RESUMEN
Emissions of gaseous elemental mercury (GEM or Hg0) from different sources in urban areas are important subjects for environmental investigations. In this study, atmospheric Hg measurements were conducted to investigate air pollution in the urban environment by carrying out several mobile surveys in Mexico City. This work presents atmospheric concentrations of GEM in terms of diurnal variation trends and comparisons with criteria for pollutant concentrations such as CO, SO2, NO2, PM2.5, and PM10. The concentration of GEM was measured during the pre-rainy period by using a high-resolution active air sampler, the Lumex RA 915 M mercury analyzer. In comparison with those for other cities worldwide, the GEM concentrations were similar or slightly elevated, and they ranged from 0.20 to 30.23 ng m-3. However, the GEM concentration was significantly lower than those in contaminated areas, such as fluorescent lamp factory locations and gold mining zones. The GEM concentrations recorded in Mexico City did not exceed the WHO atmospheric limit of 200 ng m-3. We performed statistical correlation analysis which suggests equivalent sources between Hg and other atmospheric pollutants, mainly NO2 and SO2, emitted from urban combustion and industrial plants. The atmospheric Hg emissions are basically controlled by sunlight radiation, as well as having a direct relationship with meteorological parameters. The area of the city studied herein is characterized by high traffic density, cement production, and municipal solid waste (MSW) treatment, which constantly release GEM into the atmosphere. In this study, we included the simulation with the HYSPLIT dispersion model from three potential areas of GEM release. Emissions from industrial corridors and volcanic plumes localized outside the urban area contribute to the pollution of Mexico City and mainly affect the northern area during specific periods and climate conditions. Using the USEPA model, we assessed the human health risk resulting from exposure to inhaled GEM among residents of Mexico City. The results of the health risk assessment indicated no significant noncarcinogenic risk (hazard quotient (HQ) < 1) or consequent adverse effects for children and adults living in the sampling area over the study period. GEM emissions inventory data is necessary to improve our knowledge about the Hg contribution and effect in urban megacity areas with the objective to develop public safe policy and implementing the Minamata Convention.
Asunto(s)
Contaminantes Atmosféricos , Mercurio , Contaminantes Atmosféricos/análisis , Niño , Ciudades , Monitoreo del Ambiente/métodos , Humanos , Mercurio/análisis , México , Dióxido de Nitrógeno/análisis , Medición de RiesgoRESUMEN
Cytotoxic and pro-inflammatory effects of mini-screws subject to corrosion in oral cells culture. To analysis the products of corrosion of three different commercial orthodontic mini-screws and evaluate the cytotoxicity and pro-inflammatory effects in culture with human gingival fibroblast cells (HGFs) and human osteoblast-like bone surface cells (HBCs). An experimental in vitro study was carried out with 3 different type of mini-screws: Vector-Tas®, Forestadent ORTHOEasy®, Bio-Ray® (n = 30/gp). The samples were subjected to accelerated corrosion for 24, 48, 72 and 96 hours, which were observed with a stereomicroscope and scanning electron microscope. The corrosion products were analyzed by inductively coupled plasma with mass spectrometry. The direct and indirect cytotoxicity was tested in culture with HGFs and HBCs, cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The pro-inflammatory effect was determined by the expression of prostaglandin E2 (PGE2) with the ELISA test. The data were subjected to Shapiro-Wilks normality tests, paired t-tests and Tukey's post hoc ANOVA. The mini-screw topography showed significant morphological changes after corrosion. The main ions after corrosion were Al, Ti, and Fe. Corrosion products by direct and indirect contact with cells slightly reduced (P < 0.05) cell viability, considered non-cytotoxic. The expression of PGE2 was not increased by the presence of the corrosion products even in a previous pro-inflammatory state. The corrosion products were not cytotoxic and did not induce a pro-inflammatory state in culture with HGFs and HBCs.
