Publication Date:
2011-10-26
Description:
Ombrotrophic bogs in southern Patagonia have been examined with regard to paleoclimatic and geochemical research questions but knowledge about organic matter decomposition in these bogs is limited. Therefore, we examined peat humification with depth by Fourier Transformed Infrared (FTIR) measurements of solid peat, C/N ratio, and δ13C and δ15N isotope measurements in three bog sites. Peat decomposition generally increased with depth but distinct small scale variation probably caused by environmental changes occurred. C/N ratios varied mostly between 40 and 120 and were significantly correlated (R2 〉 0.55, p 〈 0.01) with FTIR-derived humification indices. The degree of decomposition was lowest at the site with the least sea spray input, while the peat was most decomposed at the driest site with highest sea spray deposition. Decomposition of peat was also advanced near ash layers. Values of δ13C were 26.5 ± 2‰ in the peat and partly related to decomposition indices, while δ15N in the peat varied around zero and did not consistently relate to any decomposition index. Concentrations of DOM partly related to C/N ratios, partly to FTIR derived indices. DOM was enriched in 13C and in 15N relative to the solid phase probably due to multiple microbial modifications and recycling of N in these N-poor environments. In summary, paleoclimatic signals may have influenced decomposition according to depth profiles of C/N ratios, δ13C values, and FTIR spectra, but the study also suggests that decomposition was also influenced by ash layers, sea spray input and other site specific factors.
Print ISSN:
1810-6277
Electronic ISSN:
1810-6285
Topics:
Biology
,
Geosciences
