Environmental Engineering Reference
In-Depth Information
25
15
10
5
3
1
0
6
4
3
2
1
40
20
10
350
200
100
50
7,000
4,000
2,000
800
400
200
Collection date
Fig. 1
Trends in rainfall and accumulation of pollutants (in mg/kg) by GAC before and after
delivery of the E&E program. Cu, Zn and TPH bars represent mean concentrations ± one standard
error. Rain frequency (
bars
) represents the number of days mean rainfall exceeded 2 mm across
the sampling area, while mean rainfall (
line
) is the sum of daily rainfall totals in mm for the period
sample bags were exposed
Table 2
Summary of Cu, Zn and TPH concentrations accumulated by solid media. All concentra-
tions are in mg/kg
Variable N Median Mean Std error Minimum Maximum <DL (%)
Cu 264 11.0 15.3 0.8 <5 130 2.7
Zn 264 110.0 147.1 7.7 13.0 800 0
C6-C9 264 13.3 64.0 13.9 <20 2,800 60.2
C10-C14 264 45.0 200.3 80.1 <20 19,000 23.9
C15-C28 264 64.5 479.5 173.2 <50 41,000 43.2
29-C36 264 24.9 66.6 8.0 <50 1,300 77.7
TPH 264 212.6 810.4 254.0 <140 60,135 15.6*
*Proportion of samples where all hydrocarbon fractions were below their respective detection
limits. Hence, at least one hydrocarbon fraction was above detection limits in 84.4% of
samples.
