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10th ICOBTE

Mercury: environment and health

Synopsis

Mercury is a well known global pollutant that can be a toxic element in its inorganic and organic forms. It produces different kinds of neurotoxicity effects in human beings, which already were recognized during in ancient times. The different mercury compounds or species possess various degrees of risk for the environment and human health, and also different biogeochemical behaviors. Therefore, what makes this element especially interesting for environmental sciences.

Mercury is a trace element present in very different concentrations in every environmental compartment. In a geological context, it is a chalcophile element, usually bound to base-metal (Pb-Zn) and precious metals (Ag-Au, but also occasionally to Pt-group elements) ore deposits. Its normal species in this type of deposit is cinnabar (HgS), a natural compound with high physical-chemical stability, and therefore, possessing a low environmental risk. However, it is usually accomplished with native (metallic) mercury, where environmental risks are elevated, especially due to its capacity to pass to the atmosphere in the form of mercury vapor.

In superficial environments, mercury is present in soil, water and atmosphere: 1) in soil, as a consequence of the presence as trace elements in underlying rocks, or eventually in higher concentrations, as hidden sulphides ore deposits 2) In waters, as a consequence of biological and physical-chemical processes causing the formation of soluble mercury species, among which the most important, due to its extremely high toxicity, is methylmercury ([CH3Hg]+). 3) In the atmosphere, mercury is present in the form of mercury vapor, due to the high vapor pressure of metallic mercury, and also to the emission of mercury vapor throughout combustion processes of fuels (mainly coal) containing the element. In air most of the mercury is in the metallic form, but a part can be also in ionic forms. This is an additional risk, since dry- or wet deposition processes bring mercury to the surface or leach into water masses in a form where soluble species are produced.

Mercury is incorporated to the biota mainly by two pathways: from the air via respiration processes, and through the food chain. The presence of high concentrations of mercury in air affects every living being, but in different forms. Organisms, such as plants have shown that certain plant species can accumulate mercury with no toxic effects. However, in man and other vertebrates, the continuing incorporation of mercury in this way causes the illness known as “hydrargirism�. This illness mainly affected mercury mine workers as well as hatters in the past, which used mercury compounds to manufacture “felt� for their industry. It is also known to affect present-day gold miners, and workers related with chlor-alkali plants, paints, electronic components, dental fillings, pharmaceutical agrochemical products, paper and wood industry. A further form of mercury introduced into the biota is through trophic chains: plants incorporate mercury from the atmosphere and soil and therefore provide an accessible source for vertebrates; and mercury from water is easily absorbed by aquatic organisms, including fish. Particular interest is given to fish and mercury toxicity, since most fish species and in particular carnivorous fish are able to bioaccumulate mercury in its more toxic form methylmercury. This phenomenon was responsible for the most important human catastrophe linked to mercury, namely the Minamata disaster. This was caused by the leakage of organic mercury compounds to the Minamata Bay (Japan) from an acetaldehyde factory, which caused elevated methylmercury content in the fish from the Bay, and the subsequent intoxication of thousands of inhabitants within the area.

Nowadays, the main risks associated to mercury can be summarized as: possible mercury intoxication in professions still using mercury (e.g. gold recovery in artisanal mining, chlor-alkaly plants based on mercury cell technology or fluorescent lamp industry). A further important mercury intake is related to methylmercury intoxication through the food chain pathway in diets including important quantities of fish and seafood. On this basis, main lines of scientific research on the topic of “mercury, environment and health� are related to the study of the processes causing the transformation of the less toxic inorganic mercury compounds into methylmercury and related compounds. This leads to the possible development of mechanisms for mercury immobilization or inertization, as well as to the development of bioindicators for the early detection of the presence of mercury in its toxic forms in the environment.

We expect that this Special Symposium may serve as a forum to help to improve our knowledge on all the aspects related to the study of the environmental and health concerns of this trace element. This will serve to minimize the risks for all living species.

The main objective of the symposium will address to discuss the problems caused by mercury on the environment on the basis of a multidisciplinary approach, with the final idea of setting conclusions that can be baselines for the remediation of such problems.

Specific topics may include:

  • Characterisation of the origin of mercury pollution
  • Techniques for mercury monitoring and analysis
  • Risk assessment related with the presence of mercury in the environment
  • Mercury and human health
  • Remediation technologies: proposals and solutions encountered

Committee (Symposium Organizers)

Pablo L. Higueras, Rocio MillĂ n

Contact

Pablo L. Higueras
Dept. IngenierĂ­a GeolĂłgica y Minera
Universidad de Castilla - La Mancha
Escuela Universitaria Politécnica de Almadén
Pl. Manuel Meca, 1
13400 Almadén (Ciudad Real)
España / Spain
Tel: (+34) 926 295300 - Ext: 6017
pablo.higueras@uclm.es
www.uclm.es/users/higueras

Rocio Millan
CIEMAT - Dpto. Medio Ambiente
Avenida Complutense, 22 (edf. 20)
E-28040 Madrid (Spain)
rocio.millan@ciemat.es

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