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.
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机译：没有表面通道与水生系统联系的湿地洼地是大量吸收氮（N），磷（P）和有机碳（有机碳）的源。我们使用铯137（ Ed Drift Plain，EDP; Middle Atlantic Coastal Plain，MACP; Southern Coastal Plain，SCP）评估了美国三个生态区的43个洼地湿地的吸积，N，P和org.C积累速率。 sup> 137 Cs）。受最小影响的（参考）地点的平均沉积物沉积速率为0.6±0.4 mm年 -1 ，并且在各生态区域之间没有差异。 N和org的累积率。 C平均为3.1±3.1 g N m -2 年 -1 和43.4±39.0 g org。 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 年 -1 年）的磷积累速率显着高于MACP（0.01±0.01 g P m -2 < / sup> year -1 ）或SCP（0.04±0.04 g P m -2 year -1 ）站点。在SCP中分析了土地利用方式和湿地类型的影响，发现差异不大。抑郁湿地吸收了大量的养分和碳；由于景观上湿地洼地的丰富，它们的累积贡献可能会显着影响景观养分和碳的动态变化，因此有必要进行进一步的研究和潜在的分水岭规模的保护方法。
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