Why is there a lot of mercury in some fish,,esp, swordfish,,,is it from acids rain?

Question

was there always mecury in these fish,,,,, is the there more mecury contamination in some areas,,,like the norteast atlantic for example,,,,,so if i eat sword down in Argentina would it be the same amount of mercury,,,,

Answer 1

the highest concentrations of methylmercury are generally found in large fish that eat other fish

Mercury is emitted to the air by human activities, such as manufacturing or burning coal for fuel, and from natural sources, such as volcanos.

Typically, mercury is released into the atmosphere in one of three forms:

elemental mercury: can travel a range of distances, may remain in the atmosphere up to one year and may travel globally before undergoing transformation
particle-bound mercury: can fall out of the air over a range of distances
oxidized mercury (sometimes called ionic or reactive gaseous mercury (RGM)): found predominantly in water-soluble forms, which may be deposited at a range of distances from sources depending on a variety of factors including topographic and meteorologic conditions downwind of a source.

When mercury falls in rain or snow, it may flow into bodies of water like lakes and streams. When it falls out of the air as dry deposition, it may eventually be washed into those bodies by rain. Bacteria in soils and sediments convert mercury to methylmercury. In this form, it is taken up by tiny aquatic plants and animals. Fish that eat these organisms build up methylmercury in their bodies. As ever-bigger fish eat smaller ones, the methylmercury is concentrated further up the food chain. This process is called "bioaccumulation".

Methylmercury concentrations in fish depend on many factors, including mercury, the concentration in water, water pH and temperature, the amount of dissolved solids and organic matter in the water, and what organisms live in the water. Methylmercury concentrations in fish may also be affected by the presence of sulfur and other chemicals in the water. Because of these variables, and because food webs are very complex, bioaccumulation is hard to predict and can vary from one water body to another.

However, in a given water body, the highest concentrations of methylmercury are generally found in large fish that eat other fish.

Answer 2

There are several reasons for this: Most of these fish are the large fish at or near the top of the food chain and can be swimming in polluted waters. Mercury is a heavy metal; once it gets in a fish's flesh, it cannot get out. To my knowledge. acid rain has nothing to do with the mercury pollution in the water.

Answer 3

The story about "acid rain" is that it is not a simple on or off phenomenon. Rain water is almost always somewhat more acid than distilled water because it falls through the atmosphere, where there is carbon dioxide gas, some of which dissolves in the water, lowering its pH below neutral. The "acid rain" environmental problem is that, if the air contains sulfur oxides, these too dissolve in the rainwater, but they lower the pH a lot, enough for the acidity to damage the leaves of plants when the raindrops land on them. Sulfur oxides were entering the air from the burning of high sulfur coal in western US power plants, and the rain acidity was killing forests in the eastern US and Canada. Environmental policies are now in place in the US to remove much of the sulfur from the coal before it is burned, so the acidity of rainwater downwind from coal power plants is less of a problem than it used to be in North America. The problem has not gone away, but it has been mitigated. Eastern coniferous forests that were being killed by "acid rain" are now recovering, and it is hoped that if the present trend continues, the forests will eventually return to a near normal condition. The end of the "crisis" means the end of the news coverage - news is almost always about a crisis! By the way, there are other places in the world where burning high sulfur coal is causing acid air pollution downwind with various adverse effects on plants, animals, and even people. The US media do not seem to be interested in acid rain in China.

Answer 4

"Some mercury finds its way into the atmosphere naturally, from volcanoes for example. But much of the mercury that finds its way into our food derives from industrial pollution. Mercury is emitted by power plants that burn fossil fuel and travels through the air. It deposits in bodies of water, where it is first taken up by plankton (floating animal and plant life). Fish that feed on plankton accumulate organic mercury in their bodies, and fish that eat those fish accumulate even more. This process, called bioaccumulation, concentrates the mercury in animals at the top of the food chain."

Answer 5

Big fish, such as swordfish, shark and sailfish, eat lots of little fish. If the little fish pick up mercury from plants or the water, that mercury builds up and concentrates in the big fish. Big fish also tend to live longer, so have more time for mercury to accumulate in their tissues.

Answer 6

Coal-burning power plants are the single largest source of mercury pollution, and the only major source the government does not regulate. Studys have been done to assess mercury pollution from coal-burning power plants.

Its a by product from the burning of coal.

Answer 7

it is my understanding that it is from contamination of the water itself by industry dumping toxins. out of sight out of mind is their motto - or was before regulations. plants and other low food chain organisms incorporate toxins into their tissues and the fish eat them. then, when in the fish mate, i *think* it can be passed down through contamination of eggs. i'm sure there are other ways too

Answer 8

it's also from leeching from soil. it accumulates in big fish because they eat little fish. unlike plants many animals do not have the biologics to isolate toxic metals like mercury