鄱阳湖水体悬浮物反硝化潜力模拟研究

以鄱阳湖为对象,采用乙炔抑制法,分别模拟了厌氧和好氧状态下的悬浮物反硝化潜力和过程,结果表明,厌氧和好氧状态下水体悬浮物均能够产生明显的反硝化作用.受乙炔抑制,其反硝化产物N2O的浓度累积随时间呈“慢-快-慢”的节律,浓度累积曲线符合逻辑斯谛模型(P<0.01).拟合结果显示:悬浮物浓度为30g/L时,厌氧培养条件下快增期反硝化速率达到(81.76±10.37)μmolN/(L·d),好氧环境下为(14.12±2.31)μmolN/(L·d).CO2浓度累积曲线同样符合逻辑斯谛模型,但好氧条件下CO2浓度累积极值较高,约为厌氧条件下的5倍,表明好氧条件下好氧呼吸占更大的比例.水体悬浮物反硝化潜力与悬浮物浓度有关,相同悬浮物浓度下,好氧培养水体悬浮物反硝化潜力较厌氧培养弱,且达到累积极值的时间更长,水体溶解氧一定程度上抑制了悬浮物反硝化作用.依据好氧培养的试验结果,估算得到鄱阳湖悬浮物全年反硝化导致的氮素净损失为1010t,约占鄱阳湖氮素年输入量的0.74%和鄱阳湖沉积物反硝化氮去除量的14%,鄱阳湖水体悬浮物反硝化在氮素净去除中起到一定作用.

Denitrification potential of high suspend sediments in Poyang Lake,China

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.