Man began to contaminate the Himalayas hundreds of years before he started climbing his mountains. At the end of the eighteenth century, coal combustion products were transported by winds from London, the center of the Industrial Revolution, and traveled over 10,000 kilometers to the Dasuopu glacier, in the central part of the Himalayan chain, settling. This is how they gave rise to the metal deposits described in the journal of the American Academy of Sciences (Pnas) by the Ohio University group coordinated by the Italian Paolo Gabrielli.
By analyzing the metal concentrations present in the ice core collected on the Dasuopu, the researchers found 23 traces of metals accumulated between 1499 and 1992. Among these antimony, cadmium, chromium, molybdenum, nickel and zinc, which began to accumulate at the the beginning of the Industrial Revolution, in 1780. Between 1810 and 1880 the fly ash, carried by the winter winds that traveled from West to East, contributed to the accumulation of these toxic metals, depositing with the snow on the 7200 meters high glacier.
The levels of toxic metals detected were lower than expected after 1880, probably due to changes in the atmospheric circulation and to the wetter than normal winters in Europe. The researchers also found zinc levels about five times higher than natural ones, produced both from fly ash derived from coal combustion, and from large-scale forest fires that started between 1800 and 1900, "probably from 'man for the purpose of quickly deforesting large areas that could be used for agricultural and pastoral use, "observed Gabrielli.
The levels of lead found in ice in the second half of the twentieth century "are the highest of all and have been caused in all likelihood - he adds - by the combustion of lead-added petrol, particularly in Asia where there has been a very rapid and intense industrialization from the 70s ".
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