London, Feb 9 (IANS) Some history of pollution may be concealed between the lines of text preserved in old tomes and newspapers in libraries.
A scientist has found that a paper in such collections contains a record of atmospheric conditions at the time when the trees that went into making it were growing.
'Rather than going to forests all over the world to sample trees, we went to the local library,' says Dan Yakir, chemist at the Weizmann Institute of Science in Israel.
In the Weizmann library's archives, Yakir found issues of the scientific journals Science, Nature and the Journal of the Royal Chemical Society going back over 100 years to the late 19th century.
Removing small samples from the margins of successive volumes, he took them to the lab for analysis, according to a Weizmann Institute statement.
The analysis was based on a finding that the proportion of a carbon isotope - carbon 13 (13C) - to its lighter counterpart - carbon 12 (12C) - could provide information on the CO2 (carbon dioxide) added to the atmosphere from burning fossil fuel.
This is based on a cycle that begins with plants taking up CO2 in photosynthesis. All plants prefer to use CO2 made with the more common version of carbon, 12C, than the slightly heavier 13C.
Plant biomass from millions of years ago was transformed into reservoirs of oil, gas and coal, and so these are naturally low in 13C, as well.
Yakir's work shows that this continuing dilution is, indeed, clearly recorded in the archival paper and, plotted over time, it demonstrates the increasing intensity of our fossil fuel burning in the past 150 years.
Some early issues, for instance, had been printed on rag paper (made of cotton, flax, etc.) rather than wood pulp, while blips in the data around the time of WWII (world war 2) led Yakir to suspect that the paper was recycled to make up for wartime shortages.