| In recent years,as brominated flame retardants are widely used in textiles,electronics,building materials and transportation,it was released to the environment inordinately during its production,use and disposal.As a new POPs,its bioaccumulation,toxicity,durability and long-distance migration ability can make it possible to remain in the environment for a long time and cause great harm.Brominated flame retardants have strong hydrophobic,sediments in river are important carrier and different environmental factors have different impacts on its distribution.The basic work of preventing and controlling the pollution diffusion of brominated flame retardants is to study the distribution characteristics,migration and transformation rules of brominated flame retardants in different surface waters.Weihe River,an important river in the northwestern of China,plays a vital role in the development of the Northwest.Therefore,it is necessary to study the pollution status,ecological risk and adsorption behavior of brominated flame retardants in the Weihe River Basin,which is of great significance to protect the water environment in Weihe River Basin.This paper,taken the Shaanxi section of the Weihe River as the study area,analyzed the pollution level and distribution of Hexabromocyclododecane(HBCDs)Tetrabromobisphenol A(TBBPA)and in water and riverbed sediments,and used SSD model to assess the ecological risk of TBBPA and HBCDs based on detection data.Taken TBBPA and HBCDs as objects,the adsorption mechanism of TBBPA and HBCDs in sediments was further explored by basic static adsorption experiments on adsorption kinetics,isothermal adsorption,adsorption thermodynamics,environmental factors(pH,ionic strength,HA)and SEM-Energy Spectrometer Characterization and FT-IR of SR light source.The typical results were shown as follows:(1)The concentrations of TBBPA in the sediments and water samples of the Weihe River were ND-3.889 ng/g dw and ND-12.279 ng/L,respectively.The concentration of ∑HBCDs in sediments ND-4.04 ng/g dw,and it was mainly α-HBCD.Compared with other rivers,the pollution levels of TBBPA and HBCDs in the Weihe River were lower.(2)The species sensitivity distribution curve method(SSD)was constructed to evaluate the ecological risk of TBMPA and HBCDs in the Weihe River.The results showed that TBBPA at S9 and S28 points in the Weihe River had chronic toxicological risks on aquatic organisms,and corresponding risk reduction measures should be taken.TBBPA in sediment did not produce chronic ecological risk and had a low potential risk.HBCDs in the selected section of the Weihe River presented ―no risk‖.(3)The kinetic adsorption process of TBBPA and HBCDs by sediments was ultra-rapid adsorption because of their super hydrophobic properties.The isothermal adsorption process of sediments on both brominated flame retardants can be well fitted by Langmuir model and Freundlich model,and the adsorption capacity of three isomers of HBCDs was γ-HBCD>β-HBCD> α-HBCD.In addition,the thermodynamic results showed that the adsorption process of HBCDs by sediments was a spontaneous exothermic reaction,while the adsorption process of TBBPA was a spontaneous endothermic reaction.(4)Experimental result of environmental factor influence showed that,with the increase of pH,the adsorption effect of sediments on the three isomers of HBCDs was not obvious,but the adsorption of sediments on TBBPA was inhibited.With the increase of ionic strength,it inhibited the adsorption of α-HBCD and TBBPA,but had little effect on the adsorption of β-HBCD and γ-HBCD.With the increase of humic acid(HA)concentration,the adsorption of HBCDs and TBBPA increased first and then decreased.(5)The results of scanning electron microscopy-energy spectroscopy showed that the surface roughness increased significantly after adsorbing sediment,and the presence of Br was observed after adsorption.The results of infrared spectroscopy indicated that the adsorption of TBBPA on the surface of the sediment was mainly π-π bond and hydrogen bond,and the adsorption of HBCDs was mainly hydrophobic. |
PDF Full Text Request