Humic Substances and their Relation to Pesticide Sorption in Eight Volcanic Soils

Abstract

Pesticide soil sorption is a primary factor that influences the fate of pesticides in the environment, affecting regulation of microbiological and chemical degradation, volatilization and leaching. The main goal of this research was to study the effect of the organic phase of volcanic soils on sorption of agricultural pesticides. Sorption and desorption of eight agricultural pesticides were studied on eight volcanic soils that varied in the fulvic and humic constituents of their organic matter. For all pesticides, sorption was well described by a Freundlich isotherm where 1/nads values indicated that the sorption mechanism could be mainly explained by physical reactions in all soils. Kf values for carbaryl and flumioxazin were the highest with average values of 7.78 and 7.16 mL g-1, respectively. By contrast, hexazinone and metsulfuron-methyl had the lowest average Kf: 0.86 and 0.81 mL g-1, respectively, indicating that they were the least attracted to the soils. The organic fraction of the soil was the main soil factor related to the sorption of all study pesticides. Particularly, humic acid content regulated the sorption between pesticide and soil, especially through the carboxylic groups.

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

“…Pesticides can be adsorbed on through mineral (AlSi–Fe) and mineral–organic complexes (AlSi–Fe– (humic acids) (through hydroxyl or carbonyl groups of from ) [ 12 ]. Regarding the role of soil quality, it has been reported that its humic matter fraction can be more important in determining the pesticide sorption parameters given the high reactivity of [ 67 ]. Additionally, pesticides can be adsorbed by suspended sediment or colloidal matter (dissolved ( )) enhancing the pesticide leaching [ 12 , 68 ].…”

Modelling atrazine sorption in carbon-rich substrates: a case study

“…An approximated value for the standard Gibbs free energy (ΔG 0 ) (kJ mol -1 ) of the process was estimated according equation ( 12) (Alister et al, 2020;Li et al, 2021):…”

“…However, the chemical composition of SOM may also be influential on its interaction with pesticides. For atrazine sorption in soils, occurrence of pyrogenic carbon and the hydrophobic character of the SOM favors the herbicide retention (Dick et al, 2010;Martins et al, 2018;Alister et al, 2020;Novotny et al, 2020). Depending on the substrate type (e.g.…”

“…Depending on the substrate type (e.g. soil, biochar, humic substances) different atrazine interaction mechanisms have been proposed, but in general, hydrogen bonding and hydrophobic partition are the most widely reported (Alister et al, 2020;Novotny et al, 2020).…”

Humic and Fulvic Acids as Specific Sorbents of Herbicides in Water

“…Although research that correlates HAs and FAs soil content with PPPs sorption has taken place, [ 21,22 ] the investigation related to their use as organic pollutants absorbents to remove contaminants from water, soil, and sewage sludge is limited. [ 3,8,19,20,13–24,5 ] Therefore, the purpose of this work was to find an environmentally friendly, low cost and high‐efficient way to reduce the levels of herbicides in drinking water. Lignite is the youngest type of coal and is located between the peat and brown coal on the caustobiolites scale.…”