Impact of Physical/Chemical Properties of Volcanic Ash-Derived Soils on Mechanisms Involved during Sorption of Ionisable and Non-Ionisable Herbicides

Abstract

Volcanic ash-derived soils (VADSs) are of great importance in the agricultural economy of several emerging and developing countries. The surface-charge amphoteric characteristics will confer physical/chemical properties absolutely different to constant-charge soils. This surface reactivity will confer to them a particular behaviour in relation to the herbicide sorption, representing an environmental substrate that may become polluted over time due to intensive agronomic uses. Sorption is a key parameter to evaluate the fate and behaviour of herbicides in volcanic soils. Sorption type and kinetic sorption models are also necessary in order to develop and validate QSAR models to predict pesticide sorption on volcanic soils to prevent potential contamination of water resources. The use of solute sorption mechanism models and QSAR models for pesticide sorption in soils has contributed to a better understanding of the behaviour of pesticides on volcanic soils. This chapter is divided into five sections: Physical/chemical properties of volcanic ash-derived soils; Ionisable and non-ionisable herbicides' fate and behaviour in soil; Kinetic sorption: mechanisms involved during sorption of ionisable and non-ionisable herbicides on VADS; Sorption of ionisable and non-ionisable herbicides on VADS; and Physical/chemical properties in QSAR models: a mechanistic interpretation.

Study of Sorption Kinetics and Sorption–Desorption Models to Assess the Transport Mechanisms of 2,4-Dichlorophenoxyacetic Acid on Volcanic Soils

“…The sorbed fraction can be calculated by means of the IPD model if different steps are present during the sorption process. % f ast ads = 100 × C 1 /qe (11) %slow ads = 100 − % f ast ads (12) Linear model:…”

“…Volcanic ash-derived soils (VADS) are relevant in economies relying on forestry and agricultural exports [ 7 , 8 , 9 , 10 , 11 , 12 ] of countries in Asia, Africa, Oceania, and America [ 7 , 8 ]. The VADS in Chile accounts for 69% of its arable land [ 13 , 14 , 15 , 16 ], where agriculture is developed in the central region (from 19° to 56° S latitude).…”

Herbicides Mechanisms Involved in the Sorption Kinetic of Ionisable and Non Ionisable Herbicides: Impact of Physical/Chemical Properties of Soils and Experimental Conditions

“…The pseudo-second order (PSO) model ( Figure 3A) has been the best adsorption kinetic model to establish principal kinetic parameters and modeling of the adsorption process of INIH on ultisols and andisols [9,12,23]. In the Figure 3A, q t is the adsorbed quantity (μg g −1 ) at any soil-solution contact time t (min) for kinetic adsorption experiments.…”

“…The higher value of the overall rate constant k 2 of MSM with respect to DI adsorption on andisols indicates that this value reflects contributions from the favored electrostatic interactions considering both a retarded IPD as well as intra-OM-diffusion. Figure 3B and C show a different transport mechanism for glyphosate (GPS, pK a = 0.8; 2.23; 5.46; 10.14), metsulfuron-methyl (MSM, pK a = 3.3) and diuron (DI) on ultisol and andisols [9,12,23]. The IPD or Weber-Morris model ( Figure 3B) is one of the most used models to describe solute transport mechanisms of organic compounds in different adsorbents intended for remediation purposes [9,12,23].…”

“…Figure 3B and C show a different transport mechanism for glyphosate (GPS, pK a = 0.8; 2.23; 5.46; 10.14), metsulfuron-methyl (MSM, pK a = 3.3) and diuron (DI) on ultisol and andisols [9,12,23]. The IPD or Weber-Morris model ( Figure 3B) is one of the most used models to describe solute transport mechanisms of organic compounds in different adsorbents intended for remediation purposes [9,12,23]. Nevertheless, the two-site nonequilibrium (TSNE) model ( Figure 3C) has been the [9,12].…”