Geoscience Reference
In-Depth Information
Fig. 8.30 Adsorption
isotherms of chlordimeform
on Cu-treated soil a at several
chlordimeform initial
concentrations (mM): 0
(black diamond), 0.2 (black
square), 0.5 (black up-
pointing triangle), 1.0 (3),
and 2.0 (black star) and b at
several Cu concentrations
(mM): 0 (black diamond),
0.16 (black square), 0.31
(black up-pointing triangle),
0.63 (3), and 0.94 (black
star) (Undabeytia et al.
2002
)
adsorption on clay minerals decreases due to competition for the same adsorption
sites. Preadsorption of Cu on soil surfaces leads to a decrease in chlordimeform
adsorption, also as a result of competition for the adsorption sites. This behavior is
shown in Fig.
8.30
, including adsorption isotherms of chlordimeform at several Cu
concentrations and for Cu adsorption with increasing chlordimeform values on an
Ultic Haploxeralf soil derived from shales of Devonian-age parent material. The
soil adsorbent is characterized by 1.9 % OM and a CEC of 9.8 mol
c
/kg.
Considerable attention has been given to the adsorption of diquat and paraquat
by humic acids. On the basis of data from Burns et al. (
1973
), Hayes and Min-
gelgrin (
1991
) explained how the exchangeable cations on humic macromolecules
can influence the adsorption of paraquat. Adsorption decreased according to the
order Ca
2+
-humate [ H
+
-humic acid [ Na
+
-humate. Adsorption by the Na
+
-
