上覆水中碳氮浓度对黄河沉积物反硝化速率的影响

通过室内培养测定泥水界面N₂通量，研究了黄河沉积物的反硝化速率，分析了沉积物反硝化速率与上覆水碳、氮浓度和耗氧速率的响应关系。结果表明，对照处理（CK）平均反硝化速率为14.81±9.43 μg N/m2/h。碳、氮添加处理中，N1（4.5 mg N/L）和C1（2.4 mg C/L）沉积物反硝化速率最高，均值分别为21.99±12.45和24.33±14.38 μg N/m2/h。理论上，NO₃-N和溶解性有机碳添加浓度分别为9.8和4.0 mg/L时沉积物反硝化作用最大，且反硝化作用的最佳碳氮比为2.3。不同碳、氮水平上沉积物反硝化速率与耗氧速率的响应关系并不一致。低碳氮水平下反硝化速率与耗氧速率显著正相关；低碳、高氮水平下反硝化速率与耗氧速率不相关；而高碳、低氮水平下反硝化速率则与耗氧速率显著负相关。

Impact of C and N concentrations on sediments denitrification rate of the Yellow River

Intact sediment cores from the Yellow River were studied for denitrification rate (De) based on benthic fluxes of molecular nitrogen (N₂) by a laboratory incubation study; meanwhile correlation between sediments De and concentration of dissolved organic carbon (DOC) and nitrate, and sediment oxygen consumption rate (SOC) was discussed.The mean value of De for the control treatment was 14.81±9.43 μg N/m2/h.For the extragenousnitrogen addition treatment, the highest De was investigated in N1 level (4.5 mg/L) with a mean value of 21.99±12.45 μg N/m2/h.For the extragenouscarbon addition treatment, the highest De was investigated in C1 level (2.4 mg/L) with a mean value of 24.33±14.38 μg N/m2/h.In theory, sediment denitrification rate up to peak, when concentration of nitrate and DOC in overlying water was 9.8 and 4.0 mg·L-1 respectively; the optimal C/N for sediment denitrification was 2.3.Correlation between De and SOC showed different patterns depending on nitrate and DOC level.Our study investigated that De was significant positively related to SOC under lower nitrate and DOC level, while negativelyrelated to SOC under higher DOC and lower nitrate level; however, no significant correlation between De and SOC was investigated when overlying water showed higher nitrate and lower DOC level.