| Summary: | Atmospheric particles, also known as aerosols, have a significant impact on the quality of the air
we breathe, having severe consequences on human health, as well as climate. Air pollution can affect
Earth’s energy balance by reflecting or absorbing sunlight and altering cloud formation. Understanding the sources, behavior, and effects of aerosols is crucial for improving air quality and limiting their
impact on human health and the environment.
Black carbon (BC) nanoparticles, a significant component of atmospheric particulate matter, are
an important contributor to climate change due to their ability to absorb solar radiation in the atmosphere. These particles are produced through the incomplete combustion of fossil fuels and biomass
burning and are prevalent in areas with high levels of air pollution. BC particles are always coated by
organic compounds upon emission and during their presence in the atmosphere they are coated even
further, by other inorganics such as sulfates. This coating is enhancing even more the light absorption
of the BC particles.
In this study, we aim to examine the absorption of solar radiation by BC nanoparticles under various circumstances and the contribution of the coatings formed around BC particles to their optical
properties. In order to study these aspects, a method is developed which includes a thermodenuder
operating at 400oC for heating the particles connected to an Aethalometer for measuring the particle
absorption. The experiments are divided into two categories, in the first one an atmospheric simulation chamber (FORTH-ASC) is used for creating a BC rich atmosphere, originating from biomass
burning emissions while in the second category, ambient air is examined. Also, an evaluation of the
applicability of this method is performed by comparing the results of these two types of experiments.
In the laboratory experiments absorption enhancement up to 80-90% was observed for the freshly
emitted particles of olive wood burning. During the chemical aging phase, the light absorption enhancement was reduced. Finally, a strong Brown Carbon presence was observed in the olive wood
experiments, a factor that could add complexity to the BC measurements and provide some biased
concentration measurements.
The BC concentration in the ambient air surrounding the Institute was always below 1 μg m-3
. This
caused problems in the measurements and their analysis and as a result, the technique was not able to
quantify the absorption enhancement. Improvements are necessary in future efforts.
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