RESUMO
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.
Assuntos
Poluentes Atmosféricos/análise , Nitratos/análise , Material Particulado/análise , Sulfatos/análise , Poluição do Ar/estatística & dados numéricos , Atmosfera/química , Cidades , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , México , Ozônio/análiseRESUMO
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.
Assuntos
Poluentes Atmosféricos/análise , Material Particulado/análise , Poluentes Atmosféricos/química , Poluentes Atmosféricos/classificação , Poluição do Ar/estatística & dados numéricos , Cidades/estatística & dados numéricos , Monitoramento Ambiental , México , Tamanho da Partícula , Material Particulado/química , Material Particulado/classificaçãoRESUMO
The black carbon is a pollutant species primarily emitted from the combustion of fossil fuels (diesel). Their concentrations associated to PM2.5 were monitoring at two sites in the city of Guadalajara. From January to May (except April), downtown site shown 2.7, 2.6, 4.0 and 2.3 times higher monthly concentrations. The dry season two showed higher concentrations respect to at least one of the others seasons (p < 0.0001) at each site, probably due to atmospheric conditions less favorable for the dispersal of pollutants. During the 24 h period were observed at the year two peaks of concentrations: the highest morning peak and lower night peak, both probably related to anthropogenic activity.
Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Material Particulado/análise , Fuligem/análise , Emissões de Veículos/análise , Cidades , México , Tamanho da Partícula , Estações do Ano , Fatores de TempoRESUMO
The seasonal behavior of the mass of PM(2.5) and its elemental components and their contribution to the mass of the particles is described for two different sites in Guadalajara City. The average mass of the particles for the entire study period at the two sites, Centro and Miravalle (1.3 and 1.8 mg, respectively), showed significant differences (p<0.05), while differences (p<0.05) between seasons (rainy and dry season) only occurred at Miravalle. The total elemental contribution to the mass of the particles was 1.97% in Miravalle and 2.05% at Centro, with Iron and Titanium the largest contributors and most abundant elements for both sites. Likewise, the monthly contribution per element with respect to the monthly mass of all elements was estimated. The results revealed that the elements that present the biggest contribution to this mass were Iron, Titanium, Zinc and Magnesium. Iron was the largest contributor at both sites. At Miravalle, the contribution oscillated between 56 and 58% from January to June, while at Centro it oscillated between 55 and 40% for the same period of time.
Assuntos
Poluentes Atmosféricos/análise , Material Particulado/análise , Oligoelementos/análise , Poluição do Ar/estatística & dados numéricos , Monitoramento Ambiental , México , Tamanho da Partícula , Estações do AnoRESUMO
Ambient PM2.5 samples were taken at 24 h intervals at two sites (Centro and Miravalle) in the city of Guadalajara from January to June 2008. The Centro site is located in the downtown, while the Miravalle site is located in an industrial zone south of the downtown. For both sites the higher concentrations of PM2.5 were between January and May. High correlation coefficients between sulfate, nitrate and ammonium of 0.95, 0.92 and 0.91, respectively, showed low variations in the concentrations of these species in the city. It was estimated that sulfate, nitrate and ammonium represented almost 47% of the PM2.5 mass in June at the Centro site, but in general the contributions in the other months were less than 21%, while at Miravalle this percentage was between 7.7% and 27.6%.
Assuntos
Poluentes Atmosféricos/análise , Material Particulado/análise , Estações do Ano , Ânions/análise , Cátions/análise , Monitoramento Ambiental , México , Tamanho da PartículaRESUMO
Atmospheric aerosol particles were collected from January to December 2007 at two sites in the City of Guadalajara. The first site (Centro) is located in the downtown, which is characterized by high vehicular traffic, and the second site (Miravalle) is in the southern part of the city, characterized by emissions from high industrial and vehicular activity. Sulfates, nitrates, and ammonium were the most abundant ions at both sites. Similar concentrations of sulfates, nitrates, and ammonium were observed throughout the year at Centro while only sulfates and nitrates were similar at Miravalle. From the balance of anions and cations at the two sites, Centro was determined to have acidic particles, while at Miravalle, the particles were alkaline. Based on the analysis of the ammonium/sulfate molar ratios, it was determined that in Centro, there was not enough ammonium to neutralize the sulfate, while at Miravalle, ammonium practically neutralized all sulfate.
