Fig. 2.

Illustration of the steps involved in pore characterization and in combining 2D zymography and 3D X-ray µCT scanning. a The volume of the soil matrix (pink) within 180 µm distance from ≥30 µm pores (blue) was used as an approximate indicator of the size of the soil matrix that can be potentially affected by C processing taking place within pores. b After µCT scanning (at 30 µm resolution) each soil core was cut into slices, with 2 mm distance between the slices. Each core contained 8–16 slices, and, in most of the cores, zymograms of each enzyme were obtained on two slices per core. c A membrane saturated with an enzyme-specific substrate was placed on the surface of each slice and a zymogram was obtained