来自云层处理的甲甲的甲二醇只是大气中的甲酸的微不足道来源
Thanh Lam Nguyen1,2, Jozef Peeters3, Jean-François Müller4
1Quantum Theory Project, Department of Chemistry, University of Florida, Gainesville, FL 32611.
概括
大气中的酸模型预测水平低. 这项研究发现,基和甲二醇之间的反应速率要比以前想象的慢得多,大大降低了云层中估计的酸产量.
科学领域:
- 大气化学 大气化学
- 化学动力学 化学动力学
- 环境科学 环境科学
背景情况:
- 大气中的甲酸 (HCOOH) 度显著低于目前模型的预测.
- 之前的一项研究表明,基 (OH) 与甲二醇 (HOCH2OH),一种甲 (HCHO) 衍生物的反应产生了大量的HCOOH.
- 这种拟议的机制依赖于OH + HOCH2OH反应的高实验速率常数.
研究的目的:
- 准确确定OH和HOCH2OH之间的反应速率常数.
- 重新评估这种反应对大气中的酸生产的贡献.
- 研究水相过程和云动态对HCOOH形成的作用.
主要方法:
- 进行了高准确度的合集群计算.
- 使用E,J解析的二维总方程分析.
- 用全球大气模型和数值模拟来评估反应影响.
主要成果:
- OH + HOCH2OH (k1) 的计算速率常数是 (2.4 ± 0.5) × 10^-12 cm^3 s^-1 ,明显低于之前报告的7.5 × 10^-12 cm^3 s^-1.
- 水相平衡将HOCH2OH与HCHO的比率限制在2%左右,从而降低了它与OH的反应可用性.
- 从这种途径产生的全球HCOOH产量估计为3.3Tg/y,比最近的估计低约30倍.
结论:
- 大气甲基酸建模中的差异没有被建议的OH + HOCH2OH路径解决,这是由于较低的速率常数和有限的HOCH2OH可用性.
- 对这种HCOOH来源的重新评估表明,它对全球酸预算的贡献要小得多.
- 这项研究还为甲二醇提供了估计的亨利定律常数.
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