The Influence of Tubifex Bioturbation on Total Nitrogen Release from Sediment of Dongting Lake

This study investigated the release rule of total nitrogen from sediments by Tubifex tubifex bioturbation indifferent environmental conditions. Tubifex tubifex density, temperature, pH value and dissolved oxygen were selected as influencing factors. The results showed that bioturbation of Tubifex tubifex had a good accelerating effect on total nitrogen release of sediment and the concentration of total nitrogen in overlying water respectively increased to 1.2 fold and 1.3 fold when Tubifex tubifex density was 1ind./cm² and 2ind./cm² compared to control test. Appropriate increasing of water temperature was helpful to the fast growth of Tubifex tubifex, which caused that total nitrogen in overlying water raised by 56 percent when temperature increased from 15°C to 25°C. Adversity stress on Tubifex tubifex, induced by acidic and alkali environment, enhanced its bioturbation effect and also accelerated the total nitrogen releasing from sediment. Total nitrogen increase amplitude of overlying water in anaerobic was 1.3 fold compared to aerobic environment, which indicated that Tubifex tubifex had good adaptability to anaerobic environment in which bioturbation was more than in aerobic environment.