In this work, the particulate matter (PM) from three different monitoring stations in the Monterrey Metropolitan Area in Mexico were investigated for their compositional, morphological, and optical properties. The main aim of the research was to decipher the different sources of the particles. The methodology involved the ex situ sequential analysis of individual particles by three analytical techniques: scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), polarized light microscopy (PLM), and micro-Raman spectroscopy (MRS). The microanalysis was performed on samples of total suspended particles. Different morphologies were observed for particles rich in the same element, including prismatic, spherical, spheroidal, and irregular morphologies. The sequential microanalysis by SEM-EDS/PLM/MRS revealed that Fe-rich particles with spherical and irregular morphologies were derived from anthopogenic sources, such as emissions from the metallurgical industry and the wear of automobile parts, respectively. In contrast, Fe-rich particles with prismatic morphologies were associated with natural sources. In relation to carbon (C), the methodology was able to distinguish between the C-rich particles that came from different anthopogenic sources—such as the burning of fossil fuels, biomass, or charcoal—and the metallurgical industry. The optical properties of the Si-rich particles depended, to a greater extent, on their chemical composition than on their morphology, which made it possible to quickly and accurately differentiate aluminosilicates from quartz. The methodology demonstrated in this study was useful for performing the speciation of the particles rich in different elements. This differentiation helped to assign their possible emission sources.

During the winter period (January–March 2016), the total suspended particles (TSP) and particulate matter smaller than 2.5μm (PM2.5) were characterized by the application of various analytical techniques in four zones of the Metropolitan Area of Monterrey in Mexico. To evaluate the seasonal variation of some elements in the particulate matter, the results of this study were compared with those obtained during the summer season (July–September 2015). The speciation of the C1s signal by X-ray photoelectron spectroscopy revealed the contribution of aromatic and aliphatic hydrocarbons as the main components in both seasons. Conversely, carboxylic groups associated with biogenic emissions were detected only in winter. The percentages of SO42− ions were lower in winter, possibly caused by the decrease in the solar radiation, and relative humidity recorded. The results of the ICP analysis revealed that Fe, Zn and Cu were the most abundant metals in both TSP and PM2.5 in the two seasons. There were significant seasonal variations for concentrations of As, Ni and Zn in the urban area and for Fe, As, Cd, Ni and Zn in the industrial zone. This was attributed to the greater burning of fuels as well as to an increase in vehicular traffic, the effect of thermal inversion and changes in some meteorological parameters. The results of the sequential microanalysis by Raman spectroscopy and SEM/EDS allowed observation of deposits of carbonaceous material on the particles and to perform the speciation of particles rich in Fe and Pb, which helped infer their possible emission sources.

The Monterrey metropolitan area (MMA) had an estimated population of 3,776,621 inhabitants in 2010, representing 81 % of the population of the northeastern Mexican State of Nuevo León. This heavily urbanized region is characterized not only by its large commercial and industrial activities, but also by its dense suspended particulate matter (SPM) pollution. Black carbon (BC), a significant component of SPM, has been recognized as a relevant health hazard and a crucial contributor for global warming due to the high capability of absorbing sunlight and contributing to the greenhouse effect. The aim of this work was to detect, characterize, and analyze the BC content in the SPM present in the MMA by scanning electron microscopy (SEM). The standardized method may be used to assemble a dataset applicable to the development of simulated climate scenarios for the region in future years. SPM concentrations were estimated to be 96.0 ± 34.8 μg/m3. SEM analyses indicated that BC content in SPM was 1.6 ± 0.3 μg/m3, with a particle size range of 0.5–10.0 μm. It is concluded that the SPM pollution from the MMA is above the World Health Organization air quality guidelines. SPM and BC levels reported in this work position the MMA as one of the most polluted urban air areas in Latin America.

BACKGROUND: Biodegradation of diesel hydrocarbons using bioreactors has been proposed as an alternative for diesel contaminated sites remediation. To make this alternative feasible, several factors must be optimized or improved: reducing hydraulic retention times (HRT) and applying design methods to enhance the access of the microorganisms to low soluble and recalcitrant compounds like hydrocarbon fuels. In the present work a time and cost efficient continuous-flow packed bed bioreactor at low HRT was designed and evaluated. The effect of non-previously studied anionic surfactant GAELE (glycolic acid ethoxylate lauryl ether) was also investigated. RESULTS: A continuous-upflow packed bed bioreactor (CPR) was built using an inexpensive support made of volcanic and alluvial stones. The biodegradation experiments conducted with a 12-month-old biofilm at a fixed HRT of 0.5 h, recorded removal of up to 97.9% at a diesel concentration of 1120 mg L-1 with GAELE. A first-order rate constant of 0.10 h-1 was calculated. Kinetic analysis using Arvin's model, which introduces mass transfer to the biofilm, showed statistical differences in the kinetic rate parameters (P < 0.001). Moreover, GAELE significantly increased biodegradability at high concentrations, with BOD5 and COD removals up to 90.8 and 80.7%, respectively. Putative hydrocarbon degrading bacteria responsible for the degradation under nitrate-reducing conditions were positively identified. CONCLUSIONS: The continuous-upflow packed bed reactor was capable of high percentage diesel biodegradation at short HRTs. The use of GAELE increased diesel availability and thus enhanced hydrocarbon removal. Therefore, CPR packed with volcanic and alluvial stones combined with GAELE showed potential for the remediation of diesel-impacted sites. Copyright (C) 2012 Society of Chemical Industry

By means of the statistical comparison of wellbeing characteristics for two groups of households in the municipality of Zinacantepec, State of Mexico, in this work we analyze the reach of the social objectives of a social responsibility program managed by the enterprise Cementos Mexicanos (Cemex). The results establish that, on the one side the users of this program build larger houses, with more rooms and faster than their non- participant neighbors, and on the other, some social objectives of the program have not been reached yet.

