2005 Progress Report: Chemical Degradation Pathways for the Natural Attenuation of Marine BiotoxinsEPA Grant Number: R831042
Title: Chemical Degradation Pathways for the Natural Attenuation of Marine Biotoxins
Investigators: Ferry, John L. , Moeller, Peter M.
Institution: University of South Carolina at Columbia
Current Institution: University of South Carolina at Columbia , Center for Coastal Environmental Health Biomolecular Research (CCEHBR)
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2003 through August 31, 2006
Project Period Covered by this Report: September 1, 2004 through August 31, 2005
Project Amount: $404,403
RFA: Ecology and Oceanography of Harmful Algal Blooms (2002) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecosystems , Water
The overarching goal of the proposal is to explore the fundamental fate and transport processes that govern the abiotic processing of marine toxins. Our particular focus is the toxins domoic acid, kainic acid, brevetoxin B, saxitoxin, and okadaic acid. The specific objectives of the research project are to: (1) build a library of multivariate models for describing the half-life of a given toxin as a function of light intensity, suspended solids, and water quality during a bloom; (2) identify degradation products, for further toxicity evaluation or use as chemical markers of abiotic degradation in the field; and (3) build databases of Koc with respect to water quality. We believe this knowledge will be critical for predicting the impact of a harmful bloom event and also that it will yield valuable insight into the possible ecological function of marine toxins based on new understanding of their persistence in the environment. It also may suggest what variables in the water column need to be adjusted to remediate the impact of a bloom.
A high throughput approach to combinatorial photochemical fate estimation has been developed (including reactor design and testing). We have explored the photodegradation of the toxins domoic acid, kainic acid, and mixtures of domoic and kainic acids in detail. We are currently engaged in examining the photodegradation of brevetoxin. Our findings indicate that the nutrient Fe can be an important catalyst for promoting the degradation of domoic acid. This data contrasts with published accounts that harmful algal bloom events can correlate with elevated Fe. We have observed that dissolved organic matter, especially that typical of the blackwater rivers found in the southeastern United States, is also an effective promoter for domoic acid photodegradation. However, when the nutrient phosphate co-occurs with Fe, it appears to inhibit Fe’s ability to degrade domoic acid. We speculate that Fe and phosphate work together to enhance blooms not only by providing nutrients and promoting toxin production but also by restricting domoate degradation and so preserving it in the water column. This suggests that high total Fe and total phosphate may be a good predictor of the harmful impact of a bloom, especially if phosphate is in excess. In contrast, kainic acid appears to be resistant to photodegradation by Fe or by dissolved organic matter. The long term goal of this research is to determine how water conditions may be manipulated to reduce the impact of harmful algal bloom toxins in the water column.