Estrogenic activity and contributing compounds in stagnant water bodies with massive occurrence of phytoplankton

Abstract Stagnant water bodies have generally received little attention regarding the presence of endocrine disruptive compounds, although they can integrate diverse pollutants from multiple different sources. Many compounds of anthropogenic as well as natural origin can contribute to the overall estrogenicityof surface waters and some of them can exhibit adverse effects on aquatic biota even in very low concentrations. This study focused on freshwater ponds and reservoirs affected by water blooms and determined the estrogenicactivity of water by in vitro bioassay as well as concentrations of several important groups of estrogeniccompounds ( estrogenichormones, alkylphenols, and phytoestrogens) by LC-MS/MS analyses. Estrogenichormones were found at concentrations up to 7.1 ng.L −1 , similarly to flavonoids, whose concentrations did not exceed 12.5 ng.L −1 . Among alkylphenols, only bisphenol A and 4- tert -octylphenol were detected in levels reaching 100 ng.L −1  at maximum. Estrogenicactivity of water samples varied from below the quantification limit to 1.95 ng.L −1 . There does not seem to be any general causal link of the massive phytoplankton occurrence with the estrogenicityof water or concentration of phytoestrogens, since they showed no direct relationship with the phytoplankton abundance or composition across sites. The contribution of the analysed compounds to the estrogenicactivity was calculated in three scenarios. In minimum scenario, just the compounds above quantification limit (LOQ) were taken into account and for most samples, only minor part ( −1 , more than 50% of the estrogenicactivity remained unexplained even in the maximum scenario. Probably other compounds or possible interactions between individual substances cause the estrogenicactivity in these types of water bodies and in this case, the results of LC-MS/MS analyses cannot sufficiently predict the biological effects. A complex approach including bioassays is needed when assessing the estrogenicityof these types of surface waters.