Soil pollution, health effect of the soil pollution

Pollution of the soil

What Is Soil Pollution?

What Is Soil Pollution?

Soil pollution results from the build up of contaminants, toxic compounds, radioactive materials, salts, chemicals and cancer-causing agents. The most common soil pollutants are hydrocarbons, heavy metals (cadmium, lead, chromium, copper, zinc, mercury and arsenic), herbicides, pesticides, oils, tars, PCBs and dioxins.

What Is Soil Pollution?

Until the 1970s, there was little talk of soil pollution and its devastating effects. In the 1980s, the U.S. Superfund was created to set guidelines for the handling of hazardous material and soil contamination cleanup. Today there are more than 200,000 sites awaiting EPA soil cleanup, which is very expensive and labor-intensive work. Even a small cleanup project can cost $10,000, while larger areas require millions of dollars to clean it up for future use.

What Is Soil Pollution?

Following WWII and Vietnam, scientists discovered high incidences of mutation, miscarriage, mental defects, cancer and sickness in areas where nuclear warheads had been dropped. Food shortages also alerted officials that something was seriously wrong with the local soil. DDT and Dioxin were two of the worst pollutants from war aftermath.

In some cases, agricultural processes cause soil pollution. High levels of radionuclides like nitrogen and phosphorus can be found surrounding farm centers containing high population densities of livestock. Pesticides applied to plants can also seep into the ground, leaving lasting effects. Heavy metals can arrive in the soil by using polluted water to wet crops and by using mineral fertilizers.

Causes of Soil Pollution

Industry is to blame for some of the biggest soil-pollution disasters. Heavy metals come from iron, steel, power and chemical manufacturing plants that recklessly use the Earth as a dumping ground for their refuse. Plants that burn their waste on-site are guilty of releasing heavy metals into the atmosphere, which come to settle in the soil, thus leaving behind lasting effects for years to come. Even companies that try to dispose of their waste properly contribute to the problem when faulty landfills and bursting underground bins leach undesirable toxins into the soil.

Causes of Soil Pollution

Mining leaves a tremendous impact on the surrounding communities. The 2001 West Virginia Geological and Economic Survey found that people living near mines have a 70 percent higher risk of kidney disease, 64 percent higher risk for chronic obstructive pulmonary disease and a 30 percent higher risk of high blood pressure. "People in coal-mining communities need better access to health care, cleaner air, cleaner water, and stricter enforcement of environmental standards," concluded Michael Hendryx, Ph.D., associate director of the WVU Institute for Health Policy Research

Causes of Soil Pollution

Photo by Ellis Vener

Testing for Soil Pollution

o Photo by Ellis Vener

Before purchasing land for development or inhabiting, it's important to have a soil test performed to ensure a sound investment. A soil test can reveal the presence of nitrogen, phosphorus, potassium, sulphur, calcium, magnesium, iron, manganese, copper, zinc, boron, molybdenum and aluminum. It can also analyze soil acidity, electrical conductivity, organic matter, moisture content, and identify dangerous soil contaminants like benzene, petroleum hydrocarbons, xylene and toulene. Even if the soil is in fine condition for planting, landowners can use their soil tests to make more informed decisions regarding fertilizers and crop growing. Most people call in a local professional to do the job, although stores like Home Depot and Lowe's are now selling do-it-yourself mail-in kits as well.

Testing for Soil Pollution

Love Canal is perhaps the most famous case study of soil pollution. In the snowy winter of 1976, chemical waste began to seep above ground in school playgrounds and communities in Niagara Falls, New York. The area suffered high incidences of stillborn births, miscarriages and birth defects. Officials soon realized that there were over 400 toxic substances in the air, water and soil -- many of them cancerous. As it turns out, the area had been used as a chemical dumping ground for more than 22,000 tons of toxic waste at the turn-of-the-century, when no one was aware of the hazardous impact it could have decades later.

