Office of Environment and Heritage, New South Wales, Australia.
Department of Environmental Sciences, Macquarie University, New South Wales, Australia.
Sci Rep. 2019 Mar 13;9(1):4368. doi: 10.1038/s41598-019-40763-8.
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 (CH) emissions. We monitored an impounded wetland's GHG flux (CO and CH) 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 yr CO-e over 100 years, and it increased to 351 g m yr with the removal of extreme rain events. However, emission benefits were achieved through a reduction in CO emissions, not CH emissions. Overall, the wetland shifted from a prior CH sink (-0.07 to -1.74 g C m yr) 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.
人们越来越关注沿海湿地固存的“蓝碳”管理如何影响全球温室气体（GHG）预算。一种很有前景的干预措施是通过恢复潮汐交换来减少被堤坝围封的沿海湿地的甲烷（CH）排放。我们在恢复潮汐之前和之后监测了一个被堤坝围封的湿地的温室气体通量（CO 和 CH）。我们发现，生物地球化学响应在海拔梯度上有所不同。与高海拔区相比，低海拔区的水位上升幅度更大，沉积物微生物群落（16S rRNA）的海洋过渡程度更大。低海拔区的温室气体排放在 100 年内的持续全球变暖潜势减少了 264 g m yr CO-e，而在去除极端降雨事件后增加到 351 g m yr。然而，排放效益是通过减少 CO 排放而不是 CH 排放实现的。总的来说，该湿地从前的 CH 汇（-0.07 到-1.74 g C m yr）转变为一个可变的汇或源，这取决于海拔地点和降雨量。这凸显了在评估潮汐恢复对温室气体排放控制的效果时，需要考虑湿地的初始温室气体排放、海拔和未来降雨趋势。
