Is groundwater discharge an overlooked source of methane in restored coastal wetlands?
Role
Principal Investigator
Description
Coastal wetlands including saltmarsh and mangroves (known as blue carbon ecosystems) can accumulate carbon and act as a natural sink for atmospheric carbon dioxide (CO2). They, therefore, have the potential to mitigate climate change. However, the CO2 captured by wetlands may be counteracted by emissions of methane (CH4) from the wetland, which is a stronger greenhouse gas (GHG). The Australian Government has recently created a blue carbon accounting system that encourages low-lying land to be converted to blue carbon ecosystems by removing tidal floodgates. However, effective restoration for carbon storage requires a better quantitative understanding of the fate of carbon following restoration. For example, it is currently unknown how much CH4 export will occur and whether the GHG impact of this flux is larger (or smaller) than the benefit of the overall carbon sequestration following wetland restoration. Dissolved gasses including CH4 are often orders of magnitude higher in groundwaters than surface waters, suggesting groundwater seepage may be a significant, but unaccounted source of CH4 export from coastal wetlands. Determining how groundwater influences the carbon budget in coastal wetlands is complicated and costly if conventional methods of hydrogeological investigation (installation of observation bores) are used. In this study, we propose to use a novel and efficient method to estimate the contribution of groundwater to CH4 emissions from restored coastal wetlands based on natural geochemical tracers. This project expects to generate new knowledge about the fate of carbon post-wetland restoration. By knowing the dominant sources and sinks of greenhouse gases, the role that restored wetlands play in mitigating climate change will be better understood. This will provide insights into how restoration can be designed to maximize carbon storage. Hence, the results from this work will be critical and timely in developing adequate strategies to manage coastal wetlands to minimize carbon losses.
Date
01 Jul 2022 - 30 Jun 2025
Project Type
GRANT
Keywords
Groundwater;Radon;Wetland restoration;Greenhouse gases
Funding Body
The Hermon Slade Foundation
Amount
45903
Project Team
N/A