TABLE 1.
Units for expression of enumerations of attached and unattached subsurface microorganisms
| Medium | Expression | Calculationa |
|---|---|---|
| Groundwater | Per ml or cm3 of groundwater | Default |
| Groundwater | Per cm3 of in situ porous medium | (Cells/ml) · n |
| Particulate solids | Per g dry weight of solids | (Cells/g [wet wt]) · (1 + %M) |
| Particulate solids | Per cm3 of in situ porous medium | (Cells/g [dry wt]) · (bulk density, g/cm3) |
| Particulate solids | Per cm3 of solids | (Cells/g [dry wt]) · (specific gravity, g/cm3) |
| Particulate solids | Per cm3 of equivalent pore volume | (Cells/g [dry wt]) · (g [dry wt]/ml of pore water) |
| Particulate solids | Per cm2 of external surface area | (Cells/g [dry wt]) · (g [dry wt]/SAext) |
| Particulate solids | Per cm2 of total surface area | (Cells/g [dry wt]) · (g [dry wt]/SAtot) |
| Particulate solids | Per cm2 of adjusted surface area | (Cells/g [dry wt]) · (g [dry wt]/SAadj) |
| Fracture face | Per cm2 of external surface area | (Cells/ml of extract) · (ml of extract/SAfract) |
a
Cells is a generic microbiological enumeration or other quantification, e.g., biomass; n is porosity; %M is percent moisture; SAext is the external surface area of particles; SAtot is the total surface area of particles; SAadj is the adjusted surface area of particles, which includes the external and internal surfaces accessible to bacteria; SAfract is the external surface area of fracture surfaces; ml of extract is the volume of fluid in which organisms removed from fracture faces are suspended.