Asunto(s)
Tornillos Óseos , Titanio , Técnicas de Cultivo de Célula , Corrosión , Humanos , OsteoblastosRESUMEN
This paper presents atmospheric gaseous elemental mercury (GEM) data recorded during two short-term monitoring surveys in the Mexico City Metropolitan Area (MCMA) at 12th May 2019 and at 22nd May 2020, during conditions of low and high human activity respectively. Results, although they are limited, can be considered as the representative range of exposure to GEM of the inhabitants of MCMA; differences in results reveal the impact of human activities on GEM background levels (2.53 and 3.76 ng m-3, respectively). GEM concentrations and their spatial distribution does not allow for the identification of important industrial sources and do not reach intervention pollution levels. The activity of the Popocatépetl volcano is not likely to have an effect on GEM in the MCMA. In spite the evident decrease in GEM concentrations compared with data previously reported, monitoring must be carried out routinely given Mexico's participation in the Minamata Convention on Mercury.
Asunto(s)
Contaminantes Atmosféricos , Mercurio , Contaminantes Atmosféricos/análisis , Ciudades , Monitoreo del Ambiente , Humanos , Mercurio/análisis , MéxicoRESUMEN
In this work, we report metals concentrations in 80 PM10 samples collected at four sites in the Mexico City Metropolitan Area (MCMA): Tlalnepantla (NE), Xalostoc (NE), Merced (C), and Pedregal (S), during the dry/cold season (October to January) for the 2004-2014 period. Mean PM10 mass concentration (66.1 µg m-3) significantly exceeds the annual mean air quality guidelines recommended by the World Health Organization. The statistical analysis of concentration data and meteorological parameters allows us to recognize the importance of wind intensity speed (Wsp) and wind direction conditions in the enrichment of PM concentrations. The proximity and magnitude of the emitting source is also relevant for PM concentration. Such conditions favored that higher metal concentration was recognized at the north of the studied area. By means principal component analysis (PCA) was difficult to identify the groups of metals associated with specific sources (anthropogenic and geogenic) given the high complexity of the study area and the long period of time evaluated. Metal concentration trend shows an important positive trend for Pt, V and Cr, while PM10, Ni, Cu, Ag and Sb show a trend of moderate increase. In contrast, Pb and Co registered a strong percentage reduction, while Hg, Mn, As and Cd show a slight reduction, probably resulting from the implementation of regulatory measures and influenced by urban changes associated at the north of the studied area. The results of this research provide information that should be considered for evaluating the impact of anthropogenic sources and applying regulatory measures to control emissions.
Asunto(s)
Contaminantes Atmosféricos/análisis , Metales Pesados/análisis , Metales/análisis , Material Particulado/análisis , Contaminación del Aire/análisis , Ciudades , Monitoreo del Ambiente/métodos , México , Estaciones del Año , VientoRESUMEN
The data obtained in this study represent a comprehensive assessment of human exposure to metal(loids) enriched in the environment, derived from metallurgical activities in Cedral, a town in North-Central Mexico. A multi-elemental analysis (As, Cd, Cr, Cu, Fe, Mn and Sb) shows high metal(loid) content in environmental media (tailings samples, dust samples and particulate matter < 2.5 µm collected in the urban area). Blood samples from school-age children were collected and analyzed to determine exposure levels. The assessment of the data obtained from this study shows that Sb and Cd are highly enriched elements in the environment of Cedral; their respective levels in the blood samples analyzed are 10.9 and 11.3 times higher than their pediatric reference levels. The statistical analysis indicates a strong relationship between metal(loid)s in blood samples and both dust and PM2.5 samples, which reveal that ingestion and inhalation could represent important exposure routes for metal(loid) intake. Continuous monitoring in the area is paramount to assess the health impact posed by the different routes of exposure. It is also important to implement health education programs to decrease the population's exposure to metal(loid)s and to design urgent remediation measures, to be implemented as soon as possible.
