The non-equilibrium distribution of bisphenol A and nonylphenol between sediment organic matter and water at field sites influenced by mechanical mixing

Abstract

Bisphenol A (BPA) and 4-nonylphenol (4-NP) are widely used as raw materials in industry to make plastics and surfactants respectively Both of them are recognized as endocrine disrupting chemicals (EDCs) that may affect the reproductive function of wildlife and human BPA and 4-NP released to the environment were shown to accumulate in river sediment and are likely to threaten the ecosystem and human health A previous study conducted in our group demonstrated that the in-situ organic carbon-water partition coefficients (Koc) were highly influenced by the flow rate of the rivers The obtained in-situ Koc of Jishuei (JS) River (13757 L/kg) is much higher than the reported equilibrium Koc (778 L/kg) due to dilution effect caused by the high flow rate It was speculated that the equilibrium of BPA concentrations between the organic carbon and pore water can be achieved if mechanical mixing is provided In this study the concentrations of BPA and 4-NP in various matrices including surface water pore water sediment and sediment organic carbon of two rivers in Southern Taiwan Jishuei (JS) and Yanshuei (YS) Rivers were quantified after mixing for different durations (0 7 14 and 21 days) The results showed that (1) More dissolved organic matter (DOM) leached out as the mixing time increased; (2) The in-situ Koc of BPA gradually approached to the reported equilibrium Koc from 0 to 14 days but increased significantly after 21 days mixing which may be attributed to the biodegradation of BPA in pore water; (3) The in-situ Koc of 4-NP did not exhibit remarkable change during the whole mixing period Owing to the high non-polarity of 4-NP it had higher affinity to sediment and thus was hard to leach to liquid phase through mechanical mixing Overall this study provides the leaching potential of BPA and 4-NP which offers a possible approach to understand the risk of these two organic pollutants under in-situ condition Non-polar and nonionic compounds are prone to accumulate in sediment rather than move together with water

Date of Award	2017 Aug 22
Original language	English
Supervisor	Wan-Ru Chen (Supervisor)