Evaluation of water quality and nitrogen removal bacteria community in Fuhe River

摘要

The ecosystem of Fuhe River, which is the main inflow tributary of Baiyangdian Lake, is crucial to the ecological health and environmental safety of the lake. Understanding the variation of Fuhe River ecosystem and taking measures to reduce its pollutants can help relieve the eutrophication of Baiyangdian Lake. To investigate this, we monitored water quality and levels of nitrogen removal bacteria along the Fuhe River using comprehensive pollution indices and denaturing gradient gel electrophoresis (DGGE). Samples were collected in the low-flow, high-flow and mean-water periods of 2009 and 2010. The dissolved oxygen (DO) values were, on an average, lower than 4 mg/L suggesting that the river was in low oxygen conditions, mainly conducting anaerobic reactions. The chemical oxygen demand (COD_(Cr)) values decreased gradually along the river, with the highest value of 128.65 mg/L at the first sampling site. The concentrations of total nitrogen (TN) and total phosphorus (TP) increased to 56.21 mg/L and 4.96 mg/L respectively, with concentrations at the inlet of the wetland significantly higher than those in the lake. The comprehensive pollution indexes reached the highest in the low-flow period in 2009 and in 2010, up to 78.81 and 77.10, respectively. Overall, the high comprehensive pollution indices for TN and TP indicated that the Fuhe River was polluted by N and P nutrients. There were abundant denitrifying bacteria and anaerobic ammonium oxidation bacteria at the terrestrial-aquatic interface of the upstream region of the river according to the Shannon-Weiner index.