In this study, the Enrichment Factors and elemental composition profiles of the PM2.5 were used to suggest the emission sources. The selected sites were Miravalle and Centro, and in both cases there were high values lead, Cadmium, Cobalt, Chromium, Cupper, Molybdenum, Nickel, Antimony, Selenium and Zinc for EF (>5), suggesting an anthropogenic origin. The remaining elements (Iron, Magnesium, Manganese, Strontium and Titanium) had Enrichment Factors <5, attributable to a geological origin, probably due to the suspension of particles from motor vehicles or wind. Comparing the elemental composition profiles of the two sites allowed establishing similarities with some reference profiles (SPECIATE database Version 4.2-EPA) from sources such as Paved Road Dust (PRD) and Industrial Soil (IS) and profiles of combustion sources such as Diesel Exhaust (DE). Through the estimation the Enrichment Factors and of the elemental composition profiles of two different sites in the city, it was possible to suggest not only the general type of emission source (geological or anthropogenic), but also more specific sources based on elemental composition of PM2.5.

KEYWORDSIn this work, principal component regression and partial least squares regression were used for the estimation of acid dissociation constants through UV-Vis spectrophotometric measurements, considering five well-known acid-base indicators as well as two herbicides as analytes. In each case, an acid-base titration was carried out. Then, the multivariate calibration model was constructed with a few absorption spectra of the series at extreme pH values, to which values of the dissociation fraction (α) of 1 or 0 were assigned, in the case of HA or A species. After that, the prediction step consisted in the estimation of α for the rest of the series. Then, distribution diagrams were built up with α vs pH, to find α = 0.5 where pH = pKa. The results were compared with those obtained through multivariate curve resolutionalternating least squares and program stability quotients from absorbance data (SQUAD), which showed an excellent correspondence. pKa PLS PCR MCR-ALS Spectrophotometry Chemometric strategies

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Atmospheric concentrations of nitrous acid, nitric acid, nitrate and sulfate particles were obtained in this study from April to June 2008 in the center of the city of Guadalajara, while concentrations of ozone, sulfur dioxide, nitrogen dioxide and meteorological parameters (temperature and relative humidity), were acquired by the Secretaría del Medio Ambiente para el Desarrollo Sustentable del Estado de Jalisco (SEMADES). The results showed that nitric acid (2.7 μg m(-3)) was 2.7 times higher than nitrous acid (1.0 μg m(-3)). The sulfur dioxide (SO(2)) concentration indicated an opposite trend to sulfate (SO(4) (2-)), with the average concentration of SO(2) (6.9 μg m(-3)) higher in almost the entire period of study. The sulfur conversion ratio (Fs, 24.9%) and nitrogen conversion ratio (Fn, 6.2%), were revealed to be similar to that reported in other urban areas during warm seasons. It is also noted that ozone is not the main oxidizer of nitrogen dioxide and sulfur dioxide. This determination was made by taking into account the slightly positively correlation determined for Fn (r(2) = 0.084) and Fs (r(2) = 0.092) with ozone that perhaps suggests there are other oxidizing species such as the radical OH, which are playing an important role in the processes of atmospheric oxidation in this area.

Actualmente la urbanización y el crecimiento poblacional han aumentado la demanda de agua, provocando escases en diferentes regiones del país. Uno de los procesos de recolección de agua es la cosecha de lluvia que consiste en recolectar, almacenar y tratar la escorrentía de techos, azoteas y superficies impermeables. Esta agua puede utilizarse como fuente adicional a un sistema de suministro de agua, sin embargo, la calidad del agua recolectada puede verse afectada por la presencia de contaminantes en las superficies en contacto con el agua. El objetivo de este trabajo fue evaluar la calidad del agua de lluvia cosechada en la azotea de una vivienda ubicada en el Fracc. Mirasierra, en la ciudad de Saltillo Coahuila, donde se recolectaron doce muestras de agua. Para su caracterización química se utilizaron técnicas gravimétricas, volumétricas y espectrofotométricas establecidas por normas mexicanas, encontrando que el plomo sobrepasa la concentración del límite permisible establecido por la NOM-127-SSA1-2021 ya que presenta concentraciones mayores de 0.2 mg/L.