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为了研究城市河道沉积物有机质的氧化稳定性，以氧化稳定系数（ Kos ）和腐殖化程度（ HA／FA）作为评价指标，在用H2 O2处理沉积物的基础上，探讨城市污染河道有机质含量、有机质组成等对氧化稳定性的影响．结果显示，污染河道沉积物有机质含量明显高于自然水生态系统沉积物有机质含量；富里酸（ FA）、胡敏酸（ HA）、胡敏素（ HM）是污染河道沉积物有机质主要赋存形式，其中胡敏素是主体，占全部有机质的65％以上；易氧化有机质（OMr）和难氧化有机质（OMd）与总有机质含量均显著正相关（P＜0．05）；OMd的含量可以更直观地反映河道污染程度；重污染河道沉积物有机质去除量较高；随着有机质的去除，沉积物Kos在总体上有上升的趋势；不同形态有机组分其Kos差异性明显（ P＜0．05），以HM为主的紧结态腐殖质的Kos值最高；用HA／FA和OMr可从大体上表征沉积物的氧化稳定性；HA、FA是影响城市河道沉积物氧化稳定性的主要因素．

To evaluate the oxidative stability of the organic matter ( OM ) in sediments of polluted urban rivers, the organic matter content, compositions and fractions in sediments from three urban rivers ( named TL, HH and TJ) of different trophic levels were studied. Hydrogen peroxide ( H2 O2 ) was used to reduce OM content of the sediments. Oxidative stability coefficients ( Kos ) of organic carbon and humification degree ( HA/FA) were calculated and compared, and the effect of organic matter ( OM) contents, composition and fraction on the oxidative stability of OM was discussed. The result indicated that the OM content in the sediments from heavily polluted urban river was significantly higher than that in the sediments from natural aquatic ecosystem. OM in the sediments from polluted urban river existed mainly in the forms of fulvic acid ( FA ) , humic acid ( HA ) and Humin ( HM) . HM was the major fraction, accounting for more than 65%of OM. Both the content of the readily oxidized OM ( OMr ) and that of the difficultly oxidized OM ( OMd ) were significantly positively related to the total content of OM ( P<0.05) , and the content of OMd could be an intuitive index for the pollution level of urban rivers. The highest removal capacity of sedimentary OM by H2O2 was observed in the most polluted river. The value of Kos tended to increase as larger proportion of sedimentary organic matter was removed. There were significant differences in Kos among different humus fractions in the sediments. The maximum of Kos appeared in sediments with HM as the major fraction of OM. HA/FA and OMr could be indices to monitor OM oxidative stability of urban river sediments. HA and FA were the key factors on OM oxidative stability in the sediments from urban rivers.