Temporal Variability of Atmospheric Total Gaseous Mercury in Windsor, ON, Canada

Soil-air exchange of mercury from agricultural fields in Zhejiang, East China: Seasonal variations, influence factors, and models of fluxes

Mercury exchange between soil and air is an important processe governing the biogeochemical cycling of Hg. This study investigated the in situ soil-air Hg fluxes in agricultural soils of Quzhou, Zhejiang Province, China, using a dynamic flux chamber coupled with a Hg vapor analyzer. Soil-air Hg exchange fluxes were overall emission for all seasons, indicating that agricultural soil was a Hg source for the atmosphere. Seasonal variations in soil-air Hg flux were observed, with low values in winter, elevated values in spring, peak values in summer, and a decline in autumn. Mercury emissions from soils showed a clear diurnal pattern where Hg released into the atmosphere reached a maximum at 11 a.m. and declined to a minimum at 2:00 and 20:00 in spring and summer, respectively. Meanwhile, soil-air Hg flux peaked at 1 p.m. and declined to a minimum at 6:00 and 23:00 in autumn and winter, respectively. The impact of each factor on the Hg exchange between soil and air varied in different seasons. Soil temperature was the major variable controlling the Hg flux in winter and spring; soil temperature and total gaseous Hg evidently affected the Hg flux in summer, and ozone (O₃) played a dominant role in influencing the Hg flux in autumn. Models for estimating the Hg evasive flux from soils were developed, and the atmospheric O₃ concentration was used for the first time as a parameter in these models. The measured and modeled Hg fluxes showed significant linear correlations (R² = 0.61; P < 0.001).

Automated Stable Isotope Sampling of Gaseous Elemental Mercury (ISO-GEM): Insights into GEM Emissions from Building Surfaces

Atmospheric monitoring networks quantify gaseous elemental mercury (GEM) concentrations, but not isotopic compositions. Here, we present a new method for automated and quantitative stable isotope sampling of GEM (ISO-GEM) at the outlet of a commercial Hg analyzer. A programmable multivalve manifold selects Hg at the analyzer inlet and outlet based on specific criteria (location, time, GEM concentration, auxiliary threshold). Outlet Hg recovery was tested for gold traps, oxidizing acidic solution traps, and activated carbon traps. We illustrate the ISO-GEM method in an exploratory study on the effect of building walls on local GEM. We find that GEM concentrations directly at the building surface (wall inlet) are significantly enhanced (mean 3.8 ± 1.8 ng/m³) compared to 3 m from the building wall (free inlet) (mean 1.5 ± 0.4 ng/m³). GEM δ²⁰²Hg (-1.26‰ ± 0.41‰, 1 SD, n = 16) and Δ¹⁹⁹Hg (-0.05‰ ± 0.10‰, 1 SD, n = 16) at the wall inlet were different from ambient GEM δ²⁰²Hg (0.76‰ ± 0.09‰, 1 SD, n = 16) and Δ¹⁹⁹Hg (-0.21‰ ± 0.05‰, 1 SD, n = 16) at the free inlet. The isotopic fingerprint of GEM at the wall inlet suggests that GEM emission from the aluminum building surface affected local GEM concentration measurements. These results illustrate the versatility of the automated Hg isotope sampling.

A review on the distribution of Hg in the environment and its human health impacts

Exposure to mercury is a silent threat to the environment and human life. It has the potential to harm almost every organ and body system. Mercury compounds are classified in different chemical types such as elemental, inorganic, and organic forms. The most significant source of ingestion-related mercury exposure in humans and animals is the consumption of fish. Long-term exposure to mercury compounds from different sources (e.g., water, food, soil, and air) can lead to toxic effects on skin, cardiovascular, pulmonary, urinary, gastrointestinal, and neurological systems. Mercury toxicity is found to pose more significant health hazards to certain occupational groups (e.g., goldminers and dental personnel). Because continuous exposure to mercury can be dangerous, it is desirable to re-evaluate the current reference (risk-free) values. This paper reviews the route of Hg exposure to humans, its human health impacts, the associated risk assessment, and treatment based on the recent findings from various studies.