Mineralization of organic carbon in lake sediments: temperature sensitivity and a comparison to soils
(English)Manuscript (preprint) (Other academic)
Temperature alone can explain a great amount of variation in sediment organic carbon (OC) mineralization. Studies on decomposition of soil OC suggest that the temperature sensitivity is different for the decomposition of labile and recalcitrant OC, but lake sediments with different contributions of labile and recalcitrant components have been reported to show similar temperature sensitivities. Sediment mineralization is typically measured in short-term incubations. However, whether the mineralization of OC in sediments dominated by recalcitrant and labile OC have different temperature sensitivities at the longer term is not clear. Here we show that during 5 months of continuous incubation of contrasting boreal lake sediments, sediment mineralization was strongly dependent on temperature and OC quality/origin but temperature sensitivity was similar across lakes and over time. Sediment mineralization showed low overall rates in spite of low apparent activation energy (Ea) compared to published rates of soil and litter mineralization. The fraction of the total OC pool that was lost during 5 months varied between 0.4 and 14%. The non-buried sediment OC pool was lost slowly, with apparent turnover times between 2.5 and 32 years. At a large scale, lake sediments, by showing lower mineralization rates than soils are more effective as carbon sinks.
lake sediment, mineralization, temperature sensitivity, organic carbon, turnover time
Research subject Limnology
IdentifiersURN: urn:nbn:se:uu:diva-150714OAI: oai:DiVA.org:uu-150714DiVA: diva2:408446