Environmental Clean-up: Mercury

Environmental Source of Mercury

Natural Sources

Volcanic eruptions release mercury vapor into the air.

Forest fires emit mercury stored in vegetation and soil.

Natural deposits leach mercury into groundwater and nearby ecosystems.

Human-Made Sources

Coal-Burning Power Plants: Mercury vapor is released as a byproduct, settling in soil and water.

Artisanal Gold Mining: Mercury is used to extract gold, often dumped into rivers or vaporized into the atmosphere.

Industrial Processes: Mercury is used in batteries, fluorescent bulbs, and chlor-alkali plants, which release mercury waste.

Contaminated Environment

Mercury in water bodies is converted by microorganisms into methylmercury, a highly toxic form that bioaccumulates in fish.

Bioaccumulation occurs in aquatic organisms, concentrating in large predatory fish like tuna and swordfish.

Exposure to Mercury

Pathways to Humans

Diet: Eating fish or seafood contaminated with methylmercury (e.g., tuna, swordfish).

Occupation: Gold miners, factory workers, and healthcare professionals exposed to mercury vapors or spills.

Environment: Inhaling mercury in polluted air or drinking contaminated water near industrial zones.

Forms of Mercury

Elemental Mercury (Hg⁰): Vapour inhalation is toxic, but liquid ingestion is less harmful.

Methylmercury (CH₃Hg⁺): Highly toxic organic form bioaccumulated in aquatic food chains.

Inorganic Mercury (Hg²⁺): Found in industrial waste, toxic when ingested or absorbed.

Effects on Human Health

Neurological Symptoms

Short-Term Exposure (Acute): Headaches, tremors, mood swings, and irritability.

Long-Term Exposure (Chronic): Muscle weakness, memory loss, impaired coordination, and cognitive decline.

Severe Cases

Minamata Disease: Numbness, paralysis, vision loss, and developmental disabilities from severe methylmercury poisoning.

Effects on Children (Prenatal Exposure): Lower IQ, motor skill impairments, and developmental delays.

Affected Glands, Hormones, and Neuronal Processes

Neurons and the Central Nervous System (CNS)

Neurotransmission Disruption: Mercury binds to neurons, interfering with synaptic transmission, causing symptoms like tremors, cognitive dysfunction, and mood disorders.

Impaired Calcium Ion Channels: Mercury affects calcium signaling, which is crucial for neurotransmitter release, leading to coordination problems, memory issues, and motor dysfunction.

Endocrine Disruption (Inorganic Mercury)

Thyroid Gland: Mercury exposure may interfere with thyroid hormone production (T3 and T4), affecting metabolism, growth, and energy regulation. Symptoms include fatigue, weight changes, and sensitivity to cold.

Adrenal Gland: Changes in mercury levels can disrupt the production of cortisol and other stress hormones, leading to mood swings and stress-related symptoms.

Developmental Effects

In children, mercury exposure can interfere with brain development, affecting neuronal growth, synaptic pruning, and learning.

Protection from Mercury

Prevention at Source

Regulate emissions from coal plants using mercury capture technologies.

Replace mercury thermometers and fluorescent lights with digital and LED alternatives.

Train miners in mercury-free gold extraction methods, such as borax use or gravity separation.

Environmental Measures

Use water treatment technologies like activated carbon filters to remove mercury from contaminated water.

Test fish mercury levels and issue public consumption advisories.

Increase public awareness about mercury risks and safer alternatives.

Bioremediation

Use bacteria (Geobacter, Pseudomonas) to convert methylmercury into less toxic forms.

Algae and fungi absorb mercury from water and soil.

Genetically engineered microorganisms are being developed for efficient cleanup.