Case Studies of Soil Pollution

Another one of the most infamous cases of soil pollution happened in Chernobyl, a small town in Russia. A nuclear power plant exploded in April of 1986, which caused a sevenfold increase in birth defects, a marked increase in cancer that was passed down to future generations, livestock death and mutation and tainted agriculture. It's estimated that 40 percent of Chernobyl is still uninhabitable due to radiation contamination that is ten times the normal level in some places.

Case Studies of Soil Pollution

Ethiopia is filled with both air and soil pollution. The worst area is in Somalia's Ayaha valley near Hargeysa. To boost their economy, many farmers began using chemical fertilizers and pesticides to increase productivity without understanding the full ramifications. Over their war-torn years, metal drums holding 14,200 liters of chemicals like fenitrothion, malathion, diazionon and durban were punctured. As a result, land pollution has caused widespread famine and sickness.

Case Studies of Soil Pollution

China is a nation that is developing rapidly -- perhaps faster than safety permits. "It is estimated that nationwide 12 million tons of grain are polluted each year by heavy metals that have found their way into soil," Zhou Shengxian, director of the State Environmental Protection Administration, announced in July 2006. "Direct economic losses exceed 20 billion yuan (about 2.5 billion U.S. dollars). Soil pollution has worsened. According to incomplete statistics, about 150 million mu (10 million hectares) of arable land in China has been polluted."

Case Studies of Soil Pollution

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Impact of Soil Pollution

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"When old factories are relocated, they just dismantle the houses, carry away the machines and nothing else is left to be done. The land that used to be a production site either is turned into farmland or real estate. Few understand that this land has become sick," explains Zhao Qiguo of the Chinese Academy of Sciences' Institute of Soil Science.

Impact of Soil Pollution

People living near polluted land have higher incidences of migraines, nausea, fatigue, miscarriage and skin disorders. Long-term effects of pollution include cancer, leukemia, reproductive disorders, kidney and liver damage, as well as central nervous system failure. Children often suffer from developmental problems and weakened immune systems.

Impact of Soil Pollution

In addition to direct health effects, soil pollution also harms plants that feed Americans. Chemicals can sometimes absorb into food like lettuce and be ingested. Other times, the pollutants simply kill the plants, which has created widespread crop destruction and famine in other parts of the world. The entire ecosystem changes when new materials are added to the soil, as microorganisms die off or move away from contaminants.

Impact of Soil Pollution

Predators who feed off the microorganisms and worms in the polluted soil will also be affected. Researchers found that some species of birds -- like the Peregrine Falcon, the Brown Pelican and the Bald Eagle -- fell prey to DDT poisoning, which caused egg shells of future generations to thin. Mother birds would arrive home to omelets in their nests, as the thin shells could not support the weight of the incubating offspring. Mortality rates increased, nearly sending the birds to extinction.

Impact of Soil Pollution

If nothing is done to clean up soil pollution, water supplies could become contaminated, threatening the human species. Sudden fires or explosions will occur from underground landfill gases, pipelines and building structures may corrode and once beautiful regions will turn into cesspools, experts warn.

Impact of Soil Pollution

The conventional methods of soil pollution are very time-consuming and very costly. EPA officials excavate the soil to dispose of it elsewhere -- a band-aid for the problem, no doubt, but essential for toxic disasters in highly populated places. Soils can be aerated, heated up in a process called thermal remediation, contained with pavement or caps, extracted with an active electromechanical system or propagating the soil with microbes that will digest organic pollutants.

Treatment of Soil Pollution

New processes are being developed to combat the problem in a natural, less laborious way. By studying plants that grew naturally in toxic mines, scientist Chen Tongbin discovered that certain plants loved to eat heavy metals like arsenic, bronze, lead, zinc, cobalt and cadmium. The contaminants can then be retrieved from the plant's leaves and used in industrial materials. This safe and effective method isn't perfect, but it's a start.

