2. Pollution of the soil
What Is Soil Pollution?

3. 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, mer
cury and
arsenic), herbicides, pesticides, oils, tars, PCB
s and dioxins.

4. 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.

5. 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.

6. 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.

7. 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

8. Photo by Ellis Vener
o Photo by Ellis Vener

9. 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, magn
esium, 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.

10. 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.

11. 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.

12. 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.

13. 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."

14. MorgueFile.com
o MorgueFile.com

15. "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.

16. 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.

17. 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.

18. 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.

19. 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.

20. 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.

21. 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.

22. 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.

23. 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.

24. 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.

25. 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.

27. Excavation showing soil contamination at a disused
gasworks.

28. 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.

29. 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.

30. 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.

31. 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).

32. 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.

33. 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.

34. 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.

35. 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.

36. 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.

37. 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.

38. 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.

39. 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.

40. 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.

41. 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

42. 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.

43. Microbes can be used in soil cleanup

44. 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.

45.  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.

46.  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

49. 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.

50. 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.

51. 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.

52.  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.

53. 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?

54. 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.

55.  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.

56. 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!!!

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

58. 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.

59. Soil pollution by heavy metals
Soil pollution by pesticides and organic
contaminates
Soil pollution by nitrates and phosphorus
Soil pollution by artificial radionuclides

60. 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.

62. 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:

63. • 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.

64. 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.

65. 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.

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

67. 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.

69. 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.

70. Phosphorus
Phosphorus 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.

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

72. • 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).

74. 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.

75. 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.

76. 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.

77. 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.

78. 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.

79.  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.

80.  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.

81.  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.