• 关键词：珠江口  DIN  N₂O  沉积物  硝化  反硝化

• 基金项目：中国科学院知识创新工程重要方向项目(No.KZCX3SW214;No.KSCX22SW132);广东省自然科学基金(No.032622);中科院南海海洋研究所知识创新工程前沿领域项目(No.LYQY200303)

• 徐继荣
• 1. 中国科学院南海海洋研究所, 广州 510301; 2. 宁波大学建筑工程与环境学院, 宁波 315211

• 王友绍
• 中国科学院南海海洋研究所, 广州 510301

• 殷建平
• 中国科学院南海海洋研究所, 广州 510301

• 王清吉
• 中国科学院南海海洋研究所, 广州 510301

• 张凤琴
• 中国科学院南海海洋研究所, 广州 510301

• 何磊
• 中国科学院南海海洋研究所, 广州 510301

• 孙翠慈
• 中国科学院南海海洋研究所, 广州 510301

• 摘要：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NH₄⁺转化成了NO₃^-和NO₂^-.NH₄⁺与NO₃^-含量之间呈显著的负相关关系,相关系数R=-0.9(n=19).NO₃^-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N₂O的浓度范围在5～329 nmol·L^-1,饱和度在64%～4134%之间,是N₂O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:0.32～2.43 mmol·m^-2·h^-1;反硝化速率:0.03～0.84mmol·m^-2·h^-1;硝酸盐的还原速率:4.1～13.06 mmol·m^-2·h^-1.硝化与反硝化作用主要发生在沉积物的0～4 cm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NO₃^-和NH₄⁺的含量和Eh值等性质及水相中的DO浓度有关.

• Abstract：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 DOin overlay water.

• Key words：Zhujiang estuary  DIN  nitrous oxide  sediment  nitrification  denitrification

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