A Comparison of Five Pesticides Adsorption and Desorption Processes in Thirteen Contrasting Field Soils

George E. Brown, Jr. Salinity Laboratory, USDA-ARS, 450 West Big Springs Road, Riverside, CA 92507-4617, USA.
Chemosphere (Impact Factor: 3.34). 12/2005; 61(5):668-76. DOI: 10.1016/j.chemosphere.2005.03.024
Source: PubMed


Batch adsorption and desorption experiments were performed using thirteen agricultural soil samples and five pesticides. Experimental data indicated a gradient in pesticide adsorption on soil: trifluralin > 2,4-D > isoproturon> atrazine > bentazone. Atrazine, isoproturon and trifluralin adsorption were correlated to soil organic matter content (r2 = 0.7, 0.82, 0.79 respectively). Conversely, bentazone adsorption was governed by soil pH (r2 = 0.68) while insignificant effect has been shown in the case of 2,4-D. Multiple linear regressions were used to combine relationships between the various soil parameters and the Freundlich adsorption coefficient (K(f)) of each pesticide. Then desorption was assessed since it may reflect some of the interactions involved between the pesticides and the soil components. Adsorbed molecules were released into aqueous solution in the following order: bentazone > atrazine> isoproturon> 2,4-D > trifluralin. The occurrence of hysteresis did not allow an accurate interpretation of the pesticide desorption data because of the possible interplay of several processes.

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Available from: Arnaud Boivin, Sep 17, 2014
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    • ", adsorption to mineral surfaces have been demonstrated only when the phenoxy herbicides occur in anionic form.[9,10]However, some studies observed no influence of OC contents and attributed the difference in sorption of acid herbicides to different interactions of SOM (especially polarity) and pH.[2,7,11]In all cases, the linear adsorption coefficient, K d , remains a vital tool in expressing the distribution of pesticides between soil and aqueous phases. "
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    • "For instance, relatively low pH values (pH=5.4) were said to cause stronger hydrogen bonding when compared to neutral or alkali pH conditions (Boivin et al. 2005; Thangavadivel et al. 2011). As can be seen, the factors affecting sorption/desorption. "
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