From October 2003 to September 2004, we conducted a detailed study on the mass balance of total mercury (THg) and methylmercury (MeHg) of Dongfeng (DF) and Wujiangdu (WJD) reservoirs, which were constructed in 1992 and 1979, respectively. Both reservoirs were net sinks for THg on an annual scale, absorbing 3319.5 g km⁻² for DF Reservoir, and 489.2 g km⁻² for WJD Reservoirs, respectively. However, both reservoirs were net sources of MeHg to the downstream ecosystems. DF Reservoir provided a source of 32.9 g MeHg km⁻² yr⁻¹, yielding 10.3% of the amount of MeHg that entered the reservoir, and WJD Reservoir provided 140.9 g MeHg km⁻² yr⁻¹, yielding 82.5% of MeHg inputs. Our results implied that water residence time is an important variable affecting Hg methylation rate in the reservoirs. Our study shows that building a series of reservoirs in line along a river changes the riverine system into a natural Hg methylation factory which markedly increases the % MeHg in the downstream reservoirs; in effect magnifying the MeHg buildup problem in reservoirs. Reservoirs are the sink of total mercury but source of methylmercury to the aquatic systems.

An abandoned cinnabar mining and roasting site is in the major sub-basin of the watershed for Cottage Grove Reservoir, Oregon. Average surface sediment total mercury concentration in the river draining this sub-basin (0.61 ± 0.52 μg/g) was about ten-fold higher than three smaller tributaries to the reservoir. Total mercury in reservoir surface sediments averaged 1.66 ± 0.70 μg/g. Stratigraphy for two sediment cores indicated generally decreased reservoir mercury loading from 1963 to 2002 but two pronounced peaks in mercury deposition. Years of extreme precipitation immediately prior to these peaks at least partially explained them. Epaxial muscle total mercury concentrations of largemouth bass increased with body weight up to 2.5 μg/g. A gradient of mercury concentrations in soils from a 3.3 km diameter grid indicated condensation of mercury vapors from the mine site polluted the sub-basin.

The Oak Ridge Reservation, established in 1942, was the designated site for the construction of the atomic bomb. During a 20-year period from 1944 to 1963 radioactive and toxic chemical pollutants, especially mercury compounds were released into the surrounding waterways. Tree diversity and mycorrhizal presence and abundance were analyzed in the mercury-contaminated floodplains of East Fork Poplar Creek Oak Ridge (EFPC) (Tennessee). A subsequent greenhouse study was conducted to assess the phytotoxic effects of different mercuric solutions on Platanus occidentalis (American Sycamore), inoculated with soils from EFPC. Total soil mercury in the field had no effect on tree diversity. Organic species of mercury proved to be more toxic than inorganic species of mercury and soil inoculants from EFPC had no protective effects against Hg toxicity in our greenhouse study. Comparison of the effects of mercury contamination in our field and greenhouse studies was difficult due to uncontrolled factors.

Mercury contamination in water has been an issue to the environment and human health. In this article, mercury in marine and oceanic waters has been reviewed. In the aquatic environment, mercury occurs in many forms, which depend on the oxidation-reduction conditions. These forms have been briefly described in this article. Mercury concentrations in marine waters in the different parts of the world have been presented. In the relevant literature, two models describing the fate and behavior of mercury in saltwater reservoirs have been presented, a conceptual model which treats all the oceans as one ocean and the “ocean margin” model, providing that the ocean margins manifested themselves as the convergence of continents and oceans, covering such geological features, such as estuaries, inland seas, and the continental shelf. These two conceptual models have been summarized in the text. The mercury content in benthic sediments usually reflects is level in the water reservoir, particularly in reservoirs situated in contaminated areas (mines, metallurgical plants, chemically protected crops). The concentrations of mercury and its compounds determined in the sediments in surface waters in the different parts of the world have been presented. Due to the fact that the pollution caused by mercury is a serious threat for the marine environment, the short paragraph about mercury bioaccumulation in aquatic organisms has been included. The cited data demonstrated a large scatter of mercury contents both between the fish species and the water areas. Mathematical models, valuable tools which provide information about the possible responses of ecosystems, developed to simulate mercury emissions, both at a small scale, for local water reservoirs, and at a global scale, as well as to model mercury bioaccumulation in the chain web of aquatic systems have been described.

This paper presents the results of a study on mercury distribution in urban wells from the town of Almadén (central Spain), a site that not only hosted the world’s largest mercury mine but also a large roasting plant for cinnabar (HgS). The study includes data on Hg contents in the underground waters and also quality and physical-chemical parameters such as pH, conductivity, oxidation-reduction potential (ORP), dissolved oxygen, and water temperature from 27 wells and 2 monitoring drill holes. An important proportion of the wells (16 %) display Hg concentrations above the European Union Commission (EUC) and Spanish threshold (at 1 μg L⁻¹) and only 10 % exceeded the US EPA recommendation (at 2 μg L⁻¹). As expected, the highest concentrations of dissolved and total Hg are found in wells near to the mine. Hydrochemical water types depend on geogenic and anthropogenic factors, for example, higher mercury concentrations are linked to water-rock interactions (e.g., oxidation, leaching) in sectors where soluble mercury compounds have formed. Hg concentrations show a decrease from 2013 to 2015, a fact that may be due to the encapsulation of the main calcines waste dump or to dilution effects related to strong rainfall events previous to the sampling survey.

