*Urea pollution can trigger ocean algae to produce a deadly toxin called domoic acid, scientists have discovered.*
Note that this does not mean *will *create such toxins in all places, in all modes of fertilization. Issues like this raise research and monitoring concerns but do not represent a fundamental challenge to the concept of urea fertilization. ( That is not to say that there are not more fundamental challenges ... lack of scalability, phosphate utilization, low areal densities of carbon storage, etc. ) ___________________________________________________ Ken Caldeira Carnegie Institution Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA [email protected]; [email protected] http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab +1 650 704 7212; fax: +1 650 462 5968 On Fri, Dec 12, 2008 at 8:28 AM, Dan Whaley <[email protected]> wrote: > > Not sure if this was posted before... > > > Published online 27 October 2008 | Nature | doi:10.1038/news.2008.1190 > > News > Urea pollution turns tides toxic > > Kamikaze gulls that inspired Hitchcock's The Birds may have been > doomed by > leaky septic tanks. > > Amy Coombs > The BirdsRun, Tippi, run!UNIVERSAL / THE KOBAL COLLECTION > > Urea pollution can trigger ocean algae to produce a deadly toxin > called > domoic acid, scientists have discovered. > > The research may help explain several mass animal deaths, including a > historic bird stranding event thought to have inspired Alfred > Hitchcock's > horror film The Birds. > > Raphael Kudela, an ocean scientist at the University of California, > Santa > Cruz, and his team made the discovery after studying a form of sea > algae > called Pseudo-nitzschia australis. Although the algae's blooms are > normally > benign, they have long been known to sometimes begin making domoic > acid. > > Much like the kamikaze gulls portrayed in the 1963 horror film, > animals > poisoned by domoic acid have erratic behaviour patterns. On 18 August, > 1961, > residents in the town of Capitola, California, awoke to find sooty > shearwaters slamming into their rooftops, and their streets covered > with > dead birds. According to the local paper, Alfred Hitchcock ‹ who lived > a few > miles away ‹ requested news copy to use as "research material for his > latest > thriller", which was based on Daphne du Maurier's 1952 short story, > The > Birds. > Serial killer > > Although researchers can only speculate that domoic acid caused this > historic event, modern toxicologists have conclusively linked the > toxin to > more recent cases. In 1987 contaminated shellfish poisoned 100 people > on > Prince Edward Island in Canada, killing three and causing many cases > of > amnesia. In 1998, 400 disoriented sea lions died along California's > central > coast ‹ domoic acid was traced back to contaminated fish that swam > through a > toxic bloom before being eaten by the sea lions. "Every few years > there is a > big outbreak that causes otters, pelicans or sea-lion deaths," says > Kudela. > > "The acid binds very tightly to surface receptors on excitatory > neurons, > which makes it hard for the cells to switch off," says Melissa Miller, > a > veterinarian at the California Department of Fish and Game in Santa > Cruz. > While the toxin doesn't make animals homicidal, the brain damage it > causes > accounts for the strange behavior patterns that precede death, says > Miller. > > Human pollution was thought to play a role, but researchers were never > able > to identify which contaminant causes P. australis to start producing > domoic > acid. "It's definitely a combination of factors, which makes it hard > to show > a cause and effect relationship," says Kudela. > > So he and his colleagues tested a range of chemicals found in > fertilizers, > including nitrate, ammonium and urea, to determine their effects on > the > algae. Urea was the only chemical that increased domoic-acid > production. In > cases where the plankton mysteriously began making low levels of the > toxin > in clean water, adding urea nearly doubled production. > > After taking water samples off the coast of California, they also > found that > urea concentrations in Monterey Bay and San Francisco Bay were high > enough > to account for some recent harmful algal bloom events. > Human cause > > Urea isn't commonly found in agricultural fertilizers, but it is > present in > many garden products. Sewage-treatment plants tested as part of > Kudela's > study did not discharge much urea, but leaky septic tanks have been > known to > dump urea into the Chesapeake Bay and the Gulf of Mexico. "Marine > animals > release small amounts of urea, but the pollution problem is almost > entirely > human caused," says Kudela. The findings will appear in the November > issue > of Harmful Algae.1,2 > > "This work directly links human activities to the hundreds of marine > mammal > mortalities resulting from exposure to domoic acid," says Frances > Gulland, > director of veterinary science at the Marine Mammal Center in > Sausalito, > California. > > Although there is no way to know for sure if urea caused the famous > incident > that inspired The Birds, Kudela says the pollutant was probably > leaching > into the ocean at the time. "There was a lot of new development back > then, > with many unregulated septic tanks going in," he says. > > Kudela now plans to look for other chemical factors that may cause the > P. > australis tides to turn toxic. > > * > References > 1. Cochlan, W. P., Herndon, J. & Kudela, R. M., Harmful Algae > doi:10.1016/j.hal.2008.08.008 (2008). > 2. Kudela, R. M., Lane, J. Q. & Cochlan, W. P., Harmful Algae > doi:10.1016/j.hal.2008.08.019 (2008). > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
