Application of biomarkers to examine transformations of dissolved carbon and nitrogen reservoirs in Arctic rivers
The sheer magnitude of organic carbon stored in Arctic watersheds dictates that understanding its dynamics is vital to describing and modeling how current and future warming will impact the release of carbon from Arctic ecosystems. Arctic rivers carry large quantities of dissolved organic matter (DOM) and represent an important conduit connecting terrestrial and oceanic carbon pools with a major impact on biogeochemical cycles in the Arctic Ocean. This grant utilizes a geochemical approach to investigate the fate and transformations of dissolved organic carbon (DOC) and nitrogen (DON) reservoirs in Arctic rivers. The goal is 1) to provide a detailed analysis of the bioavailability of Arctic river DOM at the different stages of the hydrograph, and 2) to investigate the origins and transformations of DON in Arctic rivers. Researchers will combine molecular level analysis of carbohydrates, amino acids including D-amino acids, and phenol biomarkers on collected samples with laboratory incubation experiments. The incubation experiments with fresh-leached litter collected in Arctic watersheds will be used to internally calibrate biomarkers. Data generated during this project will be integrated with a vast array of already measured parameters (>50) to examine linkages among DOM sources, decomposition, climate, hydrology, and river chemistry. The Arctic regions have accumulated an immense reservoir of carbon in soils and biomass over the last 12,000 years. A transfer of this enormous pool of carbon due to current and anticipated climate change has a major effect on the health of the Arctic ecosystem and global climate. This application of carbohydrate, amino acids and phenolic biomarkers will improve our very limited understanding of sources and transformation processes of organic constituents in Arctic rivers as they are transported from soils to the Arctic Ocean. The project will also investigate how organic compounds decompose in different Arctic river watersheds with varying vegetation, topography, mean annual air temperature, and extent of permafrost at different flow conditions and seasons. Knowing the sources (vegetation, soil, peat etc.) of organic constituents as well as the dominant transformation processes (solution, absorption, decomposition) is crucial if we want to predict the effect that a warmer climate will have on the transfer of organic constituents from these watersheds to the Arctic Ocean. The project will provide high-impact learning experiences for undergraduate students from Texas A&M at Galveston and contribute to the development of one beginning investigator. Results from this research will be made widely available to the scientific community such that the data set may be used to construct detailed models of organic carbon transfer from Arctic regions to the Arctic Ocean.