| Abstract
| - Concentrations of estradiol, estrone, and ethinylestradiolwere measured in the water column (daily for 28 or 14 days)and in the bed sediment (weekly over the same period)of the River Nene and the River Lea, U.K., upstream anddownstream of sewage treatment works (STW). Theconcentrations of the three steroids in the STW effluentswere also measured. Estrone was detected at thehighest concentration and in almost all samples from thethree STW effluents, concentrations ranging from <0.4 to12.2 ng/L. Estradiol was also detected frequently (<0.4−4.3 ng/L), but ethinylestradiol was detected infrequently (<0.4−3.4 ng/L). Positive detections were only found for estronein the sediment, and these seemed to be unrelated tothe water column concentrations. Levels of estrone wereclearly raised above background levels in the rivers asa result of the STW discharges. Levels of estradiol andethinylestradiol were too close to their detection limits toassess the STW impact. River water estrone concentrationdeclined downstream at a rate that was in excess of thatdue to dilution. The most likely cause of this decline isa combination of sorption and biodegradation equivalentto a first-order decay half-life of 2.5 days for the River Neneand 0.5 days for the River Lea.
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