Diurnal cycles of formic and acetic acids in the northern part of the Guayana shield,Venezuela |
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| Authors: | W R Hartmann M Santana M Hermoso M O Andreae E Sanhueza |
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| Institution: | (1) Max-Planck-Institut für Chemie, Postfach 3060, D-6500 Mainz, Germany;(2) Instituto Venezolano de Investigaciones Científicas, (IVIC), Apartado 21827, 1020-A Caracas, Venezuela |
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| Abstract: | Formic and acetic acids were measured in a scrub-grass savanna and in a nearby semideciduous forest. Gaseous HCOOH and CH3COOH were collected using the mist-scrubber technique, and were determined using ion chromatography. A strong diurnal cycle was observed at both sites, with higher mixing ratios during daytime. Concentrations in the savanna were always higher than in the forest. Most of the time HCOOH/CH3COOH ratios greater than one were recorded at the savanna site, and ratios less than one at the forest site. Boundary-layer mixing ratios in the savanna region, derived from measurements during midday, are 1.3±0.4 ppbv and 0.7±0.3 ppbv for HCOOH and CH3COOH. Dry depositions velocities between 0.5 and 1 cm s-1 were estimated for the savanna region. Atmospheric residence times of <3 days and >5 days were estimated for the rainy and dry season, respectively. |
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| Keywords: | Tropical atmosphere formic acid acetic acid |
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