Biology Reference
In-Depth Information
To determine the dispersivities and flow velocities at the various sampling distances, tracer
concentrations obtained at the sampling distances, together with measured porosities of the
columns segments were simulated using HYDRUS 1-D (ŠimŮnek et al., 2008). For the fitting,
we assumed that the column was straight standing and vertical, longitudinal dispersion was the
only process causing spreading of solute concentrations, transport was one dimensional, and the
salt tracer did not interact with the sediment. The HYDRUS model performance was high
2
R = . Fitted dispersivities ranged from 10 to 90 cm. From the tracer results we concluded
that the helical column was applicable to study particle transport using the colloid filtration
theory normally applied for quantifying bacteria transport and attachment in one dimensional
cases. Maximum relative breakthrough concentrations (C max /C 0 ) for UCFL-94 reduced with
increasing transport distance ( Fig. 5.3 ). Reductions in C max /C 0 at distances between 6 and 25.65
were small compared with the differences between the first and second sampling distances. The
fraction of cells exiting the column was 0.19.
(
0.96)
0.70
Observed
0.60
HYDRUS Fitted
0.50
0.40
0.30
0.20
0.10
0.00
0
5
10
15
20
25
30
35
Time (Hours)
Figure 5.2:
Measured breakthrough curve of a NaCl tracer, and the fit with HYDRUS 1-D
 
 
Search WWH ::




Custom Search