Data from: Johnson, K. et al. Towards a mechanistic understanding of carbon stabilization in manganese oxides. Nat. Commun. 6:7628 doi:10.1038/ncomms8628 (2015).
 
Creators: Johnson, Karen/Durham University; Purvis, Graham / Newcastle University; Lopez-Capel, Elisa / Newcastle University; Ojeda, Jesus / Brunel University.

Description: Minerals are known to stabilise organic carbon in sediments, affecting biogeochemical cycles and global climate, but the mechanism is not understood. Here, the authors suggest that manganese oxides can trap organic carbon and may act as a 'mineral pump', transforming carbon between labile and refractory forms.

Abstract form article: Minerals stabilize organic carbon (OC) in sediments, thereby directly affecting global climate at multiple scales, but how they do it is far from understood. Here we show that manganese oxide (Mn oxide) in a water treatment works filter bed traps dissolved OC as coatings build up in layers around clean sand grains at 3%w/wC. Using spectroscopic and thermogravi- metric methods, we identify two main OC fractions. One is thermally refractory (<550 °C) and the other is thermally more labile (>550 °C). We postulate that the thermal stability of the trapped OC is due to carboxylate groups within it bonding to Mn oxide surfaces coupled with physical entrapment within the layers. We identify a significant difference in the nature of the surface-bound OC and bulk OC . We speculate that polymerization reactions may be occurring at depth within the layers. We also propose that these processes must be considered in future studies of OC in natural systems. 

Figure 2 - Micro-FTIR images of Bernessite
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FTIR data.xls
Figure2a.jpg
Figure2b.jpg

Figure 3 - TGA spectral analysis of Bernessite
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TGA with component fitting mnox.txt
TGA with mz 44 and mz 18 data.txt

Figures 4 and 5 - XPS spectral analysis of Bernessite
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XPS raw data.TXT
MnO BulK, MnO surface MnO thermal treatment to 1000 C Ca2p.txt
MnO Bulk MnO Surface and MnO thereaml treatment 550C N1s plots.txt
MnO theramal treatment to 1000C.txt
MnO thermal treatment and and MnO Bulk high resoution C1s spectra.txt
MnO Surface and MnO Bulk high resoution C1s spectra.txt

MnO Bulk and Bulk 550.vms
MnO bulk and surface.vms
MnO surface 1000C.vms
MnO surface 550C and 1000C.vms
MnO surface theramal treatment 1.vms

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