A study of lead traces in Arctic Ocean sediments reveals not only how much contamination is caused by humans, but also where it comes from. In the Aug. 17 Science, Carles Gobeil and his colleagues Robie MacDonald, John Smith, and Luc Beaudin at the Institut Maurice-Lamontagne in Mont-Joli, Canada, examined sediment cores collected throughout the basins of the Arctic Ocean.
In the shallower Canadian basin, lead concentrations were the same at all sampled depths. In the deeper Eurasian and Greenland Sea basins, however, they found the highest lead concentrations in the shallowest layers. Contaminants in these areas, then, most likely arrived from human sources within the last 70 years.
The team then examined the ratios of lead isotopes in the top 2 to 4 centimeters to those in deeper layers, which were used to estimate naturally occurring levels. A comparison of these findings across a number of different locations showed an anomalous ratio at the North Pole. To determine the source of this additional lead, they turned to a map of major Arctic water currents, which implicated coal combustion and industry in the former USSR and Eastern Europe arriving through the Eastern Laptev Sea.
Because only small amounts of lead are generally carried to the Arctic
in the atmosphere, the study suggests that ocean currents may be a “surprisingly
efficient” contaminant delivery system — transporting as much as 9 to 48
metric tons to the entire Eurasian basin over history. Whether more is
carried there by water or drifting ice, however, remains to be determined.
A new study in the September issue of Limnology and Oceanography says Saharan dust clouds are responsible for seeding the waters off the West Florida coast with iron, creating huge blooms of toxic red algae. Jason Lenes and his colleagues at the University of South Florida’s College of Marine Science, tracked large dust clouds leaving Africa in June 1999, using data from the Advanced Very High Resolution Radiometer, an imager aboard the National Oceanic and Atmospheric Administration’s Polar Orbiting Environmental Satellites. The Saharan dust, which contains a large percentage of iron from the soil, reached the West Florida Shelf around July 1, increasing surface-water iron concentrations 300 percent. This surge of iron increased the count of Trichodesium bacteria tenfold. The bacteria convert nitrogen in the water to a form usable by other marine organisms. The study reports that by October 1999, the large increase in dissolved organic nitrogen made possible a red tide covering 8,100 square miles between Tampa Bay and Fort Myers, Fla. Red tides can take a large toll on marine life, and can cause skin and respiratory problems in humans.
Lenes and his colleagues hope that by using satellites
to monitor dust arrivals and Trichodesium blooms, they will one day be
able to forecast red tides and close beaches and fisheries ahead of time.
Lisa M. Pinsker
In August, grainy photographs of a fossilized dinosaur with unusual spikes at its tail zoomed through the Internet, stirring intrigue and rumor among paleontologists worldwide. The Aug. 30 Science reports that the e-mail attachment did not disclose the purported fossil’s whereabouts. Researchers have yet to formally describe the specimen in the literature or at a conference.
The mystery creature is said to be a psittacosaur, a primitive horned dinosaur that grew to between 1 and 2 meters long. Paleoartist Luis Rey says the specimen has a unique tuft of long filaments that “look like quills on a porcupine” and shoot up 36 centimeters from the top of its muscular tail. Until the recent e-mail sent photographs of the fossil across the Internet, very few people, especially outside of Europe, had seen the photos. Rumors started a few years ago at a meeting of the Society of Vertebrate Paleontology. Shortly after, Rey viewed black and white photos. But, around Aug. 20, Michael Schmidt, a fossil dealer in Alberta, forwarded color photos of the specimen to some members of the DINOSAUR Internet mailing list, making them globally available.
Rey says the fossil was most likely smuggled out
of China, and since then has been sold among European dealers, maintaining
a veil of secrecy around the fossil’s location. “It is time to put the
lights on this important specimen,” he says. Many paleontologists, however,
are looking cautiously at the fossil, because of past illegal exports of
doctored specimens. The psittacosaur appears to originate from western
Liaoning Province in China. It is rumored that the psittacosaur is
now in a German museum.
Lisa M. Pinsker