Acid Rains

 

Every year more and more plants and animals disappear never to be seen again. Strangely, it is the most intelligent but most thoughtless animal that is causing most of the problems — man. Nature is very carefully balanced and if this balance is disturbed, animals can disappear alarmingly fast. Every day, thousands of species of animals draw closer to extinction. There are countless number of species which may become extinct before they are even discovered.

In many lakes the fish are dying. Fishermen are worried because every year there are fewer fish and some lakes have no fish at all. Scientists are beginning to get worried too. What is killing the fish?

The problem is acid rain. Acid rain is a kind of air pollution. It is caused by factories that burn coal or oil or gas. These factories send smoke high into the air. The wind often carries the smoke far from the factories. Some of the harmful substances in the smoke may come down with the rain hundreds of miles away.

The rain in many places isn't natural and clean any more. It's full of acid chemicals. When it falls in lakes, it changes them too. The lakes become more acidic. Acid water is like vinegar or lemon juice. It hurts when it gets in your eyes. It also kills the plants and animals that usually live in lake water. That is why the fish are dying in lakes.

But dead fish may be just the beginning of the problem. Scientists are finding other effects of acid rain. In some large areas trees are dying. Not just one tree here and there, but whole forests. At first scientists couldn't understand why. There were no bugs or diseases in these trees. The weather was not dry. But now they think that the rain was the cause. Acid rain is making the earth more acidic in these areas. Some kinds of trees cannot live in the soil that is very acidic.

Now scientists are also beginning to study the effects of acid rain on larger animals. For example, they believe that some deer in Poland are less healthy because of acid rain. If deer are hurt by the rain, what about people? This is the question many people are beginning to ask. No one knows the answer yet. But it is an important question for us all.

What Happened to the Dinosaurs?

Science may never answer the most puzzling question. What killed these mighty creatures?

One of the most popular theories about the death of the dinosaurs is that the world just grew too cold for them. Indeed, for large, cold-blooded creatures, even a few nights of cold could spell death.

Not everyone agrees that a change in weather would have been enough to kill the dinosaurs.

The latest development in the debate amongst scientists about what killed the prehistoric dinosaurs is the suggestion that acid rain was the cause. Some geologists suggest that a large meteor hitting the earth at 65 kilometers per second would have led to strongly acidic rain falling all over the world. These geologists calculated that if an ice-rich meteor weighing 12.5 million billion kilograms, hit the Earth, it would shock-heat the atmosphere enough to produce huge amounts of nitrogen oxides. This would result, they say, in strongly acid rain around the world. If the meteor were travelling more slowly, or if it were more rock-like in structure, this strongly acid rain would be limited to a small area so that the world effect would be much less important. However, other groups of researchers have suggested that volcanoes, rather than meteors, could have produced these heavy doses of acid rain, but over a much longer period — over 10,000 years.

The idea of a great asteroid or comet crash is fascinating. But it would mean the dinosaurs would all have been killed within a very short time — perhaps over a few months or years. What if the dinosaurs did not die out so quickly? Many scientists think that the dinosaurs had started to die off millions of years before the end of the Cretaceous Period. And even more amazing, fossils have been found in the United States and southern China that might show dinosaurs lived long after they were supposed to have disappeared!

Could the death of the dinosaurs have been caused by their moving into new areas? Illness and disease can be carried by travelling animals. Is it possible that dinosaurs and other creatures died of terrible diseases caught from other animals?

If this was what ended the dinosaurs, does this mean there was no asteroid or comet crash? Some scientists think the dinosaurs might have been affected by such an object from outer space, but only when they were already in trouble. Ill and dying the dinosaurs might have looked up to see a fiery ball falling from the sky.

If so, it might just have sealed the dinosaurs' fate.