Studies have investigated the role of litter type on soil organic nitrogen (SON) mineralization and the resulting chemical composition in aerobic soils; however, the roll of anaerobic conditions have been limitedly explored. We determined the SON chemical composition and N mineralization rate with depth of two different vegetation types (emergent aquatic vegetation, EAV and submerged aquatic vegetation, SAV) and prevailing flooded soil conditions in a subtropical treatment wetland. The treatment wetland provided similar water quality and climate conditions across the vegetation types. Three soil depths were sampled, the surficial floc, recently accreted soil, and soil present before constructing the treatment wetland. The surficial floc material created from emergent plants exhibited a mean total carbon (TC) and total N (TN) of 364 g C kg⁻¹ and 27 g N kg⁻¹ vs 185 g C kg⁻¹and 12 g N kg⁻¹ for submerged plants. Despite these differences, there were no significant differences in the proportion of N that was soil organic nitrogen (SON). Mean extractable ammonium was lower (95 mg N kg⁻¹) in SAV systems and may be due to increased pH (~9) during the day compared to EAV systems (207 mg N kg⁻¹). For the chemical composition, the N-associated aromatics comprised 4.8% of the SON in SAV areas compared with just 1.6% for EAV, which suggests an increased SON recalcitrance in SAV created floc. The difference in EAV and SAV chemical composition may be important for the long-term storage of SON and future studies should focus on additional environmental factors that favor the formation of stable recalcitrant SON.

研究调查了凋落物类型对土壤有机氮（SON）矿化的作用以及好氧土壤中由此产生的化学成分；然而，对厌氧条件的研究还很有限。我们确定了亚热带处理湿地中两种不同植被类型（挺水性水生植被，EAV 和沉水性水生植被，SAV）和主要淹没土壤条件的SON 化学成分和氮矿化率随深度的变化。处理湿地提供了各种植被类型相似的水质和气候条件。对三个土壤深度进行了采样，即表面絮凝物、新堆积的土壤以及建造处理湿地之前存在的土壤。由挺水植物产生的表面絮凝材料的平均总碳（TC）和总氮（TN）分别为364 g C kg^-1和27 g N kg^-1与185 g C kg^-1和12 g N kg^-1对于沉水植物。尽管存在这些差异，但土壤有机氮（SON）的氮比例没有显着差异。^{与 EAV 系统 (207 mg N kg -1}的平均可萃取铵较低 (95 mg N kg^-1)，可能是由于白天 pH 值升高 (~9)。就化学成分而言，在 SAV 区域中，与 N 相关的芳族化合物占 SON 的 4.8%，而 EAV 中仅占 1.6%，这表明 SAV 产生的絮凝物中 SON 的顽抗性有所增加。EAV 和 SAV 化学成分的差异可能对于 SON 的长期储存很重要，未来的研究应重点关注有利于形成稳定的顽固 SON 的其他环境因素。