How does mercury get into the fish and where does it come from?
In: 14
Mercury gets into lifeforms from what they eat, and the “higher up” in a food chain they are (the more types of meat they eat) the worse the mercury gets.
In its pure form, mercury isn’t too big of a deal to most things. It’s just a heavy liquid. But if it evaporates (which it is always doing, slowly; don’t mess with pure mercury without a professional) or combines with certain chemicals, it changes into a form that can mess up important chemical reactions in a living body. The times in life with the most delicate bodies (children, their creation, already sick, old age, etc.) can have the balance tipped away from healthy with this interference, and with enough even healthy things become sick. This is why mercury is bad for organics.
The mercury in the ocean has combined with some of those certain chemicals, which is why it can stay ‘floating’ in the water, but still in a form and amount that just being in ocean water doesn’t have enough of it to bother most things. It mostly comes from industrial era pollution, and it will stay in the ocean for a long time to come.
While simply being in the water isn’t a bother, there is enough of the ocean mercury that it gets into plants when they absorb water for photosynthesis. When this happens, it stays there for a long time. Long enough that more mercury is absorbed overtime, and more and more mercury is built up. Then, if the plant is eaten, all of that mercury build up is transferred into whatever fish (or crab or whatever small creature) ate the plant, which then starts storing mercury in a very similar way to the plant. Only, because the plant already concentrated the mercury through its life, the small fish starts out with all of that mercury already and builds it up even faster than the plant. Still only in amounts that are a problem for sensitive fish, but eventually quite a lot.
The same relation of concentration happens to bigger fish eating smaller fish. This is why some types of fish are considered worse for mercury sensitive conditions (like pregnancy); tuna eat a lot of smaller fish that eat smaller fish etc., so their mercury concentration is higher than anchovies that only eat plants and plankton. Tuna also aren’t the largest fish people eat, so something like a halibut or albacore (a type of larger tuna) has enough mercury that even healthy people should be cautious about how much they eat.
Latest Answers