Contaminated groundwater cannot cleanse itself why

Water Resources and Water Pollution

Life on planet Earth would be impossible without water. All life forms, from unicellular bacteria to multicellular plants and animals, contain water. Humans are composed of approximately 60 percent water by body weight and we depend on water, not only for our survival, but for our convenience: We drink it, cook with it, wash in it, travel on it, and use an enormous amount of it for agriculture, manufacturing, mining, energy, production, and waste disposal. Though 71% of the Earth’s surface is covered in water, only 0.024% of the overall water supply is available as liquid freshwater that is easily accessible. It is one of the most poorly managed resources, easily wasted and often polluted. The available freshwater is collected, purified and distributed in the hydrologic cycle, but this cycle is easily interrupted by overloading with pollution, reducing wetlands, and reducing forests.

We get water from groundwater and surface water. Groundwater is water that seeps into the ground between spaces in soil and gravel until it reaches impenetrable bedrock. One of the most important sources of freshwater. The top of the groundwater zone that moves up and down based on weather is the water table . The water table drops in level when humans remove water at a faster rate than it is replenished. Surface water is freshwater from precipitation and melted snow that flows into lakes, wetlands, rivers, and eventually into the oceans.

Water shortages are caused by many factors including dry climate and drought. In some places, the human population uses water at a faster rate than the water is replenished. 30% of the Earth’s land mass now experiences severe or extreme drought and 1 billion people lacked regular access to clean water for drinking, cooking, and washing.

Water Supplies

Aquifers, underground water supplies, are renewable as long as the groundwater doesn’t become contaminated and withdrawn too quickly. Most aquifers around the world, and in the largest food producing countries, are being used up quicker than their rate of replenishment. Dam and reservoir systems are used to capture and hold runoff water. The collected water can be released at need to control flooding, supply water for farming and cities, and to produce electricity. The use of dams and reservoirs has increased the amount of reliable surface runoff by one-third. Unfortunately, these systems also displace people, flood productive lands, and disrupt the ecological services rivers provide.

Tunnels, aqueducts, and underground pipes transfer runoff from dams and reservoirs to water-poor areas. These transfer systems can be wasteful and environmentally harmful by shrinking the water source as more is transferred to water-poor areas. Another option for freshwater is desalinization which involves removing salts from ocean or brackish water. Usually desalinization costs a lot because of the energy required; it also kills many marine organisms and creates salty wastewater, which is usually dumped in the ocean, increasing the salinity of the local ocean.

Sustainable Water Use

Cutting water waste is quicker and easier than trying to provide new freshwater supplies. Most water used is lost through evaporation, leaks, and other losses. One main reason for water wastage is the low cost to users with water costs usually being subsidized by governments. One way to sustainably use water is to cut water waste in irrigation. Most agriculture practices use flood irrigation that deliver more water than needed to the plants and loses up to 40% of water through runoff and evaporation. Drip irrigation and low-energy, precision sprinklers deliver less water, but target the plants better to insure that the water reaches the plants.

Other sustainable water use solutions are using water saving appliances in the home, especially the kitchen and bathroom. Using grey water (recycled water from the house, like shower water) to water lawns and gardens. Lining canals so that water is not lost on the way to irrigation ditches and only adding water when the soil requires it.

Ecological Services

Our water resources provide important ecological and economic services. These are particularly evident in the services provided by rivers. According to the Ecological Society of America, ecosystem (or ecological) services are processes by which the environment produces resources that we often take for granted. Although ecological systems support plants and animals, they also provide vital services to people that improve well-being. Ecosystems purify water and air, reduce flood and drought risks, provide food and fuel, and support recreation, to name a few of their many benefits. To ensure these valuable services continue, our natural areas must be healthy.

