Swirling Sediment in Gulf of Alaska

Credit: NASA/MODIS team, Posted on: Monday, 28 April 2008, 06:29 CDT Download full size image

Soft shades of turquoise and tan color the waters of the Gulf of Alaska and Prince William Sound in this photo-like image captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on March 13, 2008. Though the swirls may look delicate from space, they hint at an ocean in turmoil. Strong winds and high waves likely churned the ocean, bringing sediment to the surface in the shallow waters over the continental shelf. The deeper waters beyond the shelf edge in the lower right corner of the image are dark blue, not clouded by sediment.

Fine sediment, rocks ground to powder by glaciers, pours into the gulf through rivers. Sediment also washes into the gulf from the shore where it stains the water tan before dispersing. Phytoplankton, tiny plant-like organisms that flourish in sunlit ocean surface waters, may also add some turquoise to the water.

It was along this rugged, isolated stretch of Alaska coastline on March 24, 1989, that the Exxon Valdez oil tanker deviated from the shipping channel between the port of Valdez and the open waters of the Gulf, struck a reef, and spilled nearly 11 millions gallons of crude oil into the Sound. Hundreds of seals, thousands of sea otters, and hundreds of thousands of sea birds died in the days following the spill. Residual oil and other pollutants linger in the soils and shoreline sediments nearly two decades later.

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