Treatment of Soil Pollution

Naturally, prevention is the best cure for soil pollution. Most states have enacted tougher legislation to stop illegal dumping. For instance, one can expect five years in jail and a fine of $100,000 for soil pollution in Texas.

Prevention of Soil Pollution

Educating consumers about the dangers of littering, while encouraging recycling programs, is a good way to ensure everyone does their part to keep debris where it belongs. Consumers can also make a concerted effort to buy organic foods to demand that chemical pesticides aren't used on their foods.

Prevention of Soil Pollution

People who grow their own food can keep excess nitrogen and phosphorus out of the soil by choosing crops that do not need as many nutrients from the soil, by applying fertilizer during the growing season to replenish the soil, by shortening the grazing season / cattle density, by using organic compost, by keeping the surface moist and mulched, and by choosing fruiting crops like tomatoes, squash, peas and corn. Gardens should be situated away from old painted buildings and roadways. Outer leaves of lettuce should be discarded and all vegetables should be washed before eating.

Prevention of Soil Pollution

Over the years, stronger and more indestructible bins were created to store hazardous materials. Researchers will continue to look for ways to improve manufacturing and agricultural processes to avoid the need for toxic byproducts. Business leaders, miners and community officials will work together to reduce wastefulness and contaminants to keep the world a clean place for future generations.

Prevention of Soil Pollution

An other view: Soil Contaminmation

Excavation showing soil contamination at a disused gasworks.

Soil contamination

This type of contamination typically arises from the failure caused by corrosion of underground storage tanks (including piping used to transmit the contents), application of pesticides, percolation of contaminated surface water to subsurface strata, oil and fuel dumping, disposal of coal ash, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons, lead, polynuclear aromatic hydrocarbons (such as naphthalene and benzo(a)pyrene), solvents, pesticides, and other heavy metals. This occurrence of this phenomenon is correlated with the degree of industrialization and intensities of chemical usage.

Soil contamination or soil pollution is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment.

The concern over soil contamination stems primarily from health risks, from direct contact with the contaminated soil, vapors from the contaminants, and from secondary contamination of water supplies within and underlying the soil. Mapping of contaminated soil sites and the resulting cleanup are time consuming and expensive tasks, requiring extensive amounts of geology, hydrology, chemistry, computer modeling skills, and GIS in Environmental Contamination, as well as an appreciation of the history of industrial chemistry.

Soil contamination or soil pollution is caused by the presence of xenobiotic

(human-made) chemicals or other alteration in the natural soil environment.

It is in North America and Western Europe that the extent of contaminated land is most well known, with many of countries in these areas having a legal framework to identify and deal with this environmental problem; this however may well be just the tip of the iceberg with developing countries very likely to be the next generation of new soil contamination cases.

Soil contamination or soil pollution is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment.

The immense and sustained growth of the People's Republic of China since the 1970s has exacted a price from the land in increased soil pollution. The State Environmental Protection Administration believes it to be a threat to the environment, to food safety and to sustainable agriculture. According to a scientific sampling, 150 million mi (100,000 square kilometers) of China’s cultivated land have been polluted, with contaminated water being used to irrigate a further 32.5 million mi (21,670 square kilometers) and another 2 million mi (1,300 square kilometers) covered or destroyed by solid waste. In total, the area accounts for one-tenth of China’s cultivatable land, and is mostly in economically developed areas. An estimated 12 million tonnes of grain are contaminated by heavy metals every year, causing direct losses of 20 billion yuan (US$2.57 billion).

Soil contamination or soil pollution is caused by the presence of xenobiotic

(human-made) chemicals or other alteration in the natural soil environment.

This type of contamination or pollution typically arises from failure due to corrosion of underground storage tanks or of the piping associated with them, historical disposal of coal ash, application of pesticides, percolation of contaminated surface water to subsurface strata, oil and fuel dumping, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons, solvents, lead, pesticides, and other heavy metals. The occurrence of this phenomenon is correlated with the degree of industrialization and intensities of chemical usage.

