Study on Static and Dynamic Release Characteristics of River Sediment Pollutants

Abstract

As the main accumulation reservoir of various pollutants, the sediment plays a very important carrier role in the process of migration and transformation of pollutants. In this paper, based on the test device such as the annular water tank developed, the pollutant release characteristics of the river sediment under still water and moving water conditions were studied. The experimental results show that the content of pollutants nitrogen and phosphorus in river sediments in Nanjing is higher and the content of heavy metals is lower. The static release of pollutants in the sediment reached an equilibrium state in about 60 hours, and the release was faster in the early stage, and the release rate in the later stage gradually slowed down and tended to the equilibrium state. The velocity of river water flow directly affects the release characteristics of sediments. As the water flow velocity increases continuously, the sediments have three states: “not started”, “small amount of movement” and “general movement”. The ratio of pollutants (total nitrogen, total phosphorus, heavy metals) release to total pollutants in the sediment of the river under still water conditions is 0.96%, 0.09%, 0.01-0.06%, about 18.46%, 15.43%, and 0.05-4.55% under hydrodynamic conditions, which are much higher than the amount of pollutants released under hydrostatic conditions, and the release amount of heavy metals Zn and total phosphorus is more affected by hydrodynamic conditions than other pollutants.