RESUMEN
Biobeds are presented as an alternative for good pesticide wastewater management on farms. This work proposes a new test for in-situ biomonitoring of pesticide detoxification in biobeds. It is based on the assessment of visually appreciable injuries to Eisenia fetida. The severity of the injury to each exposed individual is assessed from the morphological changes observed in comparison with the patterns established in seven categories and, an injury index is calculated. A linear relationship between the proposed injury index and the pesticide concentration was determined for each pesticide sprayed individually in the biomixture. The five pesticides used were atrazine, prometryn, clethodim, haloxyfop-P-methyl and dicamba. In addition, a multiple linear regression model (i.e., a multivariate response surface) was fitted, which showed a good generalization capacity. The sensitivity range of the injury test was tested from 0.01 to 630 mg kg-1 as the total pesticide concentration. This index is then used to monitor the detoxification of these pesticides in a biomixture (composed of wheat stubble, river waste, and soil, 50:25:25% by volume) over 210 days. The results are compared with standardized tests (Eisenia fetida avoidance test and Lactuca sativa seed germination test) carried out on the same biomixture. The results are also compared with data on the removal of pesticides. The injury test showed a better correlation with the removal of pesticides than the avoidance test and seed germination test. This simple and inexpensive test has proved to be useful for decontamination in-situ monitoring in biobeds.
Asunto(s)
Monitoreo Biológico , Oligoquetos , Plaguicidas , Plaguicidas/análisis , Plaguicidas/metabolismo , Oligoquetos/metabolismo , Monitoreo Biológico/métodos , Animales , Atrazina/toxicidad , Atrazina/análisis , Contaminantes del Suelo/análisis , Contaminantes del Suelo/toxicidad , Monitoreo del Ambiente/métodos , Aguas Residuales/química , Prometrina/toxicidad , DicambaRESUMEN
Two pre-emergence herbicides (trifluralin and prometryn) were applied on a cotton field in Las Cruces, New Mexico, and their atmospheric particle and gas-phase concentrations were measured during mechanized soil preparation and natural wind erosion sampling events before and after herbicide application. Air sampling was conducted using samplers mounted at various heights from the ground and at various locations on the field. During mechanized soil management with a disk harrow, sampling occurred at two distances from the tractor ("near-source", 4 m downwind and "far-source", 20-100 m from the disking tractor). Natural background (no disking) sampling events occurred during daytime and at night. Both herbicides were quantifiable for all postapplication sampling events, including background sampling that occurred 8, 38, and 40 days after herbicide application. Average concentrations in both the gas and particle phases ranged from about 10 to 350 ng/m(3). Averaging by event type, mean total prometryn concentrations were 2 (night background) to 8 (near-source) times higher than the corresponding trifluralin concentrations. Prometryn/trifluralin ratios were higher in airborne samples than in soil, indicative of trifluralin losses during daytime sampling, possibly via atmospheric reactions. Prometryn particle phase mass fractions were generally higher than those for trifluralin for all sampling events, consistent with Kair/soil-oc partition coefficients, and particle-phase mass fractions were higher for near-source disking and daytime background sampling compared to far-source and nighttime. Daytime natural background prometryn concentrations could be as high as those measured during disking, and background samples showed significant relationships to meteorological parameters (air temperature, relative humidity, and dewpoint). Mechanical disturbance by tilling operations reduced the ability to predict airborne herbicide concentrations on the basis of meteorological conditions. Prometryn concentrations were higher for larger particle sizes (Dp > 1.8 µm), while no clear patterns with particle size were observed for trifluralin. Trifluralin concentrations in the smallest size bin (PM0.18) were 2-50 times higher than prometryn for the three disking events where an impactor was used, indicating the importance of measuring size-resolved herbicide distributions in future studies.