Interaction of atrazine with Laurentian soil

Abstract

Ultrafiltration and. HPLC are applied to the study of binding of the neutral polar herbicide atrazine by a well-characterized Laurentian soil. This investigation exploits the results of our previous studies on the interaction of atrazine with fulvic acid and humic components extracted from this soil. The purpose of the study is to compare behavior of separate components to that of the soil assembly. These earlier studies established that a specific site complexation model, formally similar to a Langmuir isotherm, was required to describe adsorption. Partition coefficients would not suffice because a binding capacity limit is found at low solution atrazine concentration. The same behavior is found for the soil. This small stoichiometric binding capacity of the whole soil can be approximated by two terms: (i) a strongly pH dependent term with features approximating a superposition of fulvic and humic behavior; (ii) a weakly pH dependent term, which may resemble known clay mineral behavior. The pH-sensitive binding sites are specific; atrazine and hydroxyatrazine do not compete. The aggregation of humic components has an important effect on atrazine binding. Added fulvic components compete with atrazine for binding sites. The dependence on protonation points to H bonding as a major factor in aggregation.

Effects of substrate mineralogy on the biodegradability of fuel components

“…Some models for the adsorption of organic species onto clays and other minerals assume that naturally present humic and fulvic acids coat the mineral surfaces [40,[50][51][52], and then contaminants interact with that organic coating. A common organic acid, acetic acid, becomes strongly bound to some mineral surfaces and forms soluble organo-metallic complexes with the minerals [53,54], but the rate of organic-clay reactions is relatively slow compared to the timescales of most experiments.…”

Characterization of humic substances: Implications for trihalomethane formation

“…Clinton Lake is a major source of drinking water for Lawrence, Kansas, and the Wakarusa River is the primary source for Clinton Lake Reservoir. The Laurentian soil fulvic acid (LSFA), isolated from the Laurentian area [16,17], was purchased from Fredriks Research Products. Even though this soil fulvic acid is not directly relevant to THM production in aquatic humic substances, it is important to test the analytical methods on a variety of humic structures.…”

“…Even though this soil fulvic acid is not directly relevant to THM production in aquatic humic substances, it is important to test the analytical methods on a variety of humic structures. Isolation and characterization of the SRFA, SRHA, WRHA, WRFA, CLFA, and LSFA are described in detail elsewhere [14,15,16,17].…”

Sorption of Isoproturon and Dimetomorph on lignocellulose from wheat

“…Up to now, various studies on a wide range of pesticides (Wang et al 1992) have shown that their sorption on soils or organic matter depends on the pH. Except at pH>10, where a re-dissolution of lignocellulose occurs, surprisingly, it appeared that the pH does not influence the retention capacity of the solid for both isoproturon and dimetomorph.…”