Carbonaceous aerosols and their potential role in atmospheric chemistry

Abstract

Abstract. This paper considers the nature of carbonaceous surfaces, the means by which they are activated, the nature of some functional groups that they support, and some reaction mechanisms that may be involved. Because of the strong affinity of carbonaceous surfaces for organic species and because of the ease with which compounds in a high oxidation state can oxidize the carbonaceous surface, it is highly likely that carbonaceous aerosols are interacting chemically with a range of organic species in ways that have, as yet, not been fully characterized but may significantly affect the oxidizing capacity of our atmosphere. If HONO is formed on the surface of carbonaceous aerosols then this could be a significant source of HOz as HONO is readily photolyzed to give OH, and it could explain the large values of HONO often observed in the troposphere. In general, the reduction of NO• on carbonaceous aerosols is an important consideration, and it is addressed here.

Heterogeneous conversion of NO<sub>2</sub> and NO on HNO<sub>3</sub> treated soot surfaces: atmospheric implications

“…In addition, caused by the fractal structure of soot and by the ability to act as a reducing agent, heterogeneous reactions on soot aerosols might be of importance for the transformation of atmospheric pollutants. In particular, heterogeneous reactions of nitrogen oxides on soot surfaces have attracted considerable attention during the last years since they may have an influence on the NO x /HNO 3 ratio and on the HO x balance of the atmosphere (Bekki, 1997;Hauglustaine et al, 1996;Kotamarthi et al, 2001;Lary et al, 1997Lary et al, , 1999. Unfortunately, these model studies were based either on laboratory data determined under experimental conditions not prevailing in the atmosphere, i.e.…”

Organic and Black Carbon in PM2.5 at an Urban Site at Dhaka, Bangladesh

“…A significant fraction of the particulate OC is water soluble, making it important in particle-cloud interactions (Corrigan et al, 1999;Decesari et al, 2000). Finally, carbonaceous species have the potential to influence many heterogeneous reactions involving atmospheric particles and trace gases (Grgic et al, 1998;Lary et al, 1999). Although BC and OC are important in atmospheric chemistry and physics, information concerning their spatial and temporal variability is quite limited.…”

Aerosol composition and source apportionment in the Mexico City Metropolitan Area with PIXE/PESA/STIM and multivariate analysis

“…(Schurath and Naumann, 1998;Ravishankara, 1997). Studies show that metals such as Fe and Mn may catalyze or otherwise participate in reactions like SO 2 oxidation (Chughtai, 1993), and the large surface areas of soot and dust particles have been shown to facilitate heterogeneous reactions (Lary et al, 1999;Grassian, 2001). Because urban particles come from a multitude of sources, anthropogenic to biogenic, they are very diverse in chemical composition and structure (Johnson et al, 2005;Salma et al, 2001).…”