Monitoring greenhouse gases in comandante ferraz antarctic station, King George Island

Abstract

This document presents the results of the monitoring of Greenhouse Gases (GHG) at Brazilian Antarctic Station Comandante Ferraz (EACF). The samples were taken near the Ozone and Meteorology Modules, weather conditions, such as direction and intensity of the wind, being annotated. For measurements of the concentration of GHG, a collection system that used a diaphragm pump, with samples of air being stored in stainless steel cylinders, was used. Concentrations of gases of interest in the samples collected were determined by the ozone gas chromatography laboratory, in São José dos Campos/SP. Furthermore, a continuous infrared monitor (model LI-820 Licor Gas Analyzer) was installed in the Ozone Module. There was great stability of the concentration values obtained by liquor, in that the average for these records were 378.8 ± 2.0 ppm (parts per million by volume), very close to that reported at NOAA’s (National Oceanic and Atmospheric Administration) polar station (385 ppm). Analyses of nitrous oxide (N2O) collected in the cylinders in the months of January to March 2010 resulted in an average of 334.7 ± 2.0 ppb (parts per billion by volume), very close to that reported by NOAA as a global average (323 ppb), however it was noted that this value was virtually constant in all samples, which reflected in low standard deviation, revealing an offset in our pattern to be given in subsequent samples. Samples collected in cylinders in the same period and analyzed for methane showed an average 1,791.4 ± 38.0 ppb. This value is higher than expected for the region (1,750 ppbv). However there was a wide variability in the samples (represented by the standard deviation) reflecting local sample point, mainly in the samples collected near the station. CO data did not pass in the validation tests, mainly due to their long storage time. As the CO is reactive and can undergo alteration inside the cylinder through other compounds, the storage time led to reactions inside the cylinders, causing the invalidation of the samples for this gas.