What do we Study?
Nick Ward, PhD
Towards a CONNECTED understanding of earth systems
Earth systems are intimately interconnected, yet most biogeochemical studies focus on specific components in isolation. The movement of water drives the carbon cycle, and, as such, inland waters provide a critical intersection between terrestrial and marine biospheres:
Connected Hydro-Bio-Geochemical Cycles
Interactions between organic matter (OM) and water begins in the atmosphere, with particles driving the formation of clouds, and subsequent rainfall. OM is transported with. As raindrops precipitate they entrain OM, enriching the rainfall in dissolved carbon. Rainfall either enters the ocean directly or falls over the terrestrial landscape, where it is intercepted by forest canopies and vegetation layers (e.g. throughflow and stemflow) or man-made structures.
Carbon species derived from these initial interactions immediately experience physical, chemical, and biological alteration, which continues as gravity carries water downhill via soil penetration, groundwater recharge, surface runoff, and stream/river flow. Inland waters are active bio-reactors, converting vast amounts organic carbon produced both in the terrestrial biosphere and the aquatic environment into greenhouse gasses (GHG) such as carbon dioxide and methane. Although much attention has recently been paid to the production of GHG in inland waters, oxidation of methane and autochthonous primary production in lakes, floodplains, and river channels are important mechanisms for balancing these fluxes. Likewise, as river water enters the coastal ocean there is a dynamic equilibrium between the heterotrophic breakdown of organic carbon and photosynthetic sequestration of carbon dioxide driven by river-borne nutrients.
Inland, estuarine, and coastal waters are well studied in regions near centers of human population in the Northern hemisphere. However, many of the world’s large river systems and their marine receiving waters remain poorly characterized, particularly in the tropics, which contribute to a disproportionately large fraction of the transformation of terrestrial organic matter to carbon dioxide, and the Arctic, where positive feedback mechanisms are likely to amplify global climate change.