Causes

Historical deposition of coal ash used for residential, commercial, and industrial heating, as well as for industrial processes such as ore smelting, is a common source of contamination in areas that were industrialized before about 1960. Coal natually concentrates lead and zinc during its formation, as well as other heavy metals to a lesser degree. When the coal is burned, most of these metals become concentrated in the ash (the principal exception being mercury). Coal ash and slag may contain sufficient lead to qualify as a "characteristic hazardous waste", defined in the USA as containing more than 5 mg/L of extractable lead using the TCLP procedure.

Causes

In addition to lead, coal ash typically contains variable but significant concentrations of polynuclear aromatic hydrocarbons (PAHs; e.g., benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(cd)pyrene, phenanthrene, anthracene, and others). These PAHs are known human carcinogens and the acceptable concentrations of them in soil are typically around 1 mg/kg. Coal ash and slag can be recognized by the presence of off-white grains in soil, gray heterogeneous soil, or (coal slag) bubbly, vesicular pebble-sized grains.

Causes

Treated sewage sludge, known in the industry as biosolids, has become controversial as a fertilizer to the land. As it is the byproduct of sewage treatment, it generally contains contaminants such as organisms, pesticides, and heavy metals than other soil.

Causes

Contaminated or polluted soil directly affects human health through direct contact with soil or via inhalation of soil contaminants which have vaporized; potentially greater threats are posed by the infiltration of soil contamination into groundwater aquifers used for human consumption, sometimes in areas apparently far removed from any apparent source of above ground contamination.

Health effects

Health consequences from exposure to soil contamination vary greatly depending on pollutant type, pathway of attack and vulnerability of the exposed population. Chronic exposure to chromium, lead and other metals, petroleum, solvents, and many pesticide and herbicide formulations can be carcinogenic, can cause congenital disorders, or can cause other chronic health conditions. Industrial or man-made concentrations of naturally-occurring substances, such as nitrate and ammonia associated with livestock manure from agricultural operations, have also been identified as health hazards in soil and groundwater.

Health effects

Chronic exposure to benzene at sufficient concentrations is known to be associated with higher incidence of leukemia. Mercury and cyclodienes are known to induce higher incidences of kidney damage, some irreversible. PCBs and cyclodienes are linked to liver toxicity. Organophosphates and carbamates can induce a chain of responses leading to neuromuscular blockage.

Health effects

Many chlorinated solvents induce liver changes, kidney changes and depression of the central nervous system. There is an entire spectrum of further health effects such as headache, nausea, fatigue, eye irritation and skin rash for the above cited and other chemicals. At sufficient dosages a large number of soil contaminants can cause death by exposure via direct contact, inhalation or ingestion of contaminants in groundwater contaminated through soil.

Health effects

Not unexpectedly, soil contaminants can have significant deleterious consequences for ecosystems. There are radical soil chemistry changes which can arise from the presence of many hazardous chemicals even at low concentration of the contaminant species. These changes can manifest in the alteration of metabolism of endemic microorganisms and arthropods resident in a given soil environment. The result can be virtual eradication of some of the primary food chain, which in turn could have major consequences for predator or consumer species.

Ecosystem effects

Even if the chemical effect on lower life forms is small, the lower pyramid levels of the food chain may ingest alien chemicals, which normally become more concentrated for each consuming rung of the food chain. Many of these effects are now well known, such as the concentration of persistent DDT materials for avian consumers, leading to weakening of egg shells, increased chick mortality and potential extinction of species

Ecosystem effects

Effects occur to agricultural lands which have certain types of soil contamination. Contaminants typically alter plant metabolism, most commonly to reduce crop yields. This has a secondary effect upon soil conservation, since the languishing crops cannot shield the Earth's soil mantle from erosion phenomena. Some of these chemical contaminants have long half-lives and in other cases derivative chemicals are formed from decay of primary soil contaminants.

