Special Symposia

There must be something in the water: Cloud, fog and aerosol aqueous chemistry for aerosol production

Organizers:
Annmarie G. Carlton, University of California at Irvine
V. Faye McNeill, Columbia University

Aqueous chemical processing of soluble gases in cloudwater, fogs, and wet aerosol particles is an important source of particulate matter. The production of aerosol sulfate in cloudwater is a classic example, and aqueous secondary organic aerosol (SOA) formation in clouds, aerosol water, and fog has emerged as a significant source of aerosol mass in recent years. From a policy perspective, these processes are often driven by both biogenic and anthropogenic emissions – and therefore are only partially “controllable”. A typical aerosol may take up water to form a cloud droplet, and dry out again, several times over the course of one day, leaving the signature of aqueous chemistry in both cloud and aerosol modes in its composition. The drying phase of the aerosol-cloud cycle is also believed to promote aqueous organic chemistry such as oligomerization and the formation of nitrogen-containing and sulfur-containing aerosol brown carbon species, even beyond what may be expected due to the concentration factor. This symposium will highlight studies of atmospheric aqueous chemistry and its connections to aerosol production, from field, modeling, and laboratory perspectives, and from the molecular to the regional and global scales.

 

Passive mitigation strategies to reduce exposure to near-road air pollution

Organizers:
K. Max Zhang, Cornell University
Richard W. Baldauf, US Environmental Protection Agency

Epidemiological and toxicological studies from researchers worldwide have linked human exposure to traffic-related air pollutants near roadways with a wide range of adverse health effects. While emission control technologies and programs to directly reduce air pollution emissions (referred to as “active” mitigation) are vital components of air quality management, a considerable amount of research has been carried out to identify, develop and evaluate “passive” mitigation strategies to reduce exposure to near-road air pollution. These passive strategies include, but are not limited to, alterative roadway/street configurations, solid barriers (e.g., noise barriers, low boundary walls and parked cars), porous barriers (e.g., vegetation), green walls, and indoor infiltration. Passive mitigation strategies can be incorporated into future urban planning efforts and offer long-term solutions to urban air quality. This symposium aims to bring together academics, governmental agencies, and community organizations to share the latest research findings, lessons learned from past experiences, and potential policy implications and applications.

 

Linking aerosol oxidative potential with chemical composition and biological endpoints

Organizer:
Vishal Verma, University of Illinois at Urbana-Champaign

The current national ambient air quality standards for PM2.5 are based on particulate mass. Although epidemiological research conducted in the last few decades have associated PM mass with both respiratory and cardiovascular diseases, the heterogeneous and inconsistent nature of these associations suggests that not all components of PM are equally toxic. The capability of ambient particles to generate reactive oxygen species (ROS), conveniently called the ROS activity or the oxidative potential is proposed as a better metric for relating the PM pollution with health effects, and several recent epidemiological and clinical investigations also corroborate this hypothesis. However, various studies conducted using many types of ROS assays indicate different relationships of the chemical composition with PM oxidative potential. A mechanistic understanding of the chemical components participating in the ROS generating reactions, and the linkages of these reactions with biological endpoints is still lacking. The purpose of this symposium is to bring together the researchers working on various methods of measuring PM oxidative potential, their biological relevance, and the individual or synergistic contributions of the chemical components in ROS generation, to present a current status of the research and identify the needs for future research in this emerging field.

 

Extraterrestrial Aerosols: From Mars to Titan and Beyond

Organizers:
Daniel J. Cziczo, Earth, Massachusetts Institutes of Technology
Alexandria V. Johnson, Brown University

Of the 8 planets in our solar system 7 have atmospheres. The dwarf planet Pluto and moon Titan are also know to have appreciable gas phase envelopes. Transmission spectroscopy now shows the presence of atmospheres around many of the exoplanets detected beyond our solar system. Direct measurements within our solar system and indirect evidence beyond it show that aerosol particles, and cloud condensation on them, is likely ubiquitous in these atmospheres. Despite the vast differences in temperature, pressure and composition the underlying physics and chemistry of these particulates is the same for Earth, Mars, Titan and beyond. The purpose of this special symposium is to bridge the gap that exists between traditional planetary sciences and the terrestrial aerosol and cloud communities so that we may tackle common questions about aerosol and cloud microphysics and chemistry.

 

Regional and global air quality and climate modeling

Organizers:
Havala O. T. Pye, US Environmental Protection Agency
Shantanu Jathar, Colorado State University

Combustion-related aerosols that result in poor outdoor air quality are responsible for more than three million deaths worldwide annually, and natural and anthropogenic aerosols impose large uncertainties on climate predictions through their interaction with solar radiation and cloud lifecycle processes. To quantify – and eventually mitigate – the impact of aerosols on air quality and climate in the future, continued development of aerosol processes in large-scale models is critically needed to accurately predict the spatial distribution, composition, and properties of aerosols on regional and global scales. Three-dimensional large-scale models that simulate the emissions, transport, chemistry, deposition and impacts of air pollutants are vital tools that allow us to predict the size, number, chemistry, and properties of aerosols in the troposphere. These models are frequently used in a range of applications: from studying the source-and process-level contributions to the atmospheric aerosol burden to quantifying the human health and climate impacts of aerosols to the design and implementation of technology and policy interventions that will allow access to clean air in the future. Over the past decade and a half where computational power has become inexpensive and easy to access, large-scale models have become more sophisticated and powerful and allowed us to better understand the interactions between aerosols, air quality, and climate. In this special symposium, we solicit platform and poster presentations from researchers that are developing and applying regional or global air quality and/or climate models to study the properties and impacts of atmospheric aerosols. We encourage submissions in the following three topical areas but will also consider topics in the general area of regional and global aerosol modeling:
1. Understanding the evolution of the aerosol size distribution: from new particle formation to CCN
2. Variations in aerosol-meteorological feedbacks: thinking beyond globally-averaged forcing
3. Models, field intensives, and satellites: a coupled approach to predict the atmospheric aerosol burden and impacts on climate and health