【摘要】 硝化作用是海洋氮循环的核心过程。作为硝化过程关键步骤的氨氧化过程的主要参与者，氨氧化古菌和氨氧化细菌对硝化作用的相对贡献是海洋氮循环关注的热点问题之一。本文选取渤海和南黄海20个站位的表层沉积物，通过微宇宙培养实验研究了沉积物中氨氧化古菌和氨氧化细菌对硝化潜势的相对贡献。结果表明，渤海和南黄海海域表层沉积物中潜在硝化速率（以氮计，下同）为0.004 6～0.283 1μmol/（g·d），其中氨氧化古菌潜在硝化速率为0.004 3～0.274 3μmol/（g·d），氨氧化细菌潜在硝化速率为0.000 4～0.056 0μmol/（g·d）。氨氧化古菌是硝化潜势的主要贡献者，在渤海海域的贡献率为59.79%～97.95%，在南黄海海域的贡献率为18.47%～94.26%。渤海海域潜在硝化速率显著高于南黄海海域。此外，本研究海域中盐度是影响潜在硝化速率的关键环境因子，对渤海海域的分析则表明越高的NO₃^-浓度可能指示着越高的硝化潜势。在河口及近海沉积物中，氨氧化古菌在硝化过程中起着更加重要的作用；河口和近岸沉积物硝化潜势总体高于远海。本研究为进一步认识近海海洋氮循环过程提供了参考依据。更多还原

【Abstract】 Nitrification is a pivotal process in the marine nitrogen cycle. Ammonia-oxidizing archaea(AOA) and ammonia-oxidizing bacteria(AOB) drive the ammonia oxidation, which is the first and rate-limiting step in nitrification, and their relative contributions to nitrification are ones of the most important topics related to the nitrogen cycle in ocean. In this study, surface sediment samples at 20 sites from Bohai Sea and South Yellow Sea were collected in April and May, 2019. The relative contributions of AOA and AOB to nitrification potential were studied in the microcosmic experiment. The results showed that the potential nitrification rates(PNRs, in terms of nitrogen)ranged from 0.004 6 μmol/(g·d) to 0.283 1 μmol/(g·d), in which potential nitrification rate of AOA and AOB ranged from 0.004 3 μmol/(g·d) to 0.274 3 μmol/(g·d) and 0.000 4 μmol/(g·d) to 0.056 0 μmol/(g·d), respectively. AOA was the main contributor to the nitrification therein, whose contribution rate was 59.79%-97.95% in Bohai Sea and18.47%-94.26% in South Yellow Sea, respectively. The potential nitrification rates in surface sediments from Bohai Sea were significantly higher than those from South Yellow Sea. Besides, salinity was a key environmental factor for potential nitrification rates, and high NO3-concentration might indicated high nitrification potential. It was speculated that AOA played a more vital role than AOB in estuarine and coastal areas, and nitrification potential decreased from estuarine and near-shore region to the open sea. This study provides evidences for further evaluation of nitrogen cycle in coastal areas.更多还原