What type of pollutant is mercury

Mercury may be deposited and re-emitted many times as it cycles throughout the environment, potentially cycling indefinitely. Re-emitted mercury should not be considered natural in origin , even though it may have originally come from a natural source.

As humans have introduced more mercury into the environment, re-emissions of mercury have also increased due to environmental burdens caused by the higher levels of input. This is why it is important that continued efforts are made to reduce mercury pollution. Mercury emissions have decreased drastically in recent years click here and select "Mercury" , however small amounts of mercury can still be considered toxic in foods.

There are limits placed on how much methylmercury can be contained within food before it is contaminated. For example, the limit for young children in Canada is 0. An analogy: if a 1 gram paperclip were made entirely of methylmercury and you cut it into pieces, only one of these pieces would be required for this toxic dose! Mercury itself is an element , just like lead or arsenic , and is classified as a heavy metal. It has many interesting characteristics which can be read about here , some of which make it a very dangerous pollutant.

Humans are exposed to mercury in 2 ways: [3]. The first is the largest contributor to human effects. Methylmercury is toxic and can cause extremely adverse effects when consumed, which can happen when humans eat highly contaminated fish. Through the process of biomagnification see Figure 1 the concentration of methylmercury within fishes increases as one goes higher in the food chain.

This makes it dangerous to consume top and apex predators such as those listed in Figure 1, and especially dangerous for pregnant women and young children to do so.

Mercury is a persistent, bioaccumulative, toxic pollutant. When released into the environment, it accumulates in water laid sediments where it converts into toxic methylmercury and enters the food chain.

Primary pollutants come directly from sources such as industrial facilities, automobiles and forest fires. These include sulfur and nitrogen compounds, particulate matter, volatile organic compounds such as paint fumes and solvents, and toxic metals such as mercury. Mercury emitted into the air eventually settles into water or onto land where it can be washed into water. Developing fetuses and young children are most at risk. Mercury pollution also harms wildlife and ecosystems.

Mercury emitted into the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish.

Most human exposure to mercury is from eating fish and shellfish contaminated with methylmercury, both in the United States and worldwide. Almost all people in the world have at least trace amounts of methylmercury in their tissues, reflecting its pervasive presence in the environment.

Some communities eat significantly more quantities of fish than the general population, and thus may be exposed to much greater mercury contamination than the general population. It is estimated that more than 75, newborns in the United States each year may have increased risk of learning disabilities associated with in-utero exposure to methylmercury. Natural sources of mercury include volcanic eruptions and emissions from the ocean.

Anthropogenic human-caused emissions include mercury that is released from fuels or raw materials, or from uses in products or industrial processes.