顺义潮白河再生水受水区反硝化作用初探

以顺义潮白河段再生水受水区为研究对象,沿受水区再生水补给路径布设监测点,利用N_2∶Ar法和膜进样质谱仪(MIMS)直接测定反硝化产物溶解性N_2浓度,计算水-气界面N_2通量,探究N_2通量变化特征和硝酸盐氮沿流向变化的受控因素,概算硝氮转化过程中主要作用的贡献。结果显示:减河段N_2通量为8.92~15.20 mmol N2·m~(-2)·d~(-1),潮白河段N_2通量为17.07~33.01 mmol N_2·m~(-2)·d~(-1)。NO_3~--N含量在不同河段的变化主要受控于反硝化作用和浮游植物的同化吸收,其中减河段反硝化作用除氮量和浮游植物同化吸收固氮量分别为0.041 mmol·L~(-1)和0.017 mmol·L~(-1),分别占NO_3~--N变化量的68.33%和28.33%;潮白河段为0.254 mmol·L~(-1)和0.125 mmol·L~(-1),分别占NO_3~--N变化量的63.50%和31.25%。

Preliminary investigation on the denitrification of reclaimed water intake area of the Chaobai River

Monitoring points were set along reclaimed water supply path in intake area of the Chaobai River in Shunyi. N₂:Ar ratio method and membrane introduction mass spectrometry(MIMS) were used to determine dissolved nitrogen directly, and then N₂ fluxes on water-air interface were calculated. Based on these, N₂ fluxes changing characteristics and controlling factors of NO₃^--N changes along the river were investigated, and then contributions of main factors in NO₃^--N transformation were estimated. The results showed that N₂ fluxes in the Jian River and the Chaobai River were 8.92~15.20 mmol N₂·m^-2·d^-1 and 17.07~33.01 mmol N₂·m^-2·d^-1, respectively. Denitrification combined with assimilation of phytoplankton led to variation of NO₃^--N concentration at different parts of intake area. In the Jian River, nitrogen removal amounts caused by denitrification and phytoplankton were 0.041 mmol·L^-1 and 0.017 mmol·L^-1, accounting for 68.33% and 28.33% of total NO₃^--N changes, respectively. In the Chaobai River, the values were 0.254 mmol·L^-1 and 0.125 mmol·L^-1, accounting for 63.50% and 31.25%, respectively.