and to the brownfield of the Porto Marghera industrial district. Both well-known persistent pollutants (e.g. polychlorinated dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), metals and metalloids, and aromatic surfactants and their metabolites), as well as new classes of pollutants (e.g. endocrine disrupting compounds, EDCs) were investigated. The analytical data indicated that the most persistent and toxic organic and inorganic chemicals were found mainly in bottom sediments (especially those near the Porto Marghera industrial district), while substances such as surfactants and their metabolites and EDCs occurred mainly in water and were redistributed over the whole lagoon. Exposure characterization allowed Environmental Risk Assessment (ERA) to be undertaken, including the estimation of risk for both human and environmental health. The ERA procedure, developed according to a tiered approach, was applied to contaminated soils of the Porto Marghera industrial district. The ecological risk associated with contaminated lagoon sediments for the benthic community and aquatic food web was also assessed, resulting in a significant risk posed especially by mercury, cadmium and PAHs. Finally, a risk-based decision support system (DSS) for the rehabilitation of the Porto Marghera contaminated site was developed, which included environmental risk and remediation technologies
Bayesian statistics-based procedure for sampling of contaminated sites
No full textA variable density sampling pattern based on Bayesian statistics is presented and compared to a uniform density statistical pattern and a judgmental approach in a real case study. The Bayesian statistics, supported by a software tool, supplied a soil sampling plan similar to the judgmental one, especially for the number of sampling points and their location. It allowed statistical goals to be set and expert judgment to be included in the sampling strategy in a transparent and systematic procedure. For these reasons, it appears quite suitable for inclusion into Quality Assurance Quality Control plans
Development of a site-specific Ecological Risk Assessment for contaminated sites: Part II. A multi-criteria based system for the selection of bioavailability assessment tools
No full textA comparison procedure based on Multi-Criteria Decision Analysis (MCDA) and expert judgment was developed in order to allow the comparison of bioavailability tests to implement the chemical Line of Evidence (LoE) within a TRIAD based site-specific Ecological Risk Assessment framework including three tires of investigation. The proposed methodology was included in the Module I of the Decision Support System DSS-ERAMANIA and the obtained rank supported the selection of a suitable set of available tests to be applied to the case study. A simplified application of the proposed procedure is described and results obtained by the system software are discussed
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