Abstract
Climate change is predicted to have far reaching consequences for the mobility of carbon in arctic landscapes. On a regional scale, carbon cycling is highly dependent on interactions between terrestrial and aquatic parts of a catchment. Despite this, studies that integrate the terrestrial and aquatic systems and study entire catchments using site-specific data are rare. In this work, we use data partly published by Lindborg et al. (2016a) to calculate a whole-catchment carbon mass-balance budget for a periglacial catchment in West Greenland. Our budget shows that terrestrial net primary production is the main input of carbon (99% of input), and that most carbon leaves the system through soil respiration (90% of total export/storage). The largest carbon pools are active layer soils (53% of total carbon stock or 13 kg C m−2), permafrost soils (30% of total carbon stock or 7.6 kg C m−2) and lake sediments (13% of total carbon stock or 10 kg C m−2). Hydrological transport of carbon from the terrestrial to aquatic system is lower than in wetter climates, but the annual input of 4100 kg C yr−1 (or 3.5 g C m−2 yr−1) that enters the lake via runoff is still three times larger than the eolian input of terrestrial carbon. Due to the dry conditions, the hydrological export of carbon from the catchment is limited (5% of aquatic export/storage or 0.1% of total export/storage). Instead, CO2 evasion from the lake surface and sediment burial accounts for 57% and 38% of aquatic export/storage, respectively (or 0.8% and 0.5% of total export/storage), and Two-Boat Lake acts as a net source of carbon to the atmosphere. The limited export of carbon to downstream water bodies make our study system different from wetter arctic environments, where hydrological transport is an important export pathway for carbon.
Highlights
The low temperatures and frozen soils in arctic climates result in slow organic matter turnover and, in a higher accumulation of organic matter per unit production as compared to other climatic settings (Hobbie et al, 2000; Mikan et al, 2002; Matzner and Borken, 2008; McGuire et al, 2009)
Because of low dissolved organic carbon (DOC) concentrations in fresh snow and rain (0.7– 0.9 mg LÀ1; Lindborg et al, 2016b) we assumed that the only significant atmospheric input of organic carbon was as eolian deposition
The Total Organic Carbon (TOC) concentrations in old snow containing significant amounts particulate organic carbon (POC) from eolian deposition (39–60 mg LÀ1), which translates to an estimated total input of 750 kg C yrÀ1 to the aquatic system via eolian deposition
Summary
The low temperatures and frozen soils in arctic climates result in slow organic matter turnover and, in a higher accumulation of organic matter per unit production as compared to other climatic settings (Hobbie et al, 2000; Mikan et al, 2002; Matzner and Borken, 2008; McGuire et al, 2009). With increasing air temperatures many other Arctic areas are likely to become drier (Koenigk et al, 2013), or have already begun to do so (Smol and Douglas, 2007)
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