| Summary: | Lakes and rivers receiving wastewater treatment plant effluent contain many different endocrine disrupting compounds. Previous research into the fate of these compounds has focused on laboratory experiments that investigate a single scavenging mechanism, and there has been little research on the overall loss rate constants in receiving waters. This study evaluated the fate of estrone (E1), 17??-estradiol (E2), estriol (E3) and 17??-ethinylestradiol within three different receiving waters (a river, a large lake and a small reservoir) represented by two different mathematical models (plug flow reactor and continuously stirred tank reactor) and three different hydraulic residence times (<8 hours, >50 years and about 1 year). Wastewater treatment plant effluent samples and receiving waters were analysed for the four estrogens over a one year period. E1 and E2 were the only compounds detected and there was only enough data determine the fate of E1. A receiving water loss rate constant for E1 was calculated assuming first-order reaction kinetics. E1 loss was not detectable in the river and the large lake due to a very short and very long residence time, respectively. The time-weighted E1 loss rate constant within the small reservoir was found to be 0.0106 d-??. Data suggested that there may be a seasonal component to this loss rate that requires further investigation. The rate constant found suggests that E1 can be transported great distances within rivers.
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