Science is a lot like life: Things don’t always turn out the way you thought they would.
Recently, Eva Pfannerstill and her team wanted to find out how Amazonian plants react to ecological stresses, such as heat and drought. They wondered if they release more VOCs in such a situation. To do that, they compared data from November 2012 and 2015. 2012 was a pretty “normal” year without any significant temperature or precipitation anomaly. 2015, on the other hand, was influenced by a particularly strong El Nino. It brought extremely hot temperatures and severe drought to the region. However, the scientists were surprised to find that overall emissions were pretty much the same in the two years. But they did discover a different distribution over the day. In the El Nino year, the plants emitted most VOCs during the sunset hour. In the “normal” year the peak was at noon. They attribute this unexpected discovery to more turbulent winds associated with the high temperatures. These transport the VOCs higher, above the forest canopy to the instrument.
The study was published in Frontiers in Forest and Global Change, Issue 18 under the title “Total OH Reactivity Changes Over the Amazon Rainforest During an El Niño Event” by Pfannerstill et al. and is available Open Access.
Biogenic volatile organic compounds remove OH from the atmosphere through chemical reactions, which affects processes such as cloud formation. In a new study, Pfannerstill et al. reveal the important contributions of previously not-considered BVOCs species and underestimated OVOCs to the total OH reactivity.
Nora Zannoni and her colleagues measured BVOC emissions at the ATTO tall tower in several heights. Specifically, they looked at one particular BVOC called α-pinene. They found that chiral BOVs at ATTO are neither equally abundant nor is the ratio of the two forms constant over time, season, or height. Surprisingly, they also discovered that termites might be a previously unknown source for BVOCs.
Fungal spore emissions are an important contributor to biogenic aerosols, but we have yet to understand under what conditions fungi release their spores. Nina Löbs and co-authors developed a new technique to measure emissions from single organisms and tested this out at ATTO and with controlled lab experiments. They published their results in the Open Access Journal Atmospheric Measurement Techniques.
In a new study, Nathan Gonçalves and co-authors now wanted to find out if extreme climate events such as droughts influence leaf flushing, and thereby the average leaf age and photosynthetic capacity of the forest, and if is it possible to monitor more subtle changes associated with extreme events (compared to season changes) with satellites?
Saturno et al. analyzed the concentration of black and brown carbon in the atmosphere above the Amazon. They found that the dry season is characterized by lots of biomass burnings, which produce a lot of black and brown carbon. But they also sound significant interannual variations. The results were published in ACP.