Imagine a beach where the waves suddenly turn bright pink. In 2015, scientists made that happen on purpose off Southern California.

According to Scripps Institution of Oceanography, researchers conducted three experiments near Imperial Beach, releasing non-toxic, bright pink fluorescent dye to see how it moved along the coast. The dye was used to simulate pollution.

Scripps reports that the dye moved north through the surf zone at nearly eight miles per day during a strong south swell.Researchers used bright pink dye as a stand-in for pollution in a 2015 coastal experiment. (AI-generated/ChatGPT)Why scientists turned the ocean pinkPollution is hard to track once it enters the sea, because you often cannot see it. Dye takes care of that problem.

It glows, so researchers can track it with sensors in the water and imaging equipment on an airplane. The work was part of a project called Cross-Surfzone/Inner-shelf Dye Exchange, or CSIDE, funded by the National Science Foundation.A detailed scientific account comes from a 2021 study by Derek Grimes, Falk Feddersen, and Sarah Giddings published in the Journal of Geophysical Research: Oceans.

The team followed a release made on October 8, 2015, about 0.6 miles north of Imperial Beach. Over about four hours, they pumped in about 30 gallons of dye solution and tracked it for about 30 hours, with instruments covering about 4 miles of coastline.

The leading edge of the dye crossed that stretch in roughly 11 hours.Waves breaking at an angle create a current that runs along the shore and carries dye with it. (AI-generated/ChatGPT)How the waves carried the dyeWaves did most of the work. When waves roll toward a beach at an angle, they create a current that runs along the shore.

The study found that the dye moved north in the direction predicted by the incoming waves. That matches the Scripps account of dye moving north in a strong south swell, a route that leads toward the entrance of San Diego Bay.But the picture wasn't simple.

Beyond the breaking waves, currents moved slowly south, while water in the surf zone flowed north. This meant that dye in the surf zone and dye further out were carried differently.

The dye also lingered near the coast for long periods of time.Why the pink fadedThe strongest dye reading in the surf, near the release point, was about 90 parts per billion. About 4 miles further up the coast, it was under 5.

The study attributes much of that drop to rip currents, narrow, fast streams that pull water away from shore, which carried dye from the surf zone to deeper water. The authors estimate that surf-zone water was exchanged with deeper water about every 2.3 hours.Some of that dye did not rinse out forever.

The authors show that dye stored in deeper water, which drifted south more slowly than the surf zone flowed north, could later re-enter the surf zone after the main plume had passed, a process they call recirculation. This lengthened the plume over time and produced long, fading tails in the readings at points farther along the coast.What this means for beachgoersExchange between the surf zone and deeper water reduces the dye in the surf zone, where most people are exposed, decreasing the downstream water quality impact of a pollution event.

Scripps also says more studies and model work are needed for better real-time forecasts of where pollution is going for beaches in San Diego, Imperial Beach and Coronado.But there are limits. The study looks at one release under one set of conditions, and the authors say similar long-range observations are needed to test whether their model holds up elsewhere.

Even so, the pink water gave scientists a clear view of something normally hidden, and it helped explain how shoreline pollution may travel.The Hindustan Times US Desk brings you the latest news and developments from across the United States. The team covers everything from breaking news and politics to sports, business, entertainment and stories that are trending across the country.

Our coverage includes the White House, Congress, US elections, immigration and visa updates, H-1B, green cards, Social Security, education, jobs, layoffs, the economy, technology and major policy changes. We also closely follow stories that matter to Indian and South Asian communities in the US.

The desk covers major US sports, including the NFL, NBA, MLB and NHL, along with player news, injuries, schedules, results and major events. Entertainment coverage includes Hollywood, celebrities, television, streaming, music and pop culture.

We also report on breaking developments, major incidents, weather, public safety, court cases and other stories making headlines across the country. When a major policy or news development affects people's everyday lives, the team works to explain what happened, what it means and what readers need to know.

Alongside breaking news, the US Desk produces explainers and practical stories on topics such as immigration, Social Security, taxes, education, employment and government programmes. The team also works on science, tech, business and AI stories analyzing the impact they may have on people.

The team follows developments throughout the day, keeping an eye on official announcements, public records, reliable news sources and what people are talking about across the US.Read More