Laboratory simulated transport of microcystin-LR and cylindrospermopsin in groundwater under the influence of stormwater ponds: implications for harvesting of infiltrated stormwater

Water shortages in the southeastern United States have led to a need for more intensive management and usage of stormwater for beneficial uses such as irrigation. Harvesting of infiltrated stormwater from horizontal wells in sandy aquifer sediments beneath stormwater ponds has emerged as an alternative in need of evaluation. Cyanobacteria may proliferate in stormwater ponds; cyanotoxins produced by these organisms represent potential public health concerns. Results of two, saturated flow, sand column experiments indicate breakthrough of microcystin-LR (MCLR) and cylindrospermopsin (CYL) within 1―2 pore volumes indicating little removal attributable to sorption. Concentration-based MCLR removal efficiencies up to 90% were achieved, which we hypothesize were predominantly due to biodegradation. In contrast, CYL removal efficiencies were generally less than 15%. On the basis of these results, removal of sandy soil in the stormwater pond bottom and addition of sorption media with greater binding affinities to cyanotoxins may enhance natural attenuation processes prior to water withdrawal.