State Key Laboratory for Marine Environmental Science, Institute of Marine Microbes and Ecospheres, College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361102, China.
State Key Laboratory for Marine Environmental Science, Institute of Marine Microbes and Ecospheres, College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361102, China.
Environ Res. 2022 Apr 15;206:112608. doi: 10.1016/j.envres.2021.112608. Epub 2021 Dec 23.
Indicators related to organic matter are important when assessing aquatic environment quality. The chemical oxygen demand (COD) is widely used as a water quality reference. However, oxidizing agents used to determine the COD can oxidize refractory organic matter that is not pollutant and can persist in the ocean for thousands of years. This means the COD can misrepresent the water quality. The actual water quality can be indicated better by the biochemical oxygen demand (BOD) than the COD, but determining the BOD is time-consuming and gives variable results. In this study, the optical properties of dissolved organic matter in water samples from the Chinese coast that had been incubated for a long time or directly oxidized using COD oxidant were analyzed. The results indicated that the oxidizing agent rapidly oxidized 22.93% ± 4.96% of refractory dissolved organic matter (RDOM) that was resistant to microbial degradation, implying that RDOM made a marked contribution to the COD. Meanwhile, size-fractional fluorescence spectroscopy and COD measurements indicated that the COD of the >0.7 μm fraction and the fluorescence intensity of the protein-like component significantly positively correlated with the BOD of the bulk sample. This indicated that, for monitoring organic pollutants in coastal waters, the COD of the >0.7 μm fraction could be used as a proxy for the standard COD and that the fluorescence intensity of the protein-like component could be used as a convenient proxy for the BOD. The method can help retain recalcitrant organic matter in seawater to act as a carbon sink.
在评估水环境污染质量时，与有机物相关的指标很重要。化学需氧量（COD）被广泛用作水质参考指标。然而，用于确定 COD 的氧化剂可以氧化不是污染物且可以在海洋中存在数千年的难降解有机物。这意味着 COD 可能会错误地表示水质。生化需氧量（BOD）比 COD 更能准确地指示实际水质，但确定 BOD 耗时且结果可变。在这项研究中，分析了长时间培养或直接使用 COD 氧化剂氧化的中国沿海水样中溶解有机物的光学特性。结果表明，氧化剂迅速氧化了 22.93%±4.96%的难以被微生物降解的难降解溶解有机物（RDOM），这意味着 RDOM 对 COD 有显著贡献。同时，大小分馏荧光光谱和 COD 测量表明，>0.7 μm 级分的 COD 和类蛋白组分的荧光强度与样品整体的 BOD 呈显著正相关。这表明，在监测沿海水中的有机污染物时，可以将>0.7 μm 级分的 COD 用作标准 COD 的替代物，而类蛋白组分的荧光强度可以作为 BOD 的便捷替代物。该方法有助于保留海水中的难降解有机物作为碳汇。
