tiredness, insomnia, arthritis, hallucinations and dizziness. Chronic exposure of Pb
may cause intellectual retardation, birth faults, lunacy, autism, allergies, dyslexia,
weight loss, hyperactivity, paralysis, muscular weakness, brain injure, renal dent
and may even cause death [69, 70].
Cadmium (Cd)
Cd found naturally in ores jointly with Zn, Cu and Pb. Cd compounds are utilized
as stabilizers in PVC commodities, colour pigment, numerous alloys and, now most
frequently, in re-chargeable Ni-Cd batteries. Metallic Cd has chiefly been utilized as
an anticorrosion agent. Cd is also found as impurities in phosphate fertilizers. Cd is
associated with Pd minerals so Pd mining is a source of Cd in the groundwater [70].
Tobacco is the key source of Cd intake in smokers as tobacco plants, like other
vegetations, can take Cd from the soil [67]. High concentration of Cd causes renal
dysfunction, kidney damage and gastrointestinal disorder. Long term exposure of
Cd may also causes Cancer. Premature birth and reduced birth weights are the
problems that occur if Cd exposure is elevated during human pregnancy [71].
Chromium (Cr)
Chromium is a naturally found element in rocks minerals and very much persistent
in water sediments. Chromium is present in two oxidation states +3 and +6. Cr (+6)
is more toxic to Cr (+3) as its rate of adsorption is high [50]. The higher content of
Cr is found in ultramafic igneous rocks. Chromite is concentrated in the residues of
laterite which is underlying the ultramafic rocks. Industrial sources of Cr comprise
shielding metal coatings, metal alloys, magnetic tapes, paint pigments, rubber,
cement, paper, wood preservatives, leather tanning and metal plating [70].
Chromium based dyes are one of the chief source of contamination in soil and
groundwater. Chromium (VI) compounds are extremely noxious and carcinogenic
in nature. Chromium (III), in contrast, is vital nutritional supplement for animals
and humans and has a significant function in glucose metabolism [67]. Contact to
elevated values of chromium compounds in humans can direct to the reserve of
erythrocyte glutathione reductase, which in turn diminish the ability to reduce
methemoglobin to hemoglobin [72].
Nickel (Ni)
In aqueous chemistry Nickel is considered with Ni
2+ oxidation state. It substitutes
the iron in ferromagnesian igneous rock mineral. It coprecipitates with the oxides
iron and manganese. Ni is largely used industrial element for making stainless steel.
WHO (1993) prescribed 20 µg/l Ni as permissible limit for drinking purpose. It is
an essential trace element in lesser amount but uptake in of large quantity may
cause cancer in lungs, nose, larynx and prostate, respiratory failure, asthma, birth
defects, heart disorders and renal and skin diseases.
Mercury (Hg) [73]
The Hg amalgam cinnabar was applied in ancient cave painting for red colours, and
metallic Hg was recognized in early Greece where it was applied as a beauty
Water Pollutants: Sources and Impact on the Environment …
51
may cause intellectual retardation, birth faults, lunacy, autism, allergies, dyslexia,
weight loss, hyperactivity, paralysis, muscular weakness, brain injure, renal dent
and may even cause death [69, 70].
Cadmium (Cd)
Cd found naturally in ores jointly with Zn, Cu and Pb. Cd compounds are utilized
as stabilizers in PVC commodities, colour pigment, numerous alloys and, now most
frequently, in re-chargeable Ni-Cd batteries. Metallic Cd has chiefly been utilized as
an anticorrosion agent. Cd is also found as impurities in phosphate fertilizers. Cd is
associated with Pd minerals so Pd mining is a source of Cd in the groundwater [70].
Tobacco is the key source of Cd intake in smokers as tobacco plants, like other
vegetations, can take Cd from the soil [67]. High concentration of Cd causes renal
dysfunction, kidney damage and gastrointestinal disorder. Long term exposure of
Cd may also causes Cancer. Premature birth and reduced birth weights are the
problems that occur if Cd exposure is elevated during human pregnancy [71].
Chromium (Cr)
Chromium is a naturally found element in rocks minerals and very much persistent
in water sediments. Chromium is present in two oxidation states +3 and +6. Cr (+6)
is more toxic to Cr (+3) as its rate of adsorption is high [50]. The higher content of
Cr is found in ultramafic igneous rocks. Chromite is concentrated in the residues of
laterite which is underlying the ultramafic rocks. Industrial sources of Cr comprise
shielding metal coatings, metal alloys, magnetic tapes, paint pigments, rubber,
cement, paper, wood preservatives, leather tanning and metal plating [70].
Chromium based dyes are one of the chief source of contamination in soil and
groundwater. Chromium (VI) compounds are extremely noxious and carcinogenic
in nature. Chromium (III), in contrast, is vital nutritional supplement for animals
and humans and has a significant function in glucose metabolism [67]. Contact to
elevated values of chromium compounds in humans can direct to the reserve of
erythrocyte glutathione reductase, which in turn diminish the ability to reduce
methemoglobin to hemoglobin [72].
Nickel (Ni)
In aqueous chemistry Nickel is considered with Ni
2+ oxidation state. It substitutes
the iron in ferromagnesian igneous rock mineral. It coprecipitates with the oxides
iron and manganese. Ni is largely used industrial element for making stainless steel.
WHO (1993) prescribed 20 µg/l Ni as permissible limit for drinking purpose. It is
an essential trace element in lesser amount but uptake in of large quantity may
cause cancer in lungs, nose, larynx and prostate, respiratory failure, asthma, birth
defects, heart disorders and renal and skin diseases.
Mercury (Hg) [73]
The Hg amalgam cinnabar was applied in ancient cave painting for red colours, and
metallic Hg was recognized in early Greece where it was applied as a beauty
Water Pollutants: Sources and Impact on the Environment …
51