Effects of sediment and algal growth on water quality of water samples from water conveyance channel（Shared Data）

Permanganate index is used to evaluate water quality, as it indicates the pollution level of organic and inorganic oxidizable substances in water. Sediment and algae are potential causes for the increase in I_mn, so it is imperative to explore the effects of these two factors on I_mn. In this study, we artificially added sediment to water to simulate eutrophic water for algae growth. We cultured algae for 41 days and observed the changes in I_mn, algal density, nitrogen, and phosphorus. The results showed that organic matter in sediment and algal growth promoted increase in I_mn in the water. The sediment resuspension released organic matter into the water, resulting in significant increase in I_mn. The addition of 1.6% sediment in the water sample lead to an increase in I_mn of 14.7 mg/L. The phosphate in sediment also stimulated the growth of algae resulting in release of reducing metabolites and further increase in I_mn. The I_mn of the 1.6% sediment treatment group increased to 30.1 mg/L on day 41 of culture. Correlation analysis showed that I_mn was positively correlated with algal density, whereas total phosphorus content was significantly negatively correlated with algal density.