|
Historic coal pollution found in the Arctic Scientists have found evidence for a link between coal usage and the levels of thallium, cadmium and lead in Greenland Alan Bailey Petroleum News
The pristine ice and snow of the Arctic may seem the last place to search for toxic pollutants, but a research team from the Desert Research Institute in Reno, Nev., has shown that looks can be deceptive. Analysis of a Greenland ice core containing ice dating from 1772 to 2003 indicates that elevated levels of the toxic heavy metals thallium, cadmium and lead correlate with the use of coal in Europe and North America following the industrial revolution, the researchers said in a paper published in the Aug. 26 edition of the Proceedings of the National Academy of Sciences.
A process called “global distillation” likely transferred the contaminants from relatively low latitudes through the atmosphere up to the Arctic, the researchers said. The research results showed contamination dropping after the 1940s as a result of a shift to the use of oil rather than coal and improved coal burning techniques. But the extensive use of coal in Asia at the present day leads to concerns about possible heavy metal contamination in the Pacific side of the Arctic, the researchers said.
The heavy metals pass up the natural food chain and are liable to become particularly concentrated in the marine and land animals that form a key component of the diet of the indigenous peoples of the region. And some evidence of elevated cadmium levels in some Arctic aboriginal populations has been found, the researchers said.
Started in 1860 Analysis of the Greenland ice core consistently showed heavy metal concentrations starting to climb at around 1860, a time at which the industrial use of coal was escalating. And correlations between the heavy metal concentrations and certain trace chemicals point the finger at coal as the likely source of the metals. Thallium concentrations peaked between 1911 and 1915, reaching levels six times those of the pre-1860 era. Cadmium peaked in 1906 and 1946. Lead peaked between 1893 and 1915, declining thereafter. However, lead levels climbed again somewhat between 1949 and 1970, a period that saw the extensive use of leaded gasoline in vehicle engines.
The period of the Great Depression marked a general dip in contamination levels.
And trace chemical analysis indicated a shift from coal to oil and gas as primary fuels after about 1940. Heavy metal levels declined noticeably in the last few decades of the 20th century, the time during which tight environmental controls over coal burning came into place in North America and Europe, and during which the use of unleaded gasoline became widespread.
| 