Atrazine and picloram adsorption in organic horizon forest samples under laboratory conditions

Abstract

-Adsorption of two herbicides, atrazine and picloram, displaying different sorption characteristics, were evaluated for O (organic) horizon samples collected from SMZs (streamside management zones) in Piedmont (Ultisol) of Georgia, USA. Samples were randomly collected from within 5 SMZs selected for a study of surface flow in field trials. The five SMZs represented five different slope classes, 2, 5, 10, 15 and 20%. Results indicate that 0 horizons have the potential for sorbing atrazine from surface water moving through forested SMZs. Atrazine adsorption was nearly linear over a 24-hour period. Equilibrium adsorption, determined through 24-hour laboratory tests, resulted in a Freundlich coefficient of 67.5 for atrazine. For picloram, negative adsorption was observed in laboratory experiments. This seemed to be due to interference with ELISA analyses; however, this was not confirmed. The adsorption coefficient (Kd) obtained for atrazine in 0 horizons was greater than it would have been expected for mineral soil (from 1 to 4). Picloram was not sorbed in 0 horizons at any significant degree. Although there is a significant potential for the direct adsorption of soluble forms of herbicides in SMZs, the actual value of this adsorption for protecting water is likely to be limited even for relatively strongly sorbed chemicals, such as atrazine, due to relatively slow uptake kinetics. Keywords

Atrazine immobilization on sludge derived biochar and the interactive influence of coexisting Pb(II) or Cr(VI) ions

“…Atrazine (2-chloro-4-ethylamino-6-isopropylamino-striazine), as a hydrophobic and weak basic compound, was selected as the model organic contaminant, because of its widespread use in agriculture (Pinho et al, 2007;Cao et al, 2011) and its recalcitrance toward degradation (Martin-Neto et al, 1994;Dehghani et al, 2005). In addition, it is a possible cause for dramatic damage to reproductive structures in frogs, fish, and other wildlife (Rohr and McCoy, 2009) and is associated with an increased risk of breast cancer (Muir et al, 2004).…”

Toxicidade aguda de herbicidas a tilápia (Oreochromis niloticus)

“…O risco de a molécula de atrazina lixiviar e atingir cursos de água é amplamente discutido (Sprague et al, 2000;Pinho et al, 2007). Testes de toxicidade em ambientes aquáticos têm sido bastante empregados a fim de determinar efeitos deletérios de poluentes em organismos aquáticos.…”

Fitorremediação de solo contaminado com picloram por capim-pé-de-galinha-gigante (Eleusine coracana)

“…O herbicida picloram (ácido 4-amino 3,5,6 tricloro-2-piridinacarboxílico), apesar de ser utilizado, normalmente, em pós-emergência das plantas daninhas, sobretudo de dicotiledôneas arbustivas ou arbóreas (Pinho et al, 2007) em pastagens, apresenta, em relação aos demais herbicidas registrados no Brasil, um dos maiores períodos de atividade residual em solos (Santos et al, 2006b). Essa característica impede a curto e a médio prazo o cultivo de várias espécies agrícolas em áreas onde ele tenha sido empregado.…”