As a result of pollution, Lake Erie, on the borders of the USA and Canada, is now without any living things. Pollutions in water are not simply a matter of “poisons” killing large numbers of fish overnight. Very often the effects of pollution are not noticed for many months or years because the first organisms to be affected are either plants or plankton. But these organisms are the food of fish and birds and other creatures. When this food disappears, the fish and birds die in this way a whole food chain can be wiped out, and it is not until dead fish and water birds are seen at the river’s edge or on the sea shore that people realize what is happening. Where do the substances which pollute the water come from? There are two main sources – sewage and industrial waste. As more detergent is used in the home, so more of it is finally put into our rivers, lakes and seas. Detergents harm water birds dissolving the natural substance which keep their feather waterproof. Sewage itself, if it is not properly treated, makes the water dirty and prevents all forms of life in rivers and the sea from receiving the oxygen they need. Industrial waste is even more harmful since there are many high poisonous things in it, such as copper and lead. So, if we want to stop this pollution, the answer is simple, sewage and industrial waste must be made clean before flowing into the water. It may already be too late to save some rivers and lakes, but others can still be saved if the correct action is taken at once.

Pollution in water is noticed .............

Câu hỏi liên quan

• It can be inferred from the passage that the sediment sieve has an advantage over the hand test in determining soil texture because ______.

• What is the author’s main purpose in the first paragraph of to passage?

• Doctors have tentatively concluded that cellphones may ________.

ZUNIA12

• The word “minute” is closest in meaning to ...........

• Co-education was negatively responded to in _______.

• Who opposed the bill that was introduced in the House of Commons in the early 1900s?

• We can infer from the passage that ..............

• According to the passage, the first refrigerated railcar used what material as a cooling agent?

• The word “excluded” is closest meaning to ___________ .

• It can be inferred from paragraph 4 that ..............

• The phrase “academic responsibilities” in the second paragraph is closest in meaning to .............

• It can be inferred from the passage that _____________

• It can be inferred from the passage that the Puritans who traveled to the Massachusetts colony were ............

• What does the passage mainly discuss?

• What does the passage mainly discuss?

• The word “reckless” in line 11 is closest in meaning to ..............

• What is the most likely subject of the paragraph following this passage?

• The word “itself” in paragraph 3 refers to ________.

• Extreme weather can be caused by ...............

• Who will play music at the picnic this year?