Emissions of mercury

Pacyna JM, Pacyna EG, Steenhuisen F, Wilson S. 2003. Mapping 1995 global anthropogenic emissions of mercury. Atmos Environ 37(Suppl. 1) S109-S117. 

Again, the waste treatment scenario with incineration has by far to the highest score for human toxicity. The scores for the other scenarios are more or less the same. The incineration of EoL PVC will lead to toxic emissions of metals (arsenic, lead, chromium, see Table 5) causing human health effects. However, the most important contribution to the human health effect is caused by the emission of mercury in the upchain processes of the production of mercury and sodium hydroxide. Sodium hydroxide is an auxiliary material in the waste incineration process. Mercury... 

In the results the emissions of mercury appear to have a very substantial contribution for the human toxicity impact score. These emissions are caused by the coproduction of chlorine and sodium hydroxide by electrolysis using a mercury cell. However, this technique is phased out. Therefore, the process descriptions in the Ecoinvent database do not represent up to date technology. In the Ecoinvent database the process for PVC production, in which chlorine is used as one of the compounds, is an aggregated processes based on, seemingly outdated, data from PlasticsEurope. These outdated data also influence the impacts related to waste treatment by incineration because sodium hydroxide is necessary for the waste incineration process. 

Mercury is a naturally occurring element. Natural emissions of mercury, e.g. from ore deposits and from volcanic activity, are variously estimated at amounts between 2500 and 5500 tonnes/year and are thus similar in magnitude to anthropogenic emissions, which are currently estimated at some 3600-4100 tonnes/year world-wide. Some 30000 tonnes of mercury are readily available in the environment, i.e. in the atmosphere or in the mixing zone of the oceans, with tens of millions of tonnes in the upper layers of the continental masses and still more in the deep oceans (see Table 2.1). 

Of all the metals in the periodic table, mercury, Hg (atomic number 80), is the only one to exist as a liquid at ambient temperatures. Mercury is also volatile, which means that uncontained mercury atoms evaporate into the atmosphere. Today, the atmosphere carries a load of about 5000 tons of mercury. Of this amount, about 2900 tons are from current human activities, such as the burning of coal, and 2100 tons appear to be from natural sources, such as outgassing from Earth s crust and oceans. Since the mid-igth century, however, humans have emitted an estimated 200,000 tons of mercury into the atmosphere, most of which has since subsided onto the land and sea. It is probable, therefore, that a large portion of the mercury emitted from "natural" sources is actually the re-emission of mercury originally put there by humans over the last 150 years. 

In the 1999 trial bum with mustard munitions at JACADS, emissions of mercury and cadmium exceeded regulatory standards. Newer facilities are equipped with a PFS, which would also be used at Pueblo. This system may be sufficient to bring the emissions to regulatory levels. Tests of such a system are planned in the near future. 

Mercury has been identified as a very dangerous environmental contaminant, largely by reason of the process of concentration in the food chain. Thus, the presence of mercury in coal is an extremely sensitive issue. The possible emission of mercury that may be found in coal is an environmental concern. 

The first observation of luminescence associated with a charge recombination process came in the early part of the 20th century in experiments involving oxidative electrolysis of aqueous halide solution at mercury anodes [1]. The report describes the observation of colored flames from the mercury pool surface following formation of a coating of mercury halide on the electrode surface during electrolysis and the authors relate this to flame emission of mercury halides. 

Elemental mercury, a monatomic gas, is the dominant atmospheric form and has a long residence time in the troposphere (>1 yr Fitzgerald et al., 1981 Slemr et al., 1981 Lindqvist et al., 1991 Lamborg et al., 2000, 2002a). Such longevity allows emissions of mercury to the atmosphere from natural and... 

Table 9 Major classes of anthropogenic emissions of mercury to the atmosphere in 1995.

There are three prominent processes that release mercury of mixed natural and anthropogenic origin to the atmosphere. These three include biomass burning (deliberate and natural) and the evasion of mercury from soils and the ocean. The general factors controlling emission of mercury from soils have been discussed in the section on low-temperature volatilization. The mercury... 

Nriagu J. O. and Becker C. (2003) Volcanic emissions of mercury to the atmosphere global and regional inventories. Set Tot. Environ. 304, 3—12. 

Pacyna E. G. and Pacyna J. M. (2002) Global emission of mercury from anthropogenic sources in 1995. Water Air Soil Pollut. 137, 149-165. 

Lindqvist O. 1991b. Mercury in the Swedish environment 4. Emissions of mercury to the atmosphere. Water, Air, Soil Pollution 55(l-2) 23-32. 

M.F. Coolbaugh, M.S. Gustin, and J.J. Rytuba, Annual Emissions of Mercury to the Atmosphere from Natural Sources in Nevada and California, Environ. Geol. 42(4), 338-349, July (2002). 

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