Regitano Jussara B, Koskinen William C, Sadowsky Michael J
Laboratório de Ecotoxicologia, Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Caixa Postal 96, Piracicaba, SP 13400-970, Brazil.
J Agric Food Chem. 2006 Feb 22;54(4):1373-9. doi: 10.1021/jf052343s.
Characterization of pesticide bioavailability, particularly in aged soils, is of continued interest because this information is necessary for environmental risk assessment. However, pesticide bioavailability in aged soils has been characterized by a variety of methods with limited success, due in part to methodological limitations. The objective of this study was to use solvent extraction methods to correlate simazine residue bioavailability in aged soils to simazine mineralization using a simazine-mineralizing bacterium. Soils from Brazil, Hawaii, and the midwestern United States were treated with UL-ring-labeled [14C]simazine and incubated for up to 8 weeks. At the end of each incubation period, soils were either incubated further, extracted with 0.01 M CaCl2, or extracted with aqueous methanol (80:20 v/v methanol/water). In a parallel experiment, after each incubation period, soils were inoculated with the bacterium Pseudomonas sp. strain ADP, which is capable of rapidly mineralizing simazine, and 14CO2 was determined. The inoculated soil samples were then extracted with 0.01 N CaCl2 and with aqueous methanol. This allowed for the evaluation of the bioavailability of aged simazine residues, without the contribution of simazine desorption from soil. Results of these studies indicated that simazine sorption to soil increased with aging and that amounts of simazine in aged soils extracted by 0.01 M CaCl2 and aqueous methanol were highly correlated to amounts of simazine mineralized by Pseudomonas sp. strain ADP. Consequently, 0.01 M CaCl2/methanol-extractable simazine in aged soils can be used to estimate bioavailable residues. This technique may be useful in determining the bioavailability of other s-triazine compounds in soils.
农药生物有效性的表征，尤其是在老化土壤中的表征，一直备受关注，因为这些信息对于环境风险评估至关重要。然而，老化土壤中农药的生物有效性通过多种方法进行表征，但成效有限，部分原因是方法上存在局限性。本研究的目的是使用溶剂萃取方法，将老化土壤中西玛津残留的生物有效性与利用一种能使西玛津矿化的细菌实现的西玛津矿化作用相关联。来自巴西、夏威夷和美国中西部的土壤用带有UL环标记的[14C]西玛津进行处理，并孵育长达8周。在每个孵育期结束时，土壤要么进一步孵育，用0.01 M氯化钙萃取，要么用水性甲醇（80:20 v/v甲醇/水）萃取。在一项平行实验中，在每个孵育期后，向土壤接种能够快速使西玛津矿化的假单胞菌属菌株ADP，并测定14CO2。然后对接种的土壤样品用0.01 N氯化钙和水性甲醇进行萃取。这使得能够评估老化西玛津残留的生物有效性，而不受土壤中西玛津解吸的影响。这些研究结果表明，西玛津在土壤中的吸附随老化而增加，并且用0.01 M氯化钙和水性甲醇从老化土壤中萃取的西玛津量与假单胞菌属菌株ADP矿化的西玛津量高度相关。因此，老化土壤中0.01 M氯化钙/甲醇可萃取的西玛津可用于估计生物可利用的残留量。该技术可能有助于确定土壤中其他均三嗪化合物的生物有效性。
