Contributions of terrestrial organic carbon to northern lake sediments

Cristian Gudasz,Yvonne Oelmann,Chiara Cerli,Jan Karlsson,Sabine Fiedler,Karsten Kalbitz,Marc Ruppenthal,August Andersson

doi:10.1002/lol2.10051

Abstract

AbstractSediments of northern lakes sequester large amounts of organic carbon (OC), but direct evidence of the relative importance of their sources is lacking. We used stable isotope ratios of nonexchangeable hydrogen (δ2Hn) in topsoil, algae, and surface sediments in order to measure the relative contribution of terrestrial OC in surface sediments of 14 mountainous arctic and lowland boreal lakes in Sweden. The terrestrial contribution to the sediment OC pool was on average 66% (range 46–80) and similar between arctic and boreal lakes. Proxies for the supply of terrestrial and algal OC explained trends in the relative contribution of terrestrial OC across lakes. However, the data suggest divergent predominant sources for terrestrial OC of sediments in Swedish lakes, with dissolved matter dominating in lowland boreal lakes and particulate OC in mountainous arctic lakes.

Highlights

Author Contribution Statement: CG and JK came up with the research question and designed the field survey
The sites of the arctic region were located in the oroarctic tundra (Virtanen et al 2015) and Nordic mountain birch forest-tundra ecotone (Wielgolaski 2005), while the North and South forest sites belonged to the boreal region (Kerstin et al 2008)
This study provides direct evidence for the relative importance of allochthonous vs. autochthonous organic carbon (OC) in sediments a1

Summary

Introduction

Author Contribution Statement: CG and JK came up with the research question and designed the field survey. CG, KK, and CC designed the sample treatment and CG and CC conducted the sample preparation and laboratory work. CC, CG, and SF contributed with sediment chemical analyses. MR conducted and YO made possible the isotope analyses. CG conducted the statistical analyses and AA conducted the analyses of the mixing models analyses with the Monte Carlo approach. CG wrote the paper with contributions from all authors

Methods

Results

Conclusion