Scientists studying kelp beds along the coast of Southern California have detected "pervasive" amounts of a radioactive isotope known as Iodine-131 in the waters off the ports of Los Angeles and Long Beach.
Steven Manley, a marine biologist with California State University-Long Beach, says the most probable source of the contamination is the Terminal Island Water Reclamation Plant.
Iodine-131 is regularly used to diagnose and treat cancers of the thyroid gland. The material is later expelled, and it enters sewer systems and water treatment facilities.
The isotope is also used as a radioactive tracer in the hydraulic fracturing process. But Manley said the most likely source of the contamination in the ports was wastewater from medical facilities.
I-131 is not naturally occurring, and could harm fish and other marine animals if it is absorbed in large amounts.
The discovery of the iodine isotope was made as part of a project called Kelp Watch 2014, which aims to determine if nuclear material from the Fukushima disaster has reached the West Coast of North America.
Researchers across the region have been sampling kelp because the ubiquitous rubbery sea plant soaks up radioactive material like a sponge. So far no Fukushima-related material has been found, Manley said.
However, during a survey of kelp in the two ports, Iodine-131 turned up in what Manley called "low but significant" concentrations.
His team took further samples near the ports to home in on the contamination.
"Everyone of those samples has I-131 present in kelp," Manley noted.
(A map showing the sites where kelp was retrieved for testing. Image: Steven Manley / CSULB)
Since I-131 degrades relatively quickly, this material could not have traveled from Japan and must have come from local sources, Manley said.
It has also appeared in multiple samples taken at different times, suggesting that it's a relatively permanent feature of the water in the area.
"So there appears to be pervasive I-131 in the port," Manley said.
By his calculations, the levels of I-131 are "extremely low," about 20 times less than the what the Environmental Protection Agency deems as unsafe.
The radioactive material seems to be concentrated near where the Terminal Island Water Reclamation Plant releases treated waste water.
"It's not unreasonable to assume that that's the source but we would have to look at it and investigate it a little bit further," said Mas Dojiri with Los Angeles Department of Sanitation which runs the plant.
The plant was built in 1935 and handles wastewater from over 130,000 people and 100 businesses in the industrialized region near the ports.
On average it expels on 14.5 million gallons of treated wastewater a day directly into the harbor.
Unlike new treatment plants, the Terminal Island facility has relatively short outfall pipes.
Dojiri, who manages the sanitation department's environmental monitoring division, says it's likely the plant has such a design because it was built a long time ago, when environmental concerns were not as well understood.
He added that there are advanced reverse osmosis filtering methods that can eliminate radioactive material like Iodine-131 but currently Terminal Island only uses that process for recycled water and not the material released into the harbor.
Dojiri and Manley plan to work together to conduct further tests in hopes of isolating the source of the radioactive contaminants before deciding what, if any action to take.
In the meantime, Manley said marine life in the harbor is likely absorbing the material.
"The marine life is continually exposed to it," Manley pointed out.