Sulfur Dioxide Plume Lingers over Iraq

Sulfur Dioxide Plume Lingers over Iraq

A fire burning at a sulfur plant in Qayyarah, northern Iraq since June 25, 2003, has produced a huge plume of sulfur dioxide gas over Iraq and other Middle Eastern countries. According to local media reports, the persistent plume has caused severe environmental and health impacts, such as crop damage and respiratory distress.

The area covered by the sulfur dioxide concentrations has been large enough to detect with the Total Ozone Mapping Spectrometer (TOMS) instrument, which usually can only detect large amounts of sulfur dioxide emitted by volcanic eruptions. TOMS has also detected sulfate aerosol, produced by oxidation of sulfur dioxide, in the smoke plume emanating from the fire.

TOMS has tracked sulfur dioxide plumes from the fire extending as far as Syria, Iran, Azerbaijan, and the Persian Gulf. Emissions appeared to peak between June 29 and July 1. Since then, the sulfur dioxide concentrations have become weaker, but as of July 14, a small sulfur dioxide plume was still visible. This image is a composite of visible data from the Moderate Resolution Imaging Spectroradiometer (MODIS), on the Aqua satellite, captured at 2:10 p.m. (local time) on June 29, 2003, and sulfur dioxide column concentrations from TOMS at 11:50 a.m. (local) on the same day.

The MODIS data at visible wavelengths pick out the aerosols within the plume (white), while the large, color-coded TOMS pixels (squares) indicate the concentration of sulfur dioxide gas. At the time these data were acquired, the cloud contained an estimated sulfur dioxide mass of 100,000 metric tons; for comparison, highly polluting power plants in the US emit about 20,000 metric tons of sulfur dioxide per year.

Image by Mark Gray (L-3 Communications, EER Systems Inc), Nick Krotkov (Goddard Earth Sciences and Technology Center, University of Maryland Baltimore County), and Simon Carn (TOMS Volcanic Emissions Group, Joint Center for Earth Systems Technology, University of Maryland-Baltimore County)