Heavy metal transport through natural biofilms

Quantifying the transport and determining the fate of heavy metals in aqueous systems are integral to understanding, predicting, and preventing heavy metal contamination in the natural environment. We have shown that heavy metal transport can be imaged quantitatively using MRI in natural biofilm samples.



FIG. 1. (A) Reaction cell with the biofilm held in place by agar. MRI measurements were of 14 contiguous slices, perpendicular to flow. (B) For each slice, 64 T2-weighted images are acquired with increasing echo time. (C) For each pixel, the decay of the MRI signal can be fitted to an exponential function, giving a T2 value. Taking the T2 values for each pixel yields a T2 parameter map. The approximate scale (height) of a biofilm is 1 cm. Relative dimensions are not exact.

FIG. 2. Quantitative copper concentration maps revealing copper immobilization in the biofilm after 6, 12, 18, 24, and 60 h (A, B, C, D and E, respectively). The grayscale indicates the copper concentrations (mg/litre). Scale (dashed line in panel E), 7.5 mm.

Phoenix and Holmes. Applied and Environmental Microbiology. 2008