Humans Have Boosted Atmospheric Mercury Concentrations Sevenfold – GWC Mag

Source: Geophysical Research Letters

Mercury is a naturally occurring element that under some conditions can become methylated and highly toxic. It is therefore important to understand the sources and transport of mercury to estimate its potential risks.

Volcanic activity is the primary source of natural mercury on Earth. But because volcanic activity is so volatile, the concentration and distribution of volcano-sourced atmospheric mercury haven’t been well quantified previously. Geyman et al. estimate total volcanic emissions by using satellite measurements of atmospheric sulfur dioxide. The researchers then used previous measurements of the ratio of mercury to sulfur dioxide to calculate how much mercury would be contained in those emissions. They also modeled atmospheric transport of volcanic mercury to track where the heavy metal drifts.

Volcanoes emit about 230 megagrams of mercury per year, supporting an atmospheric reservoir of about 580 megagrams of mercury, the study found. But in 2015, the total estimated atmospheric mercury reservoir was measured at about 4,000 megagrams—nearly 7 times larger than volcanoes’ natural contributions, the study revealed. Human emissions of mercury, primarily from coal combustion, mining, and industry sources such as metal and cement production, have dwarfed natural emissions.

The tropics and the extratropical Northern Hemisphere receive the most volcanic mercury emissions, the study found. But the geographic distribution of these natural emissions, which can be highly variable, could obscure regional trends in anthropogenic mercury emissions, the authors say. That should be considered in assessments for the efficacy of the 2013 Minamata Convention on Mercury, which aims to reduce global mercury emissions, they add. (Geophysical Research Letters, https://doi.org/10.1029/2023GL104667, 2023)

—Rebecca Dzombak (@bdzombak), Science Writer

Citation: Dzombak, B. (2023), Humans have boosted atmospheric mercury concentrations sevenfold, Eos, 104, https://doi.org/10.1029/2023EO230382. Published on 3 November 2023.

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