Aerosol optical properties over the South Atlantic and southern ocean during the 2010-2012 summer seasons as part of the global maritime aerosol network.

Aerosols have implications to climate and biogeochemical cycles in the global oceans. At sites under indirect influence of dust emitted by the Patagonian semi-desert, a debate exists on the potential fertilization effects of iron enriched aerossol. Considering this subject we conducted measurements of aerosols optical properties using a Microtops II sun photometer to access aerosol size distributions and other intrinsic properties oversea from Atlantic Southern mid-latitudes to Antarctica. Oceanographic cruises were developed between December 2010 to April 2011 and October 2011 to April 2012, in the context of the Brazilian Antarctic Program, and between November 2011 to December 2011. This survey was taken as part of the Global Maritime Aerosol Network (MAN/NASA). Our data of AOD (500 nm) along the South American coast depicts a steady decrease southwards following the decreased latitudinal continental extent. However, the influence of the aerosols blown from Patagonia semi-desert region was clear from latitude 53°S to 64°S. The predominance of aerosol fine mode was observed in Central Atlantic and close to the Drake Passage. An unexpected aerosol coarse mode predominance was found close to the Antarctic Peninsula. We attribute that to a possible weathering of rock outcrops due to the strong westerly winds in that region.

Relative contributions of fossil fuel and biomass burning sources to black carbon aerosol on the Southern Atlantic Ocean Coast and King George Island (Antarctic Peninsula).

Carbonaceous aerosols can affect climate, especially particles containing black carbon (BC). BC originated from the incomplete combustion of fossil fuel and biomass, which can heat the atmosphere and increase ice melting, but little is known about BC sources to Antarctica. We quantified the contribution of distant origin (biomass burning) and local emissions (fossil fuel) to atmospheric BC concentration in the King George Island (Antarctic Peninsula) and the Southern Ocean. We examine the BC concentrations using a multi-wavelength Aethalometer AE-33 and AE-42 aboard the Brazilian Oceanographic Research Ship Almirante Maximiano. The results indicate that the region is influenced by local sources and air masses coming from surrounding continents. Fossil fuel combustion was the major source of carbonaceous aerosols in the region, whereas the total average concentration was 41.8 ± 22.8 ng m-3. The findings indicate a contribution of biomass burning coming from low and mid-latitudes of South America over the Antarctic Peninsula and the Southern Ocean around 62ºS latitude. We demonstrated that fossil fuel is the main contributor to atmospheric BC concentration for the Austral summer and autumn. Scientific stations, local tourism, and traffic are possible local BC sources. Our work invokes the urgency of questionable sustainability issues about Antarctica exploration.

Amazonian Biomass Burning Enhances Tropical Andean Glaciers Melting.

The melting of tropical glaciers provides water resources to millions of people, involving social, ecological and economic demands. At present, these water reservoirs are threatened by the accelerating rates of mass loss associated with modern climate changes related to greenhouse gas emissions and ultimately land use/cover change. Until now, the effects of land use/cover change on the tropical Andean glaciers of South America through biomass burning activities have not been investigated. In this study, we quantitatively examine the hypothesis that regional land use/cover change is a contributor to the observed glacier mass loss, taking into account the role of Amazonian biomass burning. We demonstrated here, for the first time, that for tropical Andean glaciers, a massive contribution of black carbon emitted from biomass burning in the Amazon Basin does exist. This is favorable due to its positioning with respect to Amazon Basin fire hot spots and the predominant wind direction during the transition from the dry to wet seasons (Aug-Sep-Oct), when most fire events occur. We investigated changes in Bolivian Zongo Glacier albedo due to impurities on snow, including black carbon surface deposition and its potential for increasing annual glacier melting. We showed that the magnitude of the impact of Amazonian biomass burning depends on the dust content in snow. When high concentration of dust is present (e.g. 100 ppm of dust), the dust absorbs most of the radiation that otherwise would be absorbed by the BC. Our estimations point to a melting factor of 3.3 ± 0.8% for black carbon, and 5.0 ± 1.0% for black carbon in the presence of low dust content (e.g. 10 ppm of dust). For the 2010 hydrological year, we reported an increase in runoff corresponding to 4.5% of the annual discharge during the seasonal peak fire season, which is consistent with our predictions.