Lead pollution has made its way to the top of the world

Human activities have left their imprints in the farthest reaches of our planet. In a recent study, experts revealed that some of the world’s most isolated regions have not escaped the footprint of lead pollution.

Even the frosty wilderness of northwestern Tibet stands witness to the impacts of human activities.

Origins of lead pollution

Examining the Guliya ice cap in northwestern Tibet, researchers detected the presence of lead. Who invited this unexpected guest here?

The answer lies in human activities that took place during and after the Industrial Revolution. Ice core samples dating back to this transitional time period lay bare the increase in lead levels.

However, it was 1974 – the year when U.S. environmental regulations came into force – that marked a significant change in the sources of lead. Despite a drop in certain types of gasoline use, other lead sources remained prevalent.

“We measured the lead isotopic composition in a dusty ice core from the Guliya ice cap in northwest Tibet, from approximately 36 thousand years Before Present (Stone Age) to 2015, to determine the onset and sources of anthropogenic lead,” explained the study authors.

Tracing lead pollution

Roxana Sierra-Hernandez was the lead author of the study and a senior research associate at The Ohio State University’s Byrd Polar and Climate Research Center.

Through her profound research, Sierra-Hernandez was able to trace anthropogenic lead right back to its origin and highlight the indelible mark they left on the region.

“Our lead isotope samples date to about 36,000 years ago, a time when we know that no civilizations at the time were using lead – meaning that much of what we found is natural,” Sierra-Hernandez said.

“Now with this work, we can pinpoint anthropogenic lead and when they left a mark in the region.”

Millions of people depend on Tibetan glaciers for their water, but these life-sustaining sources are at risk due to global warming. As glaciers retreat, they not only reduce water levels but also release the pollutants trapped within them.

Hidden sources of pollution

“Depending on the amount of pollution there is in the environment, it sinks into these glaciers,” Sierra-Hernandez said. “If a glacier melts, that source of pollution can leak into nearby rivers.” 

While some lead originates from the Earth’s crust, a significant proportion is a result of human activities.

Health hazards of lead Exposure

Long-term exposure to lead is detrimental to human health. Its adverse effects span from causing health anomalies like cancer and cardiovascular diseases to fertility issues.

Hence, understanding the baseline of natural lead levels is pivotal for gauging humanity’s environmental impact and preparing for its consequences.

Distinguishing pollution sources

The instruments used in this study provided powerful insights which allowed the scientists to identify the type of pollution each lead trace came from.

The researchers were surprised to find that until 2007, Chinese gasoline was the primary lead source before its emissions decreased and those from coal and lead-zinc ores began to increase.

This evolution of lead sources during the last few centuries offers critical insights into how local pollution can be distributed globally. It is a challenge that goes beyond the capacity of any single country.

“Politicians need to be conscious enough to see that lead is still a concern and make policies that avoid emitting more of it, whether it’s from sources of coal or gasoline,” said Sierra-Hernandez.

Future implications of the research

Lead isotopes can act as unique markers for tracking and investigating pollution sources. This could open avenues for future studies looking to analyze and compare contaminated ice core samples from other glaciers globally.

“Future studies can build on this study to compare modern and ancient pollution trends and better identify sources due to human activities,” Sierra-Hernandez said. “It’s important to do more lead isotope studies. It’s hard and it’s time-consuming, but there’s so much to learn.”

Such scientific pursuits are integral to untangling the complex web of environmental issues plaguing our planet. Understanding the environmental impacts of our past actions is a crucial step towards making necessary changes for a healthier, cleaner future.

The study is published in the journal Communications Earth & Environment.

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