A group of scientists in San Diego, California have come up with a colorful way to track pollution: They’re dyeing the ocean pink. Cleverly titled the Cross Surfzone / Inner-shelf Dye Exchange, or CSIDE, the project tracks the dispersion of contaminated water in the surf zone (the area close to shore where waves break) as it spreads outward into the Pacific Ocean. 

The researchers from the Scripps Institution of Oceanography completed their third and final dye drop last week, tracking the flow of water from the mouth of the Tijuana River estuary into the Pacific Ocean. They dumped the dye—which is called Rhodamine WT, and is safe to drink—into the river, and watched as it swirled offshore in colorful bands.

Initially, high concentrations of dye are easy to spot with the naked eye. But as the dye travels outward into the Pacific, it becomes increasingly diffuse. Fortunately, in addition to tracking the dye the old-fashioned way—by observing it from boats just offshore—the researchers were also equipped with a range of high-tech tracking devices. By employing a jet ski outfitted with a fluorometer (an instrument that measures fluorescence), an airplane with a hyperspectral sensor that can detect dye down to half a part per billion, and an underwater robot, the researchers were able to track the dye even when they couldn’t see it themselves.

Though they’ve yet to release the stats on how far the dye spread, it’s likely that it traveled pretty far. According to WIRED, during the previous CSIDE dye drop, dye was detected more than six miles away from the initial drop site. Researchers hope that by tracking the distribution of this proxy for pollutants, they’ll ultimately be able to develop new tools for preventing more toxic spreads in the future. Check out a few photos of their work below. 


Rob Grenzeback, research associate. Image credit: Scripps Institution of Oceanography


Dye From the Tijuana River dye drop. Image credit: Scripps Institution of Oceanography



Dye From the Tijuana River dye drop. Image credit: Scripps Institution of Oceanography


Dye From the Imperial Beach dye drop. Image credit: Scripps Institution of Oceanography

[h/t: WIRED]