Uptake, accumulation, and translocation of organophosphate esters by watermifoil (Myriophyllum aquaticum) in an aquatic ecosystem: effects of chemical structure and concentrations

Abstract

In order to explore the environmental behavior of organophosphate esters (OPEs) in aquatic environment, the accumulation and distribution of OPEs in water, sediment, and plant were investigated. In this study, watermifoil (Myriophyllum aquaticum) were exposed with ten OPEs for concentrations of 200ng/g, 500ng/g, 1000ng/g, and 2000ng/g, respectively. The concentrations of Σ10OPEs in rhizosphere sediment were higher than those in non-rhizosphere sediment, demonstrating that rhizosphere processes tend to transport OPEs into the rhizosphere sediment. Most of the selected OPEs were not in equilibrium between water and sediment, and trend to retain in sediment. In addition, OPEs with relatively higher hydrophobicity had trend to retained in Myriophyllum aquaticum roots, whereas OPEs with lower hydrophobicity were more likely transported to shoots. In this study, octanol-water partition coefficient (KOW) had significantly positive correlations with organic carbon-normalized soil-water partition coefficients (KOC) and root-water concentration factors (RWCFs), but KOW was negatively correlated with translocation factors (TFs). Moreover, the substituent types and initial levels of OPEs also have impacts on the plant uptake and accumulation. These observations will improve our understanding of the distribution and translocation of OPEs in aquatic environment.