Тест 35

Mercury levels in the oceans19пропуск 19, текущийsince the Industrial Revolution, thanks to mining and the burning of fossil fuels. All sea creatures absorb some of this heavy metal directly, and, once it’s in the body, there’s no way of20пропуск 20rid of it. The amount of mercury in fish varies between species. Long-lived predators like tuna and swordfish tend to contain the21пропуск 21, because they also absorb mercury from their prey and they’ve had a long time to accumulate it. The lowest levels are found in short-lived species lower down the food chain, such as oysters and shrimp.