Environmental Engineering Reference
In-Depth Information
1.0
Soil + FA
0.8
Soil + compost (90 Mg/ha)
0.6
Soil + HA
0.4
0.2
Molinaccio soil
0
0
1
2
3
4
Aqueous concentration (µg/L)
FIGURE 6.6
Adsorption of triasulfuron (C
14
H
16
ClN
5
O
5
S) on a Molinaccio soil. HA and FA are humic acid and fulvic acid,
respectively. (Adapted from information reported by Said-Pullicino, D. et al.,
J. Environ. Qual.
, 33, 1743-1751,
20 04.)
The sorption of a herbicide, triasulfuron (C
14
H
16
ClN
5
O
5
S), in Molinaccio clay loam, with
and without humic and fulvic acids as organic materials, determined by Said-Pullicino
et al. (2004) are shown in Figure 6.6. The Freundlich isotherm values,
k
f
(μg
(1−1/
n
)
mL
1/
n
g
−1
)
were 0.14 for the soil, 0.18 (with the compost), 0.20 with the humic acid, and 0.15 with
hydrophobic dissolved organic matter. The 1/
n
values were all less than 1. The high
concentration of compost from municipal waste led to an increase in sorption. However,
in all cases, saturation was not reached, and the herbicide preferred to remain in solu-
tion and thus was highly likely to leach. The humic acids and the hydrophobic dissolved
organic matter in the compost were responsible for the sorption characteristics of the
compost.
6.4 Food Production Stressor Impacts
In addition to the chemical stressors in the form of fertilizers, pesticides, and wastes from
livestock, trace elements in the form of trace metals, heavy metals, metalloids, micronu-
trients, and trace inorganics are also found in soils and surface and groundwater. These
have been traced to application of commercial fertilizers, liming materials, irrigation
waters, and biosolids. Their presence in soils and groundwater serves to reduce the qual-
ity and functionality of soils—in addition to their potential to cause injury to human
health and other biotic receptors—as shown in Figure 2.2 in Chapter 2. The discussion in
Chapter 10 pays special attention to the presence of these kinds of contaminants in soils
and groundwater and the ways and means to minimize the adverse impacts created by
these stressors.
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