A collaborative research team involving Texas A&M University geologist Dr. Franco Marcantonio has examined the source of lead contamination in a Tibetan glacier, concluding that human activities have introduced the pollutant metal in some of the most remote regions of the world.
The team's findings, detailed in the paper titled "Source of lead in a Tibetan glacier since the Stone Age," were recently published in Nature Communications Earth and Environment, a high-impact journal in the field of earth and environmental sciences.
The Tibetan Plateau, a vast highland region in Asia, is often described as the "Roof of the World" because it's the highest and largest plateau on Earth, located mostly in southwestern China near the Himalayas and roughly four times the size of Texas. In their analysis of the Guliya Ice Cap within this region, Marcantonio and his colleagues — led by Dr. Roxana Sierra-Hernandez from The Ohio State University — discovered that significant lead pollution reached this area starting in 1974, with the highest levels of contamination occurring between 2000 and 2007.
By analyzing lead isotope ratios within Texas A&M's Williams Radiogenic Isotope Facility, Marcantino said they were able to trace the main source of this pollution to emissions from Chinese gasoline, which contained lead until its phasedown after 2007.
"Lead is a neurotoxin, and its presence in remote areas like the Tibetan Plateau shows the vast reach of human impact on the environment," explained Marcantonio, a professor in the Department of Geology and Geophysics and holder of the Jane and Ken R. Williams '45 Chair in Ocean Drilling Science, Technology and Education. "By studying lead contamination in glaciers, we not only learn about the pollution itself but also gain valuable insights into atmospheric circulation patterns and the timeline of environmental changes."
To reach these conclusions, the team measured lead isotope ratios in ice samples from layers that dated back as far as 36,000 years. These ice layers acted as a historical record, allowing the scientists to compare modern lead contamination to levels from pre-industrial times while providing a clear picture of how human activities have affected the environment on a global scale.
The work, funded by the National Science Foundation, emphasizes the importance of understanding pollution in remote ecosystems, which could have serious health implications for both humans and wildlife. As Marcantonio continues his research, he plans to trace the movement of contaminant lead across different environments, including the oceans and even the human body.
"There's still much we don't know about how lead and other contaminants move through our environment," Marcantonio said. "By following these pathways, we hope to better understand how pollution spreads and impacts different ecosystems, which can ultimately help us find solutions to reduce contamination and protect human health."
By Grant Hawkins, Texas A&M University College of Arts and Sciences
