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Heavy Metals
Published in Abhik Gupta, Heavy Metal and Metalloid Contamination of Surface and Underground Water, 2020
Mercury (Hg) has an atomic number of 80, an atomic weight of 200.590, and a density of 13.55 g cm–3. Cinnabar or mercury sulfide (HgS) is the primary ore of mercury. It has a bright red color, and was consequently used as a pigment and in jewelry and ornaments for many years, until its use was almost totally discontinued because of its toxicity. For the extraction of mercury, cinnabar is heated in a furnace, and the vapor collected and condensed to yield liquid mercury. A major industrial use of mercury is as a catalyst for the production of chlorine and alkali. Mercury was widely used in instruments for the measurement of temperature and pressure such as thermometers and barometers. Another of its traditional uses in dental amalgams has also been discontinued with the availability of various polymer resins. Mercury can form amalgams with all metals except iron, nickel, cadmium, aluminum, cobalt, and platinum. It is also used in mercury vapor lamps, X-ray tubes, switches, batteries, and rectifiers. Many of its uses such as in making felt, in tanning, taxidermy, textile manufacture, herbarium preparation, textile manufacture, photography, and in making mercury-based paints and pigments have now been discontinued because of its toxic nature (Encyclopaedia of Occupational Health and Safety 2012).
Spray Drying for Production of Food Colors from Natural Sources
Published in M. Selvamuthukumaran, Handbook on Spray Drying Applications for Food Industries, 2019
Mehmet Koç, Feyza Elmas, Ulaş Baysan, Hilal Şahin Nadeem, Figen Kaymak Ertekin
Minerals are generally defined as crystalline or geologically occurring elements or chemical compounds. Minerals have been used for a long time as natural colorants in the food and cosmetics industries. Minerals provide various color tones depending on their chemical composition and/or their physical structure. Many minerals contain metallic cations, which contain d orbital electrons. Metallic cations in minerals usually absorb and reflect visible light (Mason 2013). For example, viridian, which is a chromium oxide mineral, is a green pigment used as a colorant. Furthermore, viridian is exempt from certification in cosmetics because of being obtained from natural sources (Martins et al. 2016). The Cinnabar, Ochre, lead, a nd Realgar are some examples of red pigments, which originate from the source of minerals. Cinnabar, expresses as common bright scarlet to a brick-red form of mercury sulfide (HgS) and serves directly as dyeing pigment. Red ochre is a natural pigment that contains anhydrous and hydrated iron oxide (Fe2O3nH2O). Red ochre has several hues, which range from yellow to deep orange or brown. Red lead (Pb3O4 or 2[PbO][PbO2]) is a bright red or orange crystalline or amorphous pigment. Realgar (a-As4S4) is an arsenic sulfide mineral, which is also a mineral of arsenic. It is thought that these pigments are not safe and usage in the food industry is very limited because of this.
Evaluation of Food and Food Contaminants
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 5, 2017
William J. Rea, Kalpana D. Patel
But the FDA and the Corn Refiners Association, an industry trade group, claim there is nothing to worry about. Mercury poses different risks depending on its chemical form. In its unadulterated elemental state, mercury is relatively safe to ingest—the body absorbs only about a tenth of a percent of it. Inorganic forms of mercury, such as cinnabar, are more easily absorbed and therefore more dangerous than elemental. Organic forms, such as methylmercury, which originate from fossil fuel emissions and build up in the fatty tissue of tuna and other kinds of fish, are the worst; readily absorbed, they can cumulatively damage the brain and nervous system.
