Influencing factors of total nitrogen release from sediments in the Dagu drainage river
大沽排污河底泥释放总氮的影响

The effect of environmental factors including dissolved oxygen (DO) in overlying water and its pH, temperature and salinity, and velocity of disturbance on the release of total nitrogen from sediments of the Dagu drainage river were investigated under simulated test conditions. The results showed that when overlying water was in anaerobic conditions, the intensity of total nitrogen release was higher than that under aerobic and natural conditions. The intensity of total nitrogen release from sediments reached the highest level when pH of the overlying water was neutral, and the intensity of total nitrogen release from sediments was higher when the overlying water was acidic than alkaline. An increase in temperature could promote the release of total nitrogen from sediments. The disturbance of overlying water could increase the intensity of total nitrogen release from sediments. However, the intensity of total nitrogen release decreased when the velocity of disturbance was too high. The intensity of total nitrogen release was highest with the velocity of disturbance at 60 r·min-1. When the salinity of overlying water was 0 mg·L-1, the intensity of total nitrogen release also achieved the highest concentration until the simulation test approached to its balance.