Winter is coming. In the northern hemisphere that is. In these regions, trees are shedding their leaves this time of year, preceded by those beautiful fall colors. Tropical forests like the Amazon do not have such pronounced seasons and are evergreen. Yet they still shed leaves and flush new ones fairly regularly about once a year. What drives the seasonality of leaf flushing we still do not fully understand. But we do now know that this is a really important process because it influences the photosynthetic capacity of the forest. Simply speaking, young leaves are more effective than old ones in performing photosynthesis and sequestering carbon.
Air pollution is created by enhanced concentrations of particles in the air. Some of these particles are so large that you can easily see them, such as dust or sand. However many are much smaller so that they can’t be seen with the naked eye. This fine particulate matter (PM2.5) is often more dangerous because smaller particles can penetrate deeper into the lung. In addition, these particles play an important role in our climate system. In the atmosphere, for example, they absorb and reflect light, and act as condensation nuclei for clouds. Thus PM2.5 plays a key role for public health and for climate change.
Christopher Pöhlker and co-authors published an extensive new paper, characterizing the footprint region of ATTO. They hope that fellow researchers in the Amazon region can use this publication as resource and reference work to embed ATTO observations into a larger context of Amazonian deforestation and land use change. Pöhlker et al. published the paper Open Access in Atmospheric Chemistry and Physics Volume 19.
In their study, they used backward trajectories to first define the ATTO footprint region. With this modeling approach, you can trace air masses in the atmosphere back along their presumed transport path to ATTO. Because the source regions of observed trace gases and aerosols might be thousands of kilometers away, they did not necessarily trace it all the way back.
We hear a lot about particulate matter these days, mostly in the context of air pollution in inner cities. But what about particulate matter in the Amazon rainforest? Well, the short answer is that particulate matter is present in the air above the Amazon, too. And although its concentrations are lower than those in large cities, urbanization and deforestation fires have a significant impact. To find out what that impact exactly is, was the aim of a new study by Suzane de Sá and co-authors.
They analyzed the concentration, composition and properties of particulate matter in the central Amazon. As part of the GoAmazon campaign, they collected data during the dry season, when burning events are most frequent.… Continue reading
It is well established that aerosols are relevant for the climate, for example, because they contribute to cloud formation. However, natural, biological aerosols emitted by plants serve another important purpose. They help disperse living microorganisms across the globe, affecting their distribution. Yet little is known about those bioaerosols emitted by pristine forests such as the Amazon. And even less about the diversity of the microorganisms in the aerosols.
Felipe Souza and co-authors now collected bioaerosols at our ATTO site. Then they extracted and analyzed the DNA to determine the communities present. This is the first study which described the community of microorganisms within aerosols in the Amazon.