Ecosystem effects

Microbes can be used in soil cleanup

Cleanup options

Clean up or environmental remediation is analyzed by environmental scientists who utilize field measurement of soil chemicals and also apply computer models (GIS in Environmental Contamination) for analyzing transport[7] and fate of soil chemicals. There are several principal strategies for remediation:

Excavate soil and take it to a disposal site away from ready pathways for human or sensitive ecosystem contact. This technique also applies to dredging of bay muds containing toxins.

Cleanup options

Aeration of soils at the contaminated site (with attendant risk of creating air pollution)

Thermal remediation by introduction of heat to raise subsurface temperatures sufficiently high to volatize chemical contaminants out of the soil for vapour extraction. Technologies include ISTD, electrical resistance heating (ERH), and ET-DSPtm.

Bioremediation, involving microbial digestion of certain organic chemicals. Techniques used in bioremediation include landfarming, biostimulation and bioaugmentating soil biota with commercially available microflora.

Cleanup options

Extraction of groundwater or soil vapor with an active electromechanical system, with subsequent stripping of the contaminants from the extract.

Containment of the soil contaminants (such as by capping or paving over in place).

Phytoremediation, or using plants (such as willow) to extract heavy metals

Cleanup options

Let talk again about soil contamination and pollution

Soil Pollution Causes and Effects

Along with air and water pollution, soil pollution is an equally serious issue that the modern-day world is confronted with. For all those who are concerned about the soil pollution causes and effects, this article is a must-read.

Soil pollution!! One of the gravest problems existing on the earth today. Well, (on the earth?), the earth itself is getting contaminated and polluted! Collectively, aren't we all responsible for this? The conquest of utilizing land and soil resources and conducting experiments on it for our benefits is quite understandable, but it certainly is not at the cost of its health and wellness! Mankind has been trying out several different things and has made several arrangements in the soil, to make life happy and comfortable. However, how often have we thought about the contamination of soil? It's never too late in life, so I think this is the right time to know about all the important soil pollution causes and effects.

Soil Pollution Causes and Effects

Soil pollution is defined or can be described as the contamination of soil of a particular region. Soil pollution mainly is a result of penetration of harmful pesticides and insecticides, which on one hand serve whatever their main purpose is, but on the other hand bring about deterioration in the soil quality, thus making it contaminated and unfit for use later. Insecticides and pesticides are not to be blamed alone for soil pollution, but there are many other leading causes of soil pollution too. Let us have a look at some of them in the following text.

What is Soil Pollution?

Soil pollution is a result of many activities and experiments done by mankind which end up contaminating the soil. Here are some of the leading soil pollution causes:

Industrial wastes such as harmful gases and chemicals, agricultural pesticides, fertilizers and insecticides are the most common causes of soil pollution.

Ignorance towards soil management and related systems.

Unfavorable and harmful irrigation practices.

What Causes Soil Pollution?

Improper septic system and management and maintenance of the same.

Leakages from sanitary sewage. Acid rains, when fumes released from

industries get mixed with rains. Fuel leakages from automobiles, that get

washed away due to rain and seep into the nearby soil.

Unhealthy waste management techniques, which are characterized by release of sewage into the large dumping grounds and nearby streams or rivers.

What Causes Soil Pollution?

The intensity of all these causes on a local or regional level might appear very small and you may argue that soil is not harmed by above activities if done on a small scale! However, thinking globally, it is not your region or my place that will be the only sufferer of soil pollution. In fact, it is the entire planet and mankind that will encounter serious problems, as these practices are evident almost everywhere in the world. Want to know what are those problems which can turn more serious in the near future?

What Causes Soil Pollution?

The effects of pollution on soil are quite alarming and can cause huge disturbances in the ecological balance and health of living creatures on earth. Some of the most serious soil pollution effects are:

Decrease in soil fertility and therefore decrease in the soil yield. How can one expect contaminated soil to produce healthy crops?

