题目内容
New mercury(汞) threat to oceans from climate change
Rising temperatures could boost mercury levels in fish by up to seven times the current rates, said Swedish researchers in an article published in Science Journal. They’ve discovered warming increases levels of the toxin (毒素) in sea creatures. In experiments, they found that extra rainfall drives up the amount of organic material flowing into the seas. This alters the food chain, adding another layer of complex organisms which boosts the concentrations of mercury up the line.
Mercury is one of the world’s most toxic metals, and according to the World Health Organization, is one of the top ten threats to public health. The substance at high levels has been linked to damage to the nervous system, paralysis and mental impairment in children.
The most common form of exposure to mercury is by eating fish containing methylmercury(甲基水银), an organic form of the chemical which forms when bacteria react with mercury in water, soil or plants. Levels of mercury in the world’s ecosystems have increased by between 200% and 500%, since the industrial revolution say experts, driven up by the use of fossil fuels such as coal.
In recent years there have been concentrated efforts to limit the amount of mercury entering the environment, with an international treaty, called the Minamata Convention, signed by 136 countries in place since 2013.
Researchers hope that the Minamata treaty will be successful and countries reduce the amount of mercury that is being produced. Otherwise this discovery of a previously unknown source could have impacts for human health.
Other researchers in the field say that the new study highlights important issues that have previously been little known.
“This work experimentally proves that climate change will have a significant effect of methylmercury budgets in coastal waters and its accumulation in fish,” said Milena Horvat from the Jozef Stefan Institute in Slovenia.
“This work will also help us understand the formation of mercury in fish and help reduce mercury from emission sources (primarily industrial).”
1.Where did Swedish researchers find warming increases levels of the toxin?
A. In the Pacific Ocean. B. On the Continent.
C. In Red Sea. D. In sea creatures.
2.What can cause damage to the nervous system?
A. Exposure to mercury. B. Mercury at high levels.
C. Methylmercury. D. The use of fossil fuels.
3.How does methylmercury form?
A. By limiting the amount of mercury entering the environment.
B. By reducing the amount of mercury.
C. When bacteria react with mercury in water, soil or plants.
D. When climate change returns to normal.
4.What can we know from Milena Horvat’s words?
A. Climate change will increase the levels of mercury in food.
B. Levels of mercury in the world’s ecosystems have increased by between 200% and 500%.
C. The Minamata Convention has been signed by 136 countries in place since 2013.
D. Mercury reduction from emission sources can be beneficial to fish.
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