The water (or snow) can become acidified when a pollutant combines with______ in the air.

Which pollutant is currently the subject of urgent research（） A: nitrogen dioxide B: ozone C: lead D: particulate matter

What does the professor mean when he says this A: Little is known about defining a substance as an air pollutant. B: The substance isn’t an air pollutant when there is a very little in the air. C: The substance can’t be judged to be an air pollutant only from its actual concentration level. D: The actual concentration level means little to peopl

Which of the following will not be employed in a field investigation A: Online investigation of statistic data B: To visit the local management department C: To visit the local enterprises D: To test pollutant concentration in environment

Mercury is a metal pollutant that can disrupt the ecosystem. Why is mercury so disruptive to the ecosystem? A: Organisms excrete the mercury out as waste. B: Organisms use mercury as an enzyme to speed up reactions in an organism's body. C: Mercury slows down the respiration rates of primary consumers. D: Mercury can become concentrated in the tissues of organisms.