School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, China; Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences, Beijing 100083, China.
School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, China.
J Environ Sci (China). 2021 Jun;104:1-10. doi: 10.1016/j.jes.2020.11.009. Epub 2020 Dec 8.
Gibberellic acid (GA) is widely used in agriculture and maybe transfer with groundwater flow, which is an endocrine disruptor, but few studies have focused on the transformation pathway and toxicity assessment of GA and its products. Here, GA and its transformation products in aqueous solution were identified and quantified by liquid chromatography mass spectrometry hybrid ion trap time-of-flight (LCMS-IT-TOF) and high-performance liquid chromatography (HPLC), respectively. The results showed that the half-life of GA transformation in ultrapure water was 16.1-24.6 days at pH=2.0-8.0, with the lowest half-life occurring at pH=8.0 and highest half-life occurring at pH=3.3. Isomerized gibberellic acid (Iso-GA) and gibberellenic acid (GEA) were the main transformation products with a little hydroxy gibberellic acid (OH-GA). In North China groundwater, the mass balance of GA and its products was 76.2%, including Iso-GA (58%), GEA (7.9%), GA (7.3%) and OH-GA (3%) after reaching transformation equilibrium. Using Gaussian 09 for chemical computation, it was found that the transformation mechanism of GA was dependent upon the bond energy and the stereochemical feature of its molecular structure. GA always isomerized from the γ-lactone ring due to the lowest bond energy between the oxygen terminus of the γ-lactone ring and A ring. While GA and its transformation products all had developmental toxicity, the predicated LC (96 hr) and LD of the main products of GA were much lower than those of GA, indicating GA would be transformed into higher toxicity derivatives in water environments, posing a significant health risk to humans and the environment.
赤霉素（GA）在农业中被广泛应用，可能会随地下水流动而迁移，它是一种内分泌干扰物，但目前很少有研究关注 GA 及其产物的转化途径和毒性评估。本研究采用液相色谱-串联质谱混合离子阱飞行时间（LCMS-IT-TOF）和高效液相色谱（HPLC）分别鉴定和定量了水溶液中的 GA 及其转化产物。结果表明，在 pH=2.0-8.0 时，GA 在超纯水中的半衰期为 16.1-24.6 天，半衰期最低出现在 pH=8.0，最高出现在 pH=3.3。异构赤霉素（Iso-GA）和赤霉素（GEA）是主要的转化产物，还有少量羟基赤霉素（OH-GA）。在华北地区地下水环境中，达到转化平衡后，GA 及其产物的质量平衡为 76.2%，其中包括 Iso-GA（58%）、GEA（7.9%）、GA（7.3%）和 OH-GA（3%）。通过 Gaussian 09 进行化学计算发现，GA 的转化机制取决于其分子结构中环的氧端与 A 环之间的键能和立体化学特征。GA 总是从γ-内酯环异构化，因为γ-内酯环的氧端与 A 环之间的键能最低。虽然 GA 及其转化产物都具有发育毒性，但 GA 主要产物的预测 LC（96 小时）和 LD 值远低于 GA，这表明 GA 在水环境中会转化为毒性更高的衍生物，对人类和环境构成重大健康风险。
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