The role of soil layers in preventing ground water pollution with 17ß-estradiol hormone (E2)

Background: Estrogens include estoril (E3), estradiol and estrone (E1). These chemicals are produced in human and animal bodies as well as in synthetic chemicals (drugs). Estrogens can enter water sources in different ways. When these chemicals enter the human body through water and wastewater, they have the ability to mimic or disrupt the normal estrogen activities in humans and animals. Estrogens in wastewater are able to pass soil layers and contaminate groundwater. Therefore, in this study, the removal of the hormone 17ß-estradiol (E2) as a representative of estrogens in three types of soils was studied. The selection was chosen in respect to the importance of entering the hormone into groundwater through the soil. Methods: This study was an experimental study in which the removal of the hormone E2 from different depths of three types of soils was experimented. The soils were consisted of two different textures, the silty sandy clay and the silty sand with gravel. The hormone E2 was diluted and injected into the drilled holes. Soils were characterized in the soil mechanics laboratory. Hormone extraction from the soils was performed using a centrifuge and analyzed with the Elecsys device. The results were analyzed using the IBM SPSS version 22 software. Results: The results showed that the removal rates of hormone E2 in the three types of soils were higher than 99.5%, and the removal rate in the silty sand was more than the others. In all three soil samples, the removal rates in the first layer were high. The average injected hormone in the soil decreased from 3500 to 3112 ng/l. The results showed that the adhesion and plasticity of the soil had also affected the removal rates. Conclusion: Results showed that the soil plays a significant role in the removal of E2 hormone and this hormone was reduced or eliminated in the first layers of the soils. Thus, the risk of groundwater contamination is low.