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Final Report: Biomarkers of Ozone Damage to Sierra Nevada Vegetation
EPA Grant Number: R825433C023Subproject: this is subproject number 023 , established and managed by the Center Director under grant R825433
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: EERC - Center for Ecological Health Research (Cal Davis)
Center Director: Rolston, Dennis E.
Title: Biomarkers of Ozone Damage to Sierra Nevada Vegetation
Investigators: Fan, Teresa W-M. , Higashi, Richard M.
Institution: University of California - Davis
EPA Project Officer: Levinson, Barbara
Project Period: October 1, 1996 through September 30, 2000
RFA: Exploratory Environmental Research Centers (1992)
Research Category: Center for Ecological Health Research , Targeted Research
Description:
Objective:The objective of this research project was to more definitively correlate tree ring biochemical markers with ozone injury indices at known, ozone-impacted sites. Using pyrolysis-gas chromatography/mass spectrometry (pyro-GC/MS) to analyze tree rings, we set out to "map" a matrix of established ozone-impacted and control stands of ponderosa pines in two areas—the San Bernardino National Forest (northeast of the Los Angeles Basin) and multiple locations in the Sierra Nevada Range. We focused our initial efforts on two newly discovered biochemical markers—H:G lignin ratio and stilbene phytoalexins. We also conducted parallel analyses on the lignin, phytoalexin, and antioxidant biochemistry of the needles to probe the possible mechanism(s) of injury that result in the wood markers.
Summary/Accomplishments (Outputs/Outcomes):Because of the precursor sources and transport dynamics of ozone in California, injury to forests has been a concern with regard to photochemical oxidant effects for more than 40 years (Miller, et al., 1996). Ozone acts first at the biochemical level, so we have been able to use biochemical markers in foliage in fumigation chambers. In remote field sites, however, injury is best assessed by visual foliar damage (chlorotic mottle). Unfortunately, leaves are usually lost within 5 years, so field assessment for ozone injuries must be updated periodically. Injury assessment may be limited by the duration of the study and by a small number of assessment sites. The ultimate objective of this research project was to identify permanent biochemical markers that would allow researchers to overcome these limitations. The analysis of wood chemical structures from annual tree rings—dendrobiochemistry (Fan and Higashi, 1999)—has the potential to fill this need for a biochemical marker.
In the first phase of the research project, we used pyro-GC/MS to analyze ponderosa pine (Pinus ponderosa) tree ring radial cores from seven long-term study sites in the San Bernardino National Forest, east (downwind) of the Los Angeles Basin. Fifty biochemical markers were screened for changes in post-1945 rings relative to pre-1945 rings, from which two markers were chosen for further study (H:G lignin ratio and stilbene [a phytoalexin]). Our results showed that where historical ozone exposure was highest, trees with severe crown injury (sensitive individuals) showed decreases of H:G lignin ratio and increases of stilbene markers over time, but trees with slight crown injury (tolerant individuals) had opposite trends.
In the second phase of the research project, tree ring radial cores were sampled from seven sites in the Sierra Nevada Range. These analyses focused on the two markers established in the first phase of the research project. Compared to the first phase study in the San Bernardino National Forest, the individual trees at these sites did not have well documented injury status. Thus, we attempted to establish grove-level pattern(s) of the two markers at these sites. To this end, our data showed a higher percentage of trees exhibiting either or both H:G lignin and stilbene markers at the northernmost sites in the Sierra Nevada Range, as compared with the southern sites. One possible interpretation of this trend is that, at the grove-average level, the pines are impacted more historically by oxidants in a southerly vector.
Lastly, we investigated Fourier transform infrared (FTIR) microspectroscopy as an alternative to pyro-GC/MS. Although technically feasible, it proved to be impractical because of the requirements of skilled, tedious sample preparation and spectral acquisition. Thus, the spectroscopy, although rich in data, is potentially very time consuming and expensive (equipment costs of $120,000).
The following activities were accomplished:
• We identified two new biochemical markers (H:G lignin ratio and stilbene) of ozone injury in individual ponderosa pines. These markers will provide investigators with an inexpensive method of establishing long-term forest injury records for a large number of sites; an extremely difficult task until now. The biochemical nature of these markers also would allow us to link them to the mechanism(s) of ozone injury so that we could determine, under real field conditions, the photochemical oxidant species most injurious to trees. This information then could be used by environmental management and regulation agencies to mitigate forest ozone damage.
