Abstract：The denitrification potential of high suspend sediments (SPS) in Poyang Lake under aerobic and anaerobic conditions were performed using acetylene inhibition method. The results reflected that denitrification of SPS was found under both aerobic and anaerobic conditions, and the cumulative concentration of N2O showed “slow-fast-slow” rhythm along with incubation time, which satisfied the logistic model (P<0.01). The fitting results with SPS concentration of 30g/L showed that denitrification rate reached up to (81.76±10.37)μmolN/(L·d) during anaerobic incubation while the value was (14.12±2.31)μmolN/(L·d) under aerobic incubation. In addition, the cumulative concentration of CO2 also accorded with the logistic model. The extreme value of CO2 under oxic conditions, which was 5times higher than the value under anoxic conditions, indicated high proportion of aerobic respiration under oxic conditions. The denitrification potential was affected by the concentration of SPS. Under the same SPS concentration, weaker denitrification potential of SPS and longer time to reach extreme value of N2O under aerobic condition implied the possible inhibition of denitrification by dissolved oxygen (DO). Full-year nitrogen loss caused by SPS denitrification in Poyang Lake was estimated to be 1010t, which accounted for about 0.74% of the nitrogen input and 14% of nitrogen removal caused by bed-sediments. These estimations indicated that SPS would play an important role in nitrogen removal from waters.
