Wetland depressions without surface channel connections to aquatic systems are substantial sinks for nitrogen (N), phosphorus (P) and organic carbon (org. C). We assessed accretion, N, P and org.-C accumulation rates in 43 depressional wetlands across three ecoregions of the USA (Erie Drift Plain, EDP; Middle Atlantic Coastal Plain, MACP; Southern Coastal Plain, SCP) using caesium-137 (137Cs). The mean sediment accretion rate in minimally affected (reference) sites was 0.6 ± 0.4 mm year-1 and did not differ among ecoregions. Accumulation rates for N and org. C averaged 3.1 ± 3.1 g N m-2 year-1and 43.4 ± 39.0 g org. C m-2 year-1 respectively, and did not differ across minimally affected sites. Phosphorus accumulation rates were significantly greater in EDP (0.10 ± 0.10 g P m-2 year-1) than MACP (0.01 ± 0.01 g P m-2 year-1) or SCP (0.04 ± 0.04 g P m-2 year-1) sites. Land-use modality and wetland-type effects were analysed in SCP, with few differences being found. Depressional wetlands sequester substantive amounts of nutrients and C; their cumulative contributions may significantly affect landscape nutrient and C dynamics because of the abundance of wetland depressions on the landscape, warranting further investigation and potential watershed-scale conservation approaches.

中文翻译：

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美国三个生态区洼地湿地沉积物沉积和磷、氮和有机碳的积累

没有与水生系统表面通道连接的湿地洼地是氮 (N)、磷 (P) 和有机碳 (org. C) 的大量汇。我们使用铯 137 (137Cs) 评估了美国三个生态区（伊利漂移平原，EDP；大西洋中部沿海平原，MACP；南部沿海平原，SCP）的 43 个洼地湿地的吸积率、N、P 和 org.-C 积累率）。受影响最小（参考）地点的平均沉积物增加率为 0.6 ± 0.4 毫米第 1 年，并且在生态区之间没有差异。N 和 org 的累积率。C 平均为 3.1 ± 3.1 g N m-2 year-1 和 43.4 ± 39.0 g org。分别为 C m-2 year-1，并且在受影响最小的站点之间没有差异。EDP​​ (0.10 ± 0.10 g P m-2 year-1) 中的磷积累率明显高于 MACP (0.01 ± 0.01 g P m-2 year-1) 或 SCP (0.04 ± 0. 04 g P m-2 年-1) 站点。在 SCP 中分析了土地利用方式和湿地类型效应，几乎没有发现差异。洼地湿地固存了大量的养分和碳；由于景观中大量的湿地洼地，它们的累积贡献可能会显着影响景观养分和碳动态，需要进一步调查和潜在的流域尺度保护方法。