• We identified a biochemical marker (stilbene3) that may act as an indicator of oxidant exposure, and found that respectively averaged measurements of the H:G lignin ratio and stilbene at the pine grove level may indicate grove-level oxidant exposure. Thus, tree ring biochemistry may be able to harness the trees as very long-term ozone monitors. Such an innovation would be extraordinarily useful to investigators and, ultimately, to ozone mitigation efforts.
• Our data show higher percentages of trees exhibiting either or both of the markers in the southernmost study sites of the Sierra Nevada Range as compared with the northern sites. One possible interpretation of this trend is that, at the grove-average level, the pines are historically more impacted by oxidants in a southerly vector. This information may be useful to other investigators studying ozone formation and transport, and to environmental management agencies dealing with ozone damage.
• We determined that pyro-GC/MS is currently the most convenient, cost-effective method of identifying new, long-term, biochemical biomarkers of ozone injury in trees. We explored the use of FTIR microspectroscopy as an alternative to pyro-GC/MS, and found that although technically feasible, FTIR microscopy is impractical because of the requirements of skilled, tedious sample preparation and spectral acquisition. It is more time consuming and more expensive (equipment can cost up to $120,000) than pyro-GC/MS. Although pyro-GCMS remains expensive and technically demanding, it is an advantage relative to the large amount of detailed information that can be obtained, which is available by no other technique.
Supplemental Keywords:ecosystem, ecosystem protection, environmental exposure and risk, geographic area, international cooperation, water, terrestrial ecosystems, aquatic ecosystem, aquatic ecosystem restoration, aquatic ecosystems and estuarine research, biochemistry, ecological effects, ecological indicators, ecological monitoring, ecology and ecosystems, environmental chemistry, restoration, state, water and watershed, watershed, watershed development, watershed land use, watershed management, watershed modeling, watershed restoration, watershed sustainability, agricultural watershed, exploratory research environmental biology, California, CA, Clear Lake, Lake Tahoe, anthropogenic effects, aquatic habitat, biogeochemical cycling, ecological assessment, ecology assessment models, ecosystem monitoring, ecosystem response, ecosystem stress, environmental stress, environmental stress indicators, fish habitat, hydrologic modeling, hydrology, integrated watershed model, lake ecosystems, lakes, land use, nutrient dynamics, nutrient flux, water management options, water quality, wetlands. , Ecosystem Protection/Environmental Exposure & Risk, Geographic Area, Scientific Discipline, RFA, Ecological Risk Assessment, Fate & Transport, Environmental Chemistry, Monitoring/Modeling, Ecology and Ecosystems, Environmental Monitoring, State, biomarkers, California (CA), ozone , fate and transport, forested watersheds, ecological risk, field detection, atmospheric deposition, emissions, monitoring, analytical models, detection system, emission control, neural net techniques, air pollution, atmospheric chemistry, environmental measurement, modeling, watershed influences, vegetation, kinetics
Progress and Final Reports:
1999 Progress Report
2000 Progress Report
Original Abstract
Main Center Abstract and Reports:
R825433 EERC - Center for Ecological Health Research (Cal Davis)
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R825433C001 Potential for Long-Term Degradation of Wetland Water Quality Due to Natural Discharge of Polluted Groundwater
R825433C002 Sacramento River Watershed
R825433C003 Endocrine Disruption in Fish and Birds
R825433C004 Biomarkers of Exposure and Deleterious Effect: A Laboratory and Field Investigation
R825433C005 Fish Developmental Toxicity/Recruitment
R825433C006 Resolving Multiple Stressors by Biochemical Indicator Patterns and their Linkages to Adverse Effects on Benthic Invertebrate Patterns
