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This study explores the Hydrothermal Carbonization (HTC) treatment of lignocellulosic biomass blends, delving into the influence of several key parameters: temperature, additive nature and dosage, residence time, and biomass composition. Rapeseeds, Pinus radiata sawdust, oat husks, and pressed olive served as the studied biomasses. One hundred twenty-eight experiments were conducted to assess the effects on mass yield (MY), energy yield (EY), higher heating value (HHV), and final ash content (ASH) by a Factorial Experimental Design. The derived model equations demonstrated a robust fit to the experimental data, averaging an R2 exceeding 0.94, affirming their predictive accuracy. The observed energy yield ranged between 65% and 80%, notably with sawdust and olive blends securing EY levels surpassing 70%, while rapeseed blends exhibited the highest HHV at 25 MJ/kg. Temperature emerged as the most influential factor, resulting in an 11% decrease in MY and a substantial 2.20 MJ/kg increase in HHV. Contrastingly, blend composition and additive presence significantly impacted ASH and EY, with all blends exhibiting increased ASH in the presence of additives. Higher initial hemicellulose and aqueous extractive content in raw biomass correlated proportionally with heightened HHV.

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Glaciers in Chilean Central Andes have significatively retreated, at least, in the last 60 years. From 2004 to 2014, the largest retreat in the area (-0.15 km2 yr-1) was observed at Olivares Alpha Glacier (OAG). Previous glacier fluctuation studies proposed that two open-pit mines distant 7 km from the glacier could be the cause of its enhanced retreat. However, this had not been yet tested due to the lack of measured data. Here, we investigated the impact that major air pollutants emitted by local mining activities could have on the differences observed in OAG glacial retreat compared with a glacier of similar size and altitude with no nearby anthropogenic sources: Bello Glacier (BG), which has a reported lower retreat (-0.02 km2 yr-1). Results revealed a link between anthropogenic air pollutants and glacial retreat rates, meaning that glacial retreat is decoupled from climatic and glaciological factors. Considering that both glaciers are located in the same climatic setting, the anthropogenic air pollutants deposited onto the OAG surface appear to be forcing positive feedback in which the pollutants deposition best explain the differences in the glacier retreat. With the results of this study, it has been calculated that the impact of mining in OAG could be responsible for 82% of its total retreat since between 2004 and 2014, and only the remaining 18% would correspond to the impact of climate change.

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Some databases report global emissions of certain pollutants. Emissions Database for Global Atmospheric Research (EDGAR) project is one of these, which also records emissions by sources. In this study, the emissions of black and organic carbon and fine particulate matter from the EDGAR database were used as an input to process it in the Sparse Matrix Operator Kernel Emissions (SMOKE) model. We showed the spatial distribution of the fraction of black and organic carbon in particulate matter from each source in the Southern Hemisphere. Also, we extracted these ratios for several cities in the domain of analysis. The results and methodology of this study could improve the emission inventories with bottom-up methodology in areas without information located at Southern Hemisphere. Also, it could be relevant to obtain better performance in air quality modeling at the local level for decision-making on climate change and health effects.

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We have evaluated the spread of SARS-CoV-2 through Latin America and the Caribbean (LAC) region by means of a correlation between climate and air pollution indicators, namely, average temperature, minimum temperature, maximum temperature, rainfall, average relative humidity, wind speed, and air pollution indicators PM10, PM2.5, and NO2 with the COVID-19 daily new cases and deaths. The study focuses in the following LAC cities: Mexico City (Mexico), Santo Domingo (Dominican Republic), San Juan (Puerto Rico), Bogotá (Colombia), Guayaquil (Ecuador), Manaus (Brazil), Lima (Perú), Santiago (Chile), São Paulo (Brazil) and Buenos Aires (Argentina). The results show that average temperature, minimum temperature, and air quality were significantly associated with the spread of COVID-19 in LAC. Additionally, humidity, wind speed and rainfall showed a significant relationship with daily cases, total cases and mortality for various cities. Income inequality and poverty levels were also considered as a variable for qualitative analysis. Our findings suggest that and income inequality and poverty levels in the cities analyzed were related to the spread of COVID-19 positive and negative, respectively. These results might help decision-makers to design future strategies to tackle the spread of COVID-19 in LAC and around the world.

