Seasonality of Isoprene Emissions in the Amazon Basin
Luciana
Vanni
Gatti, IPEN - Laboratorio de Quimica Atmosferica, lvgatti@net.ipen.br
(Presenting)
Carla
Roberta
Trostdorf, IPEN - Laboratorio de Quimica Atmosferica, crtrost@net.ipen.br
Amelia
Yamazaki, IPEN - Laboratorio de Quimica Atmosferica, amelia@net.ipen.br
Simone
Avino, IPEN - Laboratorio de Quimica Atmosferica, sissa.m@terra.com.br
Carlos
Augusto Bauer
Aquino, ULBRA- Ji-Parana, paquino@brturbo.com
Lizia
Murbach, ULBRA- Ji-Parana, lizia19@ig.com.br
Williams
Castro
Martins, UFPA - Santarem, williamsmartins@hotmail.com
Alex
Guenther, NCAR - Atmospheric Chemistry Division, guenther@acd.ucar.edu
Mark
J.
Potosnak, DRI – Desert Research Institute, Mark.Potosnak@dri.edu
Volatile organic compounds (VOC) have a major influence on the atmospheric oxidative capacity, greenhouse gas concentration and the formation of aerosols, which implies a crucial role for VOCs in climate forcing. Tropical regions are responsible for the major part of isoprene emissions from the earth’s surface. Considering the importance of tropical biomes in global VOC impacts, these regions have been the least investigated to date, and flux estimates have high uncertainties. Usually, the estimates of isoprene emission consider the temperature, PAR, LAI and specific emissions factors for the ecosystem. One year of weekly samples in the Amazon basin in 4 different places shows that the hydrological cycle produces a strong seasonality in isoprene emissions.
The objective was to study the variability during the year (2001/2002) in four different places in Amazônia. In Para state, in the Floresta Nacional do Tapajos, the studies took place in a primary forest site (Km 67 BR 163) and other at a forest where selective logging is taking place, Km 83 of BR 163. In Rondonia state the measurements were made in a primary forest (Reserva biológica do Jaru) and in a pasture site (Abracos tower). The samples were taken at two heights to obtain gradient fluxes (64m and 54m in FLONA-Tapajós towers Km 67 and 83, 60m and 50m in Rebio Jarú tower and 8m and 3m in the pasture site).
High seasonality was observed at all sites. The average concentrations during the wet season, for 50m height in the two primary forests, were 1.8ppb and 4.4ppb, and during the dry season were 3.1ppb and 5.2ppb at the Flona-Tapajos and Rebio Jarú, respectively.