| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
|
| Initial Amendment Date: | March 8, 2012 |
| Latest Amendment Date: | March 8, 2012 |
| Award Number: | 1154850 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Henrietta Edmonds
hedmonds@nsf.gov (703)292-7427 OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | May 1, 2012 |
| End Date: | April 30, 2016 (Estimated) |
| Total Intended Award Amount: | $678,515.00 |
| Total Awarded Amount to Date: | $678,515.00 |
| Funds Obligated to Date: |
|
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
601 S COLLEGE RD WILMINGTON NC US 28403-3201 (910)962-3167 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
NC US 28403-5915 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | Chemical Oceanography |
| Primary Program Source: |
|
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Harmful algal blooms (HABs) are worldwide phenomena caused by microalgae or phytoplankton reaching extremely high concentrations. Naturally occurring toxins are often secreted during these blooms, engendering a variety of environmental, economic and human health impacts that have emphasized these as events of global concern.
In this project, a research team at the University of North Carolina at Wilmington will explore the photochemical behavior of brevetoxins (PbTx-2, PbTx-3) and microcystin-LR (MLR) on resuspended coastal sediments in sunlit surface waters. These algal toxins were chosen because of their widespread distribution, photochemically lability in the dissolved phase and because a significant fraction of what is produced in coastal waters is effectively scavenged onto sediments.
The team hypothesizes that photochemical processes will dramatically alter the lifetime of these sediment-bound toxins producing photoproducts with unknown toxicities and fate. Their preliminary evidence revealed a 40% increase in dissolved PbTx-2 concentration when an organic-rich sediment containing the toxin was resuspended in coastal seawater and exposed to sunlight. Accordingly, they now want to answer the following specific questions: (1) To what extent do photochemical processes alter PbTx-2, PbTx-3 and MLR on resuspended sediments exposed to sunlight and what are the major photoproducts produced? (2) How are the photoreactivities of these sorbed toxins influenced by the inorganic and organic composition of the resuspended material, by irradiation wavelength, and by suspended sediment concentration? (3) How is the photoreactivity of the sorbed algal toxins affected by the biogeochemical setting and salinity regime where the resuspended sediments originate?
Broader Impacts: These questions address novel, fundamentally important, globally significant questions regarding the lifetime and fate of algal toxins in coastal environments. It has been suggested that global change, including increases in eutrophication, sea surface water temperature, and runoff from changing land use and population growth, have exacerbated HABs worldwide. The project will support a post-doctoral researcher, two master's level graduate students, three undergraduates and one high school student per year. Part of the funding will also be used to recruit local high school science teachers during the summer. Previous high school teachers have taken the experience gained in the laboratory back to the classroom, greatly enhancing their ability to convey the excitement of scientific discovery. A participant on this project is an assistant professor at an undergraduate institution who will bring undergraduates to UNCW to work on the project in the summer and will collaborate in sample collection.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Photochemical mobilization of toxins from resuspended sediments represent a new and important process in aquatic waters. The toxins studied in this project, brevetoxin and microcyctin, have human, economic and environmental impacts. Understanding the fate of these toxins released into the environment is important to accurately assess their biogeochemical cycling. The main conclusions of this study are toxins are released from resuspended sediments upon exposure to sunlight. The magnitude of this release is quite significant. For example, the photochemical release of brevetoxin from resuspended sediments produces between 0.5 – 13% of the total toxin observed during an actual bloom. This has important implications since the potential concentrations of brevetoxin from this process are similar in magnitude to that observed during an active K. brevis bloom. As a result the negative environmental effects associated with this toxin may exist during resuspension events occurring at locations containing brevetoxin from previous blooms. A similar conclusion was drawn for microcystin as well. Model calculations suggest that photochemical processing of microcystin impacted sediments resuspended into the photic zone can replace 100% of the standing stock toxin during a bloom. These two calculations should be viewed with some caution since it does not account for particle shading, advection and settling; however, it is an important exercise in that it demonstrates the potential importance of this process in aquatic environments.
The ramifications of microcystin and brevetoxin photoproduction from impacted sediments may go well beyond increasing concentrations of the toxin in the affected watershed. This study is the first to illustrate formation of new photoproducts during resuspension of authentic toxin laden sediments. These new compounds may exhibit different toxicities and trophic transfer potential compared to the parent toxin.
The photorelease of toxin is controlled by the percent organic carbon content of the resuspended sediment. No other organic geochemical indices (e.g. carbon preference index, terrestrial aquatic ratio) correlated with the photolytic release of the toxins. Compared to the dissolved organic matter, relatively fresh, terrestrial dominated sedimentary organic matter had a higher magnitude of photorelease.
The research conducted over the duration of this award has been of interest to students at all stages of their academic career. This project has provided a unique educational opportunity and laboratory experience for 6 undergraduate students, 9 master's students and 2 postdoctoral fellows. Young students are attracted to this type of study because they perform environmental research of global relevance. Because of our team approach to research, the students involved gained invaluable educational experience in experimental design and various analytical techniques. In addition, their efforts with data analysis of real environmental samples required students to understand accuracy, precision, error analyses and correlation theory in a way not possible in a traditional classroom setting. Working with the complex environmental matrices also integrates research and education well because it solidifies their understanding of mass spectrometry, chromatography, organic extraction and purification techniques. This experience for the students is important as it makes them competitive in the job market.
Last Modified: 07/26/2016
Modified by: Ralph N Mead
Please report errors in award information by writing to: awardsearch@nsf.gov.
