Groundwater is the largest source of freshwater. Groundwater is water contained in the pore spaces between oil and rocks below the Earths surface. The supply of Groundwater is larger than all the streams and lakes of the world combined. Groundwater pollution is a serious problem because many people depend on groundwater for their drinking water. Car pollution of soil and groundwater comes from various sources, such as runoff of used motor oil, improperly disposed car batteries, and leaking gasoline tanks at gas stations.
About 300 million gallons of used motor oil is created each year in the United States. People who change their own oil pour eighty million gallons on roads, driveways, yards or into sewers and put forty two million gallons into the trash where it is collected taken to landfills. Used oil makes up the largest single source of oil pollution in our nations streams and rivers. According to EPA the oil from just one change is enough to contaminate a million gallons of freshwater.
The oil can seep into streams and lakes and groundwater and contaminate them. Oil drainage has been reported to account for more than forty percent of the total oil pollution of our nations harbors and waterways. The Association of Government Oil Recycling Officials states that fifty percent of all oil generated in the United States is lost through dumping, land spreading, incineration, or road oiling. One pint of oil can produce a slick one acre. One part of oil per million parts of water (ppm) can cause foul taste and odor problems in drinking water.
Thirty five ppm can produce a visible slick on the water that can damage aquatic life, and fifty ppm can foul the waste water treatment process.
Gas stations usually store their gasoline in underground tanks to avoid the risk of explosions and or fires. Since the tanks are underground, these leaks are hard to detect. The problem with underground storage tanks is that after about twenty years, they tend to spring leaks that contaminates the groundwater below. Many leaks were not discovered until people living near gas stations found their water spoiled with gasoline. Each station will have at least one tank for each type of gasoline, which amounts to millions of underground storage tanks across the United States. In 1984, federal legislation tried to detect these leaks and required service stations to monitor for leaks of underground storage tank at a gas station polluting the groundwater below.
Progress has been made in the recycling of car batteries in recent years. A while ago batteries were often discarded as trash and ended up in landfills, where lead and acid from the batteries could be carried away by water seeping into the soil. This seeping contaminated the soil and the groundwater below. Some battery companies only use recycled lead and plastics in their new batteries construction According to Battery Council Internationals 1996 Recycling Rate Study, the recycling rate for automobile batteries reached ninety five percent. As recently as 1986, car batteries were responsible for an estimated 138,000 tons of lead, or sixty five percent of all lead discarded in solid waste. This rate is larger than the recycling rates for all other consumer products including aluminum cans, newspapers, and glass bottles.
Groundwater is water that is found underground in cracks and spaces in soil, sand, and rocks. The place where water fills these spaces is called the saturated zone. The top of this zone is called the water table. The top of the water is the table. The water table may be deep or shallow, and may rise or fall depending on many factors including heavy rains or melting snow are included. The water table may be only a foot below the grounds surface or it may be hundreds of feet down. Groundwater can be found almost everywhere. These factors may cause the water table to rise or fall. The speed that groundwater flows at depends on the size of the spaces in the soil or rock and how well the spaces are connected. Groundwater is stored in layers of soil, sand, and rocks called aquifers. Aquifers typically are made of gravel, sand, sandstone, or fractured rock. Water in between or in the aquifers is brought to the surface naturally through a spring or can be brought up into lakes and or streams. These materials are permeable because they have large connected spaces that allow water to flow through. Groundwater can also be extracted through a well drilled into an aquifer.
A well is a pipe in the ground that fills up with groundwater. This water then can be brought to the surface by a pump. Some wells do not need a pump because natural pressures force the water up to the top of the well. Shallow wells may go dry if the water table falls below the bottom of the well. More than two million cubic miles of fresh water is stored in the earth, and half of that is within a half mile of the surface. Groundwater is also one of our most important sources of irrigation. The largest use for groundwater is to irrigate crops. Fifty percent of the United States population depends on groundwater for drinking every day. When rain falls to the ground, the water does not stop moving. Some of it moves along the surface in streams or lakes, some of it is used by plants, some of it evaporates and returns to the atmosphere, and some of it sinks into the ground. In some areas of the world, people face serious water shortages because groundwater is used faster than it is naturally filled. Groundwater supplies are filled by rain and or snow. Groundwater is used for drinking water by more than fifty percent of the people in the United States, including most everyone who lives in rural areas. If groundwater becomes polluted, it will no longer be safe to drink. In other areas groundwater is polluted by humans pollutions. Material above the aquifer is permeable and can cause pollutants to sink into the groundwater. Groundwater can be polluted by landfills, septic tanks, leaky underground gas tanks, and from overuse of fertilizers and pesticides.
