RUI: Hydrogen Peroxide Variability in Coastal Rainwater

9320971威利这项研究将调查北卡罗来纳州沿海地区雨水的化学成分。这个位置是研究雨水的理想地点，因为它接收来自大陆和海洋的降水。以前的工作已经表明，这两种一般来源类型在无机离子以及甲酸和醋酸方面的组成非常不同。这项研究的具体目标是确定强氧化剂过氧化氢(过氧化氢)在雨水中浓度的变化模式。目前，控制海洋和大陆风暴中过氧化氢浓度的因素还不明确，也无法预测。这项研究项目涉及的问题是，海洋或大陆来源的雨水中的过氧化氢浓度是否更高。可以说，大陆雨中的过氧化氢水平较低，因为它可以将二氧化硫氧化成硫酸，将氮氧化物氧化成硝酸，从而导致过氧化氢的净损失。然而，过氧化氢是与其他污染物大气氧化剂一起以光化学方式产生的，这将增加来自大陆的降雨中过氧化氢的浓度。必须确定陆雨和海雨中过氧化氢的相对浓度，以便对许多重要的大气氧化剂进行全球模拟。过氧化氢参与了其他更强的大气氧化剂的循环，包括氢过氧自由基的形成和羟基自由基的破坏。模型计算表明，由于温带纬度地区平流层臭氧的损失，未来十年大气中强氧化剂的浓度可能会急剧增加。因此，这是一个特别及时的项目。雨水和大气冷凝物由于其较大的水溶解度，是研究过氧化氢的合适介质。例如，雨水中的过氧化氢通常以微摩尔浓度存在。它可以在几个小时的雨中稳定，这使得这个实验室非常适合该项目，因为采集点和分析实验室很近。北卡罗来纳州的一个站点有大约十年的雨水成分数据。这一相对长期的数据记录将有助于解释新的测量数据，并将有助于与其他采样点的比较。***

9320971 Willey This research will investigate the chemical composition of rainwater in coastal North Carolina. This location is ideal for rainwater research because it receives precipitation of both continental and maritime origins. Previous work has shown that these two general source types are compositionally very different with respect to inorganic ions as well as formic and acetic acids. The specific objective of this study is to define patterns of variation in the rainwater concentrations of the strong oxidant hydrogen peroxide (H2O2). At this time the factors controlling the concentration of H2O2 in maritime and continental storms are poorly defined and unpredictable. The question addressed in this research project is whether H2O2 concentrations are greater in rain of marine or continental origin. It could be argued that H2O2 levels would be lower in continental rain because it can oxidize sulfur dioxide to sulfuric acid and nitrogen oxides to nitric acid, thereby resulting in a net loss of H2O2. Hydrogen peroxide is, however, photochemically produced along with other pollutant atmospheric oxidants, which would increase its concentration in rain of continental origin. The relative concentrations of H2O2 in continental versus maritime rain must be defined to allow global modeling of many important atmospheric oxidants. Hydrogen peroxide is involved in cycles of other stronger atmospheric oxidants including the formation of hydroperoxyl radical and the destruction of hydroxyl radical. Model calculations suggest that concentrations of strong atmospheric oxidants may increase dramatically during the next decade because of stratospheric ozone losses at temperate latitudes. Hence, this is a particularly timely project. Rainwater and atmospheric condensate are appropriate media for the study of H2O2 due to its large water solubility. For example, hydrogen peroxide is often present in rainwater at micromolar concentrations. It is st able in rain for time periods of hours, which makes this laboratory well suited for the project because of the proximity of the collection sites and the analytical laboratory. There is approximately a decade of rainwater composition data for one of the North Carolina sites. This relatively long term data record will be useful in interpretation of new measurement data and will also facilitate comparisons with other sampling locations. ***