Publications by authors named "Alexandre Alencar"
The Antarctic Peninsula is undergoing rapid climate changes, impacting its surrounding marine ecosystem. At that site, sea ice plays a crucial role in this ecosystem by serving as a habitat for organisms and influencing primary productivity. Studying sea ice variability and primary productivity is essential for understanding environmental changes in Antarctica.
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- Refractory black carbon (rBC) can significantly contribute to ice melt when it settles on snow and ice surfaces, and its sources include both long-range transport and local activities.
- The study used detailed measurements and data analysis from the Antarctic Peninsula to evaluate the effects of rBC from both tourism and Southern Hemisphere fires, finding a rise in rBC concentrations during late spring-summer.
- Results indicate that while local tourism impacts rBC levels regionally, both local and distant emissions need to be addressed to mitigate ice melt in the area.
Despite the extent use of geochemical tracers to track warm air mass origin reaching the Antarctic continent, we present here evidences that microorganisms being transported by the atmosphere and deposited in fresh snow layers of Antarctic ice sheets do act as tracers of air mass advection from the Southern Patagonia region to Northern Antarctic Peninsula. We combined atmospheric circulation data with microorganism content in snow/firn samples collected in two sites of the Antarctic Peninsula (King George Island/Wanda glacier and Detroit Plateau) by using flow cytometer quantification. In addition, we cultivated, isolated and submitted samples to molecular sequencing to precise species classification.
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- The Hudson volcano eruption in Southern Chile (Aug 8-15, 1991) released about 2.7 km³ of volcanic material into the atmosphere, affecting regions as far as Antarctica.
- Researchers utilized dispersion models, remote sensing, and ice core analysis to track the volcanic plume and confirmed its significant regional impact compared to the Mount Pinatubo eruption.
- Post-eruption, aerosol concentrations of elements like Ca, Fe, and Zn surged dramatically, indicating a substantial increase in particulate matter levels in the atmosphere.
Background: The Antarctic moss Sanionia uncinata (Hedw.) Loeske has shown high ultraviolet (UV)-absorbers content after exposition to high levels of UV-B radiation and can be an important source of antioxidants.
Objective: The aim was to investigate photoprotection and mutagenicity by the aqueous extract (AE) and hydroethanolic extract (HE) from the Antarctic moss S.
When mosses are exposed to increased quantities of ultraviolet (UV) radiation, they produce more secondary metabolites. Antarctica moss Sanionia uncinata (Hedw.) Loeske has presented high carotenoid contents in response to an increase in UVB radiation.
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