Grant L. Northcott

Retention of estrogenic steroid hormones by selected New Zealand soils.

We performed batch sorption experiments for 17beta-estradiol (E2) and 17alpha-ethynylestradiol (EE2) on selected soils collected from dairy farming regions of New Zealand. Isotherms were constructed by measuring the liquid phase concentration and extracting the solid phase with dichloromethane, followed by an exchange step, and analysis by HPLC and UV detection. The corresponding metabolite estrone, (E1) formed during equilibration of E2 with soil was taken into account to estimate the total percentage recoveries for the compounds, which ranged from 47-105% (E2 and E1) and 83-102% (EE2). Measured isotherms were linear, although some deviation from linearity was observed in a few soils, which was attributed to the finer textured particles and/or the allophanic nature of the soils having high surface area. There was a marked difference in K(d)(eff) (effective distribution coefficient) values for E2 and EE2 among the soils, consistent with the soils organic carbon content and ranged from 14-170 L kg(-1) (E2), and 12-40 L kg(-1) (EE2) in the soils common for both compounds. The sorption affinity of hormones in the soils followed an order: EE2<E1<E2 in Manawatu and Horotiu soils, and, E1<EE2<E2 in Pukekohe soil with average log K(oc) of about 3 (+/-0.1-0.2 log units) which was consistent with earlier published values. Formation of the transformation product E1 appears to be concomitant with E2 sorption in all but one soil. Given that quite a large amount of E1 was generated during 72 h of contact time, and given E1 sorbed to solid phases greater than the liquid phase, dissolved organic carbon facilitated transport of these hormones needs to be considered when assessing the leaching risk for these compounds in the environment.

Laboratory degradation studies of four endocrine disruptors in two environmental media

We investigated the degradation of 17beta-estradiol (E(2)), 17alpha-ethinylestradiol (EE(2)), bisphenol-A (BPA), and 4-n-nonylphenol (4-n-NP) in river water-sediment and groundwater-aquifer material under aerobic and anaerobic conditions. The results showed rapid degradation of all four compounds in both media with >90% of the four compounds degraded within the first 2 to 4 d under both conditions. However, degradation rates were extremely slow for the remaining period. Model derived 50% dissipation time (DT50) values in river water-sediment slurries ranged from 0.24 to 1.5 d (E(2)), 0.29 to 1.1 d (EE(2)), 1.2 to 1.4 d (BPA), and 0.42 d (4-n-NP), while the 90% dissipation time (DT90) values for the four endocrine-disrupting chemicals (EDCs) ranged from 0.9 to 2.8 d under both conditions. A minor difference was observed in DT50 and DT90 values for the four EDCs in groundwater- aquifer material under aerobic conditions as compared with river water-sediment. Under anaerobic conditions, DT90 values ranged from >1,000 d (EE(2)) to >300 d (BPA), in groundwater-aquifer material. Degradation of the four compounds under anaerobic conditions was attributed to the sulfate-, nitrate-, and iron-reducing conditions within the tested media; however, it was postulated that overall degradation of the compounds was also influenced by abiotic factors, accounting for nearly 6 to 40% (river water- sediment) and 0 to 18% (groundwater-aquifer material) under the two conditions tested.

Transport and Modeling of Estrogenic Hormones in a Dairy Farm Effluent through Undisturbed Soil Lysimeters

The presence of endocrine-disrupting chemicals, including estrone (E1) and 17beta-estradiol (E2), in surface waters has been associated with physiological dysfunction in a number of aquatic organisms. One source of surface and groundwater contamination with E1 and E2 is the land application of animal wastes. The processes involved in the transport of these hormones in the soil, when applied with animal wastes, are still unclear. Therefore, a field-transport experiment was carried out, where a dairy farm effluent spiked with E1 and E2 was applied on large (50 cm diameter and 70 cm depth) undisturbed soil lysimeters. The concentrations of E1 and E2 in the leachate were monitored over a 3-month period, during which irrigation was applied. The experimental data suggest that E1 and E2 were transported through preferential/macropore flow pathways. The data from the experiment also show that E1 and E2 are leached earlier than the inert tracer (bromide). This observation can be explained either by the presence of antecedent concentrations in the soil or by an enhanced transport of E1 and E2 through the soil. A state-space mixing-cell model was further developed in order to describe the transport of E1 and E2 by three transport processes in parallel. The inverse modeling of the leaching data did not support the hypothesis that antecedent concentrations of estrogens could be responsible for the observed breakthrough curves but confirmed that estrogens were transported mainly via preferential/macropore flow and also via an enhanced transport. The parameter values that characterized this enhanced transport strongly suggest that this enhanced transport is mediated by colloids. For the first time, the simultaneous transport of E1 and E2 was modeled under transient conditions, taking into account the advection-dispersion, preferential/macropore flow, and colloidal-enhanced transport processes as well as E1 and E2 dissipation in the soil. These findings have major implications in terms of management practices to decrease E1 and E2 transport and water contamination.

Passive secondary biological treatment systems reduce estrogens in dairy shed effluent.

Steroid estrogens are found at high concentrations in untreated dairy shed effluents. Reduction of estrogenic activity and steroid estrogen concentrations was assessed in two systems used to treat dairy shed effluents: the two-pond system and the advanced pond system. Both include anaerobic and aerobic treatment stages. Samples of effluent were collected from the systems and analyzed for free estrogens, conjugated estrogens and total estrogenic activity using E-Screen assay. Both systems showed increases of up to 8000% in aqueous free estrogens and estrogenic activity after anaerobic treatment, followed by decreases after aerobic treatment (36-83%). The complete systems decreased total steroid estrogen concentrations by 50-100% and estrogen activity by 62-100%, with little difference between systems. Removal rates were lower in winter for both systems. Final effluents from the advanced pond system contained total estrogens at <15-1400 ng/L and estrogenic activity at 3.2-43 ng/L. Final effluent from the two-pond system contained total estrogens at <15-300 ng/L and estrogenic activity at 3.3-25 ng/L. At times the final effluent EEQs exceeded guideline values for protection of freshwater fish and suggest further treatment may be required.