There is a growing interest in how the management of ‘blue carbon’ sequestered by coastal wetlands can influence global greenhouse gas (GHG) budgets. A promising intervention is through restoring tidal exchange to impounded coastal wetlands for reduced methane (CH4) emissions. We monitored an impounded wetland’s GHG flux (CO2 and CH4) prior to and following tidal reinstatement. We found that biogeochemical responses varied across an elevation gradient. The low elevation zone experienced a greater increase in water level and an associated greater marine transition in the sediment microbial community (16 S rRNA) than the high elevation zone. The low elevation zone’s GHG emissions had a reduced sustained global warming potential of 264 g m−2 yr−1 CO2-e over 100 years, and it increased to 351 g m−2 yr−1 with the removal of extreme rain events. However, emission benefits were achieved through a reduction in CO2 emissions, not CH4 emissions. Overall, the wetland shifted from a prior CH4 sink (−0.07 to −1.74 g C m−2 yr−1) to a variable sink or source depending on the elevation site and rainfall. This highlights the need to consider a wetland’s initial GHG emissions, elevation and future rainfall trends when assessing the efficacy of tidal reinstatement for GHG emission control.
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机译:人们越来越关注沿海湿地隔离的“蓝色碳”的管理如何影响全球温室气体(GHG)预算。一种有希望的干预措施是通过恢复与被扣留的沿海湿地的潮汐交换来减少甲烷(CH4)的排放。在潮汐恢复之前和之后,我们监测了蓄水湿地的温室气体通量(CO2和CH4)。我们发现生物地球化学响应在整个海拔梯度上变化。与高海拔区域相比,低海拔区域的沉积物微生物群落(16 S rRNA)的水位增加更大,伴随的海洋过渡更大。低海拔地区的温室气体排放量在100年内降低了264 g m -2 sup> yr -1 sup> CO2-e的持续全球变暖潜能,并增加到351 g m −2 sup> yr −1 sup>,消除了极端降雨事件。但是,通过减少CO2排放而不是CH4排放获得了排放收益。总体而言,湿地从先前的CH4汇(-0.07到-1.74 g C m -2 sup> yr -1 sup>)转移到可变的汇或源,具体取决于海拔位置和降雨。这凸显了在评估潮汐恢复对温室气体排放控制的效力时,必须考虑湿地的初始温室气体排放,海拔和未来的降雨趋势。
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