One of the major sources of water pollution is organic pollution, which is becoming more and more pressing on the environment because of the growing population of the world. It's a simple concept, the more people there are in one area, the more waste they will produce. For example, in a city there are so many people that the sewage plants and the environment can't take care of all of the waste and function in its usual manner. The sewage plants do their best, but the secondary discharge that gets into the water supply causes great problems. The excess waste acts as a food source for algae and the growth rate is uncontrollable. Everyone has been in a lake where there is a lot of dead algae on the shore and the water is clouded with algae. This situation is known as eutrophication, where algae growth is out of control and the water becomes oxygen depleted. There are natural cycles of eutrophication in the spring and fall, but the body of water can deal with those amounts. When excess waste is added to the water the body of water can no longer control the growth of the algae and the water soon becomes algae ridden and oxygen depleted. The water becomes oxygen depleted because the dead algae goes to the bottom and uses the oxygen in the deeper water to decompose, but if there is too much dead algae all the oxygen is depleted. Oxygen from the surface doesn't reach the bottom, because the warmer water is less dense than the deeper cooler water, therefor the warmer water floats on the colder water
One of the major sources of water pollution is organic pollution, which is becoming more and more pressing on the environment because of the growing population of the world. It's a simple concept, the more people there are in one area, the more waste they will produce. For example, in a city there are so many people that the sewage plants and the environment can't take care of all of the waste and function in its usual manner. The sewage plants do their best, but the secondary discharge that gets into the water supply causes great problems. The excess waste acts as a food source for algae and the growth rate is uncontrollable. Everyone has been in a lake where there is a lot of dead algae on the shore and the water is clouded with algae. This situation is known as eutrophication, where algae growth is out of control and the water becomes oxygen depleted. There are natural cycles of eutrophication in the spring and fall, but the body of water can deal with those amounts. When excess waste is added to the water the body of water can no longer control the growth of the algae and the water soon becomes algae ridden and oxygen depleted. The water becomes oxygen depleted because the dead algae goes to the bottom and uses the oxygen in the deeper water to decompose, but if there is too much dead algae all the oxygen is depleted. Oxygen from the surface doesn't reach the bottom, because the warmer water is less dense than the deeper cooler water, therefor the warmer water floats on the colder water