Spatial and seasonal variations of occurrences and concentrations of endocrine disrupting chemicals in unconfined and confined aquifers recharged by reclaimed water: a field study along the Chaobai River, Beijing.

A field study on the spatial and seasonal variations of occurrences and concentrations of five selected endocrine disrupting chemicals (EDCs), namely, estrone, 17β-estradiol, 17α-ethinyl estradiol, estriol, and bisphenol A, was conducted in Beijing, where reclaimed water is used to recharge groundwater through the permeable bed of the Chaobai River. This study collected 64 surface water samples from the Wenyu and the Chaobai Rivers and 51 groundwater samples from the unconfined aquifer (UA) and two underlying confined aquifers (CA I and CA II) at depths of 30, 50 and 80 m, respectively. EDCs were detected in 100.0%, 94.4% and 40.0% of groundwater samples from the UA, CA I and CA II, respectively, at concentrations which decreased by 1-2 orders of magnitude with depth. The occurrences and concentrations of EDCs in groundwater also decreased with the increasing distance to the river bank. In one monitoring section with seasonal wetting and drying, the occurrences and concentrations of EDCs dropped significantly during the dry season (December to March) without recharging. These results indicate that improving the removal of EDCs in reclaimed water and optimizing the management of the recharging operation could reduce the risks of endocrine disrupting chemicals. Crown