What is Environmental Chemistry?
Chemistry is everywhere in the environment surrounding us. Chemical substances comprise the air we breathe, the water we drink, and the soil to which we grow food. Certain chemicals, both man-made and naturally occurring, can exert a serious impact on the environment and its inhabitants, such as the human. Chemical reactions, taking place in the air, in the water, and of course, in our body, govern the impact of those chemicals.
Environmental Chemistry is a new branch of chemistry to understand chemistry taking place in the environment and at the interface between the environment and its inhabitants. Environmental chemistry is a highly interdisciplinary area, applying fundamentals of Analytical, Organic, Inorganic as well as physical chemistry to understand and solve the most important and imminent environmental issues.
What is Atmospheric Chemistry?
Atmospheric Chemistry is a branch of Environmental Chemistry, focusing on the chemistry taking place in the air (both outdoor and indoor), in the cloud, in small particles suspended in the air (atmospheric aerosol), as well as on surfaces exposed to the atmosphere.
Atmospheric chemistry plays a pivotal role in, arguably, two of the most important environmental problems that we are facing in the 21st century: Air Pollution and Global Climate Change.
Our Research: Atmospheric Aerosol
Our research group at the Department of Chemistry, the University of Alberta, will perform research activities to improve our fundamental understanding of Atmospheric Chemistry, knowing that a solid understanding is a prerequisite to solving those important environmental problems. In particular, we focus on the chemistry leading to the formation and evolution of suspended particulate matter called atmospheric aerosol which is playing an extremely important role in both Air Pollution and Global Climate Change.
We will take an approach combining laboratory experiments, ambient measurements, as well as computer simulation. The main focus of our research is laboratory experiment, where chemical reactions are investigated systematically under highly controlled experimental conditions.
Q: Why do things in the lab? Why can’t we directly measure pollutant concentration in the real atmosphere?
A: The atmosphere is a messy place. Measuring pollutant concentrations alone wouldn’t tell us the entire story.
In fact, hundreds of thousands of chemical species are present as gases or as aerosol components in the atmosphere. The chemical species and their concentrations can vary substantially with meteorology (weather), physical processes (e.g., convection of air), emission sources (e.g., forest fire), and atmospheric chemistry. To illustrate the complexity of the atmosphere, the figure below illustrates all the scientific processes treated in an air quality computer model. The model is called the Community Multiscale Air Quality (CMAQ) model, which is the official air quality model used by the US Environmental Protection Agency (US EPA).
Source: US EPA website https://www.epa.gov/cmaq/overview-science-processes-cmaq
The ultimate goal of atmospheric chemists is to understand every single such process, to an extent that we can confidently predict the concentration of harmful pollutants in the future. However, given the complexity of the atmosphere (figure above), the most realistic approach is to break them down into individual processes and investigate each of them systematically.
Laboratory Experiments for Atmospheric Chemistry
In the lab, we focus on one scientific question at a time. In other words, we investigate the chemistry of one chemical or one class of chemicals in each experiment. This approach ensures that we understand the observation at the fundamental level.
We simulate the atmospheric chemistry in devices called reactors. Given that sunlight is the major driving force for atmospheric chemistry, these reactors are often referred to photochemical reactors. Each reactor is designed specifically for a certain scientific purpose. A list of photochemical reactors in the Zhao group is shown here.
Advanced analytical techniques are employed to monitor the chemistry taking place in photochemical reactors. Some instruments are designed to sample and analyze pollutants in real time, and these instruments are referred to “online” or “in situ” instruments. Alternatively, samples can be collected from the reactors to perform chemical analyses afterward, and these are referred to as “offline” analyses. Offline analyses involve mass spectrometry, chromatography, and spectroscopy. Many of these techniques are covered in undergraduate courses, such as CHEM 211, 213, 305, 313, 424, and 425. A list of instrument available in the Zhao group is shown here.