白洋淀典型水域COD的组成及各组分贡献

化学需氧量（COD）是我国评估有机耗氧污染的关键指标，为探究白洋淀湖心区和沼泽区天然水体COD构成组分，通过物理连续分级和三维荧光等方法揭示水体中的耗氧有机物质主要组成、来源和影响因素.结果表明，白洋淀COD主要由类蛋白质和类腐殖质溶解性有机物质贡献（59%~93%），无机物（如Cl^-和NO₃^-等）对COD产生的贡献甚微，可忽略不计；上覆水有机物主要受内生植被降解、沉积物释放［TOC释放通量1.55~2.28 mg ·（m² ·d）^-1］等内源［生物源指数（BIX）>0.8］和人为污染、芦苇台田等陆源的共同影响（1.4<荧光指数（FI）<1.9），沉积物有机质以陆源（芦苇台田）为主.研究水域COD的组分主要受难生化降解有机物质（RDOC）控制，RDOC在天然环境中降解周期较长，重铬酸钾法会在短时间内迅速氧化大部分RDOC，因此高估了水体的有机耗氧污染水平.

Chemical Oxygen Demand(COD) Composition and Contribution in Typical Waters of Baiyangdian Lake

Chemical oxygen demand (COD) is an important index used to assess organic oxygen consumption pollution. To explore COD composition in the natural water in Baiyangdian Lake, the main composition, source, and influencing factors of oxygen-consuming organic substances in the water body were revealed through physical continuous classification, three-dimensional fluorescence, and other methods. The results showed that the COD of the two waters was affected by dissolved organic substances (protein-like and humus-like organic matters) with size of less than 220 nm (59%-93%), and inorganic substances had little effect on COD. The source of organic matter in overlying water was primarily affected by endophytic vegetation decomposition, sediment release (the release flux of TOC was in the range of 1.55-2.28 mg·(m²·d)^-1), and other endogenous sources (biological index>0.8), as well as by land-based sources such as reed platform and artificial pollution (1.4