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2004 Progress Report: New Biogenic VOC Emissions Model
EPA Grant Number: R831453Title: New Biogenic VOC Emissions Model
Investigators: Monson, Russell K. , Fall, Ray
Institution: University of Colorado at Boulder
EPA Project Officer: Bloomer, Bryan
Project Period: January 1, 2004 through December 31, 2006 (Extended to December 31, 2007)
Project Period Covered by this Report: January 1, 2004 through December 31, 2005
Project Amount: $644,044
RFA: Consequences of Global Change for Air Quality: Spatial Patterns in Air Pollution Emissions (2003)
Research Category: Air Quality and Air Toxics , Global Climate Change
Description:
Objective:The objective of this research project is to create new computer models that can be used to predict the emission of volatile organic compounds (VOCs) from tree leaves in a future atmosphere characterized by elevated carbon dioxide concentrations and warmer climates. Our work focuses on the biochemical processes in plant cells that control the emission of isoprene and acetaldehyde, two of the most abundantly emitted VOCs. Using controlled-environment growth chambers and taking advantage of existing field experiments, we will grow plants in normal conditions of carbon dioxide concentration and temperature, and in conditions of elevated carbon dioxide concentration and temperature. We will assay the plants for the activities of certain enzymes (e.g., phosphoenolpyruvate carboxylase) that are hypothesized to control the emission of isoprene and acetaldehyde. We then will use the experimental results to constrain model algorithms that we are developing in collaboration with computer modelers in Europe. Once completed, we will be able to make predictions of compound emissions given different scenarios of global environmental change.
Progress Summary:Spring/Summer (2004)
We developed new assay procedures for measuring isoprene emission from individual cells of poplar leaves. We worked in collaboration with Dr. Joost De Gouw at the National Oceanic and Atmospheric Administration Aeronomy Laboratory using his proton-transfer ion trap mass spectrometry instrument to make these measurements. These are the first measurements of isoprene emission from an individual, isolated cell; notably, acetaldehyde emissions were measured simultaneously. These measurements will allow us to better observe the actual biochemistry of the cells as we continue our research, rather than having to work with intact leaves. It gives us a tool to further elaborate the biochemical controls over the emission rates of isoprene and acetaldehyde in conditions of future environmental change.
Autumn (2004)
We cloned and sequenced the genes for two key enzymes, phosphoenolpyruvate carboxylase (PEPC) and pyruvate decarboxylase (PDC), from a poplar leaf cDNA library. We developed expression vectors for the genes of these enzymes and have made good progress on in vitro expression systems. Our aim is to develop antibodies for these enzymes, allowing us to assay the amounts of the enzymes in plants grown at normal and elevated carbon dioxide concentrations and to relate their expression to isoprene and acetaldehyde emission rates. By assaying these enzymes, we will be able to test our hypotheses concerning their role as control points in the emission of these volatiles in a future world with global environmental change.
November (2004)
Isoprene model flow paths and pools were developed in a collaborative meeting with Drs. Steffen Noe and Ulo Niinemets (University of Tartu). We focused on the use of existing quantum yield measurements of isoprene emission to constrain the model. This work continues and is leading to the mathematical framework we will use to develop the emission models. This will be the first model based on truly integrated biochemical pathways. It has the potential to replace previous models that are based on empirical data, rather than fundamental biochemical mechanisms.
A joint, 2-week field campaign is planned and will take place in August 2005 at the Poplar Free-Air CO2 Exchange (FACE) site in Tuscany, Italy. Dr. Russell Monson (one of the principal investigators on this project) will participate in collaboration with Dr. Francesco Loreto (Consiglio Nazionale delle Ricerche [CNR], Istituto di Biologia Agroambientale e Forestale, Monterotondo Scalo, Roma), and Dr. Joerg-Peter Schnitzler (Forschungzentrum Karlsruhe, Garmisch, Germany). Our aim will be to collect measurements of isoprene emission from leaves of poplar trees grown at normal and elevated carbon dioxide concentrations during this collaborative campaign. These measurements then will be used to constrain the model we are developing with the group at the University of Tartu. In other words, we will use the field measurements to make sure the model behaves properly as it runs through its mathematical calculations.
