Тип публикации: статья из журнала
Год издания: 2021
Идентификатор DOI: 10.1029/2020JG006152
Ключевые слова: dissolved organic carbon, fdom, in situ sensing, permafrost, northern siberia
Аннотация: Intense climate change and permafrost degradation impact northern watersheds and ultimately organic carbon transfer from terrestrial to aquatic ecosystems. We investigated the contemporary dissolved organic carbon (DOC) dynamics in a northern catchment underlain by discontinuous permafrost (Graviyka River, northern Siberia), where Показать полностьюhistorical meteorological and hydrological data are available since 1936. Mean annual air temperature (MAAT), in contrast to precipitation and discharge was found to show a significant increasing trend since 1950. Using in situ sensing of fluorescent dissolved organic matter (fDOM), we estimated DOC concentrations at a high temporal frequency (1h) during 3 years (2015-2018), and calculated annual specific fluxes of 5.2-5.5 g C m(2) yr(-1). High DOC concentrations (above 10 mg L-1) are sustained all year, exhibiting nearly chemostatic behavior. Nevertheless, the high-frequency survey of DOC and other water parameters revealed the seasonality of DOC origin and pathways in the watershed. The spring freshet dominates the annual export (up to 80%), but summer and autumn floods can also contribute up to 9% and 8% respectively. The high-frequency sampling was able to capture the specific dynamic of DOC concentration during spring flood (DOC peak preceding discharge, dilution during the spring freshet) and summer and autumn floods (contribution of DOC-rich, low conductivity water). These observations suggest a significant contribution of organic-rich water originating in peatlands, potentially from degrading palsas. The study demonstrates both that high-frequency sampling is essential to capture key events for DOC export, and that more long-term monitoring is urgently needed in these rapidly evolving watersheds.
Журнал: JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
Выпуск журнала: Vol. 126, Is. 10
Номера страниц: 2020
ISSN журнала: 21698953
Место издания: WASHINGTON
Издатель: AMER GEOPHYSICAL UNION