Predicting Bioavailability Of Copper And Cadmium By Diffusive Gradient In Thin Film Technique With Water-soluble Polymer As Binding Agents

In this work,water-soluble polymers as binding phases were applied for DGT assemble.CarboxymethylCellulose Sodium(CMC)and poly(ethylene imine)(PEI)as binding phases of DGT were evaluated.Bioavailabiliy of copper and cadmium to Saurogobiodabtyiwas predicted under laboratory condition.In chapter 1,The definition and classification of water-soluble polymers,interactions of CarboxymethylCellulose Sodium and poly(ethylene imine)with heavy metals,and the definition,source,harm and characteristic of heavy metals pollution were introduced.The concept of metals bioavailability and its measurement methods were described.A promising in-situ passive sampling method for heavy metals in environment,namely,diffusive gradients in thin-films(DGT)technique was introduced.The principle of DGT technique,construction of DGT device,the development of diffusive layer and binding agents,the application of DGT technique for the sampling of heavy metals in water,sediment and soil,and the prediction of metals bioavailability were summarized.The objective and innovation of this paper were presentedIn chapter 2,the measurement of labile Cue+,Cd2+ and Pb2+ by DGT device using 0.05 mol·L-1 solution of carboxymethyl cellulose sodium(CMC)as the binding phase and cellulose acetate dialysis membrane as the diffusive layer(CMC-DGT)had been systemically investigated.The effects of pH,ionic strength on the binding capacity of CMC-DGT and ligands(EDTA,tannic acid and fulvic acid)on the labile metals were studied.Comparison of CMC-DGT device with PSS-DGT device for the measurement of labile Cu2+,Cd2+ and Pb2+in spiked waters was assessed.The binding capacities of CMC-DGT for Cue+,Cd2+ and Pb2+were 0.24,0.11 and 0.45 mg·mL-1,respectively.Optimal pH ranges of CMC-DGT for Cue+,Cd2+ and Pb2+ were 3.7-8.0,4.7-9.0 and 4.7-8.0,respectively.The binding amounts of CMC-DGT for Cu2+,Cd2+ and Pb2+ decreased with the enhancement of ionic strengths in bulk solution.The Cue+,Cd2+ and Pb2+ concentrations were determined accurately and simultaneously in synthetic solution by CMC-DGT(recovery = 92.12%for Cue+,recovery =100.6%for Cd2+ and recovery = 96.43%for Pb2+).The labile concentrations of Cu2+,Cd2+and Pb2+ by CMC-DGT decreased with the enhancement of ligands concentrations.The measured values of labile Cu2+,Cd2+ and Pb2+ concentrations by CMC-DGT were obviously more than that of PSS-DGT in spiked river water,spiked industrial wastewater and spiked lake water.Results indicated that CMC-DGT showed good prospect for the measurement of labile Cu2+,Cd2+ and Pb2+ in waters.In chapter 3,a 0.050 mol·L-1 solution of poly(ethyleneimine)(PEI),had been used as a novel binding agent of diffusive gradients in thin-films(DGT)technique(PEI-DGT)for measuring the concentrations of labile Cue+,Cd2+ and Pb2+ in waters.The binding capacities of the PEI-DGT for Cu2+,Cd2+ and Pb2+ were 11.8,10.2 and 10.6 μmol·mL-1,respectively.The performance of PEI-DGT was independence of pH in the range of 4.0-8.0 and ionic strength in the range from 1×10-4 to 0.1 mol·L-1(as NaNO3).PEI-DGT could measure 104.7%of the total concentration of Cd2+,95.2%of the total Cu2+ and 99.2%of the total Pb2+ in synthetic solution.Effects of the ligands on the measurement of labile metals were also investigated in synthetic solutions containing the various concentrations of EDTA and humic acid.In EDTA solution,the concentrations of labile metals measured by PEI-DGT showed good agreement with the theoretical concentrations of free metal ions.In humic acid solution,the concentrations of labile metals measured by PEI-DGT decreased with the increase of the concentrations of humic acid.Several DGT devices with various binding agents,including PEI,sodium polyacrylate and poly(4-styrenesulfonate)solution,were used for the measurement of labile fractions of Cu2+,Cd2+ and Pb2+ in the spiked waters and in mine wastewaters.The results showed that the concentrations of labile metal measured by DGT devices with different binding agents could be significantly different,indicating that the labile fractions of metals were dependent on the binding strength of the binding agents with metals.In chapter 4,copper was used as the target pollutant,and fish(Saurogobiodabtyi)was used as the indicator.Compared with the uptake of copper in fish gill and fish body,the prediction of PAAS-DGT,PSS-DGT and CMC-DGT for copper bioavailability was investigated by the relationship between the accumulation of copper by three DGT devices and’the uptake of copper by fish.The results showed that the variation tendency for the accumulation of copper by PSS-DGT,PAAS-DGT,CMC-DGT,fish gill and fish body was same.Linear relationship(R2>0.92)between the concentration of copper in bulk solution and the accumulation of copper by PSS-DGT,PAAS-DGT,CMC-DGT,fish gill and fish body were found.There was good correlation between the uptake of copper in fish gill and fish body and the copper accumulation in the three DGT devices(R2>0.88).The three DGT devices can be used to predict the bioavailability of copper to Saurogobiodabtyi.In chapter 5,cadmium was used as the target pollutant,and Saurogobiodabtyi was used as the indicator.Compared with the uptake of cadmium in fish gill and fish body,the prediction of PAAS-DGT,PSS-DGT and CMC-DGT for cadmium bioavailability was investigated by the relationship between the accumulation of cadmium by three DGT devices and the uptake of cadmium by fish.The results showed that the variation tendency for the accumulation of cadmium by PSS-DGT,PAAS-DGT,CMC-DGT,fish gill and fish body was same.A linear relationship(R2>0.95)between the concentration of cadmium in bulk solution and the accumulation of cadmium by PSS-DGT,PAAS-DGT,CMC-DGT,fish gill and fish body were found.There was good correlation between the uptake of cadmium in fish gill and fish body and the cadmium accumulation in the three DGT devices(R2>0.89).The three DGT devices can be used to predict the bioavailability of cadmium to Saurogobiodabtyi.In chapter 6,the quantitative measurement of Cu2+,Cd2+ and Pb2+by atomic absorption spectrometry was investigated.The linear ranges of Cu2+,Cd2+ and Pb2+ were 0.500-2.500 mg L-1,0.500-2.500 mg L-1 and 1.000-5.000 mg L-1,respectively.The recoveries of Cu2+,Cd2+ and Pb2+ in different matrix including polymer solution and fish digestion solution,were in the range from 96.3 to 106.9%.RSDs%were in the range of 0.4-3.3%.The results indicated that the concentrations of Cu2+ Cd2+ and Pb2+ in solution could be determined by atomic absorption spectrometry.In chapter 7,the CMC and PEI are suitable as the binding agents of DGT technique.Compared with Saurogobiodabtyi,three DGT devices(such as CMC-DGT,PSS-DGT and PAAS-DGT)can predict the bioavailability of copper and cadmium in water and can provide strong technical support for assessing the environmental and health risks of heavy metals.