College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China; Biosphere 2, University of Arizona, Oracle, AZ, 85721-0158, United States.
Department of Environmental Science, University of Arizona, Tucson, AZ, 85721-0038, United States.
Chemosphere. 2021 Oct;280:130672. doi: 10.1016/j.chemosphere.2021.130672. Epub 2021 Apr 27.
New munition compounds have been developed to replace traditional explosives to prevent unintended detonations. However, insensitive munitions (IM) can leave large proportion of unexploded charge in the field, where it is subjected to photodegradation and dissolution in precipitation. The photolytic reactions occurring on the surfaces of IMX-101 and IMX-104 formulations and the subsequent fate of photolytic products in the environment were thoroughly investigated. The constituents of IMX-101 and IMX-104 formulations dissolve sequentially under rainfall in the order of aqueous solubility: 3-nitro-1,2,4-triazol-5-one (NTO) > nitroguanidine (NQ) > 2,4-dinitroanisole (DNAN) > 1,3,5-hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). A linear relationship between DNAN dissolution and rainwater volume was observed (r: 0.86-0.99). It was estimated that it would take 16-228 years to completely dissolve these formulation particles under natural environmental conditions in Oracle, AZ. We used LC/MS/MS and GC/MS to examine the dissolution samples from IMX-101 and 104 particles exposed to rainfall and sunlight and found six DNAN photo-transformation products including 2-methoxy-5-nitrophenol, 4-methoxy-3-nitrophenol, 4-methoxy-3-nitroaniline, 2-methoxy-5-nitroaniline, 2,4-dinitrophenol, and methoxy-dinitrophenol, which are in good agreement with computational modeling results of bond strengths. The main DNAN photodegradation pathways are therefore proposed. Predicted eco-toxicity values suggested that the parent compound DNAN, methoxy-nitrophenols, methoxy-nitroanilines and the other two products (2,4-dinitrophenol and methoxy-dinitrophenol) would be harmful to fish and daphnid. Our study provides improved insight about the rain dissolution and photochemical behavior of IM formulations under natural conditions, which helps to form target-oriented strategies to mitigate explosive contamination in military training sites.
新型弹药化合物已被开发出来以替代传统炸药，以防止意外爆炸。然而，非敏感弹药（IM）在野外会留下很大比例的未爆炸装药，这些装药会受到光降解和降水溶解的影响。本研究彻底研究了 IMX-101 和 IMX-104 制剂表面的光解反应以及光解产物在环境中的后续命运。IMX-101 和 IMX-104 制剂的成分在降雨下依次溶解，按水溶解度顺序为：3-硝基-1,2,4-三唑-5-酮（NTO）>硝基胍（NQ）>2,4-二硝基苯甲醚（DNAN）>1,3,5-六氢-1,3,5-三硝基-1,3,5-三嗪（RDX）。观察到 DNAN 溶解与雨水体积之间存在线性关系（r：0.86-0.99）。据估计，在亚利桑那州 Oracle 的自然环境条件下，这些制剂颗粒完全溶解需要 16-228 年。我们使用 LC/MS/MS 和 GC/MS 检测了暴露于降雨和阳光的 IMX-101 和 104 颗粒的溶解样品，发现了包括 2-甲氧基-5-硝基苯酚、4-甲氧基-3-硝基苯酚、4-甲氧基-3-硝基苯胺、2-甲氧基-5-硝基苯胺、2,4-二硝基苯酚和甲氧基-二硝基苯酚在内的六种 DNAN 光转化产物，这与键强度的计算建模结果一致。因此，提出了主要的 DNAN 光降解途径。预测的生态毒性值表明，母体化合物 DNAN、甲氧基-硝基苯酚、甲氧基-硝基苯胺以及另外两种产物（2,4-二硝基苯酚和甲氧基-二硝基苯酚）对鱼类和水蚤有害。本研究提供了对自然条件下 IM 制剂的雨水溶解和光化学行为的深入了解，有助于形成有针对性的策略来减轻军事训练场地的爆炸物污染。
