Biodegradability of dissolved organic carbon in the Yukon River and its tributaries: Seasonality and importance of inorganic nitrogen
Open Access
- 26 September 2012
- journal article
- Published by American Geophysical Union (AGU) in Global Biogeochemical Cycles
- Vol. 26 (4)
- https://doi.org/10.1029/2012gb004342
Abstract
[1] Northern high‐latitude rivers transport large amounts of terrestrially derived dissolved organic matter (DOM) from boreal and arctic ecosystems to coastal areas and oceans. Current knowledge of the biodegradability of DOM in these rivers is limited, particularly for large rivers discharging to the Arctic Ocean. We conducted a seasonally comprehensive study of biodegradable dissolved organic carbon (BDOC) dynamics in the Yukon River and two of its tributaries in Alaska, USA. Distinct seasonal patterns of BDOC, consistent across a wide range of watershed size, indicate BDOC is transported year‐round. Relative biodegradability (%BDOC) was greatest during winter, and decreased into spring and summer. Due to large seasonal differences in DOC concentration, the greatest concentrations of BDOC (mg C L−1) occurred during spring freshet, followed by winter and summer. While chemical composition of DOM was an important driver of BDOC, the overriding control of BDOC was mineral nutrient availability due to wide shifts in carbon (C) and nitrogen (N) stoichiometry across seasons. We calculated seasonal and annual loads of BDOC exported by the Yukon River by applying measured BDOC concentrations to daily water discharge values, and also by applying an empirical correlation between %BDOC and the ratio of DOC to dissolved inorganic N (DIN) to total DOC loads. The Yukon River exports ∼0.2 Tg C yr−1 as BDOC that is decomposable within 28 days. This corresponds to 12–18% of the total annual DOC export. Furthermore, we calculate that the six largest arctic rivers, including the Yukon River, collectively export ∼2.3 Tg C yr−1 as BDOC to the Arctic Ocean.Keywords
This publication has 62 references indexed in Scilit:
- Influence of permafrost distribution on groundwater flow in the context of climate‐driven permafrost thaw: Example from Yukon Flats Basin, Alaska, United StatesWater Resources Research, 2012
- Circumpolar synchrony in big river bacterioplanktonProceedings of the National Academy of Sciences of the United States of America, 2009
- Modeling transport and fate of riverine dissolved organic carbon in the Arctic OceanGlobal Biogeochemical Cycles, 2009
- Seasonal changes in the chemical quality and biodegradability of dissolved organic matter exported from soils to streams in coastal temperate rainforest watershedsBiogeochemistry, 2009
- Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, AlaskaGeophysical Research Letters, 2009
- Flux and age of dissolved organic carbon exported to the Arctic Ocean: A carbon isotopic study of the five largest arctic riversGlobal Biogeochemical Cycles, 2007
- Increased groundwater to stream discharge from permafrost thawing in the Yukon River basin: Potential impacts on lateral export of carbon and nitrogenGeophysical Research Letters, 2007
- Seasonal changes in the age and structure of dissolved organic carbon in Siberian rivers and streamsGeophysical Research Letters, 2006
- Biodegradation of soil-derived dissolved organic matter as related to its propertiesGeoderma, 2003
- Controls of bioavailability and biodegradability of dissolved organic matter in soilsGeoderma, 2003