Tropospheric ozone (O3) is a significant anthropogenic climate forcer with uncertain distribution in the Southern Hemisphere due to sparse observations. This study analyzes 28 years of in situ ozone, methane, carbon monoxide, and meteorological data at Tololo (30.17° S, 70.80° W, 2154 m a.s.l.), Chile, integrating reanalysis and atmospheric chemistry modeling. Here we identify a rising ozone trend of 2.1 ± 0.8 ppbv per decade since 2006, possibly driven by increasing background methane. We quantify contributions from biomass burning and transport of stratospheric and upper tropospheric air to Tololo, each adding approximately 5 ppbv per event during late winter and spring O3 maximum. Events of air of stratospheric and upper tropospheric origin are linked to synoptic-scale troughs and cutoff lows, modulated by El Niño Southern Oscillation phases. These findings enhance understanding of ozone variability in the Southern Hemisphere free troposphere and underscore the importance of sustained observations at Tololo to monitor tropospheric ozone dynamics amid climate change.
Natural gas is widely used for household cooking, with methane (CH4), its main component, being a potent short-lived greenhouse gas (GHG). While a much cleaner alternative to solid fuels like wood and charcoal, natural gas combustion and leaks also contribute to GHG emissions and indoor air pollution. Yet, combustion and fugitive methane and air pollutant emissions from residential appliances, especially cookstoves, are poorly quantified in low- and middle-income countries. In this study, we measured CH4, carbon dioxide (CO2), carbon monoxide (CO), and nitrogen oxides (NOx) emissions from cookstoves in 35 homes in Santiago, Chile, and 23 in Bogotá, Colombia, two countries experiencing growth in natural gas use over the last decades. We assessed continuous (“stove-off”) methane leaks, ignition-related emissions, and combustion emissions, using a mass balance approach that accounts for air exchange rates and gas concentrations. Our real-world measurements provide rare data on household cookstove emissions and inform emission factors used in GHG inventories. The mean (median) methane emission rate during combustion was 410.2 (63.9) mg h−1 in Bogotá and 331.2 (30.7) mg h−1 in Santiago, respectively. The equivalent energy-based methane emission factors derived from the data for residential stoves in Bogotá averaged 80.8 (median = 16.2) and Santiago 41.2 (median = 3.66) kgCH4 TJ−1 are many times higher than the Tier 1 IPCC emission factors currently used in national inventories. Notably, our data suggests that continuous leaks and ignition-related emissions, which are excluded from current national and local emission inventories, contribute significantly to total methane emissions, with around 50 % of total methane emissions likely coming from continuous and episodic leaks, with the remaining half of emissions generated during combustion. For NOx, the emission factors from the measurements were 21.4 g GJ−1 (C.I., 19.1–23.8) and 15.8 g GJ−1 (C.I., 11.4–19.6) for Bogotá and Santiago, respectively. Overall, these findings suggest that current national inventories in Chile and Colombia underestimate methane emissions from household gas use, highlighting the need for more real-world measurements and research across Latin America. Our results have important implications for improving the accuracy of GHG inventories, understanding the role of household energy use in climate change, and guiding effective mitigation strategies.
The biodiversity and biogeographical distribution of chondrichthyans in the North Atlantic and Pacific oceans, as well as their connections with Eurasia and North America, underwent significant changes during the Cretaceous-Palaeogene epochs. However, little is known about these changes in the eastern South Pacific. We conducted a review of the fossil record of chondrichthyans in Chile from the Late Cretaceous to the Eocene. Our analysis reveals the presence of 11 orders, 26 families and 43 genera of chondrichthyans. The Eocene assemblages exhibited greater diversity in genera compared to those from the Maastrichtian and Late Paleocene, both of which showed a similar genus richness, but different taxonomic compositions. Similarity analyses indicate differing order dominances, with Rajiformes and Lamniformes prevalent in the Maastrichtian and Lamniformes in Palaeogene. Despite changes in oceanographic, climatic and tectonic conditions, no significant faunal turnover was observed during the Maastrichtian-Palaeogene transition. The geographic dispersion of some taxa and the similarity in climatic and oceanographic conditions across geographically distant localities containing similar faunal assemblages could explain distribution patterns. Our findings suggest that changes in faunal composition and biogeographic distribution in Chile during the Cretaceous-Palaeogene could be linked to significant past climatic and oceanographic events on global and regional scales.
INTROCUTION:The relationship between functional ability and neuropsychiatric or cognitive factors in older adults with cognitive complaints (CCs) remains unexplored in Latin America. METHODS:290 community-dwelling older adults with CCs were recruited. Multiple regression analyzed the association between activities of daily living (ADLs) and neuropsychiatric and cognitive factors. Variance proportion in ADLs were further explored. RESULTS:Apathy was associated with reduced functional ability (T-ADLQ global score [β = -0.42, 95% CI -0.57, -0.28]). Depression was linked to impaired advanced ADLs (β = 0.94, 95% CI 0.09, 1.79) and basic ADLs (β = 0.22, 95% CI 0.03, 0.42). Naming and speeded processing were significantly associated with global ADLs ((β = -0.55, 95% CI -0.99, -0.12); (β = 0.26, 95% CI 0.04, 0.48), respectively) and distinct ADLs sub-scores. DISCUSSION:Neuropsychiatric and cognitive factors affect ADLs based on their complexity. These results call for targeted interventions supporting independence in Latin American older adults.
