The availability of Roundup Ready (RR) varieties of soybean has increased the use of glyphosate for weed control in Argentina. Glyphosate [(N-phosphonomethyl)glycine] is employed for the eradication of previous crop vegetation and for weed control during the soybean growing cycle. Its action is effective, and low environmental impact has been reported so far. No residues have been observed in soil or water, either of glyphosate or its metabolite, AMPA (aminomethylphosphonic acid). The objective of this work was to monitor glyphosate and AMPA residues in soybean plants and grains in field crops in Santa Fe Province, Argentina. Five sites were monitored in 1997, 1998 and 1999. Individual soybean plants were sampled from emergence to harvest, dried and ground. Analysis consisted in residue extraction with organic solvents and buffers, agitation, centrifugation, clean-up and HPLC with UV detection. In soybean leaves and stems, glyphosate residues ranged from 1.9 to 4.4 mg kg(-1) and from 0.1 to 1.8 mg kg(-1) in grains. Higher concentrations were detected when glyphosate was sprayed several times during the crop cycle, and when treatments approached the flowering stage. AMPA residues were also detected in leaves and in grains, indicating metabolism of the herbicide.

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resumenLos mecanismos sortivos del suelo (adsorción y desorción) determinan la distribución de los contaminantes del suelo y por ende su presencia en distintos compartimentos ambientales, influyendo sobre el transporte y degradación de estos. La gran expansión que tuvo la siembra directa en Argentina trajo aparejado un incremento en el uso del herbicida glifosato (N-fosfonometil glicina) utilizado fundamentalmente en cultivos de la soja, generando que gran parte del herbicida llegue al suelo e interactúe en él. El objetivo de este trabajo fue el estudio de la adsorción-desorción del herbicida glifosato en los suelos Argiudol Típico y Argiudol Ácuico de regiones de intensa actividad agrícola con predominio de siembra de soja transgénica. Se utilizó para este estudio glifosato ácido, 99% de pureza, y sal de isopropilamonio, formulada al 48%. Se verificó adsorción de grado medio a elevado en los horizontes A1 de ambos suelos, con valores algo superiores para el caso de la sal de isopropilamonio. Las desorciones logradas en ensayos de laboratorio señalaron valores medios de entre 51 y 69 % para ambos productos en los dos suelos estudiados. Palabras clave:glifosato, sorción, contaminación de suelo. adsorción-desorción de glifosato en dos suelos argentinosMArÍA iNÉS MAitre, eDuArDO LOreNzAtti, ArgeLiA LeNArDóN y SuSANA eNriQ

Estudou-se a cinética de degradação da mistura dos isômeros alfa e beta Endosulfan em diferentes condições de trabalho. Os compostos foram adicionados em água ultrapura, água do rio, água de rio filtrada e água ultrapura com sais (salinidade similar à agua do rio utilizada). As condições de degradação escolhidas foram: escuridão e duas temperaturas (14+1 ºC e 26+1 ºC). As amostragens foram programadas de modo a se obter dados periódicos mais freqüentes no início da experiência e posteriormente mais espaçados até o seu final (230 dias). As amostras foram submetidas à microextração e analisadas por cromatografia em fase gasosa com detector de Ni 63 e coluna Megabore DB-5. A degradação foi descrita de acordo com a cinética de primeira ordem, determinando-se os tempos de meia vida (t1/2) e as energias de ativação (Ea). Os dados obtidos evidenciaram que a temperatura é o fator preponderante, sendo possível deduzir que o alfaendosulfan, exceto para água ultrapura (AU), é mais influenciado pela temperatura do que o beta-endosulfan. O segundo efeito mais importante refere-se ao tipo de água utilizada como matriz, devido à influência da salinidade.

This work describes an analytical method for the screening of pesticide residues in water. The developed method identifies and quantitates a variety of pesticides in water samples such as organochlorine, organophosphate, chloronitrile, phthalimide, dicarboximide, and triazine. The analytical technique employed for the extraction and cleanup step involves solid-phase extraction with C-18 cartridges. The identification and determination of concentration is carried out with gas chromatography. Two columns of different polarity and two specific detectors are used. An electron capture detector is used for organochrolorine, and a thermoinic detector is used for organonitrogen and organophosphate. The good resolution achieved with the temperature program and the combination of columns is shown in the chromatograms obtained. The limits of detection, percent recovery, and their respective standard deviations are determined for each product. According to the results obtained, this method permits monitoring of the pesticides mentioned, many of which are moderately to highly toxic to aquatic organisms.