反硝化,anammox,和DNRA是河口沉积物中三个重要的氮(N)还原途径。尽管盐度是控制微生物生长和活动的重要变量,关于盐度变化对河口和沿海湿地沉积物这三个过程的影响的知识尚未得到很好的了解。在这里,我们进行了不同盐度(0、5、15、25和35‰)的60天微观世界实验,以探讨盐度在控制河口湿地沉积物中氮损失和氮保留中的重要作用。结果表明,沉积物有机质,硫化物,硝酸盐(NO3-)随着盐度的增加而大幅下降,而沉积物铵(NH4)和亚铁(Fe2)以相反的模式变化。同时,随着盐度的增加,N丢失和N保留率以及相关基因丰度受到差异抑制,虽然反硝化的贡献,anammox,DNRA对总硝酸盐的还原显然不受影响。此外,反硝化速率对盐度最敏感,然后是DNRA,而anammox是这三个过程中最弱的。换句话说,厌氧氨氧化细菌表现出广泛的耐盐性,而反硝化和DNRA都反映了它的相对有限的动态范围。我们的发现可以提供有关盐度对沉积物理化性质的时间相互作用影响的见解,N减少率和相关基因丰度。我们的发现可以增进对盐水入侵对河口和沿海沉积物中氮命运和氮平衡的影响的理解。
Denitrification, anammox, and DNRA are three important nitrogen (N) reduction pathways in estuarine sediments. Although salinity is an important variables controlling microbial growth and activities, knowledge about the effects of changing salinity on those three processes in estuarine and coastal wetland sediments are not well understood. Herein, we performed a 60-d microcosms experiment with different salinities (0, 5, 15, 25 and 35 ‰) to explore the vital role of salinity in controlling N-loss and N retention in estuarine wetland sediments. The results showed that sediment organic matter, sulfide, and nitrate (NO3-) were profoundly decreased with increasing salinity, while sediment ammonium (NH4+) and ferrous (Fe2+) varied in reverse patterns. Meanwhile, N-loss and N retention rates and associated gene abundances were differentially inhibited with increasing salinity, while the contributions of
denitrification, anammox, and DNRA to total nitrate reduction were apparently unaffected. Moreover,
denitrification rate was the most sensitive to salinity, and then followed by DNRA, while anammox was the weakest among these three processes. In other words, anammox bacteria showed a wide range of salinity tolerance, while both
denitrification and DNRA reflected a relatively limited dynamic range of it. Our findings could provide insights into temporal interactive effects of salinity on sediment physico-chemical properties, N reduction rates and associated gene abundances. Our findings can improve understanding of the effects of saltwater incursion on the N fate and N balance in estuarine and coastal sediments.