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BC can be transported through the atmosphere from low and mid-latitudes to Antarctica, or it can be emitted in the Antarctica in situ. To establish a possible relationship between BC and the human activities in Antarctica, shallow snow samples were taken in four sites from Antarctic peninsula during summer periods (2014-2019): Chilean Base O'Higgins (BO), La Paloma Glacier (LP) (6 km away from BO); Chilean Base Yelcho (BY) and P4 (5 km away from BY). BC concentration in snow samples was determined by using a novel methodology recently developed, published and patented by the authors. The methodology consisted in a filter-based optical transmission method at a wavelength of 880 nm. Results showed that snow from BO presented the highest BC concentration (3395.7 µg kg-1), followed by BY (1309.2 µg kg-1), LP 2016 (745.9 µg kg-1), LP 2015 (233.6 µg kg-1) and finally P4 (179.4 µg kg-1). BC values observed in Antarctic snow were higher than others previously reported in the literature and showed the influence of anthropic activities in the study area, considering that the two highest values of BC concentration in snow were found at sites near the bases. To evaluate the impact of the BC concentrations found in the snow of the study area, snow albedo modeling was performed, using the on-line version of the "Snow, Ice, and Aerosol Radiative" (SNICAR) Model. Modeling outputs exposed that the measured variations in BC content caused large differences in the modeled albedo in the visible range of the spectra, which showed to be more sensitive at lower BC concentrations. These data could help to understand the role of BC in the actual scenario of climate change, in which Antarctica is presented as a very fragile environment that needs to be protected, starting with the management of the activities developed in-situ.

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The Punchuncaví Valley is one of the most polluted areas in central Chile affected by anthropogenic emissions from the Ventanas Industrial Complex (IC) where the most important industry is the copper smelter and refinery. In this context, this research aims were to assess the usefulness of the Cupressus macrocarpa as a biomonitor. The leaf samples were taken from five selected sites, located between 0.8 and 15 km away from the source. A total of 34 elements were analyzed in leaf samples by ICP-MS and examined by enrichment factor (EF), hierarchical cluster analysis (HCA), and principal component analysis (PCA). Leaf concentration of As, Ca, Cd, Cu, Dy, Er, Gd, K, Li, Mg, Mn, Mo, Na, Nd, P, Pb, Pr, S, Sb, Sr, Ti, Yb and Zn showed statistically significant differences between sampling sites (p-value < 0.05). A clear trend to increase the concentration of Cu, Sb, S, As, Cd and Pb with the proximity to the IC. Besides, high values of Cu (93.4-369 mg kg-1) and As (7.6-12.7 mg kg-1) were observed near to industrial area exceed the phytotoxic levels reported in plants with EF > 3000% for Cu and >1300% for As. The application of PCA and HCA identified 6 factors related to the industrial complex, traffic and geogenic sources, providing the greatest variance the component related to industrial activity mainly with copper smelter and refinery. According to the results, the C. macrocarpa leaves are a good biomonitor to evaluate the high pollution load for anthropogenic elements in industrial areas.

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Polycyclic aromatic hydrocarbons, PM2.5 and micrometer-sized particles are mainly emitted by residential wood combustion, affecting air pollution in the cities of Chile. Eucalyptus globulus (EG) at 0% and 25% wood moisture was burning using a new controlled combustion chamber for emissions (3CE) to determine the emission factors of PM2.5, micrometer-sized particle numbers (0.265µm to 34.00µm) and 16 EPA-PAHs plus retene adsorbed on PM2.5 quartz filters. A method using accelerated solvent extraction, concentration, clean-up and GC-MS is proposed for determining emission factors for 16 EPA-PAHs for the concentration from biomass combustion. Chromatographic conditions and analytical steps were optimized in terms of linearity, selectivity, limits of detection and quantification, precision and accuracy. The recovery obtained from urban dust SRM 1649A (NIST reference material) analyses was between 63% (benzo[b]fluoranthene) and 102% (benzo[k]fluoranthene). In this investigation, it was shown that increasing the wood moisture in combustion tests decreased combustion efficiency (93% to 49%) and increased the emission factors of total PAHs (5215.47ngg-1 to 7644.48ngg-1), the gravimetric PM2.5 (2.01g kg-1 to 22.90gkg-1) and the total number of measured micrometer-sized particles (3.15×1012 particles kg-1 to 1.33×1013 particles kg-1) due to incomplete combustion. The PM2.5 emission rates (ERs) were estimated using EG at 0% WM (2.39g-1 to 3.15gh-1) and 25% WM (27.32gh-1 to 35.77gh-1) for three regions of Chile. In almost all regions, the Chilean emission regulations were exceeded for PM2.5 from wood combustion in the heater (stove with thermal power ≤8kW and emission limit of 2.5gh-1). Finally, when using wet wood for residential combustion, the amount of PAHs on the PM2.5 increased, presenting a potential hazard to population health. Therefore, improvements are necessary in the current regulation of PM emissions.

