The denitrification rates of freshwater and oligohaline tidal marsh soils with different textures (loam and sandy soils) in a subtropical estuary, and their responses to nitrogen (N) loading, were investigated. In both marshes, the denitrification rates varied significantly with the season only in loam soil. The denitrification rates were highest in oligohaline marsh loam soil and lowest in freshwater marsh sandy soil. NH₄NO₃ addition significantly increased the denitrification rates of all the marsh soils. Our findings suggest that soil texture, soil organic matter (OM) content and low‐level increases in salinity all had large effects on denitrification, indicating that the dynamics of denitrification rates in estuarine marshes with low‐level salinity were controlled by the interaction of salinity and soil texture but mainly depended on OM content. We propose that denitrification in tidal marshes plays an important role in regulating current and future N loading into estuary and inshore coastal waters, especially for tidal freshwater marshes, which introduces great uncertainty into the N dynamics of estuaries under global changes.

中文翻译：

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潮汐沼泽土壤中的反硝化速率：土壤质地，盐分和氮富集的作用

研究了亚热带河口不同质地的淡水和低盐度潮汐沼泽地（壤土和沙土）的反硝化率及其对氮（N）负荷的响应。在两个沼泽中，仅在壤土中，反硝化率随季节而显着变化。脱盐率在小盐沼沼泽壤土中最高，而在淡水沼泽沙质土壤中最低。NH ₄ NO ₃此外，显着提高了所有沼泽土壤的反硝化率。我们的发现表明，土壤质地，土壤有机质（OM）含量和盐分的低水平增加都对反硝化产生很大影响，表明低盐度的河口沼泽中反硝化速率的动力学受盐分相互作用的控制。和土壤质地，但主要取决于OM含量。我们认为，潮汐沼泽中的反硝化作用在调节当前和未来向河口和近岸沿海水域的氮负荷中起着重要作用，特别是对于潮汐淡水沼泽而言，这给全球变化下的河口氮动态带来了很大的不确定性。