Environ. Sci. Technol. 2007, 41, 4299-4304
Evidence for the Migration of Steroidal Estrogens through River Bed Sediments PIERRE LABADIE,† ANDREW B. CUNDY,‡ KEVIN STONE,‡ MICHAEL ANDREWS,† SAM VALBONESI,† AND E L I Z A B E T H M . H I L L * ,† Centre for Environmental Research, School of Life Sciences, University of Sussex, Brighton BN1 9QG, United Kingdom, and School of the Environment, University of Brighton, Lewes Road, Brighton BN2 4GJ, United Kingdom
Estrogenic substances discharged from wastewater treatment plants have been detected in surface sediments of receiving waters, but little is known of their vertical migration through buried sediments and their potential to contaminate subsurface waters. The vertical profiles of estrogenic chemicals were investigated in sediment cores at an alluvial freshwater site (Ditchling) and a clay-rich estuarine site (Lewes), both of which are downstream of wastewater discharges into the River Ouse (Sussex, U.K.). Estrone (E1) was the predominant estrogen detected in surface and buried sediments at both sites and was detected in undisturbed clay sediments >120 years old. Profiles of E1 at Ditchling were characterized by a prominent subsurface peak of E1 at the alluvium/clay interface (-15 cm) at a concentration (28.8 ( 6.0 ng/g of dry wt) that was 9-fold higher than in the surface sediment. In contrast, a steady downcore decline in E1 concentrations was observed in the clay-rich Lewes core. This work provides the first in situ evidence of estrogen migration through river bed sediments and reveals that movement of estrogens through unconsolidated sediment can result in penetration to the underlying substrata and therefore the potential for groundwater contamination.
1. Introduction There is a growing concern about the occurrence of estrogenic substances in aquatic systems impacted by anthropogenic activities. Exposure of biota to these chemicals may disrupt the reproductive system of aquatic biota especially in ecosystems with a high input of poorly diluted wastewater treatment plant (WwTP) effluents (1). The major estrogenic components in effluents of WwTPs of mainly domestic input are the natural estrogens estrone (E1) and 17β-estradiol (E2) and the synthetic estrogen 17R-ethynylestradiol (EE2) (2, 3). The concentrations of estrogens in U.K. WwTP effluents usually range from 1 to 76 ng/L for E1, 1 to 48 ng/L for E2, and 98%). Three surrogates, [2,4,16,16-4H2]E1 (E1-d4), [2,4,16,16-4H2]E2 (E2- d4), and [2,4,16,16-4H2]EE2 (EE2- d4) (isotopic purity 96% and chemical purity >98%) were obtained from Cambridge Isotope Laboratories (Andover, MA). All solvents were of LC-grade (Rathburn Chemicals, Walkerburn, U.K.). Estrogen solutions (stock solution 1 mg/ mL and working solution 0.1 ng/µL) were prepared in methanol and stored at -20 °C. Ultrapure water was dispensed from an UHQ purification system (Elga Systems, High Wycombe, U.K.). Butylated hydroxytoluene (BHT, >99%) and sodium hexametaphosphate (>65%) were supplied by Sigma-Aldrich. Scintillation fluid (Scintran Fluoransafe 2) was purchased from BDH Laboratory Suppliers (Poole, U.K.), and [4-14C]-E1 (1.998 GBq/mmol) was obtained from American Radiolabeled Chemicals (Saint Louis, MO). 2.2. Sediment Sampling. Sediments were sampled in the River Ouse catchment at two sites: (i) Ditchling (50°55′20′′N, 00°05′60′′W), 200 m downstream of a small sized WwTP (1500 populationequivalents)and(ii)Lewes(50°51′55′′N,00°01′27′′E), located 5 km downstream of the nearest WwTP (25 population equivalents) (see map in Supporting information). At both these sites, significant levels of steroidal estrogens in overlying waters were predicted using the GREAT-ER 1.0 model (Georeferenced Regional Exposure Assessment Tool for European Rivers, http://www.great-er.org/). The GREAT-ER model has been used to simulate the distribution of a range of chemicals, including estrogens, in surface waters downstream of WwTPs (e.g., ref 20). Average estrogen concentrations in the water column (December conditions) at the Ditchling site were predicted to be among the highest in the catchment: at 2.0-3.0, 0.5-1.0, and 0.3-0.4 ng/L for E1, E2, and EE2, respectively. The Lewes site was selected because it is located in the brackish reach of the catchment in the zone of the estuarine turbidity (i.e., suspended sediment) maximum and where contamination of surface waters with VOL. 41, NO. 12, 2007 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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estrogens was predicted: 0.4-1.2, 0.07-0.12, and