Asunto(s)
Metales Pesados , Metales , Niño , Polvo/análisis , Monitoreo del Ambiente , Humanos , Metalurgia , Metales/análisis , Metales Pesados/análisis , Material Particulado/análisis , Medición de RiesgoRESUMEN
The application of Sb, Pt and Hg in the development of new strategic technologies has increased significantly in recent years. This study evaluates the impact of vehicular traffic on the rise in emission of Sb, Pt and Hg in the atmospheric environmen of Mexico City and their correlation to Co, Cr, Cu, Ni, Pb, V and Zn. Ficus benjamina leaves were collected as biomonitor of atmospheric metals deposited in areas exposed to heavy vehicular traffic. High enrichment factor values (metal(loid) concentration/background values) were calculated: 146 (Sb), 52.8 (Pb), 29.7 (Pt) and 25.1 (Cr). Enrichment factors of Ni, Zn, Co, V, Cu and Hg decrease in that order and are < 10. Principal component analysis allows recognize that most of the analyzed metal(loids) are related to traffic sources; Ni and Cr are also attributable to an additional anthropogenic source. No relationship was found relating Pb to vehicular sources.
Asunto(s)
Ficus , Mercurio , Metales Pesados , Oligoelementos , Antimonio , Ciudades , Monitoreo del Ambiente , Metales Pesados/análisis , México , Platino (Metal) , Oligoelementos/análisisRESUMEN
The Mexico City Metropolitan Area (MCMA) was the object of a chemical elemental characterization (Ti, V, Cr, Mn, Co, Ni, Cu, Mo, Ag, Cd, Sb, Pb, La, Sm, Ce, and Eu) of PM2.5 collected during 2013 and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Sampling campaigns were carried out at five locations simultaneously-northwest, northeast, center, southwest, and southeast-during dry-warm season (April), rainy season (August), and dry-cold season (November). By means of enrichment factor (EF) and principal component analysis (PCA), it was possible to attribute the analyzed elements to geogenic and anthropogenic sources, as well as to identify a group of elements with mixed provenance sources. The highest concentrations for most metals were found in northwest and northeast, and during dry-warm (DW), confirming the trend observed in PM2.5 samples collected in 2011. Despite similarities between 2011 and 2013, an increase of 17% in PM2.5 mass concentration was observed, mainly attributable to geogenic sources, whereby the importance of wind intensity to the impact of emission sources is highlighted. The effect of wind intensity was revealed, by means of polar plots, as the controlling mechanism for this increase. This allowed us to conclude that high-speed episodes (5 m s-1) were responsible for raising geogenic metal concentrations rather than wind direction.
Asunto(s)
Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente , Material Particulado/análisis , Ciudades , Metales/análisis , México , Estaciones del Año , VientoRESUMEN
In this study, atmospheric mercury concentration in airborne particulate matter with an aerodynamic diameter ≤ 2.5 µm (PM2.5) was analyzed by ICP-MS. Samples were collected in the Mexico City Metropolitan Area (MCMA), during 2013, in five locations, Northwest, Northeast (NE), Central, Southwest and Southeast, along three seasons: dry warm, rainy, and dry cold (DC). It can be observed that NE shows the highest mercury concentration (p < 0.05), where pollution events were identified. The seasonal distribution shows that samples collected during DC present the highest concentration (p < 0.05). These results are in agreement with the distribution of important mercury industrial sources located in the northern urban area as well with the temperature and wind conditions during 2013. The comparison of data obtained in this work with those of similar previous studies clearly indicates a decrease, between 2006 and 2013, of mercury content in PM2.5 collected in MCMA.
Asunto(s)
Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente/métodos , Mercurio/análisis , Material Particulado/análisis , Ciudades , México , Tamaño de la Partícula , Estaciones del Año , VientoRESUMEN
Mining and metallurgy generate residues that may contain thallium (Tl), a highly toxic metal, for which it is currently not feasible to determine its geochemical speciation through X-ray absorption spectroscopy due to a combination of very low contents and the interference of accompanying high arsenic contents. Therefore, fractionation studies in residues and soils are required to analyze the mobility and bioavailability of this metal, which in turn provide information to infer its speciation. For this purpose, in this work a modification of the BCR procedure was applied to residues and contaminated soils from three mining zones of Mexico and two mining zones of Spain, spanning samples with acidic to alkaline pH values. The Tl extraction procedure consisted of the following fractions: (1) water-extractable, (2) easily exchangeable and associated to carbonates, associated to (3) poorly-crystalline and (4) crystalline Fe and Mn oxyhydroxides, and (5) associated to organic matter and sulfides; and finally a residual fraction as associated to refractory primary and other secondary minerals. The extracted contents were analyzed by Inductively-Coupled Plasma with Mass Spectrometry. Surprisingly, water-soluble, in Tl(I) oxidation state, was detected in most areas, regardless of the pH, a fact that has not been reported before in these environments, and alerts to potential health risks not previously identified. Most of the samples from a metallurgy area showed high levels of Tl in non-residual fractions and a strong correlation was obtained between extracted Mn and Tl in the third fraction, suggesting its association to poorly crystalline manganese oxides. In the majority of samples from purely mining environments, most of the Tl was found in the residual fraction, most probably bound to alumino-silicate minerals. The remaining Tl fractions were extracted mainly associated to the reducible mineral fractions, and in one case also in the oxidizable fraction (presumably associated to sulfides). Capsule: Soluble Tl(I) was found in all soil samples contaminated with either mining or metallurgical wastes. Additionally, in those affected by metallurgical wastes a very strong Tl-Mn correlation was found.