Assuntos
Aerossóis/análise , Material Particulado/análise , Cidades , Monitoramento Ambiental , Geografia , México , Nitratos/análise , Compostos de Amônio Quaternário/análise , Sulfatos/análiseRESUMO
PM2.5 samples were collected at two locations in Guadalajara: Centro and Miravalle, during 2007. The first site (Centro) is located downtown and characterized by high vehicular traffic. Miravalle is in the southern part of the city, and influenced by emissions from high industrial and vehicular activity. Samples were collected for 24 h and the annual median concentrations of PM2.5 observed were 44.1 and 52.8 microg m(-3) at Centro and Miravalle, respectively. The concentration of PM2.5 observed at the Miravalle site was significantly higher (p < 0.002). Ca, Fe, Zn, Mg and Pb were the most abundant elements found at both sites. Miravalle showed higher annual concentrations of Ca, Pb, Cu, Cr, Sr, Ni, Mo, Fe, Mn, and Sb with levels of 1013.9, 74.9, 28.2, 9.4, 6.3, 4.4, 1.0, 628.0, 23.7 and 4.6 ng m(-3), respectively. At Centro and Miravalle quarterly and annual concentrations of Pb did not exceed 290 ng m(-3) and all values are well below those specified by air quality standards. The Principal Component Analysis (PCA), Cluster Analysis and the enrichment factor (EF) based on the concentrations of each element indicated that the main source of particulates at Centro was of geological origin, while Miravalle receives emissions from natural and anthropogenic sources. Both contribute to the chemical composition of PM2.5 in Guadalajara.
Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Metais Pesados/análise , Material Particulado/análise , Poluentes Atmosféricos/química , Cálcio/análise , Cálcio/química , Análise por Conglomerados , Humanos , Metais Pesados/química , México , Tamanho da Partícula , Material Particulado/química , Análise de Componente Principal , Medição de RiscoRESUMO
The concentration of breathable particles (PM(10)) in urban areas has been associated with increases in morbidity and mortality of the exposed populations, therein the importance of this study. Organic compounds adsorbed to PM(10) are related to the increased risk to human health. Although some studies have shown the lack of correlation between specific mutagenic compounds in an organic complex mixture (OCM) and the mutagenic response in several bioassays, the same organic compounds selectively separated in less complex groups can show higher or lower mutagenic responses than in the OCM. In this study, we fractionated the OCM, from the PM(10) in four organic fractions of increasing polarity (F1-F4). The Salmonella bioassay with plate incorporation was applied for each one using TA98, with and without S9 (mammalian metabolic activation), and YG1021 (without S9) strains. The most polar fraction (F4) contained the greatest mass followed by F1 (non-polar), F2 and F3 (moderately polar). The concentrations of the OCM as well as the F4 were the only variables correlated with PM(10), atmospheric thermal inversions, fire-prone area, NO(2), SO(2), CO, rain and relative humidity. This indicated that polar organic compounds were originated in gas precursors formed during the atmospheric thermal inversions as well as the product of the incomplete combustion of vehicular exhausts and of burned vegetation. The percentages of the total PAH, and the individual PAH with molecular weight > or = 228 g mol(-1) (except retene) correlated with the percentages of indirect-acting mutagenicity in TA98+S9. The percentages of the total nitro-PAH and most of the analyzed individual nitro-PAH correlated with percentages of the direct-acting mutagenicity in both TA98-S9 and YG1021, the latter being more sensitive. In general, the highest mutagenic activity (indirect and direct) was found in F3 (moderately polar) and in F4 (polar). The non-polar fraction (F1) did not exhibit any kind of mutagenicity. In 77% of the cases, mutagenic activity was higher in the sum fractions with respect to their OCM. The combinations between F1, F2 and F4, with F3 under different or equal proportions suggested that mutagenicity reduction, in the combined matter of January (with TA98+S9 and YG1021) and of May (with YG1021), was due to concentrations of mutagens and non-mutagens in each fraction, and not to an antimutagenic effect. The organic compounds present in the non-polar fractions showed no antagonism, inhibition or reduction in the most mutagenic fractions in both indirect- and direct-acting mutagenicity, and the less polar organic compounds in F3 reduced mutagenicity in F4, in both months.