Assessing greenhouse gas structural and functional resilience of freshwater coastal wetlands subject to persistent saltwater intrusion events

Greenhouse gas production and fluxes

flux

The amount of some type of particle or energy crossing a unit area per unit time.

Source: NRC Library Source

in coastal wetlands

wetland

An area of land that is periodically saturated with water, which influences the types of plants and animals that can live there. Wetlands include swamps, marshes, bogs, and other similar areas.

Source: A student's guide to Global Climate Change Source

are controlled by complex interacting hydrological and ecological processes whose dynamics are, in turn, modified by saltwater intrusion (SWI) events. In suburban and urban transition zones, the floodwalls and levee systems built to protect infrastructure and urban development intensify the SWI events resulting from floods during storm surges. When the flood waves travel inland, they meet these barriers, and saltwater can remain stagnant for prolonged periods, increasing the exposure of adjacent coastal wetlands to salt stress (i.e., persistent SWI events). These stress conditions induced by SWI are rarely represented in biogeochemical models, limiting our capacity to predict and assess the long-term effects of SWI on coastal greenhouse gas production and fluxes. Moreover, significant knowledge gaps exist in how the ecosystem

ecosystem

A natural community of plants, animals, and other living organisms and the physical environment in which they live and interact.

Source: A student's guide to Global Climate Change Source

reorganizes after SWI disturbance. Specifically, what trajectories do biological components (ecosystem structure) and greenhouse gas production and emission (ecosystem function) follow after SWI? Also, it is not clear what the relevant scales to evaluate these trajectories are. Using an ecohydrological patch approach defined by plant functional types and water levels, this early-career proposal aims to understand better how ecosystem structure and function linked to greenhouse gas fluxes in freshwater coastal wetlands affected by the built environment are influenced by SWI in the short- (days to weeks) and long- (years to decades) term. This project will evaluate carbon dioxide

carbon dioxide (CO2)

An important heat-trapping gas, also known as a greenhouse gas, that comes from the extraction and burning of fossil fuels (such as coal, oil, and natural gas), from wildfires, and natural processes like volcanic eruptions.

Source: NASA Source

and methane

methane

A hydrocarbon that is a primary component of natural gas. Methane is also a greenhouse gas (GHG), so its presence in the atmosphere affects the earth’s temperature and climate system

Source: EPA Source

pools and fluxes before, during, and after simulated SWI events covering a wide range of salt exposure (salinity

salinity

Salinity is the dissolved salt content of a body of water. It is a strong contributor to conductivity and helps determine many aspects of the chemistry of natural waters and the biological processes within them.

Source: EPA Source

concentration, duration, and frequency). The measurements will be conducted on a multi-setting sampling approach composed of controlled mesocosm in greenhouses and experimental wetland ecosystem units and will be complemented with time-for-space replacements in coastal wetlands with a history of persistent SWI. Data collected will be used to produce and incorporate an explicit salinity-dependent function into the methane biogeochemistry module integrated into the E3SM

Energy Exascale Earth System Model (E3SM)

The Energy Exascale Earth System Model (E3SM) project includes Earth System Models, simulations, and predictions to investigate energy-relevant science using code optimized for DOE's advanced supercomputers.

Source: NVCL Web Page Source

Land Model (ELM v1). The improved module will then be used to assess the sensitivity of methane emissions to different scenarios of SWI, accounting for increased storm magnitude and frequency expected from climate change

climate change

A change in the average conditions — such as temperature and rainfall — in a region over a long period of time.

Source: NASA Climate Kids Source

and sea-level rise and exacerbated by current and projected build environments.