Absorption of solar radiation by atmospheric black carbon nanoparticles

• Κύριος συγγραφέας: Κόρκακας, Ιωάννης
• Άλλοι συγγραφείς: Korkakas, Ioannis
• Γλώσσα: English
• Έκδοση: 2023
• Θέματα: Aethalometers; Thermodenuder; Black carbon; Μαύρος άνθρακας; Αιθαλόμετρα

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.