文章大意:本文是一篇说明文。文章介绍了美国人吃过多蛋白质会导致氮污染,并且这种污染会促进有害藻类的生长,最终对环境造成负面影响。作者呼吁改变生活习惯来控制氮污染,从而在长期上节省资金。
In the U.S., people eat more protein than they need to, which might not be bad for human health, but does pose a problem for the country’s waterways. The nation’s wastewater is loaded with the leftovers from protein digestion: nitrogen compounds (氮化合物) that can feed harmful algal blooms (藻华) and pollute the air and drinking water.
Maya Almaraz, a biogeochemist at the University of California, Davis, and her team wanted to see how much of this nitrogen entered into the U.S. wastewater system because of a protein-heavy diet. The researchers found that the majority of nitrogen pollution present in wastewater — some 67 to 100 percent — is a by-product of what people consume.
Once it enters the environment, the nitrogen can have a series of ecological impacts. It helps algae grow much faster than they would normally, which is harmful to humans, other animals and plants. And when the algae eventually die, the problem is not over. Microorganisms (微生物) that feed on dead algae use up oxygen in the water, leading to “dead zones”, where many species simply cannot survive, in rivers, lakes and oceans.
Although it is possible to treat algal blooms, many of the current methods are not always effective at getting rid of all of the harmful growth. Some of these methods can even lead to additional pollution. So the best strategy for dealing with the effects of nitrogen pollution is prevention, says Patricia Glibert, an ocean scientist at the University of Maryland. Almaraz and her team state that controlling nitrogen pollution could be approached more quickly with a change in eating habits that could save billions of dollars in the long term.
12. Which aspect of Americans’ diet does Almaraz’s research focus on?
A.Its nitrogen compounds. | B.Its algal blooms. |
C.Its amount. | D.Its effect. |
13. What causes “dead zones” in the water?
A.No oxygen for many species. |
B.Death of lots of healthy algae. |
C.Microorganisms’ over-consumption of nutrients. |
D.Poisonous chemicals released by harmful algae. |
14. What can we learn about the current treatments for algal blooms?
A.They are costly but inefficiently . | B.They may cause secondary pollution. |
C.They may kill all algae. | D.They are slow to take effect. |
15. What is the best title for the text?
A.Why the Algae Grow So Rapidly? |
B.Why Eating Too Much Protein Harms the Planet? |
C.How to Prevent the Air and Water Pollution? |
D.How to Solve the Problem of Wastewater? |