Characterization and Polydispersity of Volcanic Ash Nanoparticles in Synthetic Lung Fluid.

The inhalation of natural nanoparticles (NPs) emitted from volcanic activity may be a risk to human health. However, the literature rarely reports the fate and response of NPs once in contact with lung fluids. In this work, we studied the particle size distribution of ashfall from Popocatépetl volcano, Mexico. The collected ashes (n = 5) were analyzed with scanning electron microscopy (SEM) to obtain the elemental composition and morphology, and to determine the size of the ash particles using ParticleMetric software (PMS). The PMS reported most of the ash to have submicrometric size (<1 µm) and an average equivalent circle of 2.72 µm. Moreover, to our knowledge, this study investigated for the first time the behavior of ash NPs at different times (0 to 24 h) while in contact with in vitro lung fluid, Gamble Solution (GS) and Artificial Lysosomal Fluid (ALF) using dynamic light scattering (DLS). We found a large variability in the hydrodynamic diameter, with values less than 1 nm and greater than 5 µm. Furthermore, aggregation and disaggregation processes were recognized in GS and ALF, respectively. The results of this study increase the knowledge of the interaction between NPs and lung fluids, particularly within the alveolar macrophage region.

Fluoride presence in drinking water along the southeastern part of El Bajío Guanajuatense, Guanajuato, Mexico: sources and health effects.

Drinking water with a high natural concentration of fluoride (F-) has serious consequences for the health of the rural population in the state of Guanajuato, Mexico, where the water contains levels of F- that are not allowed by national and international regulations (1.5 mg/L). This health problem is very common in multiple states throughout Mexico where drinking water is generally extracted from aquifers that are hosted in fractured volcanic rocks of the Tertiary. These aquifers show similar geological characteristics: deep basins that formed as a result of felsic eruptive events and the extensional deformation of the Basin and Range and are now filled with unconsolidated sediments. In this study, we assessed the occurrence of F in volcanic rocks collected at 11 sampling sites along the Sierra de Codornices in Guanajuato (ranging between 0.01299 and 0.146 wt%, average 0.039 wt%, and SD = 0.039 wt%; n = 10), a region where both rural and urban communities consume drinking water with a high F- content (up to 7.1 (mg/L). The F content is dispersed in volcanic rocks, and the highest levels are present in felsic rocks. The statistical and hydrogeochemical results of a sampling campaign of 32 wells in the Juventino Rosas (JR) and Villagran (Vill) municipalities in 2019 suggest that F- mobilization in groundwater is the product of silicate weathering and the dissolution of volcanic glass, alkaline desorption in the surfaces of F-containing minerals, and possibly ion exchange of minerals and clays or deep fluids enriched with F-, in addition to the precipitation of carbonates that decrease the Ca2+ concentration in groundwater. All of these processes can be accelerated by groundwater geothermal characteristics within the study area. The hydrogeochemical, fluoride exposure risk, and fluoride pollution index (FPI) results, as well as the epidemiological survey, indicate that teenagers and older adults from Praderas de la Venta are at risk of exposure to F- due to the high concentrations ingested over a long period, the toxicity of the element, and its ability to accumulate in the bones. Extended exposure to elevated levels increases the risk. This work allows us to observe how the populations of JR and Vill can be exposed to high F- contents in drinking water due to the geological characteristics of the region.

Morphological characteristics and accumulation of arsenic in Argyrochosma formosa (Liebm.) Windham developed in a highly contaminated site with arsenic in Matehuala, SLP, México.

We studied the ability of Argyrochosma formosa growing in an arsenic heavily contaminated site to accumulate this metalloid; morphological characteristics and translocation of arsenic were evaluated in the organs. Population census of wild specimens of A. formosa was done, and 14 samples of ferns and rhizosphere soil were collected randomly. We recorded morphological characteristics with scanning electronic microscopy (SEM); concentrations of As in organs of fern plants (root, rhizome, and fronds) were evaluated with inductively coupled plasma-optic emission spectrometry (ICP-OES). Two hundred ninety-four individuals at different stages of development were identified, indicating the establishment of fern on the site. Morphological characteristics of A. formosa in fern plant organs did not show structural effects, compared with herbarium plants. Arsenic distribution in fern plant tissues was 192.2-763.6 mg/kg, 188-1017 mg/kg, and 113-2008 mg/kg, in roots, rhizomes, and fronds, respectively. The calculated bioaccumulation factor in fronds ranged from 2 to 7 and the translocation factor from 0.6 to 2.1. Our data suggest that A. formosa is an arsenic-tolerant species and propose it for phytoremediation on contaminated sites with As concentrations similar to that of the studied location. Further studies should be performed to evaluate the mechanisms of accumulation of As in plant tissues.

Impact of cadmium toxicity on cartilage loss in a 3D in vitro model.

Osteoarthritis (OA) is the gradual loss of articular cartilage and decrease in subchondral space. One of the risk factors Exposure to cadmium (Cd) through tobacco smoke has been identified as a major OA risk factor. There are no reports addressing the role of Cd in OA progression at the molecular level. Our findings revealed that Cd can promote the activation of metalloproteinases (MMP1, MMP3, MMP9 y MMP13), affecting the expression of COL2A1 and ACAN, and decreasing the presence of glycosaminoglycans and proteoglycans through an inflammatory response related to IL-1ß y a IL-6, as well as oxidative by producing ROS like O2-• and H2O2. In conclusion, our findings suggest a cytotoxic role of Cd in the articular cartilage, which could affect OA development.

Adsorption/desorption of arsenic by tropical peat: influence of organic matter, iron and aluminium.

The objective of this work was to investigate the interaction of arsenic species (As(III) and As(V)) with tropical peat. Peat samples collected in Brazil were characterized using elemental analysis and 13C NMR. Adsorption experiments were performed using different concentrations of As with peat in natura and enriched with Fe or Al, at three different pH levels. Peat samples, in natura or enriched with metals, were analysed before and after adsorption processes using Fourier transform infrared spectroscopy (FTIR) spectroscopy. The adsorption kinetics was evaluated, and the data were fitted using the Langmuir and Freundlich models. The results showed that interaction between As and peat was dependent on the levels of organic matter (OM) and the metals (Fe and Al). As(III) was not adsorbed by in natura peat or Al-enriched peat, although small amounts of As(III) were adsorbed by Fe-enriched peat. Adsorption of As(V) by the different peat samples ranged from 21.3 to 52.7 µg g(-1). The best fit to the results was obtained using the pseudo-second-order kinetic model, and the adsorption of As(V) could be described by the Freundlich isotherm model. The results showed that Fe-enriched peat was most effective in immobilizing As(V). FTIR analysis revealed the formation of ternary complexes involving As(V) and peat enriched with metals, suggesting that As(V) was associated with Al or Fe-OM complexes by metal bridging.