Grantee Research Project Results
2002 Progress Report: Physiological Mechanisms of Estuarine Sediment Oxidation by Spartina Cordgrasses
EPA Grant Number: R829406Title: Physiological Mechanisms of Estuarine Sediment Oxidation by Spartina Cordgrasses
Investigators: Lee, Raymond W.
Institution: Washington State University
EPA Project Officer: Aja, Hayley
Project Period: November 1, 2001 through October 31, 2004
Project Period Covered by this Report: November 1, 2001 through October 31, 2002
Project Amount: $110,307
RFA: Phytoremediation (2001) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management
Objective:
The objective of this research project is to investigate the physiological capacity for sediment oxidation in saltmarsh grasses of the genus Spartina. The ability of Spartina grasses to oxidize contaminated sediments has the potential to accelerate microbial mediated pollutant degradation.
Progress Summary:
Investigation of the Characteristics of Oxygen and Hydrogen Sulfide Gas Transport in Spartina anglica. Experiments were conducted using an automated gas flux measurement device. These results document that S. anglica has enhanced gas transport capabilities. These capabilities may facilitate sediment oxygenation, which may in turn accelerate microbial degradation of organic pollutants.
Investigation of the Structural (Role of Aerenchyma) Basis for Enhanced Oxygen Transport in S. anglica. Percentages of gas conducting air spaces (aerenchyma) in root tissue of S. anglica were quantified and compared with the congener S. alterniflora. A new digital method for quantification of aerenchyma was developed. Efforts were made to develop an automated program for quantification using National Instruments Labview software. There does not appear to be a relationship between aerenchyma volume and oxygen transport in S. anglica. The ability to release oxygen to the medium was induced by growing plants under flooded conditions; however, aerenchyma expression was not dependent on growing conditions. Percent arenchyma in S. anglica was not greater than S. alterniflora, which does not exhibit net oxygen release to the medium. Therefore, other physiological factors may account for enhanced oxygen transport.
Investigation of Other Physiological Parameters That May Enhance Oxygen Transport in S. anglica. Comparative studies are being conducted comparing physiological and biochemical features of S. anglica and other salt marsh species (S. alterniflora, S. densiflora, S. patens, and Distichlis spicata). S. anglica exhibited substantially higher rates of oxygen release to the medium than other species tested (see Figure 1). Low alcohol dehydrogenase activity in roots (diagnostic of the potential for aerobic metabolism) in S. anglica was observed, indicating that S. anglica normally maintains oxygenated rhizosphere conditions. Photosynthetic measurements also were conducted on the marsh species to determine whether enhanced oxygen transport is related to high photosynthetic oxygen production. Root respiration was quantified to determine whether increased oxygen release is related to lower root oxygen demands because of aerobic respiration.
Figure 1. Oxygen Release Rates in Salt Marsh Grasses
Oxygen Transport Studies in the Seagrasses Zostera marina and Z. japonica. The capability of net oxygen release to the medium was investigated in two species of subtidal seagrass that may be potentially useful in phytoremediation efforts. This work was conducted in collaboration with investigators at the Environmental Protection Agency in Newport Oregon. These investigations characterized rates of photosynthesis, respiration, and nutrient uptake by above- and below-ground tissues in response to light and hydrogen sulfide. Net release of oxygen to the medium was not observed.
Investigation of Environmental Conditions That Promote Growth in S. anglica and Other Saltmarsh Grasses. Growth under varying conditions in greenhouse experiments was measured. In particular, the effects of anoxia, flooding, and salinity were investigated. S. anglica and other marsh species were found to be more tolerant of elevated salinity than previously reported. These investigations provide important information that could potentially be used for large-scale greenhouse propagation and field planting efforts.
The results from Year 1 have characterized oxygen transport by S. anglica and indicated that this species has greater potential for sediment oxygenation than other marsh species. These findings potentially account for S. anglica's extraordinary performance as an invasive species. These results indicate that S. anglica has good potential for use in sediment oxygenation in phytoremediation of contaminated estuaries.
Future Activities:
Activities in Year 2 will include investigating and determining whether marsh grasses, and S. anglica in particular, accelerate degradation of organic pollutants. These studies will be made possible by the recent acquisition of a Micromass Isoprime stable isotope mass spectrometer in the laboratory. In greenhouse experiments, 13C-labeled substrates (e.g., hexadecane) obtained from commercial sources will be added to anaerobic sediments containing plants and plant-free controls. The time course of 13C loss from sediments will be determined by analyzing residual 13C in sediment by mass spectroscopy. Comparisons will be made between species and species versus plant-free controls to determine whether marsh plants accelerate removal of substrate from the soil. Also in Year 2, we will investigate oxygen transport in additional Spartina species and Spartina collected from different locations, and further investigate effects of environmental conditions on growth and physiology of Spartina species.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
| Other project views: | All 18 publications | 3 publications in selected types | All 2 journal articles |
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Lee RW. Physiological adaptations of the invasive cordgrass Spartina anglica to reducing sediments: rhizome metabolic gas fluxes and enhanced O2 and H2S transport. Marine Biology 2003;143(1):9-15. |
R829406 (2002) R829406 (Final) |
not available |
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Maricle BR, Lee RW. Aerenchyma development and oxygen transport in the estuarine cordgrasses Spartina alterniflora and S. anglica. Aquatic Botany 2002;74(2):109-120. |
R829406 (2002) R829406 (Final) |
not available |
Supplemental Keywords:
estuary, sediment oxidation, Spartina, physiology, saltmarsh grass, oxidize, contaminated sediments., Scientific Discipline, Waste, Water, Contaminated Sediments, Remediation, Environmental Chemistry, Chemistry, Microbiology, Environmental Microbiology, Bioremediation, Biology, organic pollutants, aquatic ecosystem, plant-based remediation, degradation, degradation of organic pollutants, microbial degradation, biodegradation, estuarine sediments, bioremediation of soils, aquatic ecosystems, phytoremediation, sedimentsRelevant Websites:
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.