AI Article Synopsis

  • Anthropogenic activities release around 2,000 metric tons of mercury annually, affecting remote ecosystems and leading to inconsistencies in reported emissions and atmospheric concentrations in the Northern Hemisphere.
  • Despite reported increases in mercury emissions over the past 30 years, data analysis shows a declining trend in atmospheric mercury levels, indicating that actual emissions must have decreased significantly, contradicting existing inventories.
  • By using statistical modeling of data from 51 monitoring stations, the study highlights a decline in mercury concentrations from 2005 to 2020, suggesting that reductions in local emissions, rather than reemissions of legacy mercury, are primarily responsible for these trends and raising questions about the reliability of current emission inventories.

Article Abstract

Anthropogenic activities emit ~2,000 Mg y of the toxic pollutant mercury (Hg) into the atmosphere, leading to long-range transport and deposition to remote ecosystems. Global anthropogenic emission inventories report increases in Northern Hemispheric (NH) Hg emissions during the last three decades, in contradiction with the observed decline in atmospheric Hg concentrations at NH measurement stations. Many factors can obscure the link between anthropogenic emissions and atmospheric Hg concentrations, including trends in the reemissions of previously released anthropogenic ("legacy") Hg, atmospheric sink variability, and spatial heterogeneity of monitoring data. Here, we assess the observed trends in gaseous elemental mercury (Hg) in the NH and apply biogeochemical box modeling and chemical transport modeling to understand the trend drivers. Using linear mixed effects modeling of observational data from 51 stations, we find negative Hg trends in most NH regions, with an overall trend for 2005 to 2020 of -0.011 ± 0.006 ng m y (±2 SD). In contrast to existing emission inventories, our modeling analysis suggests that annual NH anthropogenic emissions must have declined by at least 140 Mg between the years 2005 and 2020 to be consistent with observed trends. Faster declines in 95th percentile Hg values than median values in Europe, North America, and East Asian measurement stations corroborate that the likely cause is a decline in nearby anthropogenic emissions rather than background legacy reemissions. Our results are relevant for evaluating the effectiveness of the Minamata Convention on Mercury, demonstrating that existing emission inventories are incompatible with the observed Hg declines.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11494326PMC
http://dx.doi.org/10.1073/pnas.2401950121DOI Listing

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