Environmental Alchemy: Mercury-Gold Amalgamation Mining and the Transformation of the Earth
Published in Ambix, 2023
The same geophysical processes that formed the Earth’s gold deposits also led in complex ways to the genesis of mercury deposits. Tectonic activity and volcanic processes concentrated mercury into twenty-six known mercury mineral belts scattered over the planet, though three-quarters of global mercury production has come from just five of these mineral belts.12 The most important of all of them is the Almadén mercury mineral belt in central Spain, which has produced more than one-third of the world’s mercury to date. Within each mineral belt, three main types of enriched mercury deposits developed over widely varying time periods. But the main source of mercury in each of them, with rare exceptions, is the mineral ore cinnabar. Varying in appearance from bright- to brick-red, cinnabar was – and continues to be – formed near volcanic openings known as fumaroles where hot sulphurous gasses vent to the atmosphere, and as a precipitate near hot springs heated by subterranean volcanic activity. In cinnabar ores, mercury occurs as small and irregular deposits or veinlets, and is usually less than one percent enriched. Gold and mercury are also geochemically interrelated and can occur together in several types of mineral deposits.13 In some gold-silver deposits, mercury can be present as a common trace element, and more rarely, as a mercury-gold amalgam.14 Since ancient times, alchemists have separated mercury from its surrounding materials through crushing, roasting, and finally condensing it into its liquid form known as quicksilver.
Seasonal patterns of methylmercury production, release, and degradation in profundal sediment of a hypereutrophic reservoir
Published in Lake and Reservoir Management, 2021
Byran Fuhrmann, Marc Beutel, Priya Ganguli, Liying Zhao, Sarah Brower, Andrew Funk, Jeffrey Pasek
Mercury is a toxic heavy metal and widespread contaminant (USEPA 2007). Human exposure to elevated levels of mercury can cause a variety of health problems such as neurological disorders, kidney failure, paralysis, and even death. In the United States, mercury contamination is prevalent in approximately 50% of US Environmental Protection Agency (USEPA) Superfund sites (Bigham et al. 2017), and the World Health Organization currently considers mercury to be one of the top 10 chemicals of major public health concern (Bose-O’Reilly et al. 2010). Mercury is typically found in trace concentrations in natural ecosystems. However, anthropogenic activity has dramatically increased the prevalence of mercury in the environment. More than 2 billion pounds of mercury has been extracted from naturally occurring ores like cinnabar. This extracted mercury is most frequently used in artisanal gold mining and released into the environment after being used (Hylander and Meili 2003). Other anthropogenic sources of mercury pollution to the environment include coal burning, mining, and oil refinement, which produce both volatile and water-soluble mercury (Futsaeter and Wilson 2013). Water-soluble, inorganic mercury (iHg) species can directly contaminate nearby ecosystems, as they are easily transported in water. Volatile mercury in the elemental gaseous form (Hg0) enters the atmosphere, where it reacts to form iHg. The gaseous form of mercury can be transported over large distances and returns to the earth with precipitation, accumulating in topsoil and waterbodies (Bigham et al. 2017).
Occurrence and transformation of mercury in formerly contaminated soils due to operation of amalgamation techniques and assessment of consequences
Published in Human and Ecological Risk Assessment: An International Journal, 2020
Jiřina Sysalová, Ondřej Zvěřina, Rostislav Červenka, Josef Komárek
Formerly contaminated soils, where anthropogenic activities ended several years ago, are still burdened with high levels of total mercury, and therefore contribute as additional sources to current levels of mercury pollution in the environment (Árvay et al., 2017; Dadová et al. 2016; Hojdová et al. 2009; Sysalová et al. 2017; Vaselli et al. 2013). Depending on physicochemical and environmental factors, mercury in soils can participate in several chemical and biological processes and interconvert between inorganic and organic forms (Taube et al. 2008; Yasutake et al. 2011). Some bacteria are able to resist heavy metal contamination through chemical transformation by reduction, oxidation, methylation, and demethylation (Liu et al. 2010; Száková et al. 2016). It was proven only recently that soils near an abandoned Cinnabar mine continue to exhibit significant levels of mercury contamination even after more than 150 years of mine closure. Similarly, soils previously contaminated with mercury-based fungicides still contain a considerable total amount of mercury (T-Hg). On the basis of mercury species measurements, the transformation of original soil pollutants (HgS, PhHg+) into other species, especially methylmercury compounds (CH3Hg+) or volatile gaseous elemental mercury (GEM), has been proposed (Sysalová et al. 2017).