Departamento de Química Inorgánica, Analítica y Química Fisica, Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE-UBA/CONICET), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
Estación Experimental Agropecuaria Anguil "Ing. Agr. Guillermo Covas", Instituto Nacional de Tecnología Agropecuaria (EEA Anguil, INTA), Anguil, La Pampa, Argentina.
Chemosphere. 2023 Jan;312(Pt 1):137143. doi: 10.1016/j.chemosphere.2022.137143. Epub 2022 Nov 8.
There is a growing concern about glyphosate's behavior in the environment. Herbicide behavior in soils greatly depends on adsorption-desorption phenomena, which have shown great variability in soils, although the reversibility of this process has been less examined. The adsorption-desorption behavior of glyphosate was measured on representative soil profiles of the northeast region of Argentinean Pampas, a semi-arid crop cultivating region. Two soil profiles samples (P1 and P2, both Entic Haplustoll) were collected and segmented into depth increments of 0-10, 10-20, 20-40, 40-60, 60-80, and 80-100 cm. Batch adsorption/48 h-desorption isotherms were performed in a controlled setup. Soil samples had a high sand content (77-92%), and a low content of clay (<3%), but markedly differing in the available P content, especially in the upper layers of soil profiles (0-40 cm, P1 range 133-170 ppm; P2 range 7-43 ppm). Adsorption-desorption isotherms showed a similar range of variation, between 150 and 1400 L kg for K and 450-1400 L kg for K, without appreciable evidence of hysteresis (0.95 ± 0.05). Sorption capacity parameters showed a distinct behavior with depth, P1 exhibiting a U-shape with minimum values at intermediate depths (20-60 cm), while P2 decreases sharply between 0 and 40 cm. General linear models considering the specific surface area (SSA) of each sample and the spatial correlation structure for soil profiles showed a main positive association of K and K with the soil organic matter, together with a positive association with iron content (K), and a negative association of K with available P content. These results indicate high adsorption extents and sorption reversibility of glyphosate to sandy loam soils of the region, which implies the potential for the herbicide to be available for leaching or degradation under a scenario of intensive use.
人们对草甘膦在环境中的行为越来越关注。除草剂在土壤中的行为在很大程度上取决于吸附-解吸现象，尽管人们对这一过程的可逆性研究较少，但在土壤中，吸附-解吸现象表现出很大的变异性。在阿根廷潘帕斯东北部的半干旱作物种植区，对具有代表性的土壤剖面进行了草甘膦的吸附-解吸行为测量。采集了两个土壤剖面样品（P1 和 P2，均为 Entic Haplustoll），并按深度增量 0-10、10-20、20-40、40-60、60-80 和 80-100 cm 分段。在控制设置中进行了批量吸附/48 h 解吸等温线实验。土壤样品具有高砂含量（77-92%）和低粘土含量（<3%），但在有效磷含量方面差异显著，尤其是在土壤剖面的上层（0-40 cm，P1 范围为 133-170 ppm；P2 范围为 7-43 ppm）。吸附-解吸等温线显示出相似的变化范围，K 的范围为 150-1400 L kg，K 的范围为 450-1400 L kg，没有明显的滞后现象（0.95±0.05）。吸附容量参数随深度表现出明显的变化，P1 在中间深度（20-60 cm）出现最小值，呈 U 形，而 P2 在 0-40 cm 之间急剧下降。考虑到每个样品的比表面积（SSA）和土壤剖面的空间相关结构的一般线性模型显示，K 和 K 与土壤有机质呈正相关，与铁含量（K）呈正相关，与有效磷含量呈负相关。这些结果表明，该地区沙壤土对草甘膦具有较高的吸附程度和吸附可逆性，这意味着在高强度使用的情况下，该除草剂可能具有淋溶或降解的潜力。
