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 , Center for Coastal Environmental Health Biomolecular Research (CCEHBR)
EPA Project Officer: Hiscock, Michael
Project Period: September 1, 2003 through August 31, 2006
Project Amount: $404,403
RFA: Ecology and Oceanography of Harmful Algal Blooms (2002) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecosystems , Water
During harmful algal bloom events, toxins are dispersed into the food web through planktonic, detrital, or solution pathways. We hypothesize that this transfer is occurring against a continuous backdrop of chemical reactions that can act to attenuate the chemical signature of the bloom in the water column, including direct and indirect photooxidation, adsorption onto suspended solids, and hydrolysis. Photoactive suspended solids may also engage in photocatalyzed oxidation or reduction of the toxin.
We will test this hypothesis by exposing solutions of several purified toxins to a matrix of different possible oxidizing conditions, including illumination in the presence of photosensitizers (Fe oxides, colloidal and crystalline; NO3-; varying levels of dissolved organic matter) under several different water quality conditions (varying salinity, pH, total carbonate, and suspended clays or colloidal silica). Dissolved organic matter (DOM) may also provide a hyrdophobic microenvironment for toxins to partition into, so we will measure the partitioning constant (Koc) for these toxins into dissolved organic matter as well, with particular emphasis placed on measuring how DOM and Koc vary with water quality and affect adsorption on suspended solids.
The overarching goal of the proposal is explore the fundamental fate and transport processes that govern the abiotic processing of marine toxins. The specific objectives of the study are to a) 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, b) to identify degradation products, for further toxicity evaluation or use as chemical markers of abiotic degradation in the field, and c) 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.