Estudos observacionais das principais fontes de emissão de compostos orgânicos voláteis (COV) em floresta intacta de terra firme na Amazônia Central

Abstract

On a global scale, the largest emissions of volatile organic compounds (VOCs) biogenic occur in the tropics, and tropical forests are considered to be the largest source of VOCs in the atmosphere. In the Amazon, a significant fraction of carbon that goes into the atmosphere is emitted as COVBs, and knowledge of these issues is important for understanding the Tropical Atmospheric Chemistry and Global and the carbon cycle, which, in turn, to understanding of global climate change. This study is part of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) and was developed in Cuieiras Reserve, north of Manaus. Sampling of VOCs were carried out in May and June 2009, samples were collected simultaneously at three different heights within the pefil floesta (1 m, 10 m and 20 m) in the K34 tower and ground (including litter, no litter and mineral soil) for determining the concentration of VOCs and data flows in the soil. The samples were analyzed with a gas chromatograph with Mass Spectrometer. We calculated the average concentrations of the compound isoprene, monoterpenes and sesquiterpenes in three different heights. Isoprene was predominant at all times, with an average concentration of about 4 ppb (parts per billion). The sum of the concentrations of monoterpenes was below 1 ppb and the concentrations of sesquiterpenes accounted for less than 2% of the VOCs identified. The highest concentrations of monoterpenes and sesquiterpenes were found to 10 m high, while for isoprene, its concentrations were directly proportional to height. Chemical species of monotrpenos the most abundant species were α-pinene, limonene and among the sesquiterpenes, the β-selineno stood out. We identified a dependence of the concentrations of terpenoids photosynthetically active radiation, mainly above 10 m, and a correlation between isoprene and the monoterpenes and sesquiterpenes. Flows of terpenes soil were higher in the presence of litter cover and discovered that the most abundant species were camphene, d-carene, o-cymene and α-copaene.