Movement and adsorption of methamidophos in clay loam and sandy loam soils

Characterizing and modeling of extensive atrazine elution tailing for stable manure-amended agricultural soil

“…The soil pH was measured at a 1:1 soil/water ratio using a combined pH electrode. A soil particle-size analysis was performed using the hydrometer method reported in Koleli et al (2006). Total organic carbon contents of the soil and stable manure were determined by Walkley-Black procedure (Allison, 1965).…”

“…Total organic carbon contents of the soil and stable manure were determined by Walkley-Black procedure (Allison, 1965). The total organic carbon content was multiplied by Van Bemmelen factor of 1.72 to calculate total organic matter fraction (Koleli et al, 2006). The composition and the mineralogy of the selected soil were determined by XRF and XRD, respectively.…”

Use of electrochemical techniques to characterize methamidophos and humic acid specifically adsorbed onto Pt and PtO films

“…These factors include general conditions of solutions (e.g., pH, concentration of pesticides), soil mineral content, natural organic matter (NOM) content, and characteristics of the mineral surfaces [2]. NOM may enhance or retard the migration of pesticides in subsurface environmental systems, depending on system composition (e.g., quantity and characteristics of organic ligands) [1]. The main components of NOM are humic substances (HS).…”

“…Sorption onto immobile mineral surfaces is often the key process controlling mobility and degradation in subsurface environments [1]. A number of factors contribute to the partitioning of pesticides between solutions and solid phases.…”

Riscos Ecotoxicológicos do Metamidofós

“…Sua rápida hidrólise no meio ambiente sugere que tem baixa tendência a sofrer lixiviação (EPA, 2005);  Sorção aumenta com o aumento do pH, podendo atingir seu máximo (100%) em solos com o pH em torno de 11,5 e com baixas concentrações de minerais tais óxidos de alumínio e ferro (KOLELI et al, 2006). Esse comportamento se deve, provavelmente, a presença de grupos funcionais reativos que faz com que o praguicida se ligue à matéria orgânica e/ou às superfícies minerais dos solos (SINGH et al, 1998);  Adsorção aumenta com o aumento da temperatura em solos tropicais: quantidades de 20, 40, 60, e 100 µg ml -1 do produto em 5 g de solo a 30°C apresentaram alta adsorção, cerca de 70% (YEN et al, 2000);  Dissipação rápida já foi atribuída a macropóros, à umidade elevada (CHAI et al, 2009) e a microrganismos presentes no solo.…”