140
P. Sahu
chlorate (ClO 3
− ) or fractionation of hypochlorite may possibly result in the formation of ClO 4
− radical. All the above-mentioned reactions are thermodynamically
favourable, but the major cause intended for not forming considerable amounts of perchlorate may be kinetic. It should be feasible to influence the formation of perchlorate
by providing the precursor ingredients and adequately energetic environments. With
the reference to a recent theory, it is suggested that, additionally, there is a probability
that lightning may show an important capacity to create some atmospherically produced perchlorate. Furthermore, ClO 4
− formation is also influenced by UV-mediated
photo-oxidation (Dasgupta et al. 2005). Another natural source of increased atmospheric ClO 4
− is volcanic eruptions (Furdui et al. 2018). Following its formation in
atmosphere, ClO 4
− returns to the earth’s surface in dissolved form along with precipitation. In arid and semi-arid regions, its rate of deposition is much more than its
rate of dissolution during precipitation, and therefore, with time, ClO 4
− is integrated
and becomes a part of specific geologic formations (Urbanski et al. 2001). Terrestrial
soil ClO 4
− concentrations ranging from10
−1 to 106 µg kg
−1 have been estimated
in the Atacama Desert (Chile), southwestern United States, southern Africa, United
Arab Emirates, northwestern China and Antarctica (Jackson et al.; Lybrand et al.
2016). The ClO 4
− accumulation in soils/caliche relies on its deposition rate and on
site-specific geologic, hydrologic and biogeochemical conditions (Cao et al. 2019).
Occasional precipitation in arid regions reduces the chances for ClO 4
− in potash
deposits to dissolve and migrate to groundwater. Therefore, ClO 4
− would remain
in these deposits in higher quantities than other locations with higher precipitation
(Srinivasan and Viraraghavan 2009).
6.3.1.2 Environmental Release of Natural ClO 4
− by Human Activities
The anthropogenic pathway of introduction of ClO 4
− into the environment is more
dominant than the geogenic sources. ClO 4
− containing products are the main anthropogenic sources for ClO 4
− contamination. For example, Colorado River water and
Lake Mead water are highly polluted by rocket fuel production unit in Henderson, Nevada, and it is a big anthropogenically ClO 4
− contaminated site. Paleogeochemical deposits of sodium nitrate and ClO 4
− of the Atacama Desert are considered as a rich source of naturally occurring ClO 4
− . Anthropogenic activities like
mining and application for agricultural and industrial purposes released ClO 4
− in the
environment. From 1830 onwards, Chilean nitrate was exported to the USA, France
and England for agricultural uses. But during World War I, consumption pattern of
Chilean nitrate is completely transformed from agricultural use towards gunpowder
and explosives production. As a consequence, the Chilean nitrate production raised
by many fold, almost upto 3 million tons, to meet the increased demand of explosives
during World War I and therefore, it is introduced into environment (Cao et al. 2019).
During the World War I, European countries and the USA together consumed about
97% of the total Chilean nitrate produced (Ericksen 1981; Wisniak and Garcés 2001).
Besides anthropogenic uses of Chilean nitrates, due to intensive agriculture in arid
and semi-arid environments, natural ClO 4
− accumulating in unsaturated areas can
P. Sahu
chlorate (ClO 3
− ) or fractionation of hypochlorite may possibly result in the formation of ClO 4
− radical. All the above-mentioned reactions are thermodynamically
favourable, but the major cause intended for not forming considerable amounts of perchlorate may be kinetic. It should be feasible to influence the formation of perchlorate
by providing the precursor ingredients and adequately energetic environments. With
the reference to a recent theory, it is suggested that, additionally, there is a probability
that lightning may show an important capacity to create some atmospherically produced perchlorate. Furthermore, ClO 4
− formation is also influenced by UV-mediated
photo-oxidation (Dasgupta et al. 2005). Another natural source of increased atmospheric ClO 4
− is volcanic eruptions (Furdui et al. 2018). Following its formation in
atmosphere, ClO 4
− returns to the earth’s surface in dissolved form along with precipitation. In arid and semi-arid regions, its rate of deposition is much more than its
rate of dissolution during precipitation, and therefore, with time, ClO 4
− is integrated
and becomes a part of specific geologic formations (Urbanski et al. 2001). Terrestrial
soil ClO 4
− concentrations ranging from10
−1 to 106 µg kg
−1 have been estimated
in the Atacama Desert (Chile), southwestern United States, southern Africa, United
Arab Emirates, northwestern China and Antarctica (Jackson et al.; Lybrand et al.
2016). The ClO 4
− accumulation in soils/caliche relies on its deposition rate and on
site-specific geologic, hydrologic and biogeochemical conditions (Cao et al. 2019).
Occasional precipitation in arid regions reduces the chances for ClO 4
− in potash
deposits to dissolve and migrate to groundwater. Therefore, ClO 4
− would remain
in these deposits in higher quantities than other locations with higher precipitation
(Srinivasan and Viraraghavan 2009).
6.3.1.2 Environmental Release of Natural ClO 4
− by Human Activities
The anthropogenic pathway of introduction of ClO 4
− into the environment is more
dominant than the geogenic sources. ClO 4
− containing products are the main anthropogenic sources for ClO 4
− contamination. For example, Colorado River water and
Lake Mead water are highly polluted by rocket fuel production unit in Henderson, Nevada, and it is a big anthropogenically ClO 4
− contaminated site. Paleogeochemical deposits of sodium nitrate and ClO 4
− of the Atacama Desert are considered as a rich source of naturally occurring ClO 4
− . Anthropogenic activities like
mining and application for agricultural and industrial purposes released ClO 4
− in the
environment. From 1830 onwards, Chilean nitrate was exported to the USA, France
and England for agricultural uses. But during World War I, consumption pattern of
Chilean nitrate is completely transformed from agricultural use towards gunpowder
and explosives production. As a consequence, the Chilean nitrate production raised
by many fold, almost upto 3 million tons, to meet the increased demand of explosives
during World War I and therefore, it is introduced into environment (Cao et al. 2019).
During the World War I, European countries and the USA together consumed about
97% of the total Chilean nitrate produced (Ericksen 1981; Wisniak and Garcés 2001).
Besides anthropogenic uses of Chilean nitrates, due to intensive agriculture in arid
and semi-arid environments, natural ClO 4
− accumulating in unsaturated areas can