Future research needs are proposed for improving the understanding of atmospheric mercury cycling. These include refinement of mercury emission estimations, quantification of dry deposition and air–surface exchange, improvement of the treatment of chemical mechanisms in chemical transport models, increase in the accuracy of oxidized mercury measurements, better interpretation of atmospheric mercury chemistry data, and harmonization of network operation.

The highest mercury (Hg) wet deposition in USA occurs along the Gulf of Mexico. Gaseous oxidized Hg (GOM) is a major contributor due to high water solubility and reactivity. Concentration and dry deposition of GOM were determined for OLF, Florida. Results indicated at least 5 GOM compounds in this area including HgBr₂, HgO, and Hg–nitrogen and –sulfur forms. GOM chemistry indicates reactions with local mobile source pollutants and long-range transport from outside of the USA.

This study addresses two issues related to source–receptor analysis of speciated atmospheric mercury: (1) comparing PMF and PCA and (2) testing different approaches in data selection for PMF modeling.

A better understanding of the discrepancies in multi-scale emission inventories could provide indications for their limitations and further improvements. We develop a bottom-up inventory of Hg emissions for Jiangsu, China. Compared to the national and global inventories, the largest total Hg emissions and fraction of Hg²⁺ are estimated. The crucial parameters responsible for the differences include Hg contents in coals/materials, abatement rates of emission control devices, and activity levels.

The current knowledge concerning mercury dry deposition is reviewed, including dry deposition algorithms used in chemical transport models and at monitoring sites, measurement methods and studies for quantifying dry deposition of oxidized mercury, and measurement studies of litterfall and throughfall mercury. Over all the regions, dry deposition, estimated as the sum of litterfall and throughfall minus open-field wet deposition, is more dominant than wet deposition for Hg deposition.

Understanding of spatial and temporal variations of atmospheric speciated mercury can advance our knowledge of mercury cycling in various environments. This review summarized spatiotemporal variations of TGM/GEM, GOM, and PBM in environments including oceans, continents, high elevation, the free troposphere, and low to high latitudes. Remaining questions/issues and recommendations were provided for future research.

Atmospheric airborne mercury is of particular concern because, once inhaled, both Hg and its vectors might have adverse effects on human beings. In this study, we attempted to identify the sources of PM_2.5-Hg in Beijing, China, using Hg isotopic composition. Large range and seasonal variations in both mass-dependent and mass-independent fractionations of Hg isotopes in haze particles demonstrate the usefulness of Hg isotopes for directly tracing the sources and its vectors in the atmosphere.

This study was performed to identify likely source directions and locations of total gaseous mercury (TGM) using CPF, CBPF and TPSCF. Previous studies showed the importance of long-range transport of TGM but not local sources. However, the results from various approaches suggested the importance of local sources near industrial areas including iron and manufacturing facilities, hazardous waste incinerators and the coastal areas relative to distant sources.

In this study, a state-of-the-art chemical mechanism was incorporated into a box model to investigate the atmospheric Hg cycling in different environments. As a result, for each of the three environments, GOM diurnal cycles of over half the selected cases were reasonably represented by the box model. A realistic model can be a powerful tool, providing important information on atmospheric Hg cycling and implications for policy makers.

In this study, mercury (Hg) was sampled weekly in dry and wet deposition and throughfall and monthly in litterfall, and it was volatilized from soil from August 2008 to February 2010 to identify the factors influencing the amount of atmospheric Hg deposited to forested areas in a temperate deciduous forest in South Korea.

Elevated atmospheric deposition in China is predicted to increase due to fast economic development. We quantified Hg dynamics on the forest field and measured fluxes and pools of Hg in litterfall, throughfall, stream water and forest soil in southwestern China, and found that forest field retention can prevent Hg from entering into the downstream aquatic ecosystems. However, any changes in the forest floor like deforestation or forestland degradation may strongly affect Hg budget of the region.

Reliable quantification of air-surfaces flux of elemental mercury vapor (Hg⁰) is crucial for understanding Hg global biogeochemical cycles. In this study, we provide a comprehensive review on the state of science in the atmosphere-surface exchange of elemental Hg. We compiled an up-to-date global observational flux database and discuss the implication of flux data on global Hg budget. The knowledge gap and research needs for future measurements and modeling efforts were discussed.

This study was initiated to identify the sources affecting speciated mercury concentrations measured on the island located between mainland Korea and China. The results from various approaches consistently show that Korean sources are most important for gaseous oxidized form while for other Hg species regional transport was also important. It is also suggested that the secondary formation of particulate Hg becomes more important as the significance of long-range transport increased.

For more than 20 years, scientists and engineers have tried to design simple sampling devices that can collect gaseous elemental mercury from the atmosphere without the use of a pump. A thorough review of the sampler designs that have been presented so far suggests that while some may be suitable for measuring higher air concentrations close to sources, none of them have the accuracy and precision required to record the low atmospheric mercury concentrations prevalent in background regions.

This study estimated the contributions to mercury concentration and deposition in easter China from seven categories of emission sources by CMAQ-Hg. Also, this study focuses on diagnostic and process analyses for atmospheric mercury pollution formation and on identification of the dominant atmospheric processes for mercury.

Current knowledge of receptor-based studies using speciated atmospheric mercury is reviewed and recommendations for future research needs are provided.

The Minamata Convention for mercury (Hg) has been signed by many nations and the primary objective is to protect human health and the environment from releases of Hg. A key challenge researchers is developing linkages between Hg in the atmosphere, deposition, and ecosystem contamination. Here we critically review where the science on measuring and modeling atmospheric Hg stands and offer suggestions for future research that will both advance understanding of Hg cycling and serve the convention.