Assessing water quality by ratio of the number of dominant bacterium species between surface/subsurface sediments in Haihe River Basin

• Comprehensive quality of water was assessed by using Gaverage based on the concentrations of different pollutants.
• Pollutant concentrations of water in Haihe River higher than those in discharge of municipal wastewater treatment plants.
• Using the modified PCR–DGGE method, 162 dominant bacterial species were identified.
• The ratio of dominant bacterium species between surface sediment and subsurface sediment can reflect water quality.

Sedimentary microorganisms can be used as a sensitive indicator of integrated aquatic environment quality assessment and indicate long-term water quality or toxicity. According to the Chinese National Standards of GB 3838-2002 and GB 18918-2002, the comprehensive water quality in Haihe River Basin has been described. Results showed that the comprehensive water quality in 6 sites, 4 sites, and 20 sites were good, bad, and medium. Furthermore, 162 dominant bacterial species were identified in surface and subsurface sediments in the 30 sampling sites. As revealed by two initial models constructed by logistic regression, the comprehensive water quality exhibited a pattern from good to bad as the ratio of the number of dominant bacterial species in surface sediments to that in subsurface sediments increased from 1 to 2.1. This finding possibly bridged a traditional gap between aquatic microbe indicators and water quality assessment or monitoring techniques.