沉积物硝酸盐异化还原过程的温度敏感性与影响因素——以长江口青草沙水库为例

水生态环境中硝酸盐异化还原过程反硝化、厌氧氨氧化和硝酸盐异化还原成铵（DNRA），对氮循环起着重要作用.采用泥浆培养实验，并结合¹⁵N同位素示踪技术对长江口青草沙水库沉积物硝酸盐异化还原过程的温度敏感性及影响因子进行了研究.结果表明，原位温度10℃时沉积物中反硝化、厌氧氨氧化和DNRA速率分别是0.18～6.86、0.26～3.16和0.09～0.25μmol N/（kg·h）.当培养温度升高到20℃和30℃时，反硝化速率分别是0.43～6.22和0.68～6.56μmol N/（kg·h），平均比10℃时升高了15.7%和21.6%；厌氧氨氧化速率分别是0.61～3.2和0.77～3.54μmol N/（kg·h），平均比10℃时升高了27.8%和42.6%；DNRA速率分别是0.09～0.23和0.1～0.18μmol N/（kg·h），均比10℃时降低了4.2%.沉积物厌氧氨氧化对温度最为敏感，其次是反硝化，均随温度升高而增大；而DNRA最不敏感，随温度升高而减小.相关性分析结果发现有机碳、氨氮、二价铁和硫化物是影响硝酸盐异化还原的主要环境因子.反硝化和厌氧氨氧化硝酸盐还原的贡献分别是34%～71%和28%～49%，而DNRA为2%～17%.青草沙水库沉积物反硝化和厌氧氨氧化过程每年可去除活性氮大约为3.25×10³t和1.68×10³t，约占库区输入氮的54.17%.

Temperature sensitivity and controlling factors of dissimilatory nitrate reduction processes in sediments of Qingcaosha reservoir,Yangtze Estuary

Slurry incubation experiments combinatedwith isotope-tracing techniques were conducted toexaminethe effectsof temperature on dissimilatory nitrate reductionprocesses and reveal associated environmental variables in Qingcaosha reservoir, the Yangtze Estuary.Results indicated that the potential rates of denitrification, anammox and DNRA in thereservoir sediments werein the range of 0.18~6.86, 0.26~3.16and 0.09~0.25μmol N/(kg·h), respectively, at in situ temperature (10℃). The denitrification rates ranged from 0.43to 6.22and from 0.68to 6.56μmol N/(kg·h), increased by mean value of 15.7% at 20℃ and 21.6% 30℃, compared to that in 10℃. Anammox rates varied from 0.61 to 3.2μmol N/(kg·h)at 20℃ and from 0.77 to 3.54μmol N/(kg·h)at 30℃, increased by 27.8% and 42.6%. However, DNRA rates ranged between 0.09 and 0.23μmol N/(kg·h)at 20℃, and from 0.1 to 0.18μmol N/(kg·h)at 30℃, reduced by 4.2% compared to that in 10℃. Anammoxwas most sensitive to changes in the temperature, followed by denitrification, and increased with incrasedtemperature; the DNRA was least sensitive to temperature, decreased with the incrasedtemperature. OC, NH₄⁺, Fe²⁺ and S^2- werefound to have significant influence on these nitrate reduction processes. Denitrification and anammoxcontributed respectively 34%~71% and 28%~49% to the total nitrate reduction, while DNRA only contributed 2%~17% in the Qingcaosha reservoir. Denitrificationand anammoxprocesses were estimated to remove 3.25×10³ t/a and 1.68×10³ t/a of nitrogen, accounting for 54.17% of the total external nitrogen transported into the reservoir.