Effectiveness of Carbaryl, Carbofuran and Metolachlor Retention in Soils under the Influence of Different Colloid

Abstract

The affinity of different soil colloids to retain carbaryl, carbofuran and metolachlor in sandy loam and loam soil from mineral, surface horizons was investigated. The undisturbed soil samples and soils amended with colloids—kaolinite (K), montmorillonite (Mt), illite (Il), goethite (G), humic acid (HA)—were mixed with the pesticides for sorption–desorption studies. Their sorption magnitude in pristine soils followed the sequence metolachlor > carbaryl > carbofuran, with loam soil being a better pesticides retarder than sandy soil. The biggest magnitude of carbaryl sorption in light soil was observed in samples with the addition of HA (92.7%), Il (92.3%) and Ge (87.5%), whereas for carbofuran it was goethite (52.3%). Metolachlor uptake was significantly enhanced by 2:1 clays (Mt-85.0%, Il-69.4%), goethite (73.3%) and humic acids (75.4%). The loamy soil sorption capacity of the studied pesticides was blocked by the natural organic matter potentially due to the formation of organo-mineral complexes. HA (66.8%) was the most effective sorbent for carbaryl in the loamy soil, whereas Mt (55.1%) and HA (40.3%) for carbofuran. Metolachlor was retained to the same extent in all loamy soil variants (75.8–83.6%) and its desorption values were the lowest. Carbofuran demonstrated the greatest ability to leach among the studied chemicals.

Kinetic and isotherm studies on the adsorption–desorption of technical-grade endosulfan in loamy soils under Theobroma cacao L cultivation, Southwestern Nigeria

“…In heterogenous adsorbents like soil, the sorption of non-ionic and hydrophobic organics are dependent on the level of organic matter and, to some extent, on the clay mineralogy of each soil, 16,60 and these both influence the mobility. 61,62…”

“…The varying isotherms exhibited by the adsorbate (endosulfan) may be due to the following: the extent of its binding with OM, hydrogen-bond formation, charge transfer, ionic bonds, cation bridges, hydrophobic interactions, and physical diffusion into humic substances in the different soils. 60,62,75 The hysteresis order was directly proportional to the level of organic matter in these three soils; thus making organic matter the prime factor in the hysteresis of endosulfan over the clay content and other factors. Low HI values are associated with adsorbates with a poor desorption property.…”

“…In heterogenous adsorbents like soil, the sorption of non-ionic and hydrophobic organics are dependent on the level of organic matter and, to some extent, on the clay mineralogy of each soil, 16,60 and these both inuence the mobility. 61,62 The order of clay content was: Igba > CRIN > Sore Bale, while the order of organic matter was: CRIN > Igba > Sore Bale. The latter trend was observed when the adsorption capacities of the three cocoa farm soils for aand b-endosulfan were considered, thus suggesting a greater affinity of endosulfan to TOM than to clay.…”

Deashed Wheat-Straw Biochar as a Potential Superabsorbent for Pesticides

“…They have all been detected in aquatic environments and may cause ecological or human health impacts. Pesticides chosen for this study—2,4-D, MCPA, carbofuran, carbaryl and metolachlor—can all be classified as endocrine disruptors [ 36 , 37 , 38 , 39 ], and soil is an important environmental sink for these substances [ 40 , 41 , 42 , 43 ]. They have distinct physiochemical properties, which is why finding a relatively recalcitrant biosorbent (as a filtering material or soil amendment) that will effectively immobilize both polar and hydrophobic organic xenobiotics is a challenge.…”

Influence of SOM Composition, Clay Minerals, and pH on 2,4-D and MCPA Retention in Peri-Urban Soils

“…They pose a potential risk for water sources due to their relative mobility and poor biodegradability in aqueous systems, which is related to their acidic carboxyl group [29,30]. With respect to this structural feature, both phenoxyacetic acids are mostly present in their anionic forms when applied to managed or urban soils, as their pH is usually maintained within 5.5-7.5 [31,32], which is far above the pKa levels of herbicides. This may induce their enhanced mobility in soil, as the solubility effect primarily governs their fate, especially when the soil lacks for potential herbicide sorbents.…”