The Multiplication of Atmospheric Mercury Levels Attributed to Human Actions

by Hiroshi Tanaka
Atmospheric Mercury Increase

A study has identified that since the year 1500 C.E., human endeavors have magnified the presence of mercury in the atmosphere by a factor of seven. Utilizing sulfur dioxide as a marker for volcanic output, it has been deduced that anthropogenic sources like the combustion of coal and industrial processes are the predominant causes of the elevated mercury concentrations currently observed in the atmosphere.

The research sets a pre-industrial standard for atmospheric mercury by calculating volcanic contributions.

The research conducted at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has found that human activities have led to a sevenfold surge in atmospheric mercury concentrations since the beginning of the industrial age around 1500 C.E.

Innovations in Mercury Emission Estimation Techniques

Under the leadership of Elsie M. Sunderland, the Fred Kavli Professor of Environmental Chemistry and also a Professor of Earth and Planetary Sciences, her team formulated a novel approach for the precise determination of annual volcanic mercury emissions. This figure, in conjunction with computer simulations, was instrumental in modeling the levels of mercury in the atmosphere before significant human influence.

Evaluating Mercury Levels Before Industrialization

The team estimated the average natural atmospheric mercury content to be around 580 megagrams prior to its amplification through human influence. Contrastingly, data from 2015 indicates that the atmospheric mercury pool has expanded to approximately 4,000 Mg, which is almost seven times the natural level postulated in the research.

The disparity is largely attributable to human-induced mercury emissions from sources such as coal-powered plants, waste combustion, industrial activity, and mineral extraction processes.

Decoding the Mercury Cycle

Sunderland, the senior researcher of the study, emphasized the importance of methylmercury, a highly toxic neurotoxic compound that bioaccumulates in aquatic life and humans. Understanding the mercury cycle that volcanic activity naturally sustains provides a target for mercury emission reduction policies and enhances our comprehension of the environmental impact caused by human activities.

The findings have been documented in Geophysical Research Letters.

The Complications of Mercury Measurement

Despite its considerable effects on human health, the actual quantity of mercury in the atmosphere is relatively low, making it difficult to detect from space. Mercury concentration in a cubic meter of air may be a mere nanogram, rendering satellite detection impractical.

The researchers resorted to using an alternative chemical that is released alongside mercury. In this case, sulfur dioxide, prevalent in volcanic emissions, was used as a stand-in marker.

Employing Sulfur Dioxide as an Indicator

Benjamin Geyman, a doctoral candidate at SEAS, pointed out the visibility of sulfur dioxide through satellite technology. Using it as a stand-in for mercury allows researchers to pinpoint volcanic mercury emissions both temporally and spatially.

With the aid of recorded ratios of mercury to sulfur dioxide in volcanic gases, the team could deduce the mercury levels originating from volcanic activity. Further, they employed the GEOS-Chem atmospheric model to trace how volcanic mercury disperses globally.

The Influence of Volcanic Mercury Emissions

The investigation revealed that although mercury from volcanic sources mixes into the atmosphere and can be transported far from its origin, such emissions are only responsible for a minor fraction of the mercury levels at ground in most places on Earth. Yet, there are regions, including South America, the Mediterranean, and the Pacific’s Ring of Fire, where volcanic mercury significantly complicates the monitoring of anthropogenic emissions.

Geyman highlighted the variability in natural mercury sources in places like Hawaii, affecting the precision of human impact assessments on mercury levels over time. This understanding aids in accounting for the natural fluctuations in volcanic mercury contributions, especially in areas where this impact is far from insignificant.

The paper titled “Impacts of Volcanic Emissions on the Global Biogeochemical Mercury Cycle: Insights From Satellite Observations and Chemical Transport Modeling” by Benjamin M. Geyman, Colin P. Thackray, Daniel J. Jacob, and Elsie M. Sunderland, dated 01 November 2023, is published in Geophysical Research Letters with the DOI: 10.1029/2023GL104667.

The study also credits Colin Thackray and Daniel J. Jacob, the Vasco McCoy Family Professor of Atmospheric Chemistry and Environmental Engineering, as co-authors.

The National Science Foundation provided funding for this research.

Frequently Asked Questions (FAQs) about Atmospheric Mercury Increase

What is the significance of the sevenfold increase in atmospheric mercury?

The sevenfold increase in atmospheric mercury since 1500 C.E. indicates a significant impact of human activities, such as industrial processes and coal burning, on the environment. This increase is consequential because mercury is a potent neurotoxin that can accumulate in organisms, including humans, through the food chain, particularly via fish consumption.

How was the natural baseline for atmospheric mercury established?

Researchers estimated emissions from volcanic eruptions, which are natural sources of mercury, to establish a baseline. They used sulfur dioxide as a proxy to model pre-anthropogenic mercury levels, allowing for a comparison with the current elevated levels.

What challenges are involved in detecting atmospheric mercury?

Mercury is difficult to detect in the atmosphere due to its extremely low concentration—only about a nanogram per cubic meter of air. This low level of prevalence makes it nearly invisible to satellite detection, hence requiring indirect methods such as using sulfur dioxide as a proxy for estimation.

Why is it important to understand the natural mercury cycle?

Understanding the natural cycle of mercury emissions, primarily from volcanic activity, is crucial for setting baseline goals for mercury reduction policies. It also helps in evaluating the full extent of human influence on the environment, which is essential for making informed decisions about environmental protection and public health.

How do volcanic emissions affect the global mercury levels?

Volcanic emissions contribute to global mercury levels, but they are only responsible for a small percentage of ground-level concentrations in most areas of the planet. However, in regions with significant volcanic activity, such as South America, the Mediterranean, and the Pacific Ring of Fire, volcanic emissions can obscure the extent of human-induced mercury pollution.

What new methodology was developed to estimate mercury emissions from volcanos?

The research team developed a new methodology that involves using the GEOS-Chem atmospheric model and sulfur dioxide as a proxy to estimate the amount of mercury emitted by volcanos. This approach allows for more accurate assessments of both natural and anthropogenic mercury emissions.

Who led the research on atmospheric mercury levels and what institutions were involved?

The research was led by Elsie M. Sunderland, the Fred Kavli Professor of Environmental Chemistry and Professor of Earth and Planetary Sciences at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). The study was co-authored by Colin Thackray and Daniel J. Jacob, with the National Science Foundation providing funding.

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Dave Smith November 6, 2023 - 2:27 am

The figures are pretty shocking makes you wonder what can actually be done to reverse such a trend? or is it too late for that

Mike Johnson November 6, 2023 - 5:29 am

interesting read but I think you might’ve overestimated the impact of human activity on mercury levels, what about other natural sources

Sarah K November 6, 2023 - 7:50 am

I get the importance but it seems like there’s a lot of focus on volcanic activity, are we sure its the main natural contributor here

Linda B November 6, 2023 - 12:47 pm

i read the article, really makes you think about the industrial revolution and all that followed, not just good for the economy i guess

John Adams November 6, 2023 - 4:54 pm

nice to see research like this funded by NSF, shows that we’re taking environmental issues seriously, atleast some of us are


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