Grant: Canada Research Chairs

The ocean has absorbed 25% of anthropogenic carbon emissions and plays a critical role in maintaining our climate. Of the total amount of organic carbon in the ocean, 97% is in dissolved form; that’s 32 times as much carbon than is in all of the living organisms in the ocean, from the tiny phytoplankton to the blue whales. This large pool of reduced carbon is called dissolved organic matter (DOM) and it represents a blue carbon sink of considerable size – the same size as the atmospheric CO2 pool. DOM is chemically very complex and while some parts of the DOM pool are very unreactive, acting as a carbon sink, others are rapidly cycled back to CO2 in the surface ocean, either by microbes or through sunlight-driven chemical reactions. The chemistry and biology that drives balance between these two fates is complex, but the amount of carbon in DOM is large enough to have considerable impacts on our climate system if that balance is disrupted. From rivers and coastal waters to the open ocean Dr. Reader uses a multiscale approach to answer questions about the capacity and efficiency of the blue carbon DOM sink in marine systems. Two areas are of great interest to Dr. Reader’s research. First, the coastal environments of boreal regions, where high concentrations of terrestrial material flows through rivers into the sea, affecting the colour and nutrient content of the waters. Here, there is potential for carbon burial through interactions with metals, but there is also potential to stay dissolved and deliver the same metals to open waters to be used as micronutrients. Secondly, the open ocean where freshly made DOM is recycled by microbes and rendered inert in the deep ocean. Here, the efficiency of the transfer from fresh and reactive in the surface ocean to non-reactive in the ocean interior is not well known. Each of these environments plays a unique and important role in the ocean’s blue carbon sink, Dr. Reader uses advanced analytical techniques to look for fingerprints of reactivity in DOM and assess hotspots of blue carbon storage in the marine environment. Combining fieldwork, lab experiments, and different types of chemical analysis, Dr. Reader’s work will contribute to a full assessment of the capacity of the ocean to blue carbon sink.