Premium
Modeling hydrology and silicon‐carbon interactions in taiga and tundra biomes from a landscape perspective: Implications for global warming feedbacks
Author(s) -
Smedberg Erik,
Mörth CarlMagnus,
Swaney Dennis P.,
Humborg Christoph
Publication year - 2006
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2005gb002567
Subject(s) - tundra , environmental science , snowmelt , hydrology (agriculture) , arctic , carbon cycle , permafrost , soil water , taiga , biogeochemical cycle , groundwater , total organic carbon , surface runoff , oceanography , ecosystem , geology , soil science , environmental chemistry , ecology , chemistry , geotechnical engineering , biology
We used a simple hydrological‐biogeochemical mixing model to test the hypothesis that export of total organic carbon occurring mainly during spring in taiga and tundra watersheds might be compensated by production and export of bicarbonate (HCO 3 − ) from groundwater during the rest of the year. The investigated watersheds are located in northern Sweden close to the Arctic Circle. An elevated spring flow peak due to snowmelt characterizes the hydrology of boreal and arctic river systems. During this snowmelt, total organic carbon (TOC), previously stored as soil carbon, is flushed and exported from the watersheds, and can be released to the atmosphere via heterotrophic remineralization during riverine transport to the sea, thereby contributing to atmospheric CO 2 . The TOC yields of the watersheds investigated increased with vegetation and peat cover and ranged across watersheds from 0.5 to 2.8 tons km −2 yr −1 . During frozen periods, streamflow is dominated by “old” groundwater. This water has percolated through the soils and is rich in DSi and bicarbonate; that is, atmospheric carbon that has been “consumed” in chemical weathering processes is partly exported as bicarbonate to the sea, where carbon is stored as CaCO 3 for geological time. The bicarbonate export of the watersheds investigated was between 0.4 and 1.2 tons C km −2 yr −1 corresponding to 15–73% of the TOC export. Very likely, global warming will affect water flow through the soils in taiga and tundra ecosystems and thus will have an effect on watershed carbon budgets. This bicarbonate export may compensate for significant amounts of the exported TOC, thereby reducing the positive feedback to atmospheric CO 2 .