Cyanobacterial toxin concentrations were determined weekly at six locations in eutrophic Lake Winnebago, Wisconsin and at two drinking water intakes (Appleton and Menasha). These concentrations were compared to 23 chemical, physical, and biological parameters to determine the strongest correlations to toxin presence in the raw water at each drinking water intake. Total microcystin concentrations were determined by carrying out a 70% methanol extraction of lyophilized biomass followed by LC/MS/MS analysis of four microcystins (MCLR, MCYR, MCLA, MCRR), nodularin, anatoxin-a, and six non-toxic bioactive peptides (NTBPs) including anabaenopeptins (B,F), cyanopeptolins (1007,1041,1020), and microginin-690. All microcystins and five out of the six NTBPs were detected in lake and raw drinking water. The average and max concentration of the sum of all microcystins in raw drinking water was 3.2 µg/L and 21.1 µg/L and in lake water was 10.2 µg/L and 87.0 µg/L. Significant (p&lt;0.03) correlations were observed at both the Appleton and Menasha drinking water plants, between the concentration of microcystins in raw water and turbidity (R=0.6 for Appleton; R=0.8 for Menasha) and the concentration of microcystins in raw water and <i>Microcystis</i> cells/ml (R=0.6 for Appleton; R=0.7 for Menasha). Other parameters correlated with microcystins in raw water at one of the two plants including color (R=0.7) and silica concentration (R=-0.7). These results can be further utilized to develop a modeling program to predict when elevated toxin concentrations may be a concern based on specific environmental conditions.<br/>

Algal toxin dynamics in a eutrophic lake and indicators of toxins in raw drinking water

249th National Meeting (2015)

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