While people typically blame Southern California’s smog on automobiles, a new study suggests that cows might be just as responsible, if not more so.
A large fraction of the region’s smog, especially the smallest particles, is ammonium nitrate. Those particles form when ammonia, which is generated by cars with certain types of catalytic converters and by bacteria that consume cattle waste, reacts with nitrogen oxides that are produced in large quantities in automobile emissions. Data gathered in and around the Los Angeles basin in May 2010 suggest that the region’s 9.9 million autos generate about 62 metric tons of ammonia each day. However, ammonia emissions from dairy farms in the eastern portion of the basin — home to about 298,000 cattle — range between 33 and 176 metric tons per day, researchers report in Geophysical Research Letters. Ammonia emissions from the dairy farms are concentrated, boosting atmospheric levels of the gas to more than 100 times background levels, so efforts to curb the farms’ emissions (perhaps by feeding the animals different diets) might reduce smog more than those targeting cars.
— Sid Perkins, ScienceNOW, the daily online news service of the journal Science
Scientists examining the remains of Otzi, Italy’s prehistoric iceman who lived in the Alps about 5,300 years ago, said last week that they have isolated what are believed to be the oldest traces of human blood ever found.
The German and Italian scientists said they used an atomic force microscope to examine tissue sections from the arrow wound that might have killed the Copper Age man and from a laceration on his right hand.
“They really looked similar to modern-day blood samples,” said Albert Zink, head of the Institute for Mummies and the Iceman at the European Academy in Bolzano, Italy.
Over the past two decades, scientists have collected data from the stomach, bowels and teeth of the well-preserved man, who was found protruding out of a glacier in 1991 in the Tyrolean Alps on the Austrian-Italian border.
Otzi, whose nickname derives from the German word for the area where he was found, had brown hair and type-O blood and was believed to be about 45 years old when he died.
Zink, an anthropologist, said the red blood cells his team found had a classic doughnut shape seen in healthy people today. “It is very interesting to see that the red blood cells can last for such a long time,” he said.
Earlier this year, the scientists conducted a complete genome-sequencing of Otzi, determining that the man had a predisposition for cardiovascular diseases and brown eyes that betrayed possible near-Eastern origins.
Otzi had lactose intolerance, which was common among Neolithic agrarian societies, and was also the first known carrier of Lyme disease.
Examination of the wound where the arrow entered Otzi’s back identified fibrin, a protein involved in the clotting of blood, according to a summary of last week’s report. Because fibrin is present in fresh wounds and then decays, this appears to show that the hunter died quickly rather than after a few days, as had been previously thought, it said.
To be certain that the specimens they were examining were blood and not pollen, the scientists used a second analytical method known as the Raman spectroscopy method. In that method, a laser beam illuminates a tissue sample, and analysis of the spectrum of the scattered light permits the identification of various molecules.