Third Pole lakes are considered a major destination for pollutants released by human activity and glacial melting. However, what percentage of pollutants in lake sediment could be attributed to these sources had been an uncertainty until recently. Now, according to a study published in Environmental Science & Technology, 90% of recent pollutant deposition in Third Pole sediment can be attributed to primary emissions and glacial release.
After reviewing geochemical indicators of a 28-cm sediment core obtained from a semi-enclosed proglacial lake located in the southern Third Pole, which contained environmental information going back as far as 1836, the scientists found that variation in toxic elements over time seemed to coincide with records of wars as well as industrialization. For example, two spikes during the period from 1880-1920 likely point to local wars against the British army in 1888 and 1904. Furthermore, a spike in the 1950s might be related to the Second World War (1939-1945), which saw a global increase in the release of metals into the environment. The pattern of toxic element changes is consistent with European countries and the Soviet Union before the 1980s, but since then is more similar to emission patterns in China and India.
“Our research suggests that contributions by anthropogenic sources rose from <10% in the 1850s to >40% after the 1980s,” said
Prof. WANG Xiaoping of the
Institute of Tibetan Plateau Research, Chinese Academy of Sciences, who is co-author of the study. WANG noted that signs of glacial melt water release were also clear, with the greatest contribution by ice-snow melt water to pollutant deposition (61%) occurring in the 1950s. “While the study suggests a potential relationship between historical events and sediment records, we cannot say for sure yet,” said Wang. “We still need samples from other lakes nearby to verify these findings."
Editor’s note: This study was supported by Pan-TPE, a TPE-related science project.
