Abstract
The endocrine‐disrupting impact of steroid estrogens on fish will be strongly influenced by their distribution between sediment and water. Laboratory studies were performed to investigate the potential for sorption of 17β‐estradiol (E~2~) and 17α‐ethinylestradiol (EE~2~) to bed and suspended sediments taken from five British rivers. Sediment material was collected from the Rivers Aire and Calder (located in urban and industrialized areas in Yorkshire, UK), the River Thames (at a relatively rural site in Oxfordshire, UK), and from the estuaries of the Rivers Tees and Tyne. Using anaerobic conditions to inhibit biodegradation, it was found that 80 to 90% of binding to bed sediments was complete within 1 d, but that an equilibrium had not been reached after 2 d. Bed sediments gave distribution coefficients (K~d~) ranging from 4 to 74 L/kg for E~2~ and from 8 to 121 L/kg for EE~2~ for samples taken over a range of seasons and locations. Sorption to suspended sediment gave K~d~ values ranging from 21 to 122 L/kg for E~2~ and 19 to 260 L/kg for EE~2~. However, these K~d~ values suggest less than 1% removal of the steroid estrogens from the aqueous phase given the ambient suspended sediment concentration. In the bed sediments, higher K~d~ values were associated with smaller particle size and higher organic carbon content. In most cases, the K~d~ values obtained for EE~2~ were higher than those for E~2~ by a factor of up to three.