Analysis of Reductive Substances Concentration in Surface Water in Different Water Stages-some Cases from China

Human activities, climate change and other factors which affecting the water environment vary significantly with time, which lead to changes in surface water flow, pollutant inflow into rivers, sediment release and other processes, and eventually surface water environment changes with time. Analyzing the variation of surface water quality in different water stages is an important basis for determining the source of surface water pollutants, making controlling methods and management strategies. Based on the literature database, this paper collected and screened 15 literatures about the variation of reductive substances representated by CODcr (Chemical Oxygen Demand) and COD_mn (Permanganate Index). Data of COD_mn and COD_cr in literature were extracted, and the average, standard deviation and sample size were extracted from these data in different water periods (high water period, flat water period, low water period). To analyze the variation in different periods extracted average and standard deviation were standardized.