Environmental Engineering Reference
In-Depth Information
8270c for GC-MS after extraction by Method 3540c. Total organic carbon
samples were analyzed on a Zellweger Analytic TOC analyzer, according to
instrument specifications. The nitrogen and phosphate analysis was per-
formed using the Lachat 8000 Flow Injection Analyzer (FIA). The preparation
methods were modified versions of EPA-600/4-79-020 (1983 revision) 365.1
and 351.2, respectively. Metals and total volatile solids were determined
according to standard methods (SW 846). Soil pH was determined for a
soil-distilled water slurry (1:1, w/v) using a Cole-Parmer pH meter.
7.3.10.4 Microbial analysis
Microbial biomass and community composition of the indigeneous micro-
biota (and, in the case of trough 3, the bioaugmented soil) were determined
initially and then intermittently throughout the study. Two grams (wet
weight) of the soil sample was subjected to a modified Bligh-Dyer organic
solvent extraction to quantitatively recover bacterial membrane lipid bio-
markers (ester-linked phospholipid fatty acids (PLFAs)) as outlined in
White and Ringelberg (1998). Similarities between single PLFA profiles were
evaluated by application of a hierarchical cluster analysis. Biomass was
estimated from the total concentration of membrane lipids and ester-linked
PLFAs (Balkwill et al., 1988).
7.3.10.5 Metabolic analysis
Metabolic analysis was performed on the LTUs (phase 1 only) and the
troughs in order to follow respiration of soil microbial communities. Soil gas
samples analyzed changes in O 2 and CO 2 concentrations over time and in
response to various stimuli. Respiration was normally monitored twice each
week in the LTUs. A soil gas probe was placed in the center of each of the
20 sampling sections of the LTUs. The results from the 20 cells were averaged
for each LTU to yield a single sample value. Soil sampling was performed
after gas analysis. The gas probes of LTU 2 were removed to allow tilling of
the soil and were then reinserted. The probes of LTU 1 remained in the
ground.
Each trough was divided into five sample collection zones. A gas probe
was placed in the center of each zone. At a minimum, the troughs were
monitored weekly for the first 6 months and daily thereafter. Individual
experiments occasionally required modifications of this sampling schedule.
Results of the five samples were averaged for each trough to yield a single
sample value. Following gas analysis, the probes were lifted, soil samples
taken, the troughs tilled, and the probes reinserted. Further details of the
gas analysis procedure and the soil probe are found in Nestler et al. (2001b).
7.3.10.6 Statistical analysis
The chemical analytical data were reduced to develop average sums of the
concentrations of total PAH and individual PAH compounds. BaP toxic
equivalent values were calculated by multiplying the average concentration
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