equation best describes the low P-concentrations of all sites, supported by high regression
(R2) coefficients (Table 2-1). Additionally, EPC of the soil for each site was calculated and
results reported in Table 2-2. Sites RC1 (inflow) and RC4 (outflow) had similar EPC
measurements of 94.5 and 93.2 tgL-1 respectively. The RC3 site, which is in the marsh
interior, was lower at 73.6 tgL1, though not significantly. Conversely, the RC2 site was
significantly lower (P = 0.05) than all other sites measuring 18.8 ugL1.
To ascertain the potential maximum P-sorptive capacity of the RWMA soils, additional
P-isotherms of 2000, 5000 and 10,000 [tgL-1 were run and the data added to the initial results.
The Freundlich and Langmuir equations were then applied to determine the best fit according
to R2 values (Table 2-1). While both equations fit well, according to R2 values, the
Freundlich equation is a better fit for the higher P-concentrations (Figure 2-2 a-d). P-
sorption parameters measured from each treatment concentration at each site are reported in
Table 2-2. The isotherm inflection points indicate the P-concentration at which the soil is
reaching its maximum sorptive capacity. Because inflection points (line begins to curve) on
each graph for each site is not well defined, estimates of the P-sorptive capacity of the soil is
approximated as: RC1 40-60 ug g-l, RC2 40-60 ug g-l, RC3 ~ 40-60 ug g-l, RC4 ~ 40-60
u -1
ug g .