RESUMEN
This work explores the efficiency of honey bees (Apis mellifera) as biosamplers of metal pollution. To understand this, we selected two cities with different urbanization (a medium-sized city and a megacity), and we collected urban dust and honey bees captured during flight. We sampled two villages and a university campus as control areas. The metal content in dust was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Atomic Force Microscopy (AFM) and Scanning electron microscopy (SEM) were used to investigate the shape and size distribution of the particles, and to characterize the semiquantitative chemical composition of particles adhered to honey bee's wings. Principal Component Analysis (PCA) shows a distinctive urban dust geochemical signature for each city, with component 1 defining V-Cr-Ni-Tl-Pt-Pb-Sb as characteristic of Mexico City and Ce-As-Zr for dust from Hermosillo. Particle count using SEM indicates that 69% and 63.4% of the resuspended dust from Hermosillo and Mexico City, respectively, corresponds to PM2.5. Instead, the particle count measured on the honey bee wings from Hermosillo and Mexico City is mainly PM2.5, 91.4% and 88.9%, respectively. The wings from honey bees collected in the villages and the university campus show much lower particle amounts. AFM-histograms confirmed that the particles identified in Mexico City have even smaller sizes (between 60 and 480 nm) than those in Hermosillo (between 400 and 1400 nm). Particles enriched in As, Zr, and Ce mixed with geogenic elements such as Si, Ca, Mg, K, and Na dominate honey bee' wings collected in Hermosillo. In contrast, those particles collected from Mexico City contain V, Cr, Ni, Tl, Pt, Pb, and Sb. Such results agree with the urban dust data. This work shows that honey bees are suitable biosamplers for the characterization of fine dust fractions by microscopy techniques and reflect the urban pollution of the sites.
Asunto(s)
Ciudades , Polvo , Monitoreo del Ambiente , Material Particulado , Abejas , Animales , México , Material Particulado/análisis , Polvo/análisis , Contaminantes Atmosféricos/análisis , Tamaño de la Partícula , Urbanización , Metales/análisisRESUMEN
People spend most of their time indoors, especially during the coronavirus disease. Prolonged exposure to heavy metal-contaminated dust can be harmful to human health. The objectives of this study were to identify the contamination level in outdoor and indoor dust, compare contamination in both environments, and assess the human health risk. Two-hundred thirty-nine samples of dust were taken by Mexico City citizens in 38 homes on the weekends of May 2020. Heavy metal concentrations were measured through XRF. The contamination level was set using the contamination factor with a local and global background value, mixed linear models were used to identify indoor and outdoor differences, and USEPA human health risk methodology was used. Pb, Zn, and Cu had the highest contamination levels, followed by Sr and Mn, using both the local and global background values. The Pb, Zn, and Cu contamination was greater indoors, while higher Mn, Sr, and Fe were detected outdoors. According to the outdoor/indoor ratios, the main sources of Ca, Pb, Zn, and Cu must be indoors, while the main sources of Fe, Mn, Sr, Y, and Ti are outdoors. A human health risk was not detected, as the hazard index was lower than one. However, ailments can be developed due to exposure to Pb, Mn, and Fe in children (hazard index > 0.1). A higher risk due to Pb exposition was found indoors. Indoor environments in Mexico City were more contaminated by heavy metals and represented a higher risk to human health than outdoors during the pandemic isolation.
Asunto(s)
COVID-19 , Metales Pesados , Niño , Humanos , Exposición a Riesgos Ambientales , Monitoreo del Ambiente/métodos , Plomo , México , COVID-19/epidemiología , Metales Pesados/análisis , Polvo/análisis , Ciudades , Medición de Riesgo , ChinaRESUMEN
This study aims to improve the current method of studying potentially toxic elements (PTEs) in urban dust using direct chemical evidence (from dust, rock, and emission source samples) and robust geochemical methods. The provenance of urban dust was determined using rare earth elements (REEs) and geochemical diagrams (V-Ni-Th*10, TiO2 vs. Zr, and Zr/Ti vs. Nb/Y). The geogenic or anthropogenic source of PTEs was determined using the enrichment factor (EF) and compositional data analysis (CoDA), while a PTE's point emission source was identified using a 3.1*La-1.54*Ce-Zn diagram, mineralogy, and morphology analyses. The spatiotemporal distribution of PTEs was determined using a geographic information system, and their health risk (by inhalation) was estimated using a lung bioaccessibility test and particle size distribution. We collected urban dust (n = 38), rock (n = 4), and zinc concentrate (n = 2) samples and determined PTEs and REEs in a city of 1.25 million inhabitants in central Mexico. Results showed that urban dust derived from the San Miguelito Range. REEs, Sc, and Zr were geogenic, while Mn, Cu, Zn, As, and Pb were anthropogenic. Due to the presente of sphalerite particles, a zinc refinery was identified as the point emission source of Zn, As, and Pb. High concentrations of Zn (5000-20,008 mg/kg), As (120-284 mg/kg), and Pb (350-776 mg/kg) were found in urban dust near the zinc refinery. Additionally, particles of PM2.5 (66-84%), PM5.0 (13-27%), PM10 (3-8%), and PM20 (0-2%) and lung bioaccessibility of Sr (48.5-72.4%), Zn (9.6-28.4%), Cu (10.5-27.0%), Fe (4.5-8.6%), Mn (2.9-9.2%), Cr (38.3%) and Pb (30.6%) demonstrated a latent risk to human health. These approaches improve our understanding of the provenance of urban dust and its PTE emission sources in urban areas.
