ENVIRONMENTAL FATE, BEHAVIOR AND ECOTOXICITY OF CHLORPYRIFOS IN SOILS FROM NORTH PATAGONIAN REGION

LORENA A. LATINI; AGUIAR MARÍA BELÉN; RUTH M. LOEWY; MARÍA EUGENIA PAROLO; CARLOS MELIDEO; MÓNICA C. SAVINI; MARÍA M. INDACO; LILIANA B. MONZA

Foz de Iguazu

Congreso; LAPRW 2019; 2019

The intensive use of pesticides during the past decades has highlighted the potential risk to humans and the environment, including soil biota. The presence of pesticide residues in soil, sediment and water samples has raised public and scientific concern. Among the factors that affect the environmental distribution of pesticides are agricultural practices followed during and after pesticide application, climate change, new technologies used in pesticide formulation and new application-release strategies1. The study of the pesticides soil distribution from its application, enable us to analyses their affinity with soil components and the principal factors that should be taken into account when characterizing a pesticide as leacher in order to evaluate its ability to contaminate and reach groundwater. For this purpose, the sorptive properties of twelve soils with different organic matter (OM) content (2-11%) and pH (5.5-8.2) were analyzed determining the chlorpyrifos adsorption coefficients (KD) in equilibrium conditions experiments.. On the other hand, pesticde leaching on a typical soil was determined by field lysimeters under real pesticide application and comlementary laboratory studies were carried on in undisturbed soil columnsLeached solutions were extracted by LLE (Liquid-liquid extraction), using hexane as extracting solvent. Both extracts analyzed by GC/NPD. The behavior of formulated chlorpyrifos and active principle in soils were compared by batch experiments selecting a soil representative of the region for these studies. Ecotoxicological tests are useful to indicate the extent to which a chemical are harmful and how and where their effects occur. In this work, avoidance test was carried out according to ISO 17512-1. KD values obtained (140-1100 Lkg-1) were correlated with the OM content suggesting that chlorpyrifos distributes between aqueous and solid phase as a function of the hydrophobic interactions with the soil organic matter. The laboratory undisturbed columns results show that chlorpyrifos exhibited a stronger retaining capacity in the first 5 cm of soil column and 0.31% of chlorpyrifos applied was recovery as leaching. At the end of the 48 h for avoidance tests, no earthworm mortality was observed. An integrated approach including batch experiments, laboratory sorption columns, field lysimeters and ecotoxicological tests allows us to understand pesticide behavior on agricultural and natural soils which is essential to define strategies for a sustainable development of ground-water resources.