Since March and April, the pH value and permanganate index of Dengsha River in Dalian City, Liaoning Province have exceeded the standard. Through field investigation and detailed investigation and analysis, Dalian Municipal Bureau of ecological environment found out that the pH value and permanganate index of some river reaches exceeded the standard due to natural processes such as photosynthesis and metabolism of algae and aquatic plants, which was not caused by man-made pollution or deterioration of water environment.

In order to find out the reasons for the pH value and permanganate index exceeding the standard in some reaches of Dalian City, Dalian Municipal Bureau of ecological environment has organized experts and monitoring personnel for many times, taking Denghua section and Maijia section as breakthrough points, to conduct a comprehensive field investigation on the automatic monitoring station of the section and its upstream 15 km reach in view of the river water quality, natural conditions of the river and surrounding pollution sources. At the same time, the Municipal Bureau of ecological environment also invited teams from Tsinghua University, water conservancy engineering college of Dalian University of technology and other universities to provide technical support, and organized authoritative experts from various aspects such as water environment pollution prevention and control, river basin water ecology, water body hydrodynamic force, etc. to conduct in-depth discussion and guidance, combined with the field survey results and monitoring data, the pH value and high manganese content of some river sections in Dalian were analyzed The phenomenon of acid salt index exceeding the standard was analyzed comprehensively.

The expert group believes that algae and aquatic organisms themselves are part of the water ecosystem. The seasonal pH value and permanganate index caused by algae and aquatic organisms exceed the standard, which will not have a negative impact on the health of river ecosystem. The pH value and permanganate index should not be used as the evaluation factors to restrict the water quality of local natural rivers. The expert group also proposed short-term standards and long-term mechanisms for improving river water quality in Dalian from the aspects of improving river ecological integrity, improving river hydrodynamic force, moderately adjusting assessment mechanism and comprehensive river basin regulation.

Dalian will strengthen the management, improve the ecological environment of the river, and solve the problem of water quality exceeding the standard from the root.

Source: China Environmental News