COD MEASUREMENTS CORRECTION IN THE TIDAL REACH OF THE YELLOW RIVER DELTA BASED ON ENVIRONMENTAL PROTECTION CONCEPT

In low-salinity estuaries and near coastal areas, COD determination by the potassium dichromate method is affected by salinity (chloride ion concentration), and the measured values do not accurately reflect the degree of organic pollution in these areas. In this study, water quality characteristics in the tidal reach of the Yellow River Delta were simulated by diluting seawater and adding glucose as a substrate. The potassium dichromate method was used to measure the COD of the water samples. The influence of salinity on the measurements was analyzed, and a correction formula was obtained. Cross-sectional monitoring data were used for analysis and verification. The results provide a basis for COD measurement and water quality evaluation in the tidal reach of the Yellow River Delta, and thus the effect of environmental protection is greatly improved.