After Qc has been evaluated, the head difference across the cartridge is estimated
using
AH= -P = (1-M,). t (2-7)
pg pg) Kt
where K [L/T] is the hydraulic conductivity of the porous media within the cartridge.
Equation (2-7) may then be used to calculate Vo from Eq. (2-4) if the x values of the
openings are known.
While Qc and AH can be described by a linear relationship, Figure 2-2 shows that
the relationship between head difference and velocity is not linear. Therefore the
relationship between stream velocity and the flow rate through the PSFM cartridge will
not be directly proportional.
Solute mass flux J, [M/(L2T)] may be calculated with the equation
J, = vo C, (2-8)
where flux measurements rely on estimates of the stream velocity, found using Eqs. (2-7)
and (2-4), and on the mass yield of the solute of interest from the sorptive media within
the cartridge (Klammler et al., 2004). The total mass of the solute Ms [M] retained by the
sorptive media is determined by quantitative analysis and used to estimate the
concentration of the solute C, [M/L3] in the stream flow where
C -- (2-9)
It is important to note that C, will be calculated incorrectly if any solute exits the
cartridge. Therefore, it is important to replace the cartridges before the sorption capacity
is exceeded. The duration of deployment is estimated based on the retardation factor
associated with a particular solute and the expected flow rate though the column. High