It is important to learn to protect groundwater. About twenty two percent of all freshwater withdrawals, thirty seven percent of agricultural use, thirty seven percent of the public water supply withdrawals, fifty one percent of all drinking water for the total population, and ninety nine percent of drinking water for the rural population. Contaminated groundwater is very difficult and expensive to clean up and very hard to clean up. Solutions can be found easier after groundwater has already been contaminated, but the solutions are not easy. Pollution prevention conservation methods were created to protect important groundwater supplies from being contaminated in the first place. Many have switched to phosphate free detergents and other less polluting household products. Many steps are being taken to keep pollutants from reaching groundwater supplies. Pollution control measures like as the Clean Water Act have been a big part of the protection of drinking water suppchemicals.
Since groundwater is an important resource, it is important to protect it. Protecting the quantity of groundwater is easy. Groundwater is available in very limited quantities. Groundwater is also one of the most important sources of irrigation water. Groundwater is basically a safe source of drinking water, but there are rumors that contamination may increase as toxins dumped on the ground in the past make their way into groundwater supplies and collections. By reducing the amount of water that is used, water supplies will last a lot longer.
Compounds from the surface can move through the soil and end up in the groundwater. Pollutants that contaminate groundwater are probably the same pollutants that contaminate surface water. Road salt, toxic materials from mining sites, and used motor oil can also seep into groundwater. Drinking contaminated groundwater can have serious health effects. Poisoning may be caused by toxins that have seeped into wells and other water supplies. Diseases like hepatitis and dysentery may be caused by contamination from septic tank waste. It is possible for untreated waste from septic tanks and toxic chemicals from underground storage tanks to contaminate groundwater.
Groundwater contamination occurs when man-made products like gasoline, oil, road salts, and other chemicals get into the groundwater and cause it to become unsafe and unfit for human use. Some of the major sources of these products are storage tanks, septic systems, hazardous waste sites, landfills, and the use of road salts, and chemicals. Storage tanks may contain gasoline, oil, chemicals, or other types of harmful liquids and they can either be above or below ground. An estimated ten million storage tanks are buried in the United States. Over time the tanks can corrode and crack and leaks can develop. If the contaminants leak out and get into the groundwater, groundwater contamination can occur.
Septic systems are another serious contamination source. Septic systems are for homes, offices or other buildings that are not close to a city sewer system. Septic systems are designed to slowly drain away human waste underground at a slow, harmless rate. In the United States today, there are over 20,000 known abandoned and uncontrolled hazardous waste sites. The numbers grow every year. Hazardous waste sites can lead to groundwater contamination. A system that is not properly designed, located, constructed, or maintained,, can leak bacteria, viruses, household chemicals, and other contaminants into the groundwater causing very serious problems. If a leak happens, these contaminants can eventually make their way down through the soil and into the groundwater. There are barrels or other containers laying around that are full of hazardous materials even more contamination can and will occur.
Landfills are supposed to have a protective bottom layer to prevent contaminants from getting into the water. If there is no layer or it is cracked, contaminants from the landfill can find their way down into the groundwater. Landfills are another major source of contamination. Landfills are the places that our garbage is taken to be buried. The use of road salts and chemicals will also lead to groundwater contamination. The ice melts and the salt gets washed off the roads and eventually end up in the water. Road salts are used in the winter to put melt ice on roads to keep cars from sliding around. When rain falls, the chemicals get washed into the ground and eventually end up in the groundwater. Chemicals include products used on lawns and farm land to kill weeds and insects and to fertilize the plants. We also have to remember that groundwater is part of the Hydrologic Cycle. When the Hydrologic Cycle is contaminated, it can contaminate other parts of the cycle, like air or surface water, and can eventually get into the groundwater.