Direct measurement of methane emissions is cost-prohibitive for greenhouse gas offset projects, necessitating the development of alternative accounting methods such as proxies. Salinity is a useful proxy for tidal marsh CH₄ emissions when comparing across a wide range of salinity regimes but does not adequately explain variation in brackish and freshwater regimes, where variation in emissions is large. We sought to improve upon the salinity proxy in a marsh complex on Deal Island Peninsula, Maryland, USA by comparing emissions from four strata differing in hydrology and plant community composition. Mean CH₄ chamber-collected emissions measured as mg CH₄ m⁻² h⁻¹ ranked as S. alterniflora (1.2 ± 0.3) ≫ High-elevation J. roemerianus (0.4 ± 0.06) > Low-elevation J. roemerianus (0.3 ± 0.07) = S. patens (0.1 ± 0.01). Sulfate depletion generally reflected the same pattern with significantly greater depletion in the S. alterniflora stratum (61 ± 4%) than in the S. patens stratum (1 ± 9%) with the J. roemerianus strata falling in between. We attribute the high CH₄ emissions in the S. alterniflora stratum to sulfate depletion likely driven by limited connectivity to tidal waters. Low CH₄ emissions in the S. patens stratum are attributed to lower water levels, higher levels of ferric iron, and shallow rooting depth. Moderate CH₄ emissions from the J. roemerianus strata were likely due to plant traits that favor CH₄ oxidation over CH₄ production. Hydrology and plant community composition have significant potential as proxies to estimate CH₄ emissions at the site scale.

直接测量甲烷排放量对于温室气体抵消项目来说成本过高，因此需要开发替代核算方法，例如代理。盐度是潮汐沼泽 CH ₄排放量的一个有用的替代指标，当在广泛的盐度范围内进行比较时，但不能充分解释咸水和淡水条件的变化，其中排放量的变化很大。我们试图通过比较水文和植物群落组成不同的四个地层的排放来改进美国马里兰州迪尔岛半岛沼泽综合体的盐度代理。平均 CH ₄室收集的排放量测量为 mg CH ₄ m ^-2  h ^-1列为S. alterniflora(1.2 ± 0.3) ≫ 高海拔J. roemerianus (0.4 ± 0.06) > 低海拔J. roemerianus (0.3 ± 0.07) =  S. patens (0.1 ± 0.01)。硫酸盐消耗通常反映了相同的模式，互花米草层 (61 ± 4%) 的消耗量显着高于S. patens层 (1 ± 9%)，而J. roemerianus地层介于两者之间。我们将互花米草地层中的高 CH ₄排放归因于硫酸盐消耗，这可能是由于与潮汐水的连通性有限所致。美国专利中的低 CH ₄排放地层归因于较低的水位、较高的三价铁含量和较浅的生根深度。来自J. roemerianus地层的适度 CH ₄排放可能是由于有利于 CH ₄氧化而不是 CH ₄生产的植物特性。水文和植物群落组成作为估算场地规模CH ₄排放的替代物具有巨大潜力。