Experimental investigation on the variation of acute toxicity of common endocrine disruptors in soil irrigated with reclaimed water

【Objective】Domestic wastewater contains a variety of pollutants, even after standard treatment, with endocrine disruptors being one of the most concerning. However, the biogeochemical transformation of these disruptors in soil following irrigation with reclaimed wastewater is not well understood. This study aims to investigate the changes in acute toxicity of common endocrine disruptors in soil irrigated with reclaimed water under different aerobic conditions.【Method】Bisphenol A (BPA) and nonylphenol (NP) were selected as representative endocrine disruptors in reclaimed wastewater. The changes in their acute toxicity in soil irrigated with reclaimed water under varying aerobic conditions were experimentally studied. Vibrio fischeri was used as the test organism. The concentrations of BPA and NP in the soil were based on estimated concentrations at different times following reclaimed water irrigation: 10 years (Y1), 50 years (Y2), 100 years (Y3), 500 years (Y4), and 1 000 years (Y5). The acute toxicity of the soil was measured under three conditions: aerobic (T1), aerobic-anaerobic (T2), and anaerobic (T3).【Result】Under aerobic conditions (T1), the acute toxicity of the soil increased over time but remained at a low level, with a maximum luminescence inhibition rate of 28.23%. Under the aerobic-anaerobic condition (T2), the acute toxicity initially decreased and then increased over time. This was likely due to slow degradation of endocrine disruptors in the early stages, followed by an accumulation of metabolites that increased the toxicity. However, after a sufficiently long period, the toxicity decreased. Under anaerobic conditions (T3), the degradation of endocrine disruptors was slow or even stalled. The acute toxicity of the soil ranged from 13.70% to 21.65%. 【Conclusion】 Soil with varying concentrations of endocrine disruptors did not exhibit significant acute toxicity. Additionally, degradation of these disruptors varied considerably depending on the redox conditions of the soil. Increased bioavailable oxygen enhanced the degradation of endocrine disruptors.