Natural ecosystems and the plants and animals within them provide humans with services that would be very difficult to duplicate. While it is often impossible to place an accurate monetary amount on ecosystem services, we can calculate some of the financial values. According to the Ecological Society of America, many of these services are preformed seemingly for "free," yet are worth many trillions of dollars, for example:

· Much of the Mississippi River Valley's natural flood protection services were destroyed when adjacent wetlands were drained and channels altered. As a result, the 1993 floods resulted in property damages estimated at twelve billion dollars partially from the inability of the Valley to lessen the impacts of the high volumes of water.

· Eighty percent of the world's population relies upon natural medicinal products. Of the top 150 prescription drugs used in the U.S., 118 originate from natural sources: 74 percent from plants, 18 percent from fungi, 5 percent from bacteria, and 3 percent from one vertebrate (snake species). Nine of the top 10 drugs originate from natural plant products.

· Over 100,000 different animal species — including bats, bees, flies, moths, beetles, birds, and butterflies — provide free pollination services. One third of human food comes from plants pollinated by wild pollinators. The value of pollination services from wild pollinators in the U.S. alone is estimated at four to six billion dollars per year.

In addition to the “services” listed above, our ecosystems provide the following critical services to us:

· protect people from the sun's harmful ultraviolet rays

· cycle and move nutrients

· detoxify and decompose wastes

· control agricultural pests

· maintain biodiversity

· generate and preserve soils and renew their fertility

· contribute to climate stability

· regulate disease carrying organisms

· pollinate crops and natural vegetation

Water Pollution

Water pollution is a global problem that varies in magnitude and type of pollutant from one region to another. Water pollutants come from both natural sources and human activities. Natural sources of pollution tend to be local concerns, but human-generated pollution is generally more widespread. Sources of water pollution are classified into two types, point source pollution and nonpoint source pollution. Point source pollution describes discharge pollutions into bodies of surface water at specific locations, such as drain pipes or ditches. Pollutants that enter bodies of water over large areas rather than at single point cause nonpoint source pollution , also called polluted runoff.

Agricultural practices, industrial facilities, and mining are the three main causes of water pollution and pollute the water with sediment and harmful chemicals. Water pollution can have harmful effects, often spreading infectious diseases. Fast moving streams and rivers have the ability to clean themselves of pollution through dilution and the breakdown of wastes with bacteria. This natural cleaning can stop if the rivers are over polluted. Lakes and reservoirs cannot clean themselves in the same manner and are more easily affected by pollution. These standing bodies of water can be susceptible to eutrophication, which is the nutrient enrichment of shallow bodies of water causing “blooms” of microorganisms reducing lake productivity and killing other organisms.

Pollutants, such as fertilizers, pesticides, and gasoline, can affect ground water and harm freshwater drinking supplies for many people. Preventing pollution of groundwater is the only effective way to keep groundwater safe since the standing water cannot easily cleanse itself of pollutants. In most developed countries, groundwater is purified and treated to meet government safe standards, but these purifying techniques aren’t available in all countries.

Besides freshwater, oceans are also becoming polluted. With 40% of the world’s population living near the coast, wetlands, estuaries, and coral reefs suffer from the most pollution. Most marine pollution, >80%, occurs from land pollution via agricultural and sewage runoff. Oil is also polluting the ocean. Most of these pollutants reach the ocean through tanker accidents and oil that escapes from offshore drilling rigs. Volatile organic hydrocarbons in the oil can kill many organisms on contact or tarlike balls of oil can cover seabirds and marine mammals, hindering their ability to fly or swim.

Dealing with Water Pollution

There are laws in place to help reduce water pollution by setting standards on how much chemical can be discharged into the water at a point source. Sewage treatment is also another way to reduce pollution. Primary sewage treatment is a physical process that uses screens and grit tanks to remove large floating objects and allows sediment to settle out of water column.

Secondary sewage treatment is a biological process in which aerobic bacteria remove as much as 90% of dissolved and biodegradable organic wastes. Conventional sewage treatment can be redesigned to remove toxic and hazardous chemicals, preventing them from being discharged into sludge or water. Also, homes and business could install composting toilet systems to reduce the amount of waste being treated at plants. The current shift in water pollution is away from removing pollution after the fact to stopping pollution from entering water in the beginning.