Human health risk assessment of PM10-bound heavy metals and PAHs around the Latin America's Largest opencast coal mine.

Air pollution in opencast coal mine areas is a critical issue, resulting in harmful severe effects on human health. Therefore, it is essential to understand the air pollution factors and to assess the risks to humans. This study evaluated the potential risks (carcinogen and non-carcinogen) of inhalation exposure to PM10-bound heavy metals and Polycyclic Aromatic Hydrocarbons (PAHs) in an open pit mine in northern Colombia. During February-May 2022, PM10 samples were collected at eight sites. Heavy metals (i.e., Al, Cr(VI), Mn, Cu, Zn, As, Pb) and PAHs (thirteen priority PAHs, and one non-priority PAH) levels linked to PM10 were analyzed by X-ray fluorescence and gas chromatography-mass spectrometry, respectively. PM10 concentrations were found to range between 4.70 and 59.90 µg m-3. Out of the three different zones of the study area (i.e., North Zone, South Zone, and Populated Zone), the North Zone recorded the highest daily average concentrations of Cr(VI) (104.16 ng m-3), Mn (28.39 ng m-3), Cu (33.75 ng m-3), Zn (57.99 ng m-3), As (44.92 ng m-3), and Pb (27.13 ng m-3). The fraction of the analyzed heavy metals at all monitoring sites was 82%-89% for Al, followed by Cr(VI) with 3%-6%. Cr(VI) was the major contributor to the carcinogenic risk values, while Cu, Cr(VI), and As were the main drivers for the non-carcinogenic risk. The average cancer risk range for heavy metals was 3.30 × 10-04 -5.47 × 10-04. On the other hand, the cancer risk for PAHs exposure was acceptable. The average incremental lifetime cancer risk (ILCR) values varied between 2.87 × 10-07 and 4.21 × 10-07. Benzo[a]pyrene contributed to 54%-56% of the total risk from inhalation of PM10-bound PAHs, while Indeno[1,2,3-cd]pyrene contributed to 16%-19%. Based on the Monte Carlo sensitivity analysis, exposure to Cr(VI) was the main factor affecting cancer risk in the North, South, and Populated Zones. A suitable risk assessment and management plan requires understanding PM10-bound heavy metals and PAHs concentration levels as well as their potential health risks, mainly in open-cast coal mine zones. Our study found that people living near open-pit mines face potential health risks, so it is crucial to establish policies and regulations to control emission sources.

Characterization of aerosol particles during a high pollution episode over Mexico City.

More than 7 thousand wildfires were recorded over Mexico in 2019, affecting almost 640 thousand hectares. Most of these fires occurred during the spring season generating dense smoke plumes, impacting urban areas in the central part of the Mexican plateau. From May 10 to 17, 2019, biomass burning (BB) plumes affected Mexico City (MC) and diffused across the basin, producing PM2.5 levels ~ 2 times higher than the nation's air quality standards. Average PM2.5 concentrations increased sharply from 29.4 ± 7.2 µg m-3 to 65.1 ± 13.6 µg m-3 when the dense smoke plumes were detected. The higher particle concentration impacted the aerosol optical depth (AOD) as values ~ 3 times greater than the annual mean (0.32 ± 0.12) were measured, which resulted in a 17% loss of global horizontal irradiation (GHI). Under these severe pollution conditions, the visibility (Va) was reduced by ~ 80%. The high incidence of strong absorbent particles, such as soot and tarballs was revealed through electron microscopy and X-ray fluorescence (XRF) analysis. These techniques show chemical similarities between MC aerosols and those from the high-altitude (~ 4010 m. a. g. l.) Altzomoni Atmospheric Observatory, evidencing a strong influence of the BB emissions, suggesting a regional transport of these pollutants.

HPLC determination of the major active flavonoids and GC-MS analysis of volatile components of Dysphania graveolens (Amaranthaceae).

INTRODUCTION: Dysphania graveolens is used mainly in Mexican traditional medicine against gastrointestinal ailments. Previous investigations revealed that its flavonoids are important active principles; however, there is not a reliable and accurate analytical method for determining these compounds in the crude drug or preparations of the plant. In addition, its volatile chemical composition remains unknown. OBJECTIVE: The main goals were to develop a validated HPLC method for quantifying the active flavonoids (pinostrobin (1), pinocembrin (2) and chrysin (3)) of D. graveolens and to establish its volatile composition. METHODOLOGY: Separation was carried out on a Licrospher100 RP18 column with a linear gradient acetonitrile 0.1% formic acid and aqueous 0.1% formic acid. Accuracy was determined by spiking the crude drug with the standards, the recoveries were between 99% and 101%. A systematic description of the volatile components of D. graveolens was assessed via GC-MS using headspace solid-phase microextraction (HS-SPME) and hydrodistillation extraction methods. RESULTS: The developed HPLC method represented a powerful technique for the quality control of D. graveolens allowing the quantification of the three active flavonoids. For each compound a linear response was evaluated within the range of 0.5-2.0 mg/mL for pinostrobin (1), 0.25-1.25 mg/mL for pinocembrin (2) and 0.05-0.5 mg/mL for chrysin (3). According to SPME the major components in D. graveolens were p-cymene (84.85%) and eucalyptol (11.26%). On the other hand, the essential oil had eucalyptol (42.89%) and p-cymene (16.51%) and did not contain ascaridol. Thus the most relevant volatile components in the species were monoterpenoids.