Influence of plant on the extractability of estrogen in the rhizospheric soil

Livestock wastes applied to agricultural land are potential sources of steroidal hormones （estradiol （E2）, estrone （E1）, and estriol （E3）） that can adversely affect the aquatic ecosystem as endocrine disruptors. But the effects of plants on the fate of estrogen in the environment are not clearly known. In the present report, the behavior of E1, E2 and E3 added to the rhizospheric soil in various concentrations and its effect on plant growth were examined by estrogen batch sorption test, plant pot test and estrogen extraction test. Trifolium repens was grown on the soil spiked with E2 or a mixture of E1, E2 and E3. Pots without plant were prepared as controls. All pots were watered in 50 ml dose almost every day, and the rhizosheric soil and plant body were collected 7, 19, 26, 33 days after planting. The soil was sequentially extracted with Milli-Q water, and methanol / 1M acetic acid solvent followed by methanol wash at the solid to liquid ratio of 1 ： 4 （g/mL）. Extracts were analyzed for El, E2 and E3 using a Shimadzu GCMS-QP5050. Plant dry weight （4 hours, 105 ℃） was measured as an indicator of plant growth. In batch sorption tests, E1 and E2 concentrations in the liquid phase significantly decreased within 24 hours after the addition of estrogen. The sum of methanol / 1M acetic acid extractable E 1 and E2 in the soil decreased to half of the initial added amount within 7 days. Reduction in total estrogenic activity of the soil extracts （estimated as 0.01CE1＋CE2＋0.1CE3 where CE1, CE2 and CE3 are respective El, E2 and E3 concentrations per unit soil weight） continued for 1 month due to slow oxidation of E2 to E1. Desorption of E2 from soil during the pot experiment was higher than expected from the sorption experiment.

Influence of plant on the extractability of estrogen in the rhizospheric soil