Figure 3

Plane polarised light photomicrograph, SEM‒EDX backscatter images, and EDX elemental maps of SRB traces. The analysed elements included S, Fe, C, N, and O. (a) Plane polarised light photomicrograph. (b) and (c) SEM‒EDX backscatter images. (d‒h) EDX elemental maps of Fe, S, C, N, and O, respectively.