Characterization and deployment of Solid Phase Adsorption Toxin Tracking (SPATT) resin for monitoring of microcystins in fresh and saltwater

Abstract

Fresh and brackish water cyanobacterial blooms and their associated toxins appear to be increasing globally. Current sampling methodologies for cyanotoxins typically involve point (grab) samples, and are subject to variability due to spatial and temporal heterogeneity, hydrological conditions, and the presence or absence of surface accumulations (scums) of algae. To overcome some of these issues, passive samplers including Solid Phase Adsorption Toxin Tracking (SPATT) and Polar Organic Compound Integrative Samplers (POCIS) have been used for primarily marine phycotoxins with more limited application to freshwater toxins. In this study SPATT was evaluated in both the lab and the field for use as an integrative sampler for microcystins, deployed in freshwater using DIAION HP20 resin. HP20 exhibited excellent adsorption and recovery characteristics for microcystin-LR, -YR, -LA, and -RR. Approximately weekly deployments of SPATT in Pinto Lake, CA were conducted for 16 months and compared to traditional (grab) samples. SPATT proved to be robust, detecting microcystins during every deployment in contrast to the grab samples, 42% of which were below the limit of detection using liquid chromatography–mass spectrometry for microcystin-LR. A simple canonical correlation model was built to determine if toxin concentrations co-varied with environmental parameters such as water temperature, nutrient concentrations, chlorophyll a, rainfall, or other easily obtained variables. The best individual correlate to toxin concentration was total biomass (chlorophyll a), while the first principal axis of the canonical correlation included chlorophyll a and total dissolved nitrogen as statistically significant variables. Overall, SPATT proved to be a useful adjunct or replacement for traditional grab samples.