Leachate
Leachate is the liquid formed when waste breaks
down in the landfill and water filtersthrough that
waste. This liquid is highly toxic and can pollute
land, ground water and waterways.
•
Green house gases
High levels of methane gas and CO2 are
generated by the rotting rubbish in the
ground.These are greenhouse gases, which
contribute greatly to the process of global
warming.
Direct
discharge of
agricultural
and industrial
waste to soil:
Pesticides and fertilizers used on crops fed to animals are a
major contributor to landpollution. Additionally, use of artificial
fertilizers in place of manure can eventuallydeplete soils,
making them lose their ability to hold water and makes them
subject toerosion.
Improper disposal of highly toxic industrial/chemical waste can
severely pollutethe soil. For example, the storage of toxic
wastes in landfills can result in the seepage ofthe waste into the
soil. This waste can go on to pollute groundwater as well.
Chemicalpesticides contain several hazardous substances.
Inorganic
toxic
compounds:
Inorganic residues in industrial waste cause serious
problems as regards their disposal. Theycontain metals
which have high potential for toxicity.
• Industrial activity also emits large amounts of arsenic
fluorides and Sulphur dioxide (SO2).
• Fluorides are found in the atmosphere from
superphosphate, phosphoric acid, aluminium,steel and
ceramic industries.
• Sulphur dioxide emitted by factories and thermal plants
may make soils very acidic.These compounds cause leaf
injury and destroy vegetation.
Tests of
nuclear
weapons:
Underground nuclear testing is the test detonation of
nuclear weapons that is performedunderground with no
release of radioactive materials to the atmosphere.If
radioactive substances adsorbed in the soil they
adversely affect the diversity andabundance of soil
fauna. Their radioactivity could also disturb nutrient
cycling withinecosystems through the reduced density of
soil arthropods and also lead to decompose leaf
Sewage and
sewage
sludge:
Soil pollution is often caused by the uncontrolled disposal of
sewage and sewage sludge.Irrigation with sewage water causes
profound changes in the irrigated soils. Sewage irrigationinclude
-
physical changes like leaching, changes in humus content, and
porosity etc.,
-
chemical changes like soil reaction, salinity, quantity and
availability of nutrients likenitrogen, potash, phosphorus,
etc.Sewage sludge is a mud-like residue resulting from wastewater
treatment.
Sewage sludgepollutes the soil by accumulating the metals like lead,
nickel, zinc, cadmium, etc. It alsocontains pathogens such as viruses
and bacteria which affect the plant growth.
Heavy metal
pollutants:
Heavy metals are elements having a density greater than
5g/cm³ in their elemental form.They mostly find specific
absorption sites in the soil where they are retained very
stronglyeither on the inorganic or organic colloids. They
are widely distributed in the environment,soils, plants,
animals and in their tissues. These are essential for
plants and animals in traceamounts
Main sources of heavy metals in soil areIndustryAgriculture (fertilizers,
applying lime, irrigation)Household and industrial solid waste storageBurning of
the fossil fuelUse of mobile vehiclesHeavy metals exhibit toxic effects towards
soil biotaby affecting key microbial processes and decrease the number and
activity of soilmicroorganisms.Even low concentration of heavy metals may
inhibit the physiological metabolism ofplant. Uptake of heavy metals by
plantsand subsequent accumulation along the food chain is a potential threat to
animal andhuman health
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