Louisiana State University
Arctic and boreal lakes play an influential role in the global carbon cycle. About twice as much carbon enters freshwater systems from land than is exported from land to the sea, and up to 80% of the total organic carbon in a boreal catchment can end up mineralized in lakes and released to the atmosphere as CO2. Indeed, as climate change has a disproportionally large effect on higher latitudes, the carbon budget of boreal lakes will become an increasingly important factor in global carbon dynamics.
An often-overlooked component of aquatic carbon cycling is dissolved inorganic carbon (DIC), which represents the sum of dissolved CO2, HCO3-, and CO3-.
The CO2 produced by microbial respiration of DOC and POC in the water column or respiration of organic matter in sediments results in an increase in DIC concentration in the water column and thus reveals a more detailed picture of carbon fate in an aquatic system — namely, how much organic matter is consumed within the microbial community of the lake. The fraction of this DIC that will leave the lake as CO2 gas emission depends on other factors such as alkalinity, pH, temperature and initial DIC concentration in the lake.
The CO2 flux of Sweden's Boreal lakes is dependent on external input of organic matter in either the dissolved or particulate phase. Effects of climate change will lead to increased organic matter flux into northern lakes, as well as change in the quality and timing of organic matter flux. Since DIC is produced from the microbial respiration of organic matter, changes in organic matter flux will lead to altered DIC production, resulting in whole-lake property changes. Therefore, understanding DIC production will become an increasingly critical component of carbon budgeting as climate changes.
Influences of organic matter sources on dissolved inorganic carbon in the carbon budget of a boreal lake system.
Dates: 30 May - 2 July
Supervisor: Jenny Ask