Natural Halogenated Methane Production in Mangrove Ecosystems, Niva, UG '22, (3963502)
As a combination of rising sea levels, extreme weather, and groundwater overuse leads to increasing seawater encroachment in coastal areas, it’s essential that we learn more about the resulting shifts in soil chemistry in these environments and the impacts they can have on a larger scale. Previous research on coastal wetlands found that as freshwater wetlands transition into salt marshes because of increasing marine influences, there is a corresponding increase in the emission of halomethane, which is made up of chloromethane and bromomethane. Once emitted, these molecules travel to the stratosphere where they trigger ozone degradation, leading to increased rates of skin cancer and cataracts in humans. The increased halomethane emissions were correlated with an overlap of high levels of both organic carbon and halogens or salts. This understanding led to further investigation into mangrove forests, another coastal ecosystem. These forests are exceptional in their ability to sequester immense levels of organic carbon despite the challenges of inhabiting a high salinity environment. Upon examining soil samples collected across varying depths and locations within two Panamanian mangrove forests, the same pattern of the forests with greater seawater influence having a higher halomethane emission rate was found. Additionally, levels of bromine seen in this ecosystem far outweighed those seen in the wetlands. This is particularly concerning because bromomethane is far more potent at ozone degradation than chloromethane, so increased halomethane emissions from mangrove forests would lead to significantly higher levels of ozone degradation.