| Summary: | Circumpolar river deltas are a potential hotspot for the biogeochemical cycling of dissolved organic carbon (DOC) as it is leached from the surrounding landscape into deltaic river channels and eventually discharged to the near shore Arctic Ocean. The Mackenzie Delta, an intricate network of over 45,000 lakes in the western Canadian Arctic, is strongly dependent on both the flood dynamics and biogeochemical properties of the northward flowing Mackenzie River. This study examined the seasonal and spatial variability of photochemical and biological DOC degradation within select river channels and lakes of the Mackenzie Delta. The study revealed significant differences in DOC loss via photochemical (PCD) and biological degradation (BDOC) within lakes of differing flood regimes, while river waters showed only minor losses via BDOC, but significant photochemical degradation. In addition, incubation experiments indicate that BDOC is strongly enhanced through UV exposure.
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