Bellringer What makes water hard?

Freshwater Pollution Notes

What is Pollution? Water pollution is adding any substance to water that has a bad effect on the water or the living things in the water. The substances that cause water pollution are called pollutants.

What is Pollution? A point source is a specific source of pollution that can be identified. For example, a pip pouring polluted water into a river is a point source.

What is Pollution? A widely spread source of pollution is called a nonpoint source. For example, pollutants is runoff from a farm field make up a nonpoint source.

What is Pollution? Some pollutants can build up in bodies of living things. Pesticides are an example. Pesticides are chemicals used to kill insects and other pests. Pesticides that pollute water can harm living things. pest = animal detrimental to humans. -cide = suffix meaning “to kill.”

What is Pollution? Pesticides usually buildup in microorganisms first. Then larger organisms consume large quantities of smaller organisms and the concentration of the pesticide builds up. Eventually, a human may eat a contaminated fish/bird. Enough consumption of these animals can lead to birth defects and cancers.

Human Wastes Only in the last 150 years did it become common knowledge that dumping human wastes into the water supply could cause the spread of diseases. As seen in previous sections, wastewater is usually treated before it goes back into the environment. The treatment usually kills most bacteria, but some survive and get into the drinking-water supply. Also, during stormy seasons, the sanitary sewers can flood into the storm sewers, which lead directly into natural water supplies. This usually results in a “boil water alert.”

Human Wastes Outside of cities, in rural areas, septic tanks are more common. As you know, septic tanks have an outlet pipe where the septic water will leave the septic tank and leach into the ground. For this reason, septic tanks should not be put too close to streams or wells. Ironically, the outlet pipe of a sand filter septic system is a great place for a garden.

Human Wastes Animal wastes from cattle, pigs, and chickens can also pollute water in farm areas (wells are also popular in these areas). Animal wastes can run off fields and enter streams, rivers, and aquifers.

Industrial Wastes Some factories let chemicals go into nearby rivers and lakes. This is of course, against the law. Some industries store chemicals in barrels underground. These barrels can eventually rust and begin leaking. The chemicals will pollute the soil and groundwater.

Industrial Wastes Many power plants and factories burn coal and oil. Cars and trucks burn gasoline (an oil derivative). Burning coal, oil, and gasoline puts chemicals in the air that cause acid rain. Acid rain has more acid than normal rain. Acid falls on lakes and ponds, making the lake/pond water acidic, killing the fish. Acid rain can damage trees, and even eat away at the stones of buildings.

Trees killed by acid rain

Industrial Wastes Heated water released from factories may not seem like a pollutant, but heating lakes, ponds, and rivers usually harms or even kills their inhabitants. Most aquatic organisms have a very small range of temperatures that they can survive in.

Chemical Runoff Runoff from farm fields and road causes water pollution. Farmers spread fertilizers onto fields to produce better crops. When rain falls on the fields, the fertilizers wash off. Fertilizers in runoff water are a nonpoint source of pollution. Fertilizers that pollute lakes and ponds can cause eutrophication. Gasoline and oil leak from cars onto roads. When it rains, runoff carries these oily substances into rivers, lakes and groundwater.

Water Pollution Solutions Living things in lakes, streams, and wetlands help reduce pollution. These living things filter out and break down materials. Certain plants and their roots can remove toxic metals from the water and filter out larger particles. Certain bacteria can break down chemical into benign constituent parts.

Water Pollution Solutions Humans have even constructed wetlands near toxic environments, such as coal mines, to help absorb some of the pollutants before they reach larger bodies of water.

Water Pollution Solutions Many industries recycle water, reducing water pollution. Some farmers collect runoff from fields and barnyards to use for watering crops. Some farmers plant grasses that filter out pollutants before runoff reachers rivers and ponds. You can prevent water pollution by throwing away chemicals and other harmful substances in safe ways.