The role of climate-driven factors on carbon and phosphorus sequestrations in lake sediments and soils

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The past decade has witnessed a dramatic increase in the recognition of the role of inland waters in the global carbon (C) cycle. Since in inland waters a large amount of carbon is sequestered in sediments or emitted to the atmosphere, only half from the total C transported over the terrestrial ecosystem reaches the oceans. The long-term C sinks in lake and river sediments have rarely been assessed due to the complexity of measurements and the difficulty of extrapolating results from one system to another. Even though the terrestrial-aquatic continuum is one of the key uncertainties in global and local C and phosphorus (P) balance, neither a speciation of C nor P loadings from catchments have been estimated so far. Carbon and phosphorus speciation trigger the portions of the total C and P that will remain in the sediments. Over centuries accumulated P legacy in soils is a hidden pool entering our watersheds and ending up in lakes, impacting the C and P cycles during decades and perhaps even longer. Thus, it is imperative to remediate the P legacy in watersheds and contribute to a circular P economy, an economy that is designing out waste and pollution, keeping materials in use and regenerating natural systems. The long-term goals of my program are to understand and identify potential C sources and sinks in the terrestrial-aquatic continuum, to estimate P legacy in the terrestrial-aquatic continuum, and to elucidate and develop techniques for C sequestration and a circular P economy. This proposal focuses on multidisciplinary research of C and P sequestration along the terrestrial-aquatic continuum and has the following short-term objectives: O1: To examine the impact of climate-driven factors such as air temperature, precipitation and ice cover on C and P burial fluxes in lake sediments. O2: To estimate a speciation of C and P loadings from watersheds under extreme weather events. O3: To elucidate legacy P release from soils and to develop a sustainable bioremediation technique to capture and re-use P. I will combine field and laboratory experiments and modeling studies to obtain insight into biogeochemical processes ranging from the molecular to complex environmental system scales. The anticipated findings of the changes in C and P sequestration in lake sediments due to the dynamics of climate-driven factors, such as warming and the frequencies of extreme events, will contribute to closing the fundamental knowledge gap in the field of C and P biogeochemistry and offer missing data for the global modeling. The results will provide an enhanced insight into the consequences that these processes have on management strategies for the improvement of water quality. Importantly, our expected results will foster the development of new technology for C sequestration and P remediation in a current time of P mineral resource scarcity. This research will strengthen Canada's ability in the area of watershed and freshwater ecosystem management.