Figure 6

Images and intensity maps from analysis of a thin section of granule Old-2. a) reflected light image of an area of granule Old-2 resident in soil for between 1 and 39 days, scale bar is 100 μm; high spatial-resolution μ-FTIR intensity maps for (b) ν₂ (855–890 cm⁻¹), (c) ν₄ (695–716 cm⁻¹) and (d) ν₂/ν₄ ratio map with high intensity areas indicative of ACC rich regions, e) cluster analysis map showing 4 clusters (dark blue, light blue, orange and white), f) component regression intensity map for ACC, g) component regression intensity map for calcite, h) electron microprobe Mn distribution map, i) close up of (h) focussing on area of μ-FTIR maps showing lack of correlation between elemental and ACC variation. For μ-FTIR intensity maps, red indicates high intensity, blue indicates low intensity while for the elemental maps bright indicates higher concentrations.