For many years, atmospheric mercury has been perceived as a global pollutant. Transport of mercury compounds in the atmosphere and its deposition on the earth’s surface is an important issue that requires knowledge regarding the circulation of the various forms of this metal between environmental components. There are many numerical models that can be used to study and image this phenomenon. These models are based on data concerning mercury emission sources, concentrations of this contaminant on modelling areas and meteorological data to assess air mass inflow on a regional and global scale. A method to assess mercury deposition fluxes on a local scale based only on stream intensity analysis of mercury is proposed in this study. Mercury deposition fluxes (bulk) that were assessed by the MDC method at the Zloty Potok station (regional background station for the Silesian Agglomeration) varied from 22.8 μg · m⁻² · year⁻¹ (an 8-month period in 2013) to 54.2 μg · m⁻² · year⁻¹ in 2012. Developing procedures to estimate the mercury deposition coefficient (MDC) is useful in areas where only meteorological parameters and mercury concentrations in the atmospheric air are measured. The obtained deposition coefficient values enable quantification of a selected pollutant concentration and its potential impact resulting from deposition.

Nonferrous metal smelting produces a large amount of Hg⁰ in flue gas, which has caused serious damage to the environment and human health. In this work, amorphous cobalt sulfide was synthesized by a liquid-phase precipitation method and was used for capturing gaseous Hg⁰ from simulated smelting flue gas at low temperatures (50~150 °C). In the adsorption process, Hg⁰ can be transformed into the stable mercury compound, which is confirmed to be HgS by X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption of Hg (Hg-TPD) analysis. Meanwhile, XPS results also demonstrate that S₂²⁻ species on the surface of cobalt sulfide play an important role in Hg⁰ transformation. At the temperature of 50 °C (inlet Hg⁰ concentration of 214 μg·m⁻³), the Hg⁰ adsorption capacity of cobalt sulfide (penetration rate of 25%) is as high as 2.07 mg·g⁻¹, which is much higher than that of popular adsorbents such as activated carbons and metal oxides. In addition, it was found that the Hg⁰ removal efficiency by cobalt sulfide in the flue gas with high concentration of SO₂ (5%) remained more than 94%. The good adsorption and Hg⁰ removal performance guarantee cobalt sulfide the great superiority and application potential in the treatment of Hg⁰ in smelting flue gas with high concentration of SO₂.

Mercury (Hg) speciation and mobility were determined in calcines and waste rocks collected from 9 Hg mines in China. Total Hg (THg) concentrations in the mine wastes varied widely in different Hg mines (with a range of 0.369 to 2,620 mg kg(-1)). Cinnabar is the dominant form of Hg in the mine wastes. However, Hg(2+) and Hg(0) concentrations in the calcines were significantly higher than these in the waste rocks, which suggested the retorting can produce large amounts of by-product Hg compounds. The THg and Hg(0) concentrations in certain mine wastes exceeded soil guidelines recommended by US Environmental Protection Agency; while total soluble Hg concentrations of leachates in certain mine wastes exceeded National Surface Water Quality Standard of China. Mine wastes are important Hg pollution sources to the aquatic ecosystem and atmosphere.

Background, aim, and scope Chemical oxygen demand (COD) is used as a discharge standard parameter in wastewater treatment plant design, environmental modelling and many other applications. Chloride interference is an important problem of COD measurement for wastewaters containing low organic matter and high chloride concentrations. In case of chloride concentrations up to 2,000 mg/L, mercury sulphate addition at a ratio of 10:1 (HgSO₄:Cl⁻) can adequately mask the interference. When chloride concentration exceeds 2,000 mg/L, this ratio becomes ineffective to hinder the interference. At this point, it is proposed to use a greater and constant ratio of mercury sulphate addition. However, this application sometimes results in extra mercury sulphate addition which is not necessary. Even in some cases, greater addition of mercury sulphate alone is not a solution to erroneous measurement results. The purpose of the study is to determine optimum HgSO₄:Cl⁻ ratios according to the chloride concentrations of the samples and to show the importance of the strength of the digestion solution for the correct determination of the COD parameter. Materials and methods CODs of the synthetic samples containing varying COD and chloride concentrations were measured by closed reflux colorimetric method using three digestion solutions having different strengths. Results It is indicated in this study that a constant ratio of mercury sulphate can only prevent chloride interference up to a specific chloride concentration. Conclusions Achieving high precision results in case of low organic matter and high chloride concentration can only be possible by both decreasing the concentration of oxidant and adding mercury sulphate.