Love Adam H, Vance Andrew L, Reynolds John G, Davisson M Lee
Environmental Science Division, Lawrence Livermore National Laboratory, P.O. Box 808, L-396, Livermore, CA 94551, USA.
Chemosphere. 2004 Dec;57(10):1257-64. doi: 10.1016/j.chemosphere.2004.08.041.
Laboratory experiments were conducted to determine environmental variables that affect the affinities and persistence of the nerve agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX) at dilute concentrations in environmental matrices. Quantitative analyses of VX and its degradation products were performed using LC-MS. Batch hydrolysis experiments demonstrated an increasing hydrolysis rate as pH increased, as shown in previous studies, but also indicated that dissolved aqueous constituents can cause significant differences in the absolute hydrolysis rate. Adsorption isotherms from batch aqueous experiments revealed that VX has a high affinity for hydrophobic organics, a moderate affinity for montmorillonite clay, and a very low affinity for an iron-oxyhydroxide soil mineral, goethite. The adsorption on goethite was increased with the presence of dissolved organic matter in solution. VX degraded rapidly when dried onto goethite, when specific adsorption was forced. No enhanced degradation occurred with goethite in small amounts of water. These results suggest that aqueous conditions have important controls on VX adsorption and degradation in the environment and a more mechanistic understanding of these controls is needed in order to enable accurate predictions of its long-term fate and persistence.
进行了实验室实验,以确定在环境基质中稀浓度下影响神经毒剂O-乙基-S-(2-二异丙基氨基乙基)甲基硫代膦酸酯(VX)亲和力和持久性的环境变量。使用液相色谱-质谱联用仪对VX及其降解产物进行了定量分析。批量水解实验表明,如先前研究所示,随着pH值升高水解速率增加,但也表明溶解的水性成分会导致绝对水解速率存在显著差异。批量水相实验的吸附等温线显示,VX对疏水性有机物具有高亲和力,对蒙脱石粘土具有中等亲和力,对氢氧化铁土壤矿物针铁矿具有非常低的亲和力。溶液中存在溶解有机物时,VX在针铁矿上的吸附增加。当强制进行特定吸附时,VX干燥在针铁矿上时迅速降解。在少量水中,针铁矿不会促进降解。这些结果表明,水相条件对环境中VX的吸附和降解具有重要控制作用,为了能够准确预测其长期归宿和持久性,需要对这些控制作用有更深入的机理理解。