Role of Fe(III), Phosphate, Dissolved Organic Matter, and Nitrate during the Photodegradation of Domoic Acid in the Marine Environment

• Published in: Environmental science & technology 2006-04, Vol.40 (7), p.2200-2205
• Main Authors: Fisher, J M, Reese, J G, Pellechia, P J, Moeller, P L, Ferry, J L
• Format: Article
• Language: English
• ISSN: 0013-936X
• DOI: 10.1021/es061443b

The photodegradation of domoic acid in model seawater containing varying amounts of total Fe(III) (expressed as Fe(III)), NO sub(3) super(-), total phosphate (expressed as PO sub(4) super(3-)), and dissolved organic matter (DOM) is reported. A multivariate, microscale, high-throughput experimental approach is described for evaluating how these components interact to control the removal of domoic acid from natural waters. Under the nominal conditions of the study ([Fe(III)] sub(o) 0-4 mu M; [NO sub(3) super(-)] sub(o) 0-35, mu M; [P0 sub(4) super(3-)] sub(o) 0-4 mu M; [DOM] sub(o) 0-10 mg/L), it is apparent that Fe(III) and DOM are significant promoters of domoic acid photooxidation. In contrast, PO sub(4) super(3-) interacts with Fe(III) to inhibit the photooxidation of domoic acid, but PO sub(4) super(3-) alone does not act to slow or accelerate domoic acid photodegradation. No other variables (singly or interactively) have a statistically significant impact. At an incident light intensity of 765 W/m super(2) and initial domoic acid concentration of 0.96 mu M, domoic acid half-lives range over 12-36 h, with half-life a function of [Fe(III)], [PO sub(4) super(3-)], and dissolved organic matter loadings. An NMR based technique for measuring domoic acid-Fe(III) binding (1.72 x 10 super(11)) is reported.