Photochemical Fate of Saxitoxin and Relevant Analogs in Aquatic Systems
Abstract
Saxitoxin (STX) is one of a series of toxins naturally produced by photosynthetic organisms in surface waters. STX is also classified as a Schedule 1 Chemical Warfare Agent per the Chemical Weapons Conventions of 1993. One of the main concerns associated with STX is its potential to be used to poison water or food supplies in combat operations. However, STX could also occur naturally due to an algal bloom. An attack using STX will most likely be based on the use of this compound, whereas a natural event will produce not only STX but some of its analogues. Once in the water, these toxins will degrade via biotic or abiotic pathways, where photochemical processes are expected to play a major role. There is limited information on the environmental fate of STX or its most common analogues, including the formation of transformation products (TPs). The main objective of this proposal is to investigate the photochemical fate of STX and its analogues in surface waters by evaluating the degradation kinetics and pathways and identifying the major TPs. The results from this project will offer detailed information on the photochemical transformation of STX and some of its analogues, providing information to be used for identification of the potential origin of STX contamination (e.g. natural or attack). This differentiation is proposed to be based on the differences in concentrations and transformation products for STX and its analogues observed for an attack versus a natural contamination event. The project will include three main tasks. During the first task, the project investigators will develop analytical methods for STX, its analogues, and potential TPs. These analytical methods will be based on both HPLC and high-resolution mass spectrometry. The second task will include a detailed evaluation of the photochemical transformation of STX and its analogues. This task will include also a mechanistic assessment of the main pathways leading to the photochemical degradation of STX in natural aquatic environments, including an evaluation of the role of dissolved organic matter as the main photosensitizer in surface waters. The third task will focus on the use of high-resolution mass spectrometry to identify the principal TPs formed during the photochemical transformation of STX and its analogues. The results from this project will: a) inform army intelligence regarding the lifetime of STX and related analogues in surface waters under different environmental conditions; b) allow tracking of potential STX contamination of source waters by identifying characteristic TPs that could serve as indicators for STX exposure (either natural or via a chemical attack); and c) inform the environmental chemistry community regarding the degradation pathways for STX analogues. The University of Colorado Boulder is an accredited U.S. institution of higher education engaged in fundamental research in science and engineering. Our research is intended to be, and is, widely and openly published and made available to the scientific and academic community. CU Boulder is submitting its proposal against the subject RFP with the understanding that the work to be performed and the results generated are considered to be fundamental research, intended to be published and shared broadly within the scientific community. This abstract is approved to be publicly releasable.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 09, 2020
- Source ID
- W911NF2010040
Entities
People
- Fernando L Rosario-Ortiz
Organizations
- Army Contracting Command
- United States Army
- University of Colorado Boulder