California Salt Marsh May Contribute to Ocean Pollution
By Cat Lazaroff
HUNTINGTON BEACH, California, May 29, 2001 (ENS) - A team of California researchers may rewrite environmental textbooks after uncovering evidence that a manmade saltwater marsh is a source of potentially hazardous fecal bacteria that is contaminating the swimming and surfing waters of one of the state's most popular beaches. The study suggests that environmental managers should take care in designing artificial wetlands.
Grant, a professor of environmental engineering in the department of chemical and biochemical engineering and material science at the University of California-Irvine, identified droppings from resident sea gulls as the source of the contamination, which spreads from the marsh to the shallow ocean water near the Huntington City Beach.
Depending on a wetland's size and water flow rates, some 4.6 million saltwater marshes in the continental United States could be similarly affected, Grant said. Research to that effect could throw those favoring the expansion of wildlife habitats for a loop - to say nothing of the environmental scientists - he suggested.
"One scenario is that anywhere along the coast in the United States, you might run into this problem," said Grant. "We thought there were multiple sources for the bacteria at Huntington Beach. What we've found is that the marsh is one of those sources. This beach is ground zero of what could be a national problem."
Elevated fecal bacteria levels were discovered in California after a 1999 state law set uniform bacteria standards for the state's beaches and required additional water testing, Grant said. The tests in Huntington Beach forced the beach closures.
Federal legislation calling for similar standards nationwide is now under consideration in the U.S. Congress.
Previous studies failed to find the cause of the contamination in Huntington Beach, and data from virtually all previous studies said wetlands should filter pollutants. Those studies were based on freshwater wetlands, however, which may function differently from the saltwater wetland at Huntington Beach, Grant said.
More information is needed on the effects of saltwater marshes on water quality, Grant concluded.
"The irony is that we may be introducing a source of contamination where one didn't exist before," said Mark Sobsey, Ph.D., a professor of environmental microbiology at the University of North Carolina who is familiar with wetlands and efforts to restore them. "We're trying to help the environment, but we may also be adding to a wildlife population that can lead to pollution where we want to swim."
The researchers found that Talbert Marsh regularly flushes millions of gallons of bird droppings into the Pacific Ocean, Grant said. Its rapid flow sweeps water from the marsh into the ocean in less than 40 minutes, according to his study. A slower flow rate would likely prevent most contamination, since longer exposure to salt water and sunlight kills the bacteria, said Grant.
In Huntington Beach, the researchers measured more than a dozen sites and found enterococci bacteria levels up to about 5,700 bacteria per 100 milliliters of water. Almost 15 percent of approximately 2,000 samples taken ranged above the 104 parts per 100 milliliter standard that requires surf zone postings.
The University of California-Irvine team's conclusions are reported in the June 15 issue of "Environmental Science and Technology," a peer reviewed journal of the American Chemical Society, the world's largest scientific society.
The research was funded by a grant from the National Water Research Institute with matching funds from Orange County and the California cities of Huntington Beach, Newport Beach, Costa Mesa, Santa Ana, and Fountain Valley.