水样不同处理方式对高锰酸盐指数测定值的影响

EFFECT OF SAMPLE PRETREATMENT ON DETERMINATION OF PERMANGANATE INDEX IN WATER

研究了水样不同处理方式对三峡水库干流江段高锰酸盐指数(COD_(Mn))测定值的影响。结果表明,悬浮颗粒物浓度(SS)是澄清样和浑样之间、清样和浑样之间、清样和澄清样之间高锰酸盐指数差别的主要影响因子;用非线形回归方法得出了水样不同处理方式下高锰酸盐指数间的经验关系,并用实测数据进行了验证,结果表明,计算值和实测值吻合良好。依据SS和所得经验关系,可计算高锰酸盐指数所表征有机物(COD_(Mn))即OS(COD_(Mn))作为一个整体在水-固两相之间的分配,及其在粗颗粒物和细颗粒物上的赋存比例。河床上覆水体中溶解态、颗粒态OS(COD_(Mn))所占比例皆随SS而发生显著变化。SS大于1000 mg/L时,80%以上的OS(COD_(Mn))赋存于悬浮颗粒物,澄清30 min能去除60%以上的OS(COD_(Mn))。

The effect of sample pretreatment on determination of permanganate index in the Yangtze River water of Three Gorges Reservior Section was studied. It is found that the content of suspended solids （SS） was the major factor leading to the difference in determination of permanganate index in various pretreated water samples. The empirical relationship of the differences was obtained using nonlinear regression method and verified with the determined data. Results showed that the values calculated from empirical equations coincided well with the determined values. The distribution of organic substances corresponding to permanganate index-OS（CODMn） as a whole between water phase and solid phase, as well as between coarse particles and fine particles in overlying water can be calculated using the empirical equations. The proportions of dissolved OS（CODMn）, particulate OS（CODMn）,and OS（CODMn） existing in the coarse or fine particles changed significantly with the content of SS. When SS exceeded 1 000 mg/L,over 80% of OS （CODMn） existed in suspended solids,and over 60% of OS（CODMn） can be removed during 30min settlement.