Mediante la comparación estadística de características de bienestar para dos grupos de hogares del municipio de Zinacantepec, Estado de México, en este trabajo se estima el alcance de los objetivos sociales de un programa de responsabilidad social administrado por la empresa Cementos Mexicanos (Cemex). Los resultados establecen que, por una parte, los usuarios de este programa construyen viviendas más grandes, con más habitaciones y en menos tiempo que sus vecinos no participantes, y por otra, que algunos objetivos sociales del programa aún no han sido alcanzados.

The efficient use of irrigation water and turf nutrition in sports fields requires the development of a management program oriented to attain both, esthetics (plant density, color and height) and sustainability. The hydroponic system under study consisted in a professional soccer field made up of sand and Bermuda grass (Cynodon dactylon). A turf nutrition and irrigation program was developed from plant nutrient removal analysis, dry matter accumulation growth data and plant water use calculations. Turf growth, measured as dry matter accumulation was adjusted using a three parameter sigmoid model (R 2 =0.981). By deriving the growth equation the maximum daily rate of dry matter accumulation was 0.579 g m -2 day -1 . Calculation of daily water evapotranspiration rate was 4.29 mm day -1 . The developed hydroponics management protocol suggests that the amounts of macronutrients (g) that should be applied to the sport field per week per m 2 must be: N, 1.74; P, 0.184; K, 0.83; Ca, 0.576 and Mg, 0.266 Along with macronutrients, the quantities of micronutrients (in mg) should include Cu, 0.361; Fe, 1.87; Mn, 1.53 and Zn, 2.25. Split doses of macronutrient and micronutrient solutions into three equal fractions for the first three irrigations each week is recommended.

En este artículo se analizan nuevas propuestas teóricas sobre tres orientaciones principales en el gasto en responsabilidad social corporativa (rsc) y se construyen índices por tipo de gasto en rsc, así como un índice de competencia. Para ello se emplearon modelos de regresión y se encontró que el tipo de gasto en rsc influye directamente sobre la utilidad esperada. La nueva propuesta teórica cuestiona gran parte de la evidencia empírica sobre la relación que guardan los gastos en rsc y la rentabilidad de las empresas que los llevan a cabo.

In this article we analyse new theoretical proposals about three main lines regarding the expenditure on corporative social responsibility (CSR) and construct indices by type of expense in CSR, as well as a competitiveness index. In order to do this, we have employed regression models to find what kind of expense in CSR directly affects the expected return. The new theoretical proposal puts into question a great deal of the empirical evidence of the relationship between CSR expenditure and the profitability of the companies that apply it.

The biodegradation kinetics of BTE-oX and MTBE, mixed all together, in the presence of bioaugmented bacterial populations as high as 880 mg/L VSS was evaluated. The effect of soil in aqueous samples and the effect of Tergitol NP-10 on substrate biodegradation rates were also evaluated. Biodegradation kinetics was evaluated for 36 hours, every 6 hours. Benzene and o-xylene biodegradation followed a first-order one-phase kinetic model, whereas toluene and ethylbenzene biodegradation was well described by a first-order two-phase kinetic model in all samples. MTBE followed a zero-order removal kinetic model in all samples. The presence of soil in aqueous samples retarded BTE-oX removal rates, with the highest negative effect on o-xylene. The presence of soil enhanced MTBE removal rate. The addition of Tergitol NP-10 to aqueous samples containing soil had a positive effect on substrate removal rate in all samples. Substrate percent removals ranged from 95.4–99.7% for benzene, toluene and ethylbenzene. O-xylene and MTBE percent removals ranged from 55.9–90.1% and 15.6–30.1%, respectively.

BTEX removal under aerobic conditions by unleaded gasoline acclimated biomass and BTEX acclimated biomass, and the effect of surfactant on BTEX biodegradation were evaluated. The effect of BTEX concentration as the sole source of carbon for biomass acclimation and the effect of yeast extract on cell growth in unleaded gasoline-fed reactors were also evaluated. For the unleaded gasoline acclimated biomass, benzene was shown the most recalcitrant among all BTEX, followed by o-xylene and toluene with 16–23%, 35–41% and 57–69% biodegradation, respectively. Ethylbenzene was consistently the fastest BTEX chemical removed with 99% biodegradation for the four bioreactor acclimated biomasses tested. For the 1,200 ppm BTEX acclimated biomass, benzene showed the highest removal efficiency (99%) among the four biomass environmental conditions tested, along with 99% toluene and 99% ethylbenzene biodegradation. O-xylene showed 92–94% removal. In all bioassays tested Tergitol NP-10 was fully removed, and did not have a substantial effect on BTEX biodegradation at the end of a 10-day evaluation.