Mercury inventory

Statistical variation - mercury inventories in cells are so large, and emissions so small, that the calculations involving very small differences between very large numbers are inevitably subject to statistical error. 

The work summarized in Section 9.04.3 notwithstanding, most studies indicate that soils and terrestrial sediments act as net sinks of mercury on timescales of centuries. Such a statement is supported by a review of the mercury content of soils from around the world and supporting data that allow determinations of mercury inventories in various soil horizons (Table 12). For comparison, we have estimated the excess mercury inventories resulting from anthropogenic activities using the integrated... 

Olin cells have a number of unique features in size, arrangement, and adjustment of anodes for voltage regulation. Olin pioneered the development of vertical decomposers, which reduce the mercury inventory required by the cells. 

Vertical decomposers are towers packed with graphite spheres or particles 8-20 mm in diameter. A typical cross section is 0.35 m per l(X)kA of cell load. The amalgam flows from the top and water is fed into the bottom of the tower. Since the volume of the decomposer is small, it is necessary to cool the hydrogen generated during the course of the amalgam decomposition reaction. The mercury inventory is small with the vertical decomposer. However, the caustic contains more mercury. 

The retirement of mercury-cell plants has created a new issue, the disposal of their mercury inventory. This has been considered a waste by some. However, mercury remains a useful commodity and automatically regarding it as a hazardous waste may be counterproductive [96]. Handling of mercury is an issue that requires an accepted societal policy. The metal is available from strategic reserves, retired or converted cell rooms, and reclamation processes. Total stocks worldwide are estimated roughly to be 25-50,000 tons [97]. The gradual run-down of mercury inventory before retiring a plant is not a useful technique. The opposite approach, increasing the amount of mercury in the cells, has in fact been used in older plants to improve cell performance and reduce the loss of mercury to the environment [98]. 

For example, direct isotope dilution analysis is used for mercury inventory in industry (Cowley et al. 1966 Enomoto et al. 1975). The mass X of mercury in electrolytic chlorine cells is determined using Hg, Hg, or a mixture of them. An aliquot of known mass Wo and activity Ao and hence known specific activity So is taken from a stock of mercury labeled with the tracer, added to each electrolytic cell, and left to mix. After homogenization, a sample of mercury is taken from each cell. The samples are shaken with 15-20% HCl to decompose amalgam. The mass W and activity A of the samples are measured to yield to S and, accordingly, X. The accuracy is better than 1%. 

Hines, D. B. Chlor-alkali Plant Mercury Inventory with Mercury-203 Radioisotope. Proc. 15th Meeting Chlorine Plant Managers (The Chlorine Institute, Inc., February, 1972), p. 

The U.S. Defense Logistics Agency (DLA), which maintains the U.S. National Defense Stockpile (NDS), sold 267 t of stockpiled mercury in 1992 (14). The DLA also sold 103 t of secondary mercury from the Department of Energy (DOE) stocks at Oak Ridge, Teimessee. The DLA accepts bids for prime virgin mercury on a daily basis, and for secondary mercury once a month. Inventories on December 31, 1992 were 4766 t of mercury in the NDS and 121 t of DOE mercury (14). The goal for both is zero. 

Chlor—alkah production is the largest iadustrial source of mercury release ia the United States (see Alkali and chlorine products). For the 1991 reporting year, chlor—alkah faciUties accounted for almost 20% of the faciUties that reported releases of mercury to the U.S. Environmental Protection Agency (EPA) for inclusion onto the Toxics Release Inventory (TRI) (25). 

Pacyna EG, Pacyna JM, Steenhuisen F, Wilson D. 2006. Global anthropogenic mercury emission inventory for 2000. Atmospheric Environment 40 4048 063. 

Much of the mercury that enters freshwater lakes is deposited in bottom sediments (Rada et al. 1993). Sedimentary pools of mercury in these lakes greatly exceed the inventories of mercury in... 

Therefore data on anthropogenic and natural emissions in the Asian region are necessary for the assessment of heavy metal pollution in these countries. Pollution of Kazakhstan and Kyrgyzstan by mercury and lead has been initially assessed by means of hemispheric modeling using the available global emission inventories of the considered heavy metals. The outcomes of the assessment are presented in this section. 

Commenting ona January 5,1999 proposal, environmental groups in early April called again on EPA to lower its proposed Toxic Release Inventory (TRI) reporting threshold to zero for certain chemicals. The chemicals include mercury, dioxins, and lead. Currently facilities are only required to report chemical releases if they manufacture or process at least 25,000 pounds or otherwise use 10,000 pounds annually of a fisted TRI chemical. The environmental advocates argued that any releases of chemicals considered to be persistent, bioaccumulative and toxic should be reported as a threat to public health. This abstract includes all the information contained in the original article. 

Sunderland, E.M., and Chmura, GL. (2000) An inventory of historical mercury pollution in Maritime Canada implications for present and future contamination. Sci. Total Environ. 256, 39-57. 

Five-gallon size waste forms were fabricated. Typical waste loading was 35-40 wt%. A small amount of potassium sulfide was added to the Ceramicrete binder mixture for stabilization of Hg, and dense and hard ceramic waste forms were produced. Just before solidification, TCLP results were obtained on small aliquots of the mixing slurry that was separated and allowed to set. Mercury levels in the leachate were found to be 0.05 /rg/1, well below the LfTS limit of 0.025 mg/1. The entire waste was treated, removed from the inventory, and sent to the Radioactive Waste Management Complex at the Idaho National Engineering and Environmental Laboratory for disposal. 

CONSENSUS REPORTS lARC Cancer Review Group 2B, Human Inadequate Evidence IMEMDT 58,239,93. EPA Extremely Hazardous Substances List. Reported in EPA TSCA Inventory. EPA Genetic Toxicology Program. Mercury and its compounds are on the Community Right-To-Know List. 

CONSENSUS REPORTS Mercury and its compounds are on the Community Right-To-Know List. Reported in EPA TSCA Inventory. 

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