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Managing Mercury in Air

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  • In 2007, New York enacted Steam Generating U6 NYCRR Part 246, Mercury Reduction Program for Coal-Fired Electric Utility Steam Generating Units (link leaves DEC website)to reduce mercury from electric generating units (EGUs) commonly known as electric power plants. Part 246 establishes an emission cap on facility-wide mercury emissions for the years 2010 through 2014, and establishes a facility-wide emission limit for each applicable facility beginning in 2015. Applicable facilities are not permitted to generate and trade mercury reductions with other facilities or other states. Starting in 2015, in conjunction with other electric power plant regulations such as the Regional Greenhouse Gas Initiative (RGGI) and the second phase of the Clean Air Interstate Rule (CAIR), the second phase of the State mercury regulation will take effect.
  • On May 3, 2011, the United States Environmental Protection Agency (EPA) proposed a National Emission Standard for Hazardous Air Pollutants (NESHAP) regulation to reduce toxic air pollutant emissions from coal-fired and oil-fired electric generating utilities. The proposed toxics rule would reduce emissions of heavy metals, including mercury (Hg), arsenic, chromium, and nickel, and acid gases, including hydrogen chloride (HCl) and hydrogen fluoride (HF). These toxic air pollutants, also known as hazardous air pollutants or air toxics, are known or suspected of causing cancer and other serious health effects.
  • Mercury emissions from the Portland cement industry can be significant based upon several factors. These factors include the mercury content of the fuel, the mercury content of the limestone rock used in the process, and other additives which contain trace mercury concentrations. Lafarge Building Materials, Inc. (Lafarge) was determined to be one of New York State's larger mercury emitters based on a 2009 emission test (PDF, 492 KB) which tested the mercury concentration of the raw material inputs and stack outlet mercury concentrations. In September 2010, the Department issued Lafarge a Title V air permit which set the requirements for sampling, monitoring, record-keeping, and reporting of mercury from the kilns using the provisions in 6 NYCRR Part 212 (link leaves DEC website.) The Lafarge kilns are a wet-based system and a slurry mixture is added to the kilns to produce the first step of Portland cement manufacturing. The Department is requiring Lafarge to use a slurry and fuel-based mass balance approach to determine the total annual mercury emissions in the most accurate, verifiable, and cost effective way possible. Cement kilns do not emit mercury uniformly, the single-short term or "snap shot" data obtained from an annual stack testing permit requirement was thought to be not indicative of the long-term performance or emissions from Lafarge's kilns. The slurry-based method improves the accuracy of estimating mercury emissions on a continuous basis by measuring the mercury content of the slurry itself, which includes the mercury contributions from all raw materials. New York is one of the first states to take it upon themselves to reduce mercury from the Portland cement manufacturing industry.

Mercury Management in New York State

Diagram of Mercury cycle
The Mercury Cycle.
(click on image to see a larger view)

Human-caused (anthropogenic) emissions (past and present) have resulted in increased concentrations of mercury in the environment. Approximately 158 tons of mercury are emitted from U.S. manmade sources every year. Over 85% of these emissions are from combustion sources, including fossil fuel and waste combustion. The global input to the atmosphere of all sources of mercury (including natural, oceanic and manmade) is estimated to be 5,500 tons. Rates of mercury deposition are increased in the Northeast relative to other parts of the country due to prevailing west to east wind patterns and mercury emissions within the region.

The majority of mercury in the atmosphere is in the form of gaseous elemental mercury, Hg(0). This form of mercury can travel long distances in the atmosphere for many months.

Some Hg(0) is converted into 2 other forms of mercury:

  1. a more water soluble form of mercury, divalent or oxidized mercury, Hg (II)
  2. it can bind with particulate matter or aerosols to form particulate mercury, Hg(p)

These two forms of mercury are rapidly removed form the atmosphere in precipitation and fall onto land and into waterbodies, including the ocean.

In a waterbody and in the sediments of the waterbody mercury may be converted by bacterial action into an organic form, methylmercury, CH3Hg. Acidic conditions and elevated ozone levels are believed to promote this conversion. Methylmercury can bioaccumulate up the food chain as a result of the ingestion of the contaminated aquatic organisms. Large fish and aquatic mammals at the top of the food chain may contain dangerously high levels of methylmercury. Contaminated fish become a human health hazard when they are consumed.

Methylmercury is slowly eliminated from the body. Animal studies and accidental poisonings have demonstrated that the embryo/fetus and young children are more sensitive to mercury than the adult. Methylmercury can travel across the placenta and accumulate in the fetal brain. It can also be found in breast milk. In the embryo/fetus and young children methylmercury has been shown to inhibit the normal development of the nervous system and produce generalized lesions throughout the brain. Lower levels of exposure may not be apparent until later when the child's motor and verbal skills may be delayed or abnormal. Pregnant women may not show any effects but their unborn children may be adversely effected. EPA has estimated that 8% of women of childbearing age in the general U.S. population have blood levels of mercury higher than the EPA's reference level for mercury.

In adults, methylmercury concentrates in the kidneys, liver and brain. Nephritis, as well as neurological and cardiovascular effects, may result in adults. In conclusion, neurodevelopmental deficits are the most sensitive and well-documented health effects.

By reducing mercury emissions to the atmosphere from anthropogenic (manmade) combustion sources we hope to reduce the level of mercury in fish flesh and decrease the subsequent threat to the health of humans and wildlife.

Effective October 30, 2002: 6 NYCRR Subpart 219-1, Incineration-General Provisions, Subpart 219-2, Municipal and Private Solid Waste Incineration Facilities, and new Subpart 219-7, Mercury Emission Limitations for Large Municipal Waste Combustors that are Constructed on or before September 20, 1994, pursuant to Environmental Conservation Law (ECL) Sections 1-0101, 3-0301, 19-0103, 19-0105, 19-0301, 19-0303, 19-0305, and 19-0306. Promulgation of this rule lowered the mercury emission limit for large municipal waste combustor plants from 80 ug/dscm or 85% removal, whichever is less stringent, to 28 ug/dscm or 85% removal, whichever is less stringent. This regulation will reduce mercury emissions and subsequent environmental loading of mercury in New York and the Northeast.