Fig. 1
From: Distinct nitrogen cycling and steep chemical gradients in Trichodesmium colonies
Schematic cross-section of the modelled colony as a porous sphere with variable porosity (a) and single trichome as a solid cylinder (b), both with geometrical symmetry along the z-axis. Cells were considered as solid objects. In the colony, a radially decreasing cell density towards the colony surface was assumed, as illustrated by the gradual shading (a). The distance from the colony centre r, as used in Eq. 4, was defined as \({{r = }}\sqrt {\rho ^2{\mathrm{ + }}z^2}\)
