- Spilled chemicals, leaking gas tanks and city sewage all mingled with floodwaters from Hurricane Katrina that eventually drained into the Gulf of Mexico. The toxic soup went somewhere. But its destination remains a mystery.
- Potential damage to cities, chemical plants and industrial sites - now and in years to come - could spell calamity for the Gulf's treasured wetlands, beaches, coral reefs, surf and sea life.
- How communities and industries that continue to crowd the region are so blind to their environmental risk-taking and the harm they cause the Gulf
NEW ORLEANS - Spilled chemicals, leaking gas tanks and city sewage all mingled with floodwaters from Hurricane Katrina that eventually drained into the Gulf of Mexico. The toxic soup went somewhere. But its destination remains a mystery. Scientists still don't know whether the slug of germs and chemicals is floating toward Florida's coast, drifting out to the Atlantic or lurking somewhere in between.
The massive dose of pollution stands as one of the storm season's critical environmental lessons: The Gulf roils with looping, whirling currents able to turn one shore's mess into another's lasting misery.
That message is growing more urgent with predictions that hurricanes will punch harder and more often in coming decades.
Potential damage to cities, chemical plants and industrial sites - now and in years to come - could spell calamity for the Gulf's treasured wetlands, beaches, coral reefs, surf and sea life. At the very least, hurricane batterings will heighten threats to an ecosystem already burdened with dead zones, toxic algae and mysterious plumes of pollution-laden black water off Florida's coast.
"Where does the Gulf of Mexico reach the tipping point where it can no longer fix itself?" asked Enid Sisskin, legislative chair for the Panhandle's Gulf Coast Environmental Defense.
The Gulf of Mexico's expanse - the world's fifth-largest sea - is really an illusion. Shaped like a fishbowl, upside down and slightly canted, its widest span equals a line from Orlando to New York. But the distance is easily conquered.
A hummingbird migrates from Mississippi to Mexico in 18 hours. Ships laden with wheat steam from Beaumont, Texas, to beyond Key West in 48 hours. Natural-gas molecules surge through a pipeline under the Gulf from Mobile Bay to Tampa Bay in 59 hours.
It's not hard to see how a mess in one part of the Gulf can arrive quickly in others.
At Padre Island National Seashore, near Corpus Christi, Texas, researchers have traced trash to offshore rigs, shrimp boats, recreational boaters and more-distant sources, such as Midwest farms, said park science chief Darrell Echols.
After Mississippi River floods in the 1990s, crews hauled off everything from cow carcasses to roof trusses. After Katrina, workers returned to the park for truckloads of storm debris.
Yet how currents morph and whirl remains such a mystery that scientists aren't certain about how pollution travels. Predicting serpentine movements in the Gulf isn't nearly as reliable as forecasting a tropical storm.
"We have lots of weather observations on land," said Steve Murawski, chief fisheries scientist for the National Oceanic and Atmospheric Administration in Washington. "In the Gulf, we have a handful of buoys."
Stress on the Gulf of Mexico began in earnest decades ago as increasing development contributed polluted runoff, and industries found it a convenient dumping ground. Catastrophes not only added to the mess but proved how trouble in one area can extend for miles.
The world's second-worst ocean oiling issued a wake-up call in 1979. Workers on a rig near Mexico's Yucatan Peninsula lost control of a well, unleashing 140 million gallons of crude into the Gulf during the next nine months.
Despite efforts to skim, burn and dissolve the spill, slicks smeared Mexico's coast and drifted 600 miles to Texas, washing onto 160 miles of shoreline. In Florida, 900 miles from the blowout, officials feared tar balls on beaches and petroleum poisoning of fish.
Scientists found encouraging but worrisome news.
Mexican oil hadn't traveled to Florida. But their research at the time showed that crude from other faraway parts of the Gulf had made the journey. It came from tankers scrubbing out their holds. It wasn't a small amount of oil. The discharged oil had been swallowed by turtles - green, hawksbill and loggerhead - that washed up dead on Florida shores.
It was a clear sign that Florida needs to keep a lookout far beyond its own share of the Gulf's blue depths.
The unknowns of the Gulf have contributed to the mystery of what happened to the slug of pollution that flowed out of New Orleans.
Nobody can say how fast or in what direction it traveled. But they know more than 66 billion gallons drained out of the city - more than enough to fill the 50-square-mile Lake Apopka west of Orlando.
The giant plume set off such worries that an unprecedented armada of oceanographers, marine biologists and chemists fanned out in several ships across the northern Gulf of Mexico, from Florida to west of the Mississippi River delta.
Health authorities already had reported that evacuees who waded in floodwaters in New Orleans were breaking out with rashes and blistered skin.
"We had no way of knowing what to expect," said Shailer Cummings, chief scientist for one of the cruises sponsored by NOAA.
A University of South Florida oceanographer, in a separate effort, offered a theory. Using computer calculations and satellite observations of sea-surface changes, he estimated the swiftest-moving New Orleans contamination could have traveled the Gulf in circular detours for a month before hooking around South Florida to the Atlantic Ocean.
NOAA deployed "drifters" - floating electronic buoys - that broadcast their locations while riding currents. Some migrated toward Texas. Others meandered toward Florida.
The scientists never found fish kills, tainted shellfish or the pollution. Perhaps toxic floodwaters were neutralized by exposure to sun, sank to the bottom, decayed or were diluted.
Robert H. Gore, a marine scientist who wrote a book about the Gulf's wonders and plight in the early 1990s, doesn't expect that many of Florida's residents will see Katrina's mess as a warning.
He has marveled at how communities and industries that continue to crowd the region are so blind to their environmental risk-taking and the harm they cause the Gulf.
"You built your own nest," Gore said. "Now you have to sit in it."