Suchergebnisse

AbstractAmazonas state represents 37% of the Amazônia biome in Brazil. Although Amazonas remains 98% forested, its contribution to annual biome deforestation increased substantially in the past ten years. Herein, the connections between population and deforestation in Amazonas are investigated from 1985 through 2020. Anthropogenic landcover fraction and population density varied spatially and temporally across the 62 municipalities of the state. The temporal variability had specific geographic patterns, and three microregions were identified. Economic development along the southern border, arising from agricultural activities in the pattern of classical deforestation in Amazônia, was characterized by large increases in anthropogenic landcover but only small changes in population. Economic development along the Amazon River, characterized by large increases in population and anthropogenic landcover, represented urbanization and the growth of industry and agriculture. Economic development along the western border, based on trade and commerce with Peru and Colombia, corresponded to increases in population without large increases in anthropogenic landcover. The three microregions were quantitatively characterized by different slopes between anthropogenic landcover fraction and population density. The connections between deforestation and population varied by a factor of 50 × among the different microregions, suggesting important considerations for the future forest preservation in Amazonas. That time is now given the increasing importance of this region, which twice approached 20% of the total annual deforestation in Amazônia over the past decade.

One of the least understood aspects in atmospheric chemistry is how urban emissions influence the formation of natural organic aerosols, which affect Earth's energy budget. The Amazon rainforest, during its wet season, is one of the few remaining places on Earth where atmospheric chemistry transitions between preindustrial and urban-influenced conditions. Here, we integrate insights from several laboratory measurements and simulate the formation of secondary organic aerosols (SOA) in the Amazon using a high-resolution chemical transport model. Simulations show that emissions of nitrogen-oxides from Manaus, a city of ~2 million people, greatly enhance production of biogenic SOA by 60–200% on average with peak enhancements of 400%, through the increased oxidation of gas-phase organic carbon emitted by the forests. Simulated enhancements agree with aircraft measurements, and are much larger than those reported over other locations. The implication is that increasing anthropogenic emissions in the future might substantially enhance biogenic SOA in pristine locations like the Amazon. © 2019, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.