Hg, Cd, Pb, Cu, Ni, Cu and natural radionuclides (
238 U,
232 Th and
210 Po) (Kanter
2018; Stewart et al. 2005). Liu et al. (2015) and Cang (2004) found significant levels
of heavy metal(loid)s in soil from livestock and poultry operations. In many
countries, use of biomedical wastes as manure is also a chief source of soil pollution
(Shankar and Shikha 2017).
16.2.2.5 Miscellaneous Sources
Nuclear testing laboratories and industries are the prime sources of radioactive
substances (
106 Rh,
131 I,
140 Ln,
144 Ce,
44 Ru,
106 Ru and
140 Ba) in the soil (Jadiyappa
2018). Long-term deposition of radionuclides in soil emits gamma radiation which is
harmful for the health of soil living organisms (Jadiyappa 2018). The excreta of
animals, birds and humans are also one of the contributory sources of soil pollution
by biological agents (Clark 2014). In the developing countries, wastewater irrigation, wrong methods of agricultural practices and application of animal manures
constitute serious soil pollution problems (Alloway 2013). Military and warfare
activities accustom non-degradable weapons of destruction and chemicals (remains
of ammunitions, landmines, leftover chemicals, radioactive and biological toxic
agents) that persist in the affected soils for centuries after the end of the conflict
(FAO and ITPS 2015).
16.3 Major Pollutants in Soil
Anthropogenic sources are the main drivers of wide range of organic as well as
inorganic pollutants in the soil. Pollutants based on their chemical characteristics are
categorized into organic and inorganic forms (Fig. 16.3).
16.3.1 Inorganic Pollutants
Small- and large-scale industries mainly associated with textiles, glass, rubber,
chemicals, tanneries, pharmaceuticals, detergent and soap production are the major
contributors of salts (mainly NaCl) produced in the world today (Fig. 16.3). Inorganic pollutants mainly include radionucleotides, non-metals, heavy metals and
metalloids (Fig. 16.3). Heavy metal(loid)s refer to the group of metals and metalloids
with high atomic density > 4.5 g cm
À3 (Hawkes et al. 1997). Heavy metal(loid)s are
further categorized into two main groups: (1) elements such as molybdenum (Mo),
Ni, Zn, Cu, iron (Fe) and magnesium (Mg), which are essential to life and
ecosystems but are noxious to plants and animals when their concentrations exceed
certain threshold levels (Buchmann 2008), and (2) elements such as As, Cd, Hg, Cr
and Pb, which do not pose any significant role in any biochemical processes, but
their presence alters the soil quality and normal metabolic functioning in living
beings (Edelstein and Ben-Hur 2018; Patinha et al. 2018).
Radionuclides in soil occur in three different forms, viz. primordial, cosmogenic
and man-made radionuclides (United States Environmental Protection Agency
16 Causes, Effects and Sustainable Approaches to Remediate Contaminated Soil
457
238 U,
232 Th and
210 Po) (Kanter
2018; Stewart et al. 2005). Liu et al. (2015) and Cang (2004) found significant levels
of heavy metal(loid)s in soil from livestock and poultry operations. In many
countries, use of biomedical wastes as manure is also a chief source of soil pollution
(Shankar and Shikha 2017).
16.2.2.5 Miscellaneous Sources
Nuclear testing laboratories and industries are the prime sources of radioactive
substances (
106 Rh,
131 I,
140 Ln,
144 Ce,
44 Ru,
106 Ru and
140 Ba) in the soil (Jadiyappa
2018). Long-term deposition of radionuclides in soil emits gamma radiation which is
harmful for the health of soil living organisms (Jadiyappa 2018). The excreta of
animals, birds and humans are also one of the contributory sources of soil pollution
by biological agents (Clark 2014). In the developing countries, wastewater irrigation, wrong methods of agricultural practices and application of animal manures
constitute serious soil pollution problems (Alloway 2013). Military and warfare
activities accustom non-degradable weapons of destruction and chemicals (remains
of ammunitions, landmines, leftover chemicals, radioactive and biological toxic
agents) that persist in the affected soils for centuries after the end of the conflict
(FAO and ITPS 2015).
16.3 Major Pollutants in Soil
Anthropogenic sources are the main drivers of wide range of organic as well as
inorganic pollutants in the soil. Pollutants based on their chemical characteristics are
categorized into organic and inorganic forms (Fig. 16.3).
16.3.1 Inorganic Pollutants
Small- and large-scale industries mainly associated with textiles, glass, rubber,
chemicals, tanneries, pharmaceuticals, detergent and soap production are the major
contributors of salts (mainly NaCl) produced in the world today (Fig. 16.3). Inorganic pollutants mainly include radionucleotides, non-metals, heavy metals and
metalloids (Fig. 16.3). Heavy metal(loid)s refer to the group of metals and metalloids
with high atomic density > 4.5 g cm
À3 (Hawkes et al. 1997). Heavy metal(loid)s are
further categorized into two main groups: (1) elements such as molybdenum (Mo),
Ni, Zn, Cu, iron (Fe) and magnesium (Mg), which are essential to life and
ecosystems but are noxious to plants and animals when their concentrations exceed
certain threshold levels (Buchmann 2008), and (2) elements such as As, Cd, Hg, Cr
and Pb, which do not pose any significant role in any biochemical processes, but
their presence alters the soil quality and normal metabolic functioning in living
beings (Edelstein and Ben-Hur 2018; Patinha et al. 2018).
Radionuclides in soil occur in three different forms, viz. primordial, cosmogenic
and man-made radionuclides (United States Environmental Protection Agency
16 Causes, Effects and Sustainable Approaches to Remediate Contaminated Soil
457