太湖沉积物硝酸盐依赖亚铁氧化性能研究

Nitrate dependent ferrous oxidation in the sediments of Lake Taihu

采集太湖不同区域的沉积物进行厌氧培养,利用高通量测序、同位素示踪等技术手段,对硝酸盐依赖亚铁[Fe(Ⅱ)]氧化(NDFO)反应是否可以在太湖沉积物中发生、Fe(Ⅱ)添加能否促进太湖沉积物反硝化脱氮等问题进行了探究.厌氧培养24h后,上覆水中硝酸盐氮(NO_(3)^(−)-N)和Fe(Ⅱ)浓度均快速下降,呈现出显著正相关(P<0.01),而Sideroxydans等NDFO功能相关菌属的相对丰度也从厌氧培养前的0.69%±0.07%提高到4.23%±0.90%,结合沉积物颜色的变化,可以推断沉积物中发生了NDFO反应.不同Fe(Ⅱ)添加量的厌氧培养实验中,对照组和Fe(Ⅱ)添加量最少的处理组中的NO_(3)^(−)-N浓度显著高于其它处理(P<0.05,ANOVA),而亚硝酸盐氮(NO_(2)^(−)-N)浓度随着Fe(Ⅱ)添加量的增加而显著增加(P<0.01,ANOVA),表明添加一定量的Fe(Ⅱ)可以促进NO_(3)^(−)快速还原,并造成亚硝酸盐(NO_(2)^(−))积累.添加少量Fe(Ⅱ)(约1.9mg/g沉积物)后,太湖不同区域沉积物的潜在反硝化速率达到213~252mg N/(m^(2)·d),说明Fe(Ⅱ)可能在太湖反硝化脱氮过程中起到重要作用.

The sediments collected from different areas of Lake Taihu were anaerobically cultured,in combination with high-throughput sequencing and isotope enrichment technologies,to explore whether nitrate dependent ferrous[Fe(Ⅱ)]oxidation(NDFO)can occur in the sediments of Lake Taihu,and whether Fe(Ⅱ)addition can promote nitrogen removal from Lake Taihu.After anaerobic incubation for 24h,the concentrations of NO_(3)^(−)-N and Fe(Ⅱ)in the overlying water decreased simultaneously,showing a significantly positive correlation(P<0.01).The relative abundance of NDFO related genera in cultured sediments increased from 0.69%±0.07%to 4.23%±0.90%.Combined with the change of sediment color,it can be inferred that NDFO occurred during anaerobic culture.The concentrations of NO_(3)^(−)-N in the control and the treatment added with lowest levels of Fe(Ⅱ)(2.8mg)were significantly higher than those in other treatments(P<0.05,ANOVA),while the concentration of nitrite(NO_(2)^(−))increased significantly with the increase of Fe(Ⅱ)addition(P<0.01,ANOVA),indicating that a certain amount of Fe(Ⅱ)can promote the reduction of NO_(3)^(−)and cause the accumulation of NO_(2)^(−).After the addition of a small amount of Fe(Ⅱ)(about 1.9mg/g sediment),the potential denitrification rate of the sediment in the different areas of Lake Taihu reached 213~252mg N/(m^(2)·d),indicating that Fe(Ⅱ)may play an important role in the denitrification process in Lake Taihu.