Reactive bromine and sulfur emissions at Salar de Uyuni, Bolivia

Abstract

Field measurements of reactive halogen and sulfur gas emissions were performed at the world's largest salt pan, the Salar de Uyuni, Southern Altiplano, Bolivia (19.8°–20.7°S, 67.0°–68.2°W), during the dry season in October/November 2002. Bromine monoxide (BrO) and sulfur dioxide (SO2) were studied by ground‐based scattered light Multi Axis Differential Optical Absorption Spectroscopy (MAX‐DOAS) at various locations upwind and inside the salar. Significant amounts of BrO were found at all locations with the lowest levels at the northern edge of the salar (upwind), while BrO slant column densities (differential with respect to zenith) of up to 3.7 × 1014 molec/cm2 were observed inside the salar. Using the MAX‐DOAS vertical profile information BrO mixing ratios of >20 ppt are calculated, which can have significant impact on tropospheric ozone chemistry both locally and regionally. SO2 slant column densities of >5 × 1016 molec/cm2 were found around the salar, suggesting emissions from volcanic activity.