Geoscience Reference
In-Depth Information
Fig. 12.31
Transport of Cu and Zn in soil cores as a function of depth (Collins et al.
2012
)
and 160 days following addition of contaminants. The results showed no signifi-
cant difference in the concentration of Cu and Zn in the surface layer and only
modest variations in the second horizon at the third sampling period, compared
with the 7-day samples (Fig.
12.31
). In the third horizon, however, the concen-
tration of Zn and Cu doubled. The significant increase in Cu ENPs is clearly
demonstrated, suggesting continuous vertical transport of ENPs. Zinc speciation in
the third horizon indicates significant dissolution of the ZnO and was corroborated
by the strong post-edge feature associated with an adsorbed Zn phase (Collins
et al.
2012
). The 30-day samples also provided additional evidence for the
increased mobility of ZnO NPs compared with CuO NPs since there was a marked
increase in Zn concentrations throughout the soil profile as compared to Cu
(Collins et al.
2012
).
12.3 Pesticides
We discuss a series of experiments on redistribution of organic contaminants
(pesticides) in irrigated fields between the years 1973 and 1999, reported in a
number of research studies (Yaron et al.
1974
; Gerstl and Yaron
1983
; Yaron and
Gerstl
1983
; Indelman et al.
1998
; Russo et al.
1998
; Toiber-Yasur et al.
1999
;
Dror et al.
1999
). The experimental fields were located at the Gilat and Bet-Dagan
ARO-experimental stations, Israel, on loessial sandy loam soil (organic matter of
0.6 %; pH 8.4) and on sandy loam Mediterranean red soil (organic matter ranging
from 1.2 to 0.7 %, from soil surface to 130 cm depth; pH ranging from 7.7 to 8.2).
Under sprinkler or trickle irrigation and rainfall, the redistribution with depth of a
number of nonconservative pesticides (Table
12.6
), applied together with passive