Autumn/Winter (2004/2005)
The two environment-controlled growth chambers were purchased and set up for use in the biochemical studies. These chambers were purchased from Conviron, Inc., and currently are operational on the fourth floor of the Ramaley Biology Building at the University of Colorado. We currently are preparing poplar plants to be grown in the chamber at normal and elevated carbon dioxide.
Winter (2005)
A biochemical assay for pyruvic acid was developed using a microtiter plate technology. This work currently is being expanded to include phosphoenolpyuvate (PEP) with the intention of simultaneous measurements of both pyruvate and PEP in poplar leaves subjected to normal and high carbon dioxide growth regimes.
Future Activities:One major change is expected in the proposed research for the next reporting period. Russell Monson will take part in a 2-week campaign in Tuscany, Italy, to obtain measurements of isoprene emissions (and possibly acetaldehyde emissions) on poplar trees at a Poplar FACE site. This campaign was not included in our original research plan. The opportunity, however, appeared for Dr. Monson to take part in the campaign at a greatly reduced cost. Dr. Monson currently is spending a sabbatical year in Germany working on isoprene emission from poplar trees. Thus, this campaign fits easily into his location and research emphasis. It also is entirely consistent with the U.S. Environmental Protection Agency research plan we originally submitted, because we had planned to conduct these same measurements on FACE sites in the United States. We have applied for supplemental funds to cover the cost of this campaign through the CNR Visiting Fellows program.
We will continue developing the computer models of isoprene emission and assimilating the field-collected data for model testing.
We will initiate our originally planned experiments on the measurements of plants grown in growth chambers with elevated and normal carbon dioxide concentrations. The chambers are operational. During spring 2005, we will establish poplar saplings in the chambers and begin growing them for summer measurements. By that time, we should have access to several of the biochemical probes we had intended to develop for the study, including assays for leaf-level activities of PEPC, PDC, and isoprene synthase, as well as each of the substrates for these enzymes.
As soon as antibodies to these three enzymes are obtained, we will extend the experiments described to include leaf-level measurements of PEPC, PDC, and isoprene synthase protein levels.
Journal Articles:No journal articles submitted with this report: View all 9 publications for this project
Supplemental Keywords:risk assessment, ecological effects, oxidants, terrestrial,
air, ecosystem protection/environmental exposure and risk, pollutants/toxics,
air pollutants, air pollution effects, air quality, atmosphere, atmospheric
sciences, chemicals, chemistry, ecological risk assessment, ecology and ecosystems,
environmental engineering, environmental monitoring, monitoring/modeling, air
toxics, climate change, particulate matter, BVOCs, global climate change, volatile
organic compounds, VOCs, aerosol formation, aerosols, air quality models, airborne
aerosols, ambient aerosol, ambient air pollution, anthropogenic stress, atmospheric
aerosol particles, atmospheric chemistry, atmospheric dispersion models, atmospheric
models, atmospheric particulate matter, atmospheric transport, biogenic VOC
emissions model, climate, climate model, climate variability, climatic influence,
ecological models, ecosystem models, emissions monitoring, environmental measurement,
environmental stress, global change, greenhouse gas, greenhouse gases, meteorology,
modeling,
,
Ecosystem Protection/Environmental Exposure & Risk, POLLUTANTS/TOXICS, Air, Scientific Discipline, RFA, Air Quality, Air Pollutants, climate change, Air Pollution Effects, Atmosphere, air toxics, Chemicals, Chemistry, Atmospheric Sciences, particulate matter, Environmental Chemistry, Monitoring/Modeling, Environmental Monitoring, aerosols, meteorology, climate model, Global Climate Change, Volatile Organic Compounds (VOCs), atmospheric models, airborne aerosols, BVOCs, ozone, atmospheric dispersion models, greenhouse gas, climatic influence, air quality models, climate models, aerosol formation, monitoring of organic particulate matter, atmospheric chemistry, climate variability, environmental measurement, environmental stress, global change, atmospheric particulate matter, emissions monitoring, modeling, ambient air pollution, anthropogenic stress, atmospheric aerosol particles, ecological models, biogenic VOC emissions model, ambient aerosol, atmospheric transport, ecosystem models, greenhouse gases
Relevant Websites:
http://spot.colorado.edu/~monsonr 
Progress and Final Reports:
Original Abstract
2005 Progress Report
2006 Progress Report
Final Report