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

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 estrogenicity of 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 estrogenic activity of water by in vitro bioassay as well as concentrations of several important groups of estrogenic compounds (estrogenic hormones, alkylphenols, and phytoestrogens) by LC-MS/MS analyses. Estrogenic hormones 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. Estrogenic activity 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 estrogenicity of 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 estrogenic activity 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 (<6%) of the biological activity could be explained. In the mean and maximum scenarios, we included also compounds below LOQ into the calculations at the level of LOQ/2 and LOQ, respectively. In these cases, a considerable part of the estrogenic activity could be attributed to the possible presence of steroid estrogens below LOQ. However, for the samples with estrogenic activity greater than 1 ng.L-1, more than 50% of the estrogenic activity remained unexplained even in the maximum scenario. Probably other compounds or possible interactions between individual substances cause the estrogenic activity 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 estrogenicity of these types of surface waters.

LC-MS analyses of microcystins in fish tissues overestimate toxin levels-critical comparison with LC-MS/MS.

Microcystins are cyclic peptide toxins with hepatotoxic and tumour-promoting properties which are produced in high quantities in freshwater cyanobacterial water blooms, and several studies have reported microcystin accumulation in fish with possible food transfer to humans. In this study, we provide the first comparison of liquid chromatography with single mass-spectrometric and with tandem mass-spectrometric detection for analyses of microcystins in complex fish tissue samples. Use of traditional single mass spectrometry (i.e. monitoring of ions with m/z 519.5 for microcystin-RR and m/z 995.5 for microcystin-LR) was found to provide false-positive responses, thus overestimating the concentrations of microcystins in the tissue samples. More selective tandem mass spectrometry seems to provide more reliable results. The concentrations of microcystins detected by tandem mass spectrometry in fish from controlled-exposure experiments were more than 50% lower in comparison with concentrations obtained by single mass spectrometry. Extensive analyses of edible fish parts-muscles (148 fish specimens from eight different species from five natural reservoirs with dense cyanobacterial water blooms)-showed negligible microcystin concentrations (all analyses below the limit of detection; limit of detection of 1.2-5.4 ng/g fresh weight for microcystin-RR, microcystin-YR and microcystin-LR in multiple reaction monitoring mode). Our findings have practical consequences for critical re-evaluation of the health risks of microcystins accumulated in fish.

Using supercritical fluid extraction to measure the desorption and bioaccessibility of phenanthrene in soils.

The aim of this paper was to measure the changing desorbable fraction and bioaccessibility of phenanthrene in two different soils with increasing soil-phenanthrene contact time using supercritical fluid extractions (SFE). Both soils were spiked with 100 mg kg(-1) phenanthrene and aged for 28d. Desorption profiles were measured every 7d using selective SFE conditions and the results were compared to 14C-phenanthrene mineralisation assays. Selective SFE showed significant differences in the rates and extents of desorption in the two soils, likely to be due to different organic matter composition. Post-extraction fitting of data yielded consistent SFE extraction times within ageing soils for bioaccessibility prediction.