珠江口入海河段DIN形态转化与硝化和反硝化作用

Transformation of dissolved inorganic nitrogen species and nitrigication and denitrification processes in the near sea section of Zhujiang river

在自广州中大码头(ST1)沿珠江主航道到虎门外的龙穴水道(ST9)之间设9个采样站,其中ST2、ST5、ST9号3个为沉积物采样站,研究珠江口入海河段溶解态无机氮形态转化与硝化和反硝化作用.水质分析和培养结果表明,水体中存在着强烈的硝化作用.从ST1到ST9站约有88%的NH+ 4转化成了NO- 3和NO- 2 .NH+ 4与NO- 3含量之间呈显著的负相关关系,相关系数R =-0 97(n =19) .NO- 3的变化趋势与其它要素相反,沿入海方向逐渐升高.珠江水相中的N2 O的浓度范围在5 7～3 2 9nmol·L- 1 ,饱和度在674%～413 4%之间,是N2 O的一个重要排放源.采用乙炔抑制法研究微生物作用下发生在沉积物中的硝化、反硝化作用,结果显示,沉积物中存在着强烈的硝化与反硝化作用,硝化速率:0 3 2～2 43mmol·m- 2 ·h- 1 ;反硝化速率:0 0 3～0 84mmol·m- 2 ·h- 1 ;硝酸盐的还原速率:4 17～13 0 6mmol·m- 2 ·h- 1 .硝化与反硝化作用主要发生在沉积物的0～4cm的区域,各站点由于沉积物性状不同而有所差异.硝化和反硝化速率与沉积物中NO- 3和NH+

The transformation of DIN (Dissolved Inorganic Nitrogen) and nitrification and denitrification processes in near sea section of Zhujiang River were studied. And nine sampling sites, three sampling sites for sediment among them, were located along Zhujiang River from Zhongshan Universty dock to Longxu water course.The values of water parameters showed that there are notably positive correlations between the concentrations of ammonium and COD, phosphate, and silicate. But the correlation between ammonium and nitrate was obviously negative (R=-0.97, n=19). About 88% ammonium was converted to nitrate from ST1 to ST9. The distribution tendency of nitrate concentrations was increased toward the sea opposite to the other factors as a consequence of ammonium oxidation during flowing into the sea. The concentrations of nitrous oxide varied between 57～329nmol·L^(-1), and the saturation ware from 674%～4134%.It suggested that the area was an emissive source of nitrous oxide. The acetylene inhibition technique was employed to evaluate the rates of nitrification, denitrification and nitrate reduction by bacterial activities. The average of nitrification, denitrification and nitrate reduction rates ranged from 0.32 to 2.43mmol·m^(-2)·h^(-1), 0.03 to 0.84(mmol·m^(-2)·h^(-1)) and 4.17 to 13.06mmol·m^(-2)·h^(-1) respectively. The vertical profiles of the sediments showed that the nitrification and denitrification processes mainly took place in the depths from 0 to 4cm and there were differences among these sampling sites. The rates of nitrification, denitrification and nitrate reduction were dominated by Eh, nitrate and ammonium concentrations in sediment and DO in overlay water.