Bromine and chlorine chemistry in volcanic plumes

火山气体研究是火山监测的既定工具，可增进对火山现象的了解。这一拟议项目的核心问题是，一氧化溴（BrO）与二氧化硫（SO2）之间的比例是否有可能作为火山过程的指标。BrO和SO2具有测量相对容易的优点，并且可以在距离排放源安全距离处进行测量。为了回答上述问题，将卤素氧化物的测量与单个卤素物种的总排放通量联系起来，并了解气象条件对卤素氧化物的形成和测量的影响是非常重要的。利用所获得的知识，我们将评估使用卤素氧化物测量作为某些火山过程指标的可行性。此外，火山卤素化学对大气的影响将根据新的见解重新调查。为了从数量上了解火山羽流的化学性质，将分析意大利的埃特纳山、墨西哥的波波卡特普特勒和尼加拉瓜的马萨亚的气体排放和火山羽流的组成。连续监测测量将通过三项密集活动进行补充，这些活动采用差分光学吸收光谱（DOAS）来表征卤氧化物（BrO、ClO、OClO，可能是OBrO和IO）的浓度、它们与SO2的比率并量化排放通量。现场气体测量、气象数据测量和入射太阳辐射测量将补充这套数据。

Volcanic gas studies are an established tool for volcanic monitoring and enhance the understanding about volcanic manifestations. The central question of this proposed project is whether the ratio between bromine monoxide (BrO) to sulphur dioxide (SO2) can potentially serve as indicator for volcanic processes. BrO and SO2 have the advantage of being measured relatively easy and measurements can be carried out at safe distances from the emission source. To answer the question above, it is of great importance to link the measurements of halogen oxides to the total emission flux of individual halogen species and to understand the influences of meteorological conditions on the formation and measurements of halogen oxides. With the gained knowledge we will evaluate the feasibility of using halogen oxide measurements as an indicator of certain volcanic processes. Additionally, the impact of volcanic halogen chemistry on the atmosphere will be reinvestigated in light of the novel insights. To gain a quantitative understanding of volcanic plume chemistry, gas emissions and volcanic plume composition of Mt Etna, Italy, Popocateptl, Mexico and Masaya, Nicaragua will be analysed. Continuous monitoring measurements will be complemented by three intensive campaigns employing Differential Optical Absorption Spectroscopy (DOAS) to characterize the concentrations of halogen oxides (BrO, ClO, OClO, possibly OBrO and IO), their ratios to SO2 and to quantify emission fluxes. In-situ gas measurements, measurement of meteorological data and incident solar radiation will complement the data-set.