Ground based measurements of SO₂ and NO₂ emissions from the oil refinery "la Teja" in Montevideo city

We present preliminary results of ground based measurements of SO₂ and NO₂ emissions from "La Teja" oil refinery located in the northern part of Montevideo Bay. Our study is part of a long term effort to localize and monitor relevant emission sources in the city area of Montevideo. These measurements were performed with a Miniature Multi AXis Differential Optical Absorption Spectrometry (MiniMAX-DOAS) instrument, which is basically a temperature controlled medium-resolution spectrometer (~ 0.5 nm) equipped with a small telescope and a stepper motor allowing automatic scans in one dimension.

We present a discussion about the evolution and transformation of both above species in the atmosphere. Our observation site was approximately 1.9 km away from the oil refinery and we were able to perform vertical and horizontal scans of the plume emitted (during our measurements) almost horizontally from its stacks. The maximum value of the SO₂ slant column density (SCD) was found to be ~ 4×10¹⁷ molec cm⁻² directly over the oil refinery, decreasing as the plume disperses. In contrast, the NO₂ SCD peaks at ~ 1×10¹⁶ molec cm⁻² directly over the source and increases continuously as the plume disperses. The SO₂ flux measured immediately downwind of the refinery was found to be about 1200 kg h⁻¹ (±40% uncertainty).