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Biodiesel, an alternative energy source, is promoted as cleaner and safer than other fuel options due to its reported reduction of particulate and gaseous emissions (CO2, CO, and total hydrocarbons). However, its volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbon (PAHs) emissions are key to understanding its toxic, mutagenic and carcinogenic risk factors. This research was developed to assess the genotoxic impact of exhaust emissions using biodiesel from animal fat, palm oil and soybean oil blended with diesel (B80). Diluted exhaust gases were analyzed simultaneously for pollutant emissions and for toxicity using an exposure chamber called the BioToxMonitor, where Tradescantia pallida and a KU-20 clone were exposed to exhaust following Trad-MCN and Trad-SH bioassays. The results show differences in the emission compositions and considerable mutagenic potential among the three biodiesels tested, with palm oil biodiesel emissions being the least harmful, based on its low pollutant concentrations and the negative response in the TradSH bioassay. In contrast, the animal fat biodiesel and soybean oil biodiesel emissions were as toxic as the diesel emissions, being positive in both Trad bioassays. This could be related to the PAH and carbonyl concentrations found in the vehicular exhaust. The genotoxicity of diesel emissions was related to PM1 and the concentrations of both gas and particle PAHs concentrations, which were two times higher compared to the highest concentrations observed for biodiesel. The data suggest that micronucleus assays in Tradescantia pallida are more sensitive for gaseous pollutant exposure. This is the first reported study of biodiesel exhaust biomonitoring in situ and under controlled conditions inside an exposure chamber.

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Open-air burning of agricultural wastes from crops like corn, rice, sorghum, sugar cane, and wheat is common practice in Mexico, which in spite limiting regulations, is the method to eliminate such wastes, to clear the land for further harvesting, to control grasses, weeds, insects, and pests, and to facilitate nutrient absorption. However, this practice generates air pollution and contributes to the greenhouse effect. Burning of straws derived from the said crops was emulated in a controlled combustion chamber, hence determining emission factors for particles, black carbon, carbon dioxide, carbon monoxide, and nitric oxide throughout the process, which comprised three apparent stages: pre-ignition, flaming, and smoldering. In all cases, maximum particle concentrations were observed during the flaming stage, although the maximum final contributions to the particle emission factors corresponded to the smoldering stage. The comparison between particle size distributions (from laser spectrometer) and black carbon (from an aethalometer) confirmed that finest particles were emitted mainly during the flaming stage. Carbon dioxide emissions were also highest during the flaming stage whereas those of carbon monoxide were highest during the smoldering stage. Comparing the emission factors for each straw type with their chemical analyses (elemental, proximate, and biochemical), some correlations were found between lignin content and particle emissions and either particle emissions or duration of the pre-ignition stage. High ash or lignin containing-straw slowed down the pre-ignition and flaming stages, thus favoring CO oxidation to CO2.

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There is a current tendency to develop and apply environmentally friendly techniques that meet the requirements of green analytical chemistry as an alternative to conventional analytical methods. For toxicity evaluation, these alternatives may be found in bioassays such as Tradescantia. This technique, developed in the 1980s, is highly sensitive to evaluate environmental mutagens, simple and cheap. In this paper, the sensibility of both the Tradescantia micronucleus bioassay (Trad-MCN) and the Tradescantia stamen hair bioassay (Trad-SH) were studied for carbaryl, dimethoate and iprodione, common agricultural and domestic pesticides that are currently used in Chile, which have never been tested with such bioassays. Biomonitor exposures were performed by capillary absorption for each individual pesticide over a wide range of concentrations, from maximum residue limits (trace levels) up to the application dose in agricultural fields. In addition, the organochloride 4,4'-DDE was included but only in the concentration range from 0.01mgL-1 to 1mgL-1, mimicking residue concentrations since it is not a commercial product but, rather, the main breakdown product of the persistent organochloride pesticide 4,4-DDT, whose use was discontinued in Chile in the 1980s. The Trad-MCN bioassay revealed a significant increase in micronucleus frequency at the early tetrads of meiotic pollen mother cells of the biomonitor Tradescantia pallida var. purpurea, induced by 4,4'-DDE (for 1mgL-1), dimethoate (for 40mgL-1, 200mgL-1, 400mg/L-1) and carbaryl (for 889mgL-1). Iprodione did not generate any significant change at the tested concentration. Meanwhile, the Trad-SH bioassay was carried out by analysis of the phenotype variations of the stamen hair cells of the Tradescantia clone KU-20 for the same pesticides and doses. This bioassay was not sufficiently sensitive for toxicity evaluation of most of the pesticides tested, with exception of dimethoate in low doses (2 and 5mg/L-1).

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