Occurrence, distribution, and environmental risk of 61 glucocorticoids in surface water of the Yellow River Delta, China

Glucocorticoids (GCs), as important endocrine disrupting compounds and emerging contaminants, could have irreversible adverse effects on aquatic organisms even at ng/L levels. However, previous studies have only focused on the dissolved concentrations of GCs in the water, and limited data are available for their occurrences in the solid phase. In this study, the occurrence, distribution, and environmental risks of 61 natural and synthetic GCs in surface water of the Yellow River Delta (YRD) were simultaneously analyzed by investigating water, suspended particulate matter (SPM) and sediment samples at 64 sites in six major rivers in the wet season. Overall, 51 GCs were detected in all samples from different matrices, and their concentrations were in the range of not detected (ND)-274 ng/L in water, ND-42 ng/g dry weight (dw) in SPM and ND-9.98 ng/g dw in sediment. Natural GCs were the dominant compounds in all samples, followed by synthetic halogenated esters. High concentrations of GCs were observed in discharge outlet samples from livestock farming, aquaculture and industrial production, and the composition differences of GCs between human/animal sources and industrial sources could be used as indicators to identify pollution sources. Most GCs were distributed in the water phase, while compounds with higher log octanol/water partition coefficients (log Kow) tended to be adsorbed to SPM and sediment. The spatial distribution of GCs was primarily affected by anthropogenic activities and hydrodynamic conditions. Four synthetic compounds (budesonide [BD], fluocinolone acetonide [FOA], fluticasone propionate [FP], and clobetasol propionate [CBSP]) were identified as the main contributors to GC activity with a combined contribution of 57 %-95 %. Risk assessment using the risk quotient revealed that low to moderate risks are posed to aquatic organisms in surface water.