Effect of Spiked Soils with Aflatoxin on Its Sorption and Bioavailability

Document Type : Original Article

Authors

1 Regional center for Food and Feed, Agricultural Research center, Cairo, Egypt

2 Regional center for Food and Feed, Agricultural Research center, Alexandria, Egypt

Abstract

The study was conducted to elucidate the sorption and bioavailability of aflatoxins mixture (B1, B2, G1, and G2) in two soils (clayey and sandy) differed in physicochemical properties under (un)treated soil with manure or urea fertilizer. Sorption and greenhouse experiments were designed for this purpose. Sorption isotherms were obtained using the batch equilibrium technique. The sorption isotherms fit the Freundlich adsorption equation according to the high R2 determination coefficients. In clayey soil, there was not detected aflatoxin concentration in soil-aqueous phase which referred to high sorption of aflatoxin in soil-solid phase, and all the aflatoxin disappearance from solution was referred to sorption reaction not for biodegradation. The high content of clay fraction in this soil could be the reason for this high sorption capacity.  In sandy soil, the sorption isotherm data indicated high retention of aflatoxin in the soil. This sorption isotherm is characterized by H-type of Giles classification. When sandy soil was amended with manure, urea, or the both fertilizers, the amount of aflatoxin sorbed on sandy soil significantly decreased as expressed by decreasing Freundlich kd value which decreased from 774.46 to 9.00, 398.38, and 2.01, respectively. The results of sorption experiments showed that clayey soil rich in clay fraction can detoxificate this toxic compound in soil environmental system due to the high affinity between aflatoxin and clays. Greenhouse experiment showed undetected limit of aflatoxins in plant tissues of tomato (Lycopersicon esculentum) and watercress (Eruca sativa) cultivated in the two studied soils.

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