A publication of Work On Waste USA, Inc., 82 Judson, Canton, NY 13617 315-379-9200 June 20, 1990
The Gavle conference was the first of its kind where 180 researchers focused solely on the mercury problem. In general there was a broad consensus that mercury contamination had reached severe levels in many areas of the world and that resolution of the problem would be difficult. There was also general agreement that anthropogenic emissions, primarily airborne, represent the largest source of the problem...The consumption of fish containing methyl mercury was identified as the most serious threat. Mercury Emissions from Combustion Sources: Researchers have known for some time that the burning of fossil fuels and wastes such as trash and sewage sludge are the largest uncontrolled anthropogenic sources of airborne mercury contamination. Leading Swedish researcher, Oliver Lindqvist, presented the results from a series of lab scale, high temperature reactions of mercury with chlorine, hydrochloric acid and other chemicals generated by the burning of garbage. He confirmed that the principal species emitted from trash incinerators would be the divalent (mercuric chloride) form that would deposit within 100 km of the source. However, his data also showed that some of the mercuric chloride appears to be reduced at 160 deg. C (typical of the inlet of a baghouse) to elemental mercury vapor. This may explain why the much relied upon spray dryer/baghouse systems are not capturing much mercury. Lindqvist also showed that the more easily removed mercuric oxide species is unlikely to be formed except in the presence of an activated carbon catalyst.
Results from the Swedish National Study. Throughout the conference Swedish scientists presented results from the most comprehensive study ever attempted of the causes of mercury pollution and its effects on the ecosystem. This national study was organized in response to the discovery in the early 80s of extensive mercury contamination in freshwater fish throughout the country. Key findings are as follows:
- Mercury contamination in South and Central Sweden has increased by a factor of five in the twentieth century. Most of this increase is believed to result from an escalation of mercury emissions since World War II. Waste Incineration has been a major factor.
- Despite considerable progress in reducing domestic emissions the mercury content of fish is still rising. The reasons are (l) long range transport of emissions from Europe and (2) leaching of mercury previously deposited in Swedish forests;
- Mercury is strongly adsorbed by natural humic matter. Some 600 tons of mercury is stored in the human layer of Swedish forests and is available for leaching;
- Methyl mercury content in fish is highly correlated to the acidity of the lake water (and, by inference, to acid rain). It is also highly correlated to color (humic content) of the lake water. Inorganic mercury is transformed to methyl mercury by bacteria in the anaerobic zone of lake sediment and in the water column;
- Both inorganic and methyl mercury are toxic to spruce seedlings, suppressing chlorophyll content and interfering with uptake of nutrients. There is growing concern about mercurys toxicity to plants. Researchers believe that 0.4 to 0.5 ppm is the toxicity threshold concentration in soils. This level has already been reached in some areas of Sweden.
- Dry deposition is almost as great a factor as wet deposition due to the scavenging of mercury by (pine, spruce) needles. For the most part these and other results were in concurrence with parallel research performed by U.S. scientists in lakes and forests in Wisconsin, Minnesota and California where airborne wet and dry deposition is believed to be the primary contributor to mercury contamination in pristine lakes...
Soil Mobility: The binding of mercury to humic matter is the limiting factor on soil mobility. Depth distribution of mercury in soil follows the percentage of humic matter. However, soil mobility and plant uptake are significantly increased by low pH (acidity) and high chloride content. Thus soil mobility of mercury will be influenced by the combustion of fossil fuels and wastes, acid rain and the species of mercury deposited. Dry Deposition: U.S. scientist Steven Lindberg reported that a (large leaf) forest canopy acts like a sponge for dry deposition of mercury. The velocity of deposition is modulated by internal leaf resistence and increased with temperature. ie. dry deposition is higher in the summer. There is also a substantial increase in ambient air mercury concentration with temperature. Natural Sources and Marine Impacts: American marine scientist W.F. Fitzgerald estimated that about 60% of all mercury contamination is produced by the activities of man. His figures for natural mercury emissions from volcanos were consistent with recent measurements by other scientists that suggest, contrary to previous notions, only a small contribution. Further, he noted that emissions from underseas vents have never been measured. (Thus estimates of natural outgassing of mercury from the sea are shaky). Fitzgerald also reported the first unequivocal evidence of methyl mercury in the open seas. He believes that the high chloride concentration in the sea renders mercury from airborne sources mostly reactive and available for methylation in anoxic layers. Belgian scientists presented a paper documenting very high mercury levels in porpoises. Thus evidence is building that marine life can be and is heavily affected by anthropogenic mercury contamination. A Danish researcher noted that the principal source of mercury in peat bogs is from the air. Natural input from rock underneath is small due to the limited capillary action of the bog. In the past some regulatory authorities have considered peat bogs a natural source of mercury. A Ubiquitous and Insidious Pollutant: This conference leads to the conclusion that mercury is a worldwide environmental problem that equals or exceeds the impact of acid rain on aquatic resources. Mercury pollution will command increasing attention as more health advisories on fish consumption are declared and as problems with marine life increase. Geographical areas heavily impacted by acid rain can expect serious problems with mercury contamination. Further the correlation of mercury in fish to lake water color (humic matter), the increase of dry deposition with temperature and mercury mobility in high chloride soils all point to the vulnerability of Floridas aquatic ecosystem. In the foreseeable future we may begin to see a direct impact on the growth of our forests from mercury in the soil...
THE INSTITUTE FOR LOCAL SELF-RELIANCE (ILSR) publishes news releases called Facts To Act On which are available free from the ILSF, 2425 18th Street, NW, Washington, DC 20009, tel: 202-232-4108. Facts to Act On will soon publish a fuller account of Vollands mercury report.
EPA MEETING ON MERCURY BATTERIES. The following are excerpts from EPA minutes of a 2-8-90 meeting on mercury in batteries, held at Research Triangle Park, NC: ...nickel-cadmium and lithium batteries do not contain mercury. However, alkaline, carbon-zinc, zinc air, mercury oxide, and silver oxide batteries do contain mercury...46.8 tons of mercury was used in mercury oxide batteries with consumer applications (e.g., hearing aids) in 1988. Mercury oxide batteries used in medical and hospital applications and miscellaneous industrial applications (combined) accounted for another 42.7 tons. These batteries come in many different shapes and sizes and do not look like consumer button cell batteries. Finally, military applications consumed about 83.1 tons of mercury. Ray Balfour (Rayovac) does not know how many of these batteries would enter the municipal waste stream...Total mercury use has decreased from about 778 tons in 1984 to a projected 131 tons in 1989 and 62 tons in 1990. These tonnages include only batteries in consumer uses, not those in hospital, industrial, or military uses. It also does not include imports, however Ray Balfour said imports would not add more than about 10 percent to the total tonnage of mercury in household batteries. If it is assumed that mercury in all consumer batteries in 1990 is 62 to 70 tons, and that about 46 tons are used in mercury oxide consumer batteries, then about 65 to 75 percent of the total mercury in household batteries can be attributed to mercury oxide button cell batteries. Only recently has it been true that mercuric oxide button cell batteries account for the majority of mercury used in household batteries...In 1990, alkaline batteries sold in the U.S. typically contain 0.025 to 0.05 percent mercury; and by 1993, all batteries (except mercury oxide batteries) will contain 0.025 percent mercury or less in the U.S. and in Europe...