Normally, human waste goes through various treatment plants to become uncontaminated, but during a heavy rain storm, human waste can back up and overflow into rivers or the water supplies. This waste can also cause disease and it can rob the water of oxygen which kills the wildlife that lives in the water.
When rain runs off the land it picks up dirt and silt and carries them into the water. When the dirt and silt (sediment) settle in the water body they enter, these sediments can keep sunlight from reaching aquatic plants, plants that live in and grow in the water. When the sun can't reach the plants, they die. The sediments can also clog fish gills, and smother organisms that live on the bottom of the body of water.
When oil is spilled into the water, the effects on the ecosystem and its components are devastating. Some animals, such as birds, mammals, and fish may and can be killed if they ingest oil. Many may die from eating oil contaminated prey. Birds may die if the oil coats their feathers. They can neither fly nor stay warm. Furthermore, when oil coats the feathers they can become sick and die. Oil and antifreeze can cause the water to have a bad odor and leave a sticky film on the surface of water that kills animals and fish. Oil is one of the most devastating pollutants of water.
When contaminated water seeps into the ground it can have serious effects. People can get very sick and have the possibility of developing liver or kidney problems, cancer or other illnesses, depending on if contaminated water seeps into the ground.
Water, from rain, runs down the slopes of the land which may include farm areas that use fertilizers, pesticides, and other farming chemicals. After that they travel down into the rivers, lakes, or oceans. Fertilizers and some chemicals may cause plants to grow quicker. With the growth of more plants, more bacteria will grow (bacteria eat dead plants). Bacteria need oxygen to survive and if there are more bacteria in a river than normal, there is less oxygen for fish and some of them may die. In addition, some fish in the Great Lakes suffer from tumors and the populations of some species in these waters are declining. Other chemicals besides farming chemicals effect humans as well. Nitrates in drinking water can cause diseases to infants that might cause them death. Cadmium (a metal in sludge-derived fertilizer) can be absorbed by crops, and if people ingest this in sufficiently it can cause diarrheal disorders, liver, and kidney damage. The culprit is suspected to be inorganic substances such as mercury, arsenic, and lead. Also, other chemicals can cause problems with the taste, smell, and the color of water. Pesticides, PCB's, and PCP's (polychlorinated phenols) are some examples that are toxic to all life. Pesticides are used in farming, forestry, and homes. PCB's can still be found as insulators in old electrical transformers, and PCP's can be found in products such as wood preservatives. They are very toxic and that is what makes them a threat to our ecosystem.
Many factories have pipes that drain chemicals into rivers or streams. These chemicals can damage aquatic life as they are carried downstream. Furthermore, the added chemicals can warm the river, which decreases the amount of oxygen that the fish need to live.
Many people today dump their garbage into streams, lakes, rivers, and oceans. Some examples of this garbage are cans, paper, furniture, and other household products. When people dump cleaning products into the ecosystem they are endangering its inhabitants. When plastic is dumped in lakes, ducks are at risk because they might be strangled and when dumped in the ocean, dolphins might be killed. Aluminum cans can cut the animals and fish.
Eutrophication, occurs when lake water is artificially supplemented with nutrients, which causes abnormal plant growth. The cause of eutrophication can be runoff of chemical fertilizers from fields. Eutrophication can produce problems such as bad tastes and odors as well as green scum algae. Also, the growth of rooted plants increases, which decreases the amount of oxygen in the deepest waters of the lake. A common chemical change is the precipitation of calcium carbonate in hard waters. Eutrophication makes some lakes void of life.
The effects of acid rain are most clearly seen in lakes, streams, rivers, oceans, and other bodies of water. Acid rain directly falls on water, but it can flow into rivers after it falls on land. Lakes and streams become acidic (pH value goes down) when the water and the land around it can not neutralize the acid rain. Animals that live in the water environment are hurt and possibly killed. Some fish can only tolerate a certain amount of acid before dying. The more acid rain that falls, the life in the bodies of water decreases. Furthermore, animals that eat prey that is affected will be killed because they will be consuming acid.
