96
D. J. Sarkar et al.
9.7 kg/person) is low as compared to USA (109 kg/person) and Europe (65 kg/person)
(Tata Strategic 2014). However, the Asian countries are suffering most in generating
mismanaged plastic waste, and the load of plastic waste in their natural ecosystem is
considered to be huge (Jambeck et al. 2015). Thus, it is highly likely that microplastics abundance in the Asian rivers systems is enormous as compared to many other
global river systems. A recent predictive model has highlighted that among the rivers,
Yangtze River of China contributes the highest annual plastic debris discharge (0.33
million tonnes per year) to marine system followed by Ganga River of Indian subcontinent (0.12 million tonnes per year) (Lebreton et al. 2017; Mukherjee et al. 2020;
Singh et al. 2019). The institute, ICAR-Central Inland Fisheries Research Institute,
India, explored the abundance of MPs in Ganga River sediment at the eastern part
of the country and found that MPs are abundant in the river sediment in the mass
range of 11.48–63.79 ng/g sediments (Sarkar et al. 2019; Deka et al. 2015). Similarly,
various literature report presence of MPs in marine as well as terrestrial ecosystems,
and it is now a well-established fact that MPs are ubiquitously distributed around
the world. The occurrence of MPs has been widely studied in the marine ecosystem,
including estuaries, lagoon, seafloor, etc. (Cole et al. 2011). However, their abundance study and fate analysis in the freshwater system, especially riverine ecosystem,
are still in the infancy stage covering only few major rivers of the world (Klein et al.
2015; Horton et al. 2017; Lebreton et al. 2017; Wang et al. 2017; Sarkar et al. 2019).
It was reported that only 3.7% of the total publications on MPs contains the term
‘freshwater’ (Lambert and Wagner 2018).
4.2 Source and Transport of Microplastics in River
MPs including other plastic fragments enter into the riverine ecosystem through various routes, and it was observed that the routes differ with different geographical
regions. On the basis of source, the MPs can be classified into two categories, viz.
primary MPs and secondary MPs (Fig. 4.1). Primary MPs are produced industrially
and utilised either as pellets for further industrial process or in the cosmetic products, viz. facial scrub, tooth paste, etc. (van Wezel et al. 2016; Kumar 2016). The
amount of MPs beads used in cosmetics for use in European countries during 2012
was estimated to be 4000 ton (Gouin et al. 2015). However, the primary MPs only
represent a little fraction of estimated environmental plastic load, and further, this
fraction can be easily addressed, and their use can be minimised (Lassen et al. 2015).
The main cause of concern is secondary MPs which are produced in the environment
during disintegration of bigger plastic particles in small fragments or debris. The
source of secondary MPs includes improper management of plastic waste, discarded
to the environment directly or disposed in landfills and ultimately reaching aquatic
ecosystem through wind or water-driven transport (Gouin et al. 2015). Further, industrial abrasion process, erosion of synthetic paints and car tyres are important sources
of MPs (Lassen et al. 2015; Patel et al. 2019b). Another most important source of
D. J. Sarkar et al.
9.7 kg/person) is low as compared to USA (109 kg/person) and Europe (65 kg/person)
(Tata Strategic 2014). However, the Asian countries are suffering most in generating
mismanaged plastic waste, and the load of plastic waste in their natural ecosystem is
considered to be huge (Jambeck et al. 2015). Thus, it is highly likely that microplastics abundance in the Asian rivers systems is enormous as compared to many other
global river systems. A recent predictive model has highlighted that among the rivers,
Yangtze River of China contributes the highest annual plastic debris discharge (0.33
million tonnes per year) to marine system followed by Ganga River of Indian subcontinent (0.12 million tonnes per year) (Lebreton et al. 2017; Mukherjee et al. 2020;
Singh et al. 2019). The institute, ICAR-Central Inland Fisheries Research Institute,
India, explored the abundance of MPs in Ganga River sediment at the eastern part
of the country and found that MPs are abundant in the river sediment in the mass
range of 11.48–63.79 ng/g sediments (Sarkar et al. 2019; Deka et al. 2015). Similarly,
various literature report presence of MPs in marine as well