summary

Summary

The soils in Polar Regions make up a substantial source of organic carbon, and are currently undergoing various changes because of global warming. This makes lakes such as Sisi 15 important case studies for interpreting the impacts that past warming has had on Greenland and on other parts of the world in order to predict and understand the future effects of warming.

When the climate becomes warmer, much of the carbon stored in Arctic soils is released directly into the atmosphere as CO2. However, it can also reach the atmosphere when it is dissolved in water, allowing it to move through rivers and into lakes in the catchment area as particulate organic matter, which is then degassed as CO2 via microbial activity in the rivers, and lakes (Lamb et al, 2006). Despite these processes not all carbon is released into the atmosphere and a significant amount is stored in lake sediments and so is no longer part of the terrestrial carbon cycle (Roberts et al, 2009; Leng et al, 2012).

The data from sediments in Sisi 15 show how it interacts with its catchment area, shows how this has varied under changing climatic conditions, and demonstrates the resultant changes in soil development and vegetation. The Sisi 15 sediments give stable isotope information from throughout the Holocene including C/N, TOC, δ13C and S. Moreover, because the same data has been collected from various other lakes from the coast to the Greenland ice cap, Sisi 15 is compared to these to demonstrate the effect that the different catchment conditions along this natural climate gradient have had on carbon cycling.

Sisi 15 and nearby coastal lakes such as Sisi 12 are net heterotrophic as primary production is less than the ecosystem respiration (Leng & Anderson, 20...

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... appear to be a result of greater input of terrestrial organic matter through its burial due to enhanced soil instability (Leng et al, 2012). Whilst further inland in the lakes of Kangerlussuaq changes in lake productivity have a greater effect on the geochemistry (Fritz et al, 2013).

The influences on carbon cycling are particularly complex for Sisi 15 during the late Holocene; this is most likely due to the effects of its proximity to the sea, and because of melting of remnants of glaciers in the area (Anderson et al, 2012).

The results from this and other studies on lakes throughout this region of Greenland show that there are many influences on the geochemistry of the lakes which cause them to show a considerable variability, this is due to both catchment and lake processes effecting the way that climate influences the geochemical composition of lake sediments.