内蒙古大克泊碱湖氮移除及其影响因素

为了研究碱湖N₂O释放速率及其对盐度与pH的响应,选取内蒙古大克泊碱湖的五个沉积物样点,采用¹⁵N同位素标记模拟实验,研究反硝化和厌氧氨氧化的速率、相对比例和气体产生情况,揭示高盐和高pH对碱湖氮移除的影响。发现大克泊湖潜在氮移除速率为0~16.06 n mol N mL-1 h-1,潜在反硝化速率为0~12.62 n mol N mL-1 h-1,潜在厌氧氨氧化速率为0~9.81 n mol N mL-1 h-1；当盐度34.00 g·L-1与pH 10.22时,厌氧氨氧化对氮移除贡献较大,达到43.18%~71.79%。反硝化过程气体产物以N₂为主,几乎无N₂O气体释出。另外,该区域潜在氮移除速率与pH呈正相关关系,与TOC、NO-₃、HCO-₃呈负相关关系；未发现氮移除速率与盐度之间的相关关系。因此,在研究的碱湖中,氮移除过程中主要为N₂排放,而N₂O低于检测水平；氮移除过程的影响因素复杂且不限于最主要的环境变量(盐度与pH)。这些结果为研究湖泊N₂O排放提供了数据基础。

Nitrogen Removal and Its Influencing Factors in Habor Lake, Inner Mongolia

It is of great environmental significance to study N2O release rate and its response to high salinity and high pH in alkaline lakes. In this study, 15N isotope labeling simulation experiments were employed to study the potential rate, relative ratio and gas production of denitrification and anammox in five sediment samples of Habor Lake in Inner Mongolia, and to reveal the effects of high salinity and pH on nitrogen removal in alkaline lakes. The potential removal rates of nitrogen, denitrification rates and anammox rates were 0~16.06 n mol N mL-1 h-1, 0~12.62 n mol N mL-1 h-1 and 0~9.81 n mol N mL-1 h-1, respectively. Anammox occurred at all sites, and accounted for 43.18~71.79% at HL5 (salinity=34.00 g L-1, pH=10.22). In the denitrification process, N2 was the main gas product, and almost no N2O was detected. In addition, there was a positive correlation between potential nitrogen removal rate and pH, and a negative correlation between potential nitrogen removal rate and TOC, NO3-, HCO3-. No correlation was found between nitrogen removal rate and salinity. In alkaline lakes, the influencing factors of nitrogen removal process are complex and not limited to the most important environmental variables (salinity and pH); nitrogen removal process is mainly N2 emission, while N2O is lower than the detection level. This result provides a data base for our study of N2O emission from lakes.