Loss of soil and natural nutrients present in it. Plants also would not thrive in such soil, which would further result in soil erosion.

Disturbance in the balance of flora and fauna residing in the soil.

Increase in salinity of the soil, which therefore makes it unfit for vegetation, thus making it useless and barren.

What are the Effects of Soil Pollution?

Generally crops cannot grow and flourish in polluted soil. Yet, if some crops manage to grow, they would be poisonous enough to cause serious health problems in people consuming them.

Creation of toxic dust is another potential effect of soil pollution.

Foul smell due to industrial chemicals and gases might result in headaches, fatigue, nausea, etc., in many people.

Soil pollutants would bring in alteration in the soil structure, which would lead to death of many essential organisms in it. This would also affect the larger predators and compel them to move to other places, once they lose their food supply.

What are the Effects of Soil Pollution?

I hope the above discussion was enough to make you understand the severity of the soil pollution causes and effects. Soil pollution can be cured by transporting the contaminated soil layer to some remote place, thus making it once again fit for use. Harmful chemicals from the soil can also be removed by aerating it. These are just 'tentative solutions'. However, let us remember the proverb, 'prevention is better than cure', and follow proper a soil management system, maintain sewage systems, and avoid the overuse of fertilizers and pesticides in the soil. So let us begin the movement of soil pollution prevention from our own lands itself!!!

What are the Effects of Soil Pollution?

Past and present economic activities have often resulted in the pollution of the underlying soil where these activities take place.

Soil

The most common toxic soil pollutants include metals and their compounds, organic chemicals, oils and tars, pesticides, explosive and toxic gases, radioactive materials, biologically active materials, combustible materials, asbestos and other hazardous materials. These substances commonly arise from the disposal of industrial and domestic waste products in designated landfills or uncontrolled dumps.

Soil

Soil pollution by heavy metals 

Soil pollution by pesticides and organic contaminates 

Soil pollution by nitrates and phosphorus 

Soil pollution by artificial radionuclides 

Soil

The existence of unauthorised dumps is one of the environmental problems in Europe that deserves utmost attention. The remediation costs of polluted areas in Europe are roughly estimated at more than EUR 100 billion.

Soil

Heavy metals

Soil contamination by heavy metals, such as cadmium, lead, chromium, copper, zinc, mercury and arsenic, is a matter of great concern.

Heavy metals are present naturally in the soil, but their levels are increased by:

Heavy metals

• industry (non-ferrous industries, power plants, iron, steel and chemical industries);

• agriculture (irrigation with polluted water, use of mineral fertilisers)

• waste incineration;

• combustion of fossil fuels; and

• road traffic.

Heavy metals

Pollution of agricultural soils by heavy metals may lead to reduced yields and elevated levels of these elements in agricultural products, and thus to their introduction into the food chain.

Heavy metal deposits on grassland soils remain predominantly in the top few centimetres and are directly ingested with soil by grazing animals.

Heavy metals

Heavy metals are toxic and inhibit the soil's microorganic activity. Their concentration in the soil can remain for decades or even centuries.

Reduction of heavy metal emissions is the most direct way to decrease the atmospheric deposition of these elements and their build-up in the soil. Despite the great increase in traffic, for example, a reduction in lead emissions has been achieved through incentives to use unleaded petrol.

Heavy metals

Nevertheless, emissions of heavy metals from industrial plants in Central and Eastern Europe are still prevalent.

Heavy metals

Implementing complex measures that reduce soil acidification could more efficiently reduce heavy metals. On agricultural land, heavy metal quantities can be decreased by using low-metal content resources for fertilisers, replacing inorganic pesticides with organic products, and other similar methods.

Heavy metals

Nitrates and phosphorus

Nitrogen and phosphorus are elements essential to all forms of life and are therefore relevant to soil systems and food crops. Although they are important plant nutrients, excessive application may lead to nitrogen or phosphate saturation in the soil, and eventual contamination of the groundwater. The amount of leaching depends on the soil, the local climate and the style of crop management.

