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Assessing branched tetraether lipids as tracers of soil organic carbon transport through the Carminowe Creek catchment (southwest England)
- Source :
- Biogeosciences, 17(12), 3183. European Geosciences Union, Biogeosciences, Vol 17, Pp 3183-3201 (2020)
- Publication Year :
- 2020
-
Abstract
- Soils represent the largest reservoir of organic carbon (OC) on land. Upon mobilization, this OC is either returned to the atmosphere as carbon dioxide (CO2) or transported and ultimately locked into (marine) sediments, where it will act as a long-term sink of atmospheric CO2. These fluxes of soil OC are, however, difficult to evaluate, mostly due to the lack of a soil-specific tracer. In this study, a suite of branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are membrane lipids of soil bacteria, is tested as specific tracers for soil OC from source (soils under arable land, ley, grassland, and woodland) to sink (Loe Pool sediments) in a small catchment located in southwest England (i.e. Carminowe Creek draining into Loe Pool). The analysis of brGDGTs in catchment soils reveals that their distribution is not significantly different across different land use types (p>0.05) and thus does not allow land-use-specific soil contributions to Loe Pool sediments to be traced. Furthermore, the significantly higher contribution of 6-methyl brGDGT isomers in creek sediments (isomerization ratio (IR) = 0.48±0.10, mean ± standard deviation (SD); p) compared to that in catchment soils (IR = 0.28±0.11) indicates that the initial soil signal is substantially altered by brGDGT produced in situ. Similarly, the riverine brGDGT signal appears to be overwritten by lacustrine brGDGTs in the lake sedimentary record, indicated by remarkably lower methylation of branched tetraethers (MBT5ME′=0.46±0.02 in creek bed sediments and 0.38±0.01 in lake core sediments; p) and a higher degree of cyclization (DC = 0.23±0.02 in creek bed sediments and 0.32±0.08 in lake core sediments). Thus, in this small catchment, brGDGTs do not allow us to trace soil OC transport. Nevertheless, the downcore changes in the degree of cyclization and the abundance of isoprenoid GDGTs produced by methanogens in the Loe Pool sediment do reflect local environmental conditions over the past 100 years and have recorded the eutrophication history of the lake.
- Subjects :
- 010504 meteorology & atmospheric sciences
Evolution
lcsh:Life
Drainage basin
010502 geochemistry & geophysics
01 natural sciences
Sink (geography)
chemistry.chemical_compound
Behavior and Systematics
lcsh:QH540-549.5
Ecology, Evolution, Behavior and Systematics
0105 earth and related environmental sciences
Earth-Surface Processes
Total organic carbon
geography
geography.geographical_feature_category
Ecology
lcsh:QE1-996.5
Sediment
Soil carbon
15. Life on land
6. Clean water
lcsh:Geology
lcsh:QH501-531
chemistry
Environmental chemistry
Carbon dioxide
Soil water
Environmental science
lcsh:Ecology
Eutrophication
Subjects
Details
- Language :
- English
- ISSN :
- 17264189 and 17264170
- Database :
- OpenAIRE
- Journal :
- Biogeosciences, 17(12), 3183. European Geosciences Union, Biogeosciences, Vol 17, Pp 3183-3201 (2020)
- Accession number :
- edsair.doi.dedup.....32750ecf616d20bfe0b98fed939afe02