Carbon Dioxide and Methane Emissions From A Temperate Salt Marsh Tidal Creek
Carbon Dioxide and Methane Emissions From A Temperate Salt Marsh Tidal Creek
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DOI：
10.1029/2019jg005558
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发表时间：
2020-08
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影响因子：
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通讯作者：
B. Trifunovic;A. Vázquez‐Lule;M. Capooci;A. Seyfferth;C. Moffat;R. Vargas
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文献类型：
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作者：
B. Trifunovic;A. Vázquez‐Lule;M. Capooci;A. Seyfferth;C. Moffat;R. Vargas
沿海盐沼储存了大量的碳，但温室气体(温室气体；即二氧化碳(CO2)和甲烷(CH4))通量的大小和模式尚不清楚。关于这些生态系统温室气体通量的信息来自对沉积物或生态系统规模(涡旋协方差)的研究，但潮汐小溪的温室气体通量未知。我们测量了水中的温室气体浓度、水质、气象参数、沉积物二氧化碳外流、生态系统尺度的温室气体通量和植物物候；所有这些都是在一年中每隔半小时测量一次。利用人工测得的小溪温室气体通量计算了气体传输速度(K)，并对水到大气的温室气体通量模型进行了参数化。这条小溪是大气中温室气体的来源，潮汐模式控制着海底的变化。溶解氧和风速与小溪CH4排放呈显著负相关。尽管缺乏季节模式，溪流二氧化碳流出与物候阶段的浊度等驱动因素相关。总体而言，夜间溪流CO_2流出量(3·6±0·63μ/m~2/S)至少是夜间沼泽沉积物CO_2流出量(1·5±1·23μ·μ/m~2/S)的2倍。小溪甲烷排放通量(17.5±6.9nmol/m2/S)比生态系统尺度的甲烷排放通量(68.1±52.3nmol/m2/S)低4倍。这些结果表明，潮汐小溪是二氧化碳排放的潜在热点，并可能由于甲烷在水中的过饱和(>；6,000μ/摩尔)而有助于向沿海海洋侧向输送甲烷。这项研究为模拟潮汐小溪的温室气体排放提供了启示，并表明潮汐阶段的变化在确定通量大小时盖过了水温。
Coastal salt marshes store large amounts of carbon but the magnitude and patterns of greenhouse gas (GHG; i.e., carbon dioxide (CO2) and methane (CH4)) fluxes are unclear. Information about GHG fluxes from these ecosystems comes from studies of sediments or at the ecosystem‐scale (eddy covariance) but fluxes from tidal creeks are unknown. We measured GHG concentrations in water, water quality, meteorological parameters, sediment CO2 efflux, ecosystem‐scale GHG fluxes, and plant phenology; all at half‐hour intervals over 1 year. Manual creek GHG flux measurements were used to calculate gas transfer velocity (k) and parameterize a model of water‐to‐atmosphere GHG fluxes. The creek was a source of GHGs to the atmosphere where tidal patterns controlled diel variability. Dissolved oxygen and wind speed were negatively correlated with creek CH4 efflux. Despite lacking a seasonal pattern, creek CO2 efflux was correlated with drivers such as turbidity across phenological phases. Overall, nighttime creek CO2 efflux (3.6 ± 0.63 μmol/m2/s) was at least 2 times higher than nighttime marsh sediment CO2 efflux (1.5 ± 1.23 μmol/m2/s). Creek CH4 efflux (17.5 ± 6.9 nmol/m2/s) was 4 times lower than ecosystem‐scale CH4 fluxes (68.1 ± 52.3 nmol/m2/s) across the year. These results suggest that tidal creeks are potential hotspots for CO2 emissions and could contribute to lateral transport of CH4 to the coastal ocean due to supersaturation of CH4 (>6,000 μmol/mol) in water. This study provides insights for modeling GHG efflux from tidal creeks and suggests that changes in tide stage overshadow water temperature in determining magnitudes of fluxes.