R825433C007 Environmental Chemistry of Bioavailability in Sediments and Water Column
R825433C008 Reproduction of Birds and mammals in a terrestrial-aquatic interface
R825433C009 Modeling Ecosystems Under Combined Stress
R825433C010 Mercury Uptake by Fish
R825433C011 Clear Lake Watershed
R825433C012 The Role of Fishes as Transporters of Mercury
R825433C013 Wetlands Restoration
R825433C014 Wildlife Bioaccumulation and Effects
R825433C015 Microbiology of Mercury Methylation in Sediments
R825433C016 Hg and Fe Biogeochemistry
R825433C017 Water Motions and Material Transport
R825433C018 Economic Impacts of Multiple Stresses
R825433C019 The History of Anthropogenic Effects
R825433C020 Wetland Restoration
R825433C021 Sierra Nevada Watershed Project
R825433C022 Regional Transport of Air Pollutants and Exposure of Sierra Nevada Forests to Ozone
R825433C023 Biomarkers of Ozone Damage to Sierra Nevada Vegetation
R825433C024 Effects of Air Pollution on Water Quality: Emission of MTBE and Other Pollutants From Motorized Watercraft
R825433C025 Regional Movement of Toxics
R825433C026 Effect of Photochemical Reactions in Fog Drops and Aerosol Particles on the Fate of Atmospheric Chemicals in the Central Valley
R825433C027 Source Load Modeling for Sediment in Mountainous Watersheds
R825433C028 Stress of Increased Sediment Loading on Lake and Stream Function
R825433C029 Watershed Response to Natural and Anthropogenic Stress: Lake Tahoe Nutrient Budget
R825433C030 Mercury Distribution and Cycling in Sierra Nevada Waterbodies
R825433C031 Pre-contact Forest Structure
R825433C032 Identification and distribution of pest complexes in relation to late seral/old growth forest structure in the Lake Tahoe watershed
R825433C033 Subalpine Marsh Plant Communities as Early Indicators of Ecosystem Stress
R825433C034 Regional Hydrogeology and Contaminant Transport in a Sierra Nevada Ecosystem
R825433C035 Border Rivers Watershed
R825433C036 Toxicity Studies
R825433C037 Watershed Assessment
R825433C038 Microbiological Processes in Sediments
R825433C039 Analytical and Biomarkers Core
R825433C040 Organic Analysis
R825433C041 Inorganic Analysis
R825433C042 Immunoassay and Serum Markers
R825433C043 Sensitive Biomarkers to Detect Biochemical Changes Indicating Multiple Stresses Including Chemically Induced Stresses
R825433C044 Molecular, Cellular and Animal Biomarkers of Exposure and Effect
R825433C045 Microbial Community Assays
R825433C046 Cumulative and Integrative Biochemical Indicators
R825433C047 Mercury and Iron Biogeochemistry
R825433C048 Transport and Fate Core
R825433C049 Role of Hydrogeologic Processes in Alpine Ecosystem Health
R825433C050 Regional Hydrologic Modeling With Emphasis on Watershed-Scale Environmental Stresses
R825433C051 Development of Pollutant Fate and Transport Models for Use in Terrestrial Ecosystem Exposure Assessment
R825433C052 Pesticide Transport in Subsurface and Surface Water Systems
R825433C053 Currents in Clear Lake
R825433C054 Data Integration and Decision Support Core
R825433C055 Spatial Patterns and Biodiversity
R825433C056 Modeling Transport in Aquatic Systems
R825433C057 Spatial and Temporal Trends in Water Quality
R825433C058 Time Series Analysis and Modeling Ecological Risk
R825433C059 WWW/Outreach
R825433C060 Economic Effects of Multiple Stresses
R825433C061 Effects of Nutrients on Algal Growth
R825433C062 Nutrient Loading
R825433C063 Subalpine Wetlands as Early Indicators of Ecosystem Stress
R825433C064 Chlorinated Hydrocarbons
R825433C065 Sierra Ozone Studies
R825433C066 Assessment of Multiple Stresses on Soil Microbial Communities
R825433C067 Terrestrial - Agriculture
R825433C069 Molecular Epidemiology Core
R825433C070 Serum Markers of Environmental Stress
R825433C071 Development of Sensitive Biomarkers Based on Chemically Induced Changes in Expressions of Oncogenes
R825433C072 Molecular Monitoring of Microbial Populations
R825433C073 Aquatic - Rivers and Estuaries
R825433C074 Border Rivers - Toxicity Studies