Page 172 - Soil Degradation, Conservation and Remediation

6.2 Sources of Soil Pollutants 161

Table 6.2 Hazardous waste generated by industries and businesses
Industries/manufacturer Waste type
Chemical manufacturers Acids and bases
Spent solvents
Reactive waste
Wastewater containing organic constituents
Printing industry Heavy metal solutions
Waste inks
Solvents
Ink sludges containing heavy metals

Petroleum refining industry Wastewater containing benzene and other
hydrocarbon
Sludge from refi ning process
Leather products manufacturing Toluene and benzene
Paper industry Paint waste containing heavy metals
Ignitable solvents
Construction industry Ignitable paint waste
Spent solvent
Strong acids and bases
Metal manufacturing Sludges containing heavy metals
Cyanide waste
Paint waste

In many countries, use of agrichemicals is highly regulated. Fertilizers and manures
cause soil pollution by introducing heavy metals and their compounds into the
soil. The heavy metals associated with some phosphate fertilizers are arsenic,
cadmium, manganese, uranium, vanadium, and zinc. Common phosphate fertilizers
are manufactured from rock phosphates, and the heavy metal contents of the raw
material depend on their source ores (Helal and Sauerbeck 1984 ). Poultry manure
and pig manure may pollute the soil with zinc, copper, and arsenic.
A pest is a living organism that degrades the health, value, utility, condition, or
amenity of another organism, a structure, or a place. Pest organisms can be
plants, fungi, algae, vertebrate or invertebrate animals, or microorganisms such
as bacteria, molds, slimes, and fungi. Pesticides are substances or organisms used to
eliminate, incapacitate, modify, inhibit growth of, or repel pests. They can be natural
or synthetic chemicals, mixtures of these, or living organisms that act as biological
control agents. According to the British Food and Environment Protection Act , 1985, a

pesticide is defined as any substance or preparation prepared or used for any of the

following purposes:
• Destroying organisms harmful to plants or to wood or other plant products

• Destroying undesired plants
• Destroying harmful creatures
Pesticides are divided into insecticides, fungicides, and herbicides according
to their target organisms. The use of pesticides in agriculture has been steadily
increasing during the recent decades.