Does the Arctic have very high concentrations of persistent organic pollutants and why does the mercury end up in the sea bass and sunfish??
Hi Rk,
Fascinating questions
Persistent Organic Pollutants (POPs) in the Arctic:
- Persistent Organic Pollutants (POPs) are toxic chemicals that linger in the environment due to their slow degradation. They can travel long distances and accumulate in ecosystems.
- Arctic Vulnerability: The Arctic is particularly susceptible to POPs due to its unique environmental conditions. Here's why:
- Transport from Afar: While many POPs originate outside the Arctic, they are transported there via air, water, and migratory species. These pollutants come from mines, military sites, and power stations.
- Cold Trapping: The cold Arctic climate favors the persistence of POPs. Once they arrive, they become "trapped" due to the low temperatures, preventing their rapid breakdown.
- Bioaccumulation and Biomagnification: POPs accumulate in animals' fatty tissues (bioaccumulation) and transfer up the food chain (biomagnification). Predators like seals, bears, and toothed whales can have high pollutant levels. These animals are also part of the traditional diet of Arctic communities.
- Health Implications: Exposure to POPs can lead to serious health issues, including impaired mental functioning, growth problems, and damage to the nervous system. The Arctic ecosystems and Indigenous communities are particularly at risk [1].
- Methylmercury Toxicity: Mercury has various forms, and methylmercury is the most toxic to humans. It accumulates in fish, especially in their muscle tissue.
- How Mercury Gets There:
- Airborne Release: Mercury is released into the air through natural events (volcanic eruptions, forest fires) and human activities (burning coal, oil, and wood).
- Conversion to Methylmercury: Mercury settles into water bodies once in the air. Bacteria and microorganisms convert it into methylmercury.
- Fish Absorption: Fish absorb methylmercury from water. When we consume fish, we also absorb this toxic form.
- Health Risks:
- Pregnant Women and Children: High mercury levels can harm developing fetuses and newborns. Pregnant women and young children should limit their consumption of fish high in mercury.
- Brain and Kidney Damage: Mercury can cause irreversible damage to the central nervous system, leading to cerebral palsy, impaired lung function, and more.
- Safe Consumption: The U.S. FDA recommends that pregnant women and young children eat no more than two servings of low-mercury fish per week.
Sources
Yes, the Arctic is known for having high concentrations of persistent organic pollutants (POPs) like mercury. This happens for a couple of reasons:
- Long-range transport: Pollutants like mercury can travel long distances through the atmosphere before settling in the colder regions like the Arctic. Since these pollutants are persistent, they don't break down easily and can accumulate in the environment.
- Food chain bioaccumulation: Mercury gets converted into methylmercury by bacteria in the water. Fish absorb methylmercury through their gills and diet. Larger fish, like sea bass and sunfish, are predators and tend to eat smaller fish that have already accumulated some mercury. This process is called bioaccumulation. As these larger fish continue to eat, the mercury concentration in their bodies increases. So, even though the overall mercury levels in the Arctic waters might be lower, predatory fish end up with higher concentrations.
POPs and Methyl mercury (CH3Hg) are accumulation in marine species with the Biologicalmanification in several reports, but Arctic areas have limited data.
Yes, the Arctic is known for having high concentrations of persistent organic pollutants (POPs) like mercury. This happens for a couple of reasons: Long-range transport: Pollutants like mercury can travel long distances through the atmosphere before settling in the colder regions like the Arctic. Once in the Arctic, the special environmental conditions tend to “trap” the pollutants as the cold favors their persistence compared to warmer environments. POPs are also stored and concentrated in animals' fatty tissues through a process as bioaccumulation. High POPs and mercury levels in the environment are detected through monitoring in the Arctic. The contaminants accumulate in the food chain and pose a threat to different species and humans. These contaminants come from wastewater as well as long-range pollution both based in the atmosphere and from oceanic movement. Commercial fisheries as well as chemical and waste emissions from resource exploitation including mining, minerals, oil and gas extraction are among the many pollutants. In the summer when the ice melts, the toxins get washed into the sea and rivers. The main contaminants in the Arctic region are heavy metals, such as mercury and lead, and persistent organic pollutants (POPs) such as DDT, PCBs and dioxins, which evaporate into the air but are slow to degrade.The methylmercury is absorbed by the bigger animal, and since the bigger the fish, the longer it lives and the more it eats larger fish species accumulate a lot more methylmercury in their body. In other words, fish higher up the food chain “bioaccumulate” more methylmercury than do those lower on the food chain. Once in a lake or river, mercury is converted to methylmercury by bacteria and other processes. Fish absorb methylmercury from their food and from water as it passes over their gills. Each year coal-fired plants worldwide emit vast quantities of mercury, of which some 2,000 metric tons enters into the world's oceans in gas form. Once it is in seawater, the heavy metal, which can adopt various chemical forms, can pose hazards to marine ecosystems.
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