Nitrates and phosphorus

PhosphorusPhosphorus accumulates in the upper layer of soil in regions with high livestock densities. In soils saturated with phosphorus, especially those with shallow groundwater, high phosphorus concentration occurs in the upper groundwater layer and in surface water, resulting in eutrophication.

Nitrates and phosphorus

NitrogenThe problem of nitrate pollution is recognised internationally and is usually associated with intensive agriculture practices. Good agricultural practices that alleviate the problem are:

Nitrates and phosphorus

• the selection of crops that require fewer nutrients;

• a timely application of fertiliser (in the growing season);

• improved methods of manure application;

• shortening the length of the grazing season; and

• reducing the intensity of grassland use (by lowering cattle density).

Nitrates and phosphorus

Pesticides and organic contaminants

Pesticides pollute the soil directly by affecting the organisms that reside in it. Soil, however, can act as a vector for the pollution of surface water and groundwater. Organic pollutants enter the soil via atmospheric deposition, direct spreading onto land, contamination by wastewater and waste disposal.

Pesticides and organic contaminants

In addition to pesticides, organic contaminants include many other components, such as oils, tars, chlorinated hydrocarbons, PCBs and dioxins. There is such a wide variety of organic substances that their detection and monitoring in the soil is practically impossible.

Pesticides and organic contaminants

Pesticides (mainly fungicides, herbicides and insecticides) are used in agriculture to protect crops and to ensure a quality harvest. Persistent or mobile pesticides are especially dangerous, as are those that affect non-targeted organisms.

Pesticides and organic contaminants

The use of pesticides may lead to:

• destruction of the soil's micro-flora and fauna, leading to both physical and chemical deterioration;

• severe yield reduction in crops; and

• leaching of toxic chemicals into groundwater and potentially threatening drinking water resources.

Pesticides and organic contaminants

Some improvements in application and legislation may reduce the side effects of pesticides, such as:

• banning broad-spectrum and highly mobile pesticides;

• employing integrated pest-management;

• enforcing biological control; and

• developing biotechnologies.

Pesticides and organic contaminants

Primordial radionuclides are left over from the creation of the Earth. They typically have half-lives of hundreds of millions of years. Examples include uranium-235, uranium-238, thorium-232, and potassium-40. Primordial radionuclides end up in soil as part of the rock cycle, which includes weathering.

Tree or plant roots dig down into cracks in the earth, prying the rock apart and turning it into soil. Natural radioactivity in soil varies on soil type, mineral make up and density. Man-made activities, such as mining, may accelerate the movement of primordial radionuclides into soil.

Primordial Radionuclides

Radionuclides are continuously produced by bombardment of stable nuclides by cosmic rays, primarily in the atmosphere. These cosmogenic radionuclides can have long half-lives, but the majority have shorter half-lives than the primordial radionuclides. Cosmogenic radionuclides include carbon-14, tritium-3, and beryllium-7; worldwide, cosmic radiation is the primary source of these radionuclides.

Another way radionuclides become part of the soil is through natural cosmic radiation, radiation produced in outer space when heavy particles from other galaxies (nuclei of all known natural elements) bombard Earth.

Some of these radionuclides fall to Earth and are deposited on the soil.

Cosmogenic Radionuclides

The third way radionuclides enter the soil is through man-made activities, such as the fallout from atmospheric testing of nuclear weapons and radiological events like the Chernobyl accident. Deposition studies of these activities indicate that radioactive particles travel around the world on streams of air. The weight of the particle and weather determine how soon they fall to the ground. Sometimes a heavy rain will bring the radioactive particles to the ground quickly. Improper disposal of radioactive material also may contribute to radionuclides in the soil.

Radionuclides in the soil can move into the water, air and even our food supply. Many different agencies are involved in setting standards and monitoring to keep us safe.

Man-made Radionuclides and Activities

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