In order to solve the overestimation problem of existing NR/DAPI co-staining-fluorescence counting method for determination of microplastics in tap water,the methods for water samples and experimental devices treatment were optimized.The optimized test results showed that,burning the glass wares and the filter membrane for 1 h at 500℃could significantly reduce the MPs brought into the sample by the experimental e-quipment.Digesting tap water samples with 30%H2O2(VH2O2:VH2O = 1∶5)for 24 hours could eliminate the overestimation of experimental results caused by organic matters in water samples.Using the improved NR/DAPI co-staining-fluorescence counting method to determine tap water samples from different districts of Hefei city,the results showed that,the average concentrations of MPs in those samples was in the range of 350-1 250 n/L,polyethylene(PE)accounting for the largest proportion(40%-60%)followed by the proportion of PMs with a size less than 10 μm(36%-71%).The MPs in tap water samples had significant temporal distribution charac-teristics,during the low water usage period at night,the flow rate of tap water in the pipeline network was low,and small particles of MPs settled and accumulated,resulting in a significantly higher concentration of MPs in the initial discharge tap water in morning than in other time periods.
维普
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