Asunto(s)
Monitoreo del Ambiente , Metalurgia , Minería , Contaminantes del Suelo/análisis , Talio/análisis , Arsénico/análisis , Carbonatos , Fraccionamiento Químico , Contaminación Ambiental/análisis , Contaminación Ambiental/estadística & datos numéricos , Compuestos de Manganeso , México , Minerales/análisis , Óxidos , Suelo/química , España , Sulfuros/análisis , Espectroscopía de Absorción de Rayos XRESUMEN
The study of airborne metals in urban areas is relevant due to their toxic effects on human health and organisms. In this study, we analyzed metals including rare earth elements (REE) in particles smaller than 2.5 µm (PM2.5), collected at five sites around the Mexico City Metropolitan Area (MCMA), during three periods in 2011: April (dry-warm season, DW), August (rainy season, R), and November (dry-cold season, DC). Principal component analysis allowed identifying factors related to geogenic sources and factors related to anthropogenic sources. The recognition of the high impact of geogenic sources in PM2.5 is in agreement with the REE distribution patterns, which show similar behavior as those shown by igneous rocks, confirming the influence of the regional geogenic material. Metals associated to geogenic sources showed higher concentration (p < 0.05) at NE of the MCMA and a significant correlation with prevalent winds. Geogenic metals show similar seasonal distribution, with the highest concentration during DW (p < 0.05), suggesting a possible metal resuspension effect which affects more significantly at lower relative humidity (RH). The metals associated with anthropogenic sources are in agreement with the urban complexity of the area, showing homogenous distribution throughout MCMA (p > 0.05) and no similar seasonal pattern among them. These unexpected results exposed outstanding information regarding the identification of different geogenic sources as the main contributors of metals in the atmospheric environment in the MCMA and highlighted the importance of meteorology in the spatial and seasonal metal patterns.
Asunto(s)
Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente , Metales/análisis , Material Particulado/análisis , Ciudades , Humanos , México , Estaciones del Año , VientoRESUMEN
Tree rings may be used as indicators of contamination events providing information on the chronology and the elemental composition of the contamination. In this framework, we report PGEs enrichment in growth rings of Taxodium mucronatum ten for trees growing in the central area of Mexico City as compared to trees growing in a non-urban environment. Concentrations of PGE were determined by ICP-MS analysis on microwave-digested tree rings. The element found in higher concentrations was Pd (1.13-87.98 µg kg(-1)), followed by Rh (0.28-36.81 µg kg(-1)) and Pt (0.106-7.21 µg kg(-1)). The concentration trends of PGEs in the tree-ring sequences from the urban area presented significant correlation values when comparing between trees (r between 0.618 and 0.98, P < 0.025) and between elements within individual trees (r between 0.76 and 0.994, P < 0.01). Furthermore, a clear increase was observed for rings after 1997, with enrichment of up to 60 times the mean concentration found for the sequence from the non-urban area and up to 40 times the mean concentration for the pre-1991 period in the urban trees. These results also demonstrate the feasibility of applying T. mucronatum ten to be used as a bioindicator of the increase in PGE in urban environments.
