Atmospheric monitoring of trace gases

Dr. Erna Frins, Facultad de Ingeniería

The study of the atmosphere is a very broad field and optics offers very powerful tools to study and understand the chemical and physical phenomena that occur in it. One of the problems to be studied continuously are the various chemical constituents that have a great impact on human life and climate. For example, bromine and chlorine compounds play an important role in the chemistry of the stratosphere. In particular, BrO and OClO are responsible for the destruction of ozone, with the consequent penetration of ultraviolet radiation into the atmosphere, generating health problems such as the known skin cancer. This destruction is carried out by catalytic reactions with NO2, radicals such as HOx, oxygen atoms or excited oxygen. In turn, sulfur dioxide emissions due to combustion and volcanic emissions, can lead to oxidation processes with the consequent release of so-called “acid rain”. These are just a few examples of the importance of continuous atmospheric monitoring, with reliable and easily implemented techniques.

The Applied Optics Group of Faculty of Engineering has been working for more than 10 years in the development of optical methods that allow monitoring the presence in the atmosphere of different trace gases, such as O3, NO2, SO2, and HCHO, among others. Our analysis is based on the Differential Optical Absorption Spectroscopy technique (DOAS) and the fact that each trace gas (gas present at a very low concentration) absorbs electromagnetic radiation in a unique way, thus allowing each gas to be identified And quantified without ambiguity. This technique allows remote measurements, without having to be close to the emission source. The Group has developed methods to measure the concentration of gases from several kilometers away from the observation point, using reflected light on different surfaces (ToTaL-DOAS), to study gaseous emissions from chimneys and to analyze the speed of formation in The atmosphere of NO2. We also regularly carry out measurements of the ozone layer from our monitoring station located in the Faculty of Engineering, which are compared with satellite data.

The objectives of our work at the Artigas Scientific Base will be: i) to carry out measurements using the DOAS technique to investigate the presence of halogenated radicals and stratospheric ozone; Ii) To perform measurements using the ToTaL-DOAS technique, using different elements of the landscape as targets; (Iii) to study the technical feasibility of permanently mounting a measuring equipment at the base; Iv) make visits to other bases to know similar research lines and possible collaborations.