黄河泥沙中的腐殖质对高锰酸盐指数测定的影响

通过模拟试验研究了黄河泥沙对高锰酸盐指数的影响,结果表明:①浑水高锰酸盐指数(COD_Mn)和水样加酸处理后水相COD_Mn随着泥沙含量的增加而显著增长;但水样未加酸处理水相的COD_Mn随着泥沙含量的增加只呈微上升趋势;②随着泥沙含量的增加,浑水生化需氧量(BOD₅)的增长率显著低于浑水COD_Mn和加酸处理条件下的水相COD_Mn的增长率;③黄土中含量仅为0.76%的腐殖质对含泥沙浑水COD_Mn的贡献较大,当泥沙含量为7.5g/L和15g/L时,腐殖质对浑水COD_Mn的贡献分别为15.9%和 21.7%;④泥沙中腐殖质的主要组成之一富里酸溶于酸,当泥沙含量为7.5g/L和15g/L时,富里酸对水样加酸处理后水相COD_Mn的贡献分别为23.6%和50.6%.由于富里酸在自然条件下不容易发生生物降解,因此,目前黄河水质监测中的COD_Mn夸大了黄河耗氧性有机物的污染.

Influence of Humic Substance in Solids on CODMn of the Yellow River

Experiments were carried out to study the influence of humic substance in solids (Loess soil) on CODMn in the Yellow River. Several significant results were abtained from the study: (1) The total CODMn of water sample including liquid and solid phases increased significantly with the increase of solid content; The CODMn of liquid phase of water sample under pre-treatment with acid (LPWSPC) also increased significantly with the increase of solid content while that without pre-treatment did not increased significantly. (2) With the increasing of solid content, the total BOD5 of water sample increased much slower than the total CODMn and the CODMn of LPWSPC. (3) The humic substances with the content of 0.76% in solids (Loess soil) contributed greatly to the total CODMn of water sample. When the solid contents were 7.5 g/L and 15.0 g/L, the humic substances in solids accounted for 15.9% and 21.7% of the total CODMn of water sample, respectively. (4) When solid contents were 7.5 g/L and 15.0 g/L, fulvic acid,one of the main compositions of humic substance contributed to 23.6% and 50.6% of the CODMn of LPWSPC, respectively. Since the fulvic acid can hardly be biologically oxidized under natural conditions, the CODMn of LPWSPC in water quality monitoring exaggerates the oxygen-consuming organic contamination of the Yellow River.