Molecular studies in the Phyllosphere
EMSL Project ID
48676
Abstract
This proposal will facilitate EMSL laboratory access for Alex Guenther to conduct research in support of the EMSL Atmospheric Aerosol Systems Science Theme Leadership area. Aerosol radiative forcing, both direct effects and indirect impacts by modifying clouds, is the largest single source of uncertainty in simulations of global climate change [IPCC, 2007]. Climate models urgently require better quantitative understanding of the origins and effects of these particles, their precursor source strengths, formation mechanisms, transformation, and removal processes. Terrestrial ecosystems are a major source of atmospheric aerosol including both primary emissions of biological particles and emissions of gases that are oxidized in the atmosphere and then condense to form secondary organic aerosol. Land ecosystem-atmosphere fluxes of these biological materials are key components of earth system models used to investigate the processes controlling climate change. The foliage of terrestrial plants has long been considered the major terrestrial source of biogenic aerosol with relatively small contributions from other aboveground parts of plants (flowers, fruits, trunks), below ground (soil microbes, decomposing detritus, roots), and fauna. This assumption was based on enclosure studies that isolated individual ecosystem components. State-of-the-art biogenic emission models (e.g., the Model of Emissions of Gases and Aerosols from Nature, MEGAN) that are used to simulate biogenic aerosol and precursor emissions in the DOE/BER supported Community Land Model (CLM) component of the Community Earth System Model (CESM) currently consider only the role of vegetation foliage in simulating the processes controlling variations in fluxes of these compounds. This may be an oversimplification that introduces substantial errors in estimates of aerosol distributions and thus climate model predictions. This initiative would improve our quantitative understanding of organic aerosol lifecycle which is central to BER Atmospheric Systems Research (ASR). The proposed initiative supports BER/ASR 5-year research priorities to “Support integrated studies of key processes driving aerosol-cloud-precipitation-radiation interactions” and “Investigate dominant atmospheric processes with targeted regional experiments (e.g., GoAmazon)” and BER Terrestrial Ecosystem Science (TES) 5-year research priority to “Support large-scale coupled modeling and process research projects and ecosystem manipulations”. This includes studies of the role of phyllosphere microbes in determining emissions of organics into the atmosphere and the contribution of biogenic potassium salt seed particles to atmospheric concentrations of cloud condensation nuclei. This study would assess the importance of the phyllosphere in determining biogenic organic aerosol. This will be accomplished by using a leaf enclosure system to measure volatile organic compound emission and uptake from sterilized and control leaves under a range of environmental conditions (e.g., humidity, temperature, soil moisture). Molecular characterization of phyllosphere microbial community would be conducted to determine how variations in these populations relate to biogenic VOC (BVOC) fluxes. Target plant species would include grapes, oaks and poplars. The experiment requires a leaf cuvette gas exchange system (LICOR 6400), BVOC analysis system (PTRMS and GCMS), and a plant growth chamber. VOC analysis would include PTRMS and GCMS. The goal of this initial study would be to determine if the phyllosphere can significantly impact atmospheric organics. If this is the case then we will develop a plan to extend this work to field measurements associated with the DOE/BER GoAmazon field campaign.
Project Details
Start Date
2014-10-01
End Date
2015-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members