Asunto(s)
Contaminantes Atmosféricos/metabolismo , Monitoreo del Ambiente , Metales Pesados/metabolismo , Taxodium/metabolismo , Emisiones de Vehículos/análisis , México , Platino (Metal)/metabolismoRESUMEN
The increase in platinum (Pt) in the airborne particulate matter with size ≤2.5 µm (PM2.5) in urban environments may be interpreted as result of the abrasion and deterioration of automobile catalyst. Nowadays, about four million vehicles in Mexico City use catalytic converters, which means that their impact should be considered. In order to evaluate the contribution of Pt to environmental pollution of the metropolitan area of Mexico City (MAMC), airborne PM2.5 was collected at five different sites in the urban area (NW, NE, C, SW, SE) in 2011 during April (dry-warm season), August (rainy season) and December (dry-cold season). Analytical determinations were carried out using a ICP-MS with a collision cell and kinetic energy discrimination. The analytical and instrument performance was evaluated with standard road dust reference material (BCR-723). Median Pt concentration in the analyzed particulate was is 38.4 pg m(-3) (minimal value 1 pg m(-3) maximal value 79 pg m(-3)). Obtained Pt concentrations are higher than those reported for other urban areas. Spatial variation shows that SW had Pt concentration significantly higher than NW and C only. Seasonal variation shows that Pt median was higher in rainy season than in both dry seasons. A comparison of these results with previously reported data of PM10 from 1991 and 2003 in the same studied area shows a worrying increase in the concentration of Pt in the air environment of MAMC.
Asunto(s)
Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente , Material Particulado/análisis , Platino (Metal)/análisis , Ciudades , Polvo/análisis , Espectrometría de Masas/métodos , México , Tamaño de la Partícula , Estaciones del AñoRESUMEN
Concentrations of vanadium, chromium, cobalt, nickel, copper, zinc, antimony, and lead were measured in Ficus benjamina leaves from the Mexico City urban area in order to assess their enrichment against background values. The instrumental analysis was performed using inductively coupled plasma mass spectrometry and the analytical method was tested using two certified reference materials from the National Institute of Standards and Technology (1547 Peach Leaves and 1573a Tomato Leaves). Enrichment factors were calculated, i.e., total to background concentration ratio, for each metal. Low enrichments of vanadium, cobalt, nickel, and copper (≈2), and mild enrichments of chromium and zinc (4.4, 4.5 respectively) were found in the entire area; oppositely, high enrichments were assessed for antimony (28.6) and lead (17.2). However, results indicate that metal concentrations strongly depend on the specific urban sub-area. Increments of metals were attributed to natural, vehicular, and industrial sources.
Asunto(s)
Contaminantes Atmosféricos/metabolismo , Atmósfera/química , Ficus/metabolismo , Metales Pesados/metabolismo , Contaminación del Aire/estadística & datos numéricos , Monitoreo del Ambiente , México , Hojas de la Planta/metabolismoRESUMEN
The environmental damage caused by industrial activities in Cromatos de México, (Tultitlán, México) has been evaluated in terms of heavy metal concentrations in topsoils of the surrounding area. The concentrations of lead, copper and zinc demonstrate a significant enrichment with respect to unpolluted levels. Their maximum enrichment factors are 37.7, 21.1 and 9.6 mg kg⻹, respectively; such increase is related to traffic emissions. Nickel concentrations show no significant difference in the analyzed samples. Total chromium concentrations show a significant decrease with distance from the industrial facilities, ranging from 15 to 1,837 mg kg⻹. The enrichment factors of chromium (total), with respect to the background values reach up to 40.8 mg kg⻹. In spite of this pronounced increase, only three analyzed samples show chromium (VI) concentrations over 0.5 mg kg⻹ (instrumental detection limit) and do not exceed the values recommended by the Mexican official norm. The current results show that the chromium present in the studied area does not represent serious health risks and environmental damage in the zone, nevertheless, it is necessary to consider that the oxidation of chromium (III) is determinate by changes in redox and/or pH conditions which would imply significant impacts upon its toxic risk. This study suggests that the waste material generated during the industrial activities of Cromatos de Mexico represents a relevant metal pollution source for the area even 30 years after the closure of the industrial facilities.