When it comes to particles in the atmosphere, state matters.
Recent observations reveal that aerosol particles in the Amazon are mostly liquid, in contrast to previous studies.
The properties and size distribution of aerosol particles influence Earth’s "energy balance" either directly, by altering or absorbing sunlight, or indirectly, by affecting cloud formation. Whether organic particulate matter exists in a liquid, semi-solid, or solid state can affect particle growth and reactivity and hence particle number, size, composition, optical properties, and ability to nucleate clouds.
Research conducted during the Department of Energy’s (DOE) GOAmazon field campaign provides a new twist to a recently proposed theory about atmospheric particulates and paints a clearer picture of how these particles behave. The research found that atmospheric particles tied to plant life can be either solid or liquid, depending on the environment in which they form. These findings expand on a previous study that posited such particles favor a solid state. The previous research, which found that atmospheric particles over forests are in a solid or semi-solid state, was conducted in a boreal (pine) forest in Finland. There, pine trees release alpha-pinene, an organic building block that reacts with other substances such as ozone to produce atmospheric organic particulate matter. The research team decided to test that theory in the Amazon rainforest, which has about 80 percent humidity, compared to the pine forest’s 30 percent. In the Amazon, the reaction products of the compound isoprene provide the basic building block for atmospheric organic particulate matter. The team found that 80 percent of the time, the atmospheric organic particles that formed in the Amazon were in a liquid state. Liquid particles absorb molecules from the gas phase and grow. Semi-solid particles, on the other hand, grow layer by layer and remain smaller, which affects the types of clouds that form and their propensity to rain. The results of the present study highlight a biome-dependent distribution of liquid and non-liquid particulate matter over forested regions. These differences arise both because of intrinsic differences related to emissions of volatile organic compounds and oxidation pathways, as well as extrinsic differences in climatology of relative humidity and temperature, among other possible factors. Climate models must be able to treat aerosol particles as either liquid or solid, depending on the region, to accurately model their climate impacts.
Contacts (BER and non-BER)
BER - Sally McFarlane, SC-23.1, 301-903-0943; and Ashley Williamson, SC-23.1, 301-903-3120
Gordon McKay Professor of Environmental Chemistry
This project was funded by DOE’s Office of Science, Office of Biological and Environmental Research, Atmospheric Radiation Measurement and Atmospheric System Research programs; São Paulo (Brazil) Research Foundation (FAPESP); Amazonas State Research Foundation (FAPEAM); and Brazil Scientific Mobility Program (CsF/CAPES).
Bateman, A. P., Z. Gong, P. Liu, B. Sato, G. Cirino, Y. Zhang, P. Artaxo, A. K. Bertram, A. O. Manzi, L. V. Rizzo, R. A. F. Souza, R. A. Zaveri , and S. T. Martin. 2015. “Sub-Micrometre Particulate Matter is Primarily in Liquid Form over Amazon Rainforest,” Nature Geoscience 9, 34-37. DOI: 10.1038/ngeo2599. (Reference link)
ARM news feature
Harvard news feature
SC-23.1 Climate and Environmental Sciences Division, BER
BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER
Aug 24, 2019
New Approach for Studying How Microbes Influence Their Environment
A diverse group of scientists suggests a common framework and targeting of known microbial processes [more...]
Aug 08, 2019
Nutrient-Hungry Peatland Microbes Reduce Carbon Loss Under Warmer Conditions
Enzyme production in peatlands reduces carbon lost to respiration under future high temperatures. [more...]
Aug 05, 2019
Amazon Forest Response to CO2 Fertilization Dependent on Plant Phosphorus Acquisition
AmazonFACE Model Intercomparison. The Science Plant growth is dependent on the availabi [more...]
Jul 29, 2019
A Slippery Slope: Soil Carbon Destabilization
Carbon gain or loss depends on the balance between competing biological, chemical, and physical reac [more...]
Jul 15, 2019
Field Evaluation of Gas Analyzers for Measuring Ecosystem Fluxes
How gas analyzer type and correction method impact measured fluxes. The Science A side- [more...]
List all highlights (possible long download time)