Asunto(s)
Metales Pesados , Metales de Tierras Raras , Humanos , Metales Pesados/análisis , Monitoreo del Ambiente/métodos , Polvo/análisis , Plomo/análisis , México , Metales de Tierras Raras/análisis , Ciudades , Zinc/análisis , Medición de RiesgoRESUMEN
Oxidative stress (OS) associated with metals in urban dust has become a public health concern. Chronic diseases linked to general inflammation are particularly affected by OS. This research analyzes the spatial distribution of metals associated with OS, the urban dust´s oxidative potential (OP), and the occurrence of diseases whose treatments are affected by OS. We collected 70 urban dust samples during pre- and post-monsoon seasons to achieve this. We analyzed particle size distribution and morphology by scanning electron microscopy, as well as metal(loid)s by portable X-ray fluorescence, and OP of dust in artificial lysosomal fluid by using an ascorbic acid depletion assay. Our results show that the mean concentration of Fe, Pb, As, Cr, Cu, and V in pre-monsoon was 83,984.6, 98.4, 23.5, 165.8, 301.3, and 141.9 mg kg-1, while during post-monsoon was 50,638.8, 73.9, 16.7, 124.3, 178.9, and 133.5 mg kg-1, respectively. Impoverished areas with the highest presence of cardiovascular, cancer, diabetes, and respiratory diseases coincide with contaminated areas where young adults live. We identified significant differences in the OP between seasons. OP increases during the pre-monsoon (from 7.8 to 237.5 nmol AA min-1) compared to the post-monsoon season (from 1.6 to 163.2 nmol AA min-1). OP values are much higher than measured standards corresponding to contaminated soil and urban particulate matter, which means that additional sources beside metals cause the elevated OP. The results show no risk from chronic exposure to metals; however, our results highlight the importance of studying dust as an environmental factor that may potentially increase oxidative stress.
Asunto(s)
Monitoreo del Ambiente , Metales Pesados , Adulto Joven , Humanos , Monitoreo del Ambiente/métodos , Metales/análisis , Polvo/análisis , Estrés Oxidativo , Enfermedad Crónica , Metales Pesados/toxicidad , Metales Pesados/análisis , Medición de RiesgoRESUMEN
In this work, a methodology for chemical speciation analysis of inorganic As and Sb in urban dust using slurry sampling and detection by fast sequential hydride generation atomic absorption spectrometry is proposed. Doehlert design and desirability function were used to find the optimum conditions for hydride generation (1.0 mol L-1 HCl and 0.9% m v-1 NaBH4). The accuracy of the analytical method was evaluated by analysis of reference material fly ash (BCR 176R), addition and recovery tests for inorganic As species, and comparison of independent methods for Sb determination in urban dust samples. The determination of the total concentrations of As and Sb and their inorganic species presented good accuracy, between 80 ± 1 and 101 ± 6%. Precision was expressed as the relative standard deviation and was better than 4.7% (n = 3). The limit-of-quantification values were 0.23 and 1.03 mg kg-1 for As and Sb, respectively. The methodology was applied to eight samples of dust collected in an urban area of Salvador and Jaguaquara cities, Bahia, Northeast, Brazil, with an aerodynamic size lower than 38 µm. Concentrations of pentavalent inorganic species (iAs5+ and iSb5+) in relation to trivalent species (iAs3+ and iSb3+) were found in urban dust collected in the city of Salvador, which are regarded as more toxic for both elements. The enrichment factor and geoaccumulation index (Igeo) values showed that for some samples, the concentrations of iAs and iSb presented strong enrichment and, and regarding environment, strong to moderately polluted by iAs and iSb, with an indication of anthropogenic contributions. The occurrence of these inorganic constituents in the urban area of Salvador can be related with intense industrial activities and vehicular traffic.