杏林湾水体的硝化作用及其影响因素研究

Abstract

文章采用现场调查结合实验室模拟培养，研究了2011年8月和2012年2月杏林湾表层水体溶解无机氮的分布、硝化作用强度及其影响因素。结果表明，杏林湾水体溶解无机氮和硝化作用强度的空间差异和季节变化显著，湾区上游和下游的溶解无机氮的浓度和硝化速率均比中游高，夏季溶解无机氮的浓度和硝化速率比冬季高，说明溶解无机氮的浓度和温度是控制硝化作用空间变化和季节变化的主要因素。实验室培养的结果表明，温度、pH、氨的浓度和颗粒物对硝化菌的硝化作用均有重要的影响，其中温度和颗粒物对硝化作用强度影响最为显著。在20℃~30℃之间，温度升高10℃硝化速率提高2.9倍；水样经3 μm的滤膜过滤去除颗粒物后，硝化作用强度减弱为原水的1/5。pH对硝化作用有较大影响，当pH值为8.0时，硝化速率最大。当氨的浓度< 3.0 mg∙N∙L−1 (即214 μmol∙N∙L−1)时，提高氨浓度可有效促进硝化作用，但是较高的氨浓度、较高的温度反而会抑制硝化作用，反映了微生物对长期生境的适应性。根据实验结果估算，硝化作用可以把输入杏林湾水体的38%~52%的氨氮转化为硝氮，对区域氮循环具有重要意义。 The spatial distribution and seasonal variation of dissolved inorganic nitrogen, the performance of nitrification and its impact factors in Xinglin Bay were investigated based on field observation and laboratory simulation incubations in August 2011 (summer) and February 2012 (winter). The results showed that the inorganic nitrogen and nitrification rates had significant spatial and seasonal variation. The relative higher concentrations of inorganic nitrogen coupling with higher nitrification rates were observed at the upstream and downstream of the Bay as compared to the middle stream, suggesting that inorganic nitrogen was the major factor affecting the spatial distribution of nitrification. Seasonally, the concentrations of inorganic nitrogen and nitrification rates were higher in summer than that in winter, indicating that inorganic nitrogen concentrations and the water temperature were the major factors affecting the seasonal variation of nitrification in the Bay. The laboratory experiments showed that temperature, pH, ammonia concentration and particulate matter had important effects on nitrification. Especially, the temperature and particulate mater had significant effects on nitrifying capacity. The increase of 10˚C of temperature, the nitrification rate could be increased by 2.9 times within the temperature range 20˚C - 30˚C. The nitrification rate in the filtered water (through ~3 μm pore size filter) was only 1/5 of that in unfiltered water. At low concentration ( -N < 3 mg∙L−1), the increase of ammonia concentration could enhance the nitrification. However, higher temperature and ammonia concentration could inhibit the process of ni-trification. The optimum conditions for nitrification were pH 8.0, temperature 30˚C and ammonia concentration 3.0 mg∙N∙L−1, indicating that the microorganism adapted to the long-term habitat. It was estimated that around 38% - 52% of input ammonia was removed by nitrification in water column in the Bay, suggesting that nitrification was important on nitrogen cycle in Xinglin Bay.