Related Experiment Video
Updated: Mar 26, 2026

Production and Measurement of Organic Particulate Matter in the Harvard Environmental Chamber
Published on: November 18, 2018
Unexpected seasonality in quantity and composition of Amazon rainforest air reactivity
A C Nölscher1, A M Yañez-Serrano1,2, S Wolff1,2
1Air Chemistry and Biogeochemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany.
Abstract:
The hydroxyl radical (OH) removes most atmospheric pollutants from air. The loss frequency of OH radicals due to the combined effect of all gas-phase OH reactive species is a measureable quantity termed total OH reactivity. Here we present total OH reactivity observations in pristine Amazon rainforest air, as a function of season, time-of-day and height (0-80 m). Total OH reactivity is low during wet (10 s(-1)) and high during dry season (62 s(-1)). Comparison to individually measured trace gases reveals strong variation in unaccounted for OH reactivity, from 5 to 15% missing in wet-season afternoons to mostly unknown (average 79%) during dry season. During dry-season afternoons isoprene, considered the dominant reagent with OH in rainforests, only accounts for ∼20% of the total OH reactivity. Vertical profiles of OH reactivity are shaped by biogenic emissions, photochemistry and turbulent mixing. The rainforest floor was identified as a significant but poorly characterized source of OH reactivity.
Related Concept Videos
What is Climate?
The Sulfur Cycle
Global Climate Change
Precipitation Processes
Precipitation Reactions
Microbes and Climate Change

