Hydrogen Sulfide Eruption Along the Coast of Namibia

A milky green cloud in the water off Namibia marks an eruption of hydrogen sulfide gas from bacteria on the ocean floor.

A milky green cloud of water off the Namib Desert coast of Namibia in southern Africa is a tell-tale sign of sulfur rising to the surface. The yellowish clouds of sulfur come from hydrogen sulfide gas produced by anaerobic bacteria (bacteria that can live without oxygen) at the ocean floor. In this region, strong currents bring abundant food from the bottom of the ocean to nurture large plant and animal populations. As the surface life dies, it sinks to the bottom of the ocean, where it becomes food for anaerobic bacteria.. The bacteria release hydrogen sulfide gas, which produces pure sulfur when it reacts with oxygen near the surface. In the first stages of the reaction, the sulfur appears white, and in this image creates a milky-green green tinge to the water. When the transformation is more complete, the yellowish sulfur and the blue water will combine to make the plume appear very green.

The hydrogen sulfide gas is highly toxic to fish. Periodic die-offs of whole populations of fish and other commercial seafood are ongoing concerns for the regional fishing industry. This true-color Moderate Resolution Imaging Spectroradiometer (MODIS) image was acquired by the Terra satellite on March 5, 2004. The diagonal stripes that run across the image mark the beginning and end of the rotation of MODIS’ double-sided scan mirror. The scan lines are caused by small differences between the two sides of the scan mirror.

The high-resolution image provided above is at MODIS’ maximum resolution of 250 meters per pixel. The image is available in additional resolutions.

Metadata

  • Sensor

    Terra/MODIS

  • Start Date

    2004-03-05

  • Event Start Date

    2004-03-05

  • NH Image ID

    11988

  • NH Event ID

    10295

  • NH Posting Date

    2004-03-08