Health Risks

Mercury is usually released into the environment by manufactories as emissions or waste. Eventually this mercury gets into the water bodies and then is converted by bacteria living in the sediment into methyl mercury. Methyl mercury can be ingested by smaller aquatic plants and animals. The danger here is that through biomagnification animals higher in the food chain will have larger concentrations of methyl mercury in their systems. This is dangerous especially for large fish, birds, and humans. Additionally, through bioaccumulation small amounts of consumed toxins can build up within one’s system over time, leading to mercury poisoning. The most common form of mercury poisoning comes from methyl mercury. According to the Environmental Protection Agency, almost everyone in the world has trace amounts of methyl mercury in their bodies because of its abundance in our environment, but in larger concentrations, it can be dangerous.

For infants and children:

• Impaired neurological development
• Impaired cognitive thinking, memory, attention, and language skills
• Impaired fine motor and spatial visual skills

For adults:

• "pins and needles” in the hands, feet, and around the mouth
• impairment of the peripheral vision
• lack of coordination of movements
• impairment of speech and hearing
• muscle weakness

Extreme cases of high mercury poisoning:^[3]

• Kidney and respiratory failure
• Death

Case Study

Onondaga Lake: Commonly known as the “Most Polluted Lake in America”, Onondaga Lake suffers from industrial waste and sewage pollution (i.e. ammonia and phosphorus which cause high algal blooms and suffocation of other organisms in the Lake).
Since the 1800s Allied Chemical, recently succeed by Honeywell International, is credited for dumping a total of 165,000 lbs of mercury into the lake, resulting in the contamination of about 7 million cubic yards of lake-bottom sediments.^[4] Their continuous polluting only ceased in the last few decades, but the damage had already been done.^[4]
Mercury contamination usually is caused by industrial emissions. The mercury enters the environment as an industrial emission and then moves through the water system before entering the lake. Once in the lake, the mercury is transformed by sediment-dwelling bacteria into methyl mercury, which has a high tendency to bioacculumate in aquatic life.^[5] Even now, the State Health Department advises staying clear of eating any fish that come out of the Lake. In addition, through biomagnification, the methyl mercury has made it’s way up the food chain and has been found in bats and birds surrounding Onondaga Lake area. Researchers found that the Spotted-Sand piper was the most affected bird.^[6] The levels of mercury found in the animals is so high that only about 20% of all birds’ chicks survive. Furthermore, scientists have reasons to believe that the mercury poisoning will continue to work its way up the food chain unless direct action is taken.

Remediation Efforts: The Upstate Freshwater Institute has been working to prevent the mobilization of methyl mercury from the deep sediments of the Lake. To do so, they have been adding a common agricultural fertilizer, calcium nitrate, solution to the bottom on the lake, which has been successful in lowering the concentration of mercury in fish dramatically.^[7] In addition, Honeywell International has been working since 2012, 24 hours a day, 6 days a week, between April and November on dredging the contaminated mud on the bottom of the lake. Earlier this summer, Honeywell attorneys said that there were 800,000 cubic yards of dredging to complete and they estimated being able to complete this amount by the end of the season in 2014. The cost of such efforts is estimated at $451 million.^[8] The Metropolitan Syracuse Wastewater Treatment Plant, which dumps about 20% of the water that goes into Onondaga Lake, has spent millions of dollars on making sure that there is no further lake pollution. Although major progress has occurred on the mercury levels on Onondaga Lake. It takes millions of dollars of remediation efforts to fix the polluted ecosystem and years for the biomagnification effects to resolve themselves.^[9] has been successful in lowering the concentration of mercury in fish dramatically.^[10]

Current Remediation Techniques

Although the EPA is working with the National Institute of Standards and Technology to reduce mercury use and pollution, there are still a number of already contaminated areas that are being remediated now.^[11] Nitrate Immobilization: The use of calcium nitrate to prevent methyl mercury from moving throughout bodies of water.^[12] Dredging: Mercury containing sediments are removed or dug up from the lake bottom.^[12] ISMS (In Situ Mercury Stabilization): Developed by Brookhaven researchers, the ISMS treats and removes mercury content from the soil, sludge, and other industrial waste; therefore stopping mercury from entering the water source.^[13] Thermal desorption: This involves heating the contaminated soil to high temperatures so that the mercury will vaporize away and can be separated from the soil.^[13]

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References

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1. Ref 1
2. Ref 2
3. Ref 3