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Environmental Transformations and Interactions

Terrestrial-Atmospheric Processes

The terrestrial ecosystem is a major source of aerosols and chemical species to the atmosphere. These include biological aerosol particles such as pollen and soil microorganisms or cell fragments, soil minerals ejected during rainfall or entrained during wind erosion, and volatile organic compounds released by plants (which produce familiar aromas). These particles, ranging in size from nano- to micrometers, remain aloft and undergo extensive chemical transformations as they react with other atmospheric constituents. Notably, these processes include warm and cold cloud droplet formation. Aerosols thus play important roles in regulating Earth’s climate and hydrological, as well as biogeochemical cycles.

The molecular processes by which aerosols transform and age strongly influences these behaviors. The Environmental Molecular Sciences Laboratory (EMSL) ’s Terrestrial–Atmospheric Processes Integrated Research Platform (TAP IRP) is investigating these molecular transformations, the physical processes that control them, and the coupling of terrestrial and atmospheric processes. Knowledge from these studies allows us to understand the mechanisms by which they control air quality, Earth’s radiation budget, cloud formation, and nutrient deposition.

The Science

Research in the TAP IRP will address emission mechanisms of aerosols and gases from plants and soil into the atmosphere and will develop molecular-level understandings of the multiphase interfacial chemistry and aging processes occurring near Earth’s surface and extending up to the atmospheric boundary layer. We will investigate how aerosols participate in warm and cold cloud formation by acting as cloud condensation nuclei or ice nucleating particles and how these impact Earth’s radiative budget. We will also study the deposition of aerosols on terrestrial ecosystems. These activities will generate critical experimental and observational data to support Earth systems and climate models. 

The key science topics covered by this IRP include:

  • Molecular compositions of biogenic and anthropogenic volatile organic compounds (VOCs) emitted from soil-plant-atmosphere systems
  • Formation and evolution of secondary aerosol and their phase states and volatility distributions
  • Emission processes of primary biological aerosol particles and their transport and fate in the atmosphere
  • Aging processes and multi-phase chemistry of biogenic, geogenic, and anthropogenic aerosols in the atmosphere
  • Physical and chemical properties of long-range transported particles in the free troposphere
  • Physical, chemical, and optical properties of atmospheric aerosols and their impact on Earth’s radiative budget  
  • Physical and chemical processes that influence warm and cold cloud formation by atmospheric aerosols
  • Molecular mechanisms of atmospheric ice formation on aerosols
  • Mechanisms of coupling between biogeochemical and atmospheric processes, such as the roles of aerosolized soil microbe cell fragments in atmospheric ice formation and nucleation mechanisms specific to these particles
  • Compositions of aerosol deposited onto terrestrial ecosystems and the processes by which deposition occurs

Synergy and relationship with other Environmental Transformations and Interaction IRPs:

The focus on emissions from plants and soils is highly complementary to the Rhizosphere Function Integrated Research Platform (RF IRP) that focuses on belowground root-soil interactions and the Biogeochemical Transformations Integrated Research Platform (BGT IRP) that focuses on the soil organic matter, microbiomes, and minerals. The TAP IRP mechanistically connects the BGT and RF IRP research domains to atmospheric processes and illuminates how belowground, surficial, and atmospheric components interact as a complex system-of-systems. TAP research supports the Molecular Observation Network (MONet) strategic research areas, including field sensors, Model–Experiment (ModEx) integration and multiscale modeling, and MONet field sites.

How we do the science

EMSL will use a multi-modal suite of capabilities to study complex atmospheric systems and provide data for Earth system models. Chief among these are microscopy imaging, spectroscopy, and multi-ionization high-resolution mass spectrometry approaches. EMSL capabilities and instruments that uniquely support this IRP science mission include: