Abstract This work investigates the effect of public policies related to vehicle emissions on the lower tropospheric concentrations of H2O2 in a typical midsized city in tropical Brazil. The concentrations of H2O2, SO42−, and NO3− in rainwater samples were determined from 2014 to 2017 in the municipality of Ribeirao Preto in Sao Paulo State. A fluorometric method, based on the formation of a highly fluorescent product (2′,7′-dichlorofluorescein, DCF), was adapted and optimized for the measurement of H2O2 in natural water samples including seawater. The method was highly specific, accurate and sensitive (LOD = 2 nmol L−1). Its main advantage compared to others, was that the fluorophore remained stable for at least 48 h, offering a longer time interval in which to perform the analysis and therefore facilitating fieldwork. Concentrations of H2O2 in rainwater ranged from 5.8 to 96 μmol L−1, with VWM of 28.6 ± 1.4 μmol L−1 (n = 77). Solar radiation appeared to have a greater impact on production than on consumption of H2O2. The annual VWM concentrations of H2O2 in rainwater were negatively correlated with sulfate (at pH

中文翻译：

---

使用荧光法的新应用调查巴西热带地区典型中型城市雨水中的过氧化氢

摘要 这项工作调查了与车辆排放相关的公共政策对巴西热带地区典型中型城市中较低对流层 H2O2 浓度的影响。2014 年至 2017 年在圣保罗州的 Ribeirao Preto 市测定了雨水样本中 H2O2、SO42− 和 NO3− 的浓度。一种基于形成高荧光产物（2',7'-二氯荧光素，DCF）的荧光测定方法经过调整和优化，用于测量包括海水在内的天然水样中的 H2O2。该方法具有高度特异性、准确度和灵敏度（LOD = 2 nmol L−1）。与其他产品相比，它的主要优势是荧光团在至少 48 小时内保持稳定，提供了更长的时间间隔来进行分析，从而促进现场工作。雨水中的 H2O2 浓度范围为 5.8 至 96 μmol L-1，VWM 为 28.6 ± 1.4 μmol L-1（n = 77）。太阳辐射对生产的影响似乎大于对 H2O2 消耗的影响。雨水中 H2O2 的年 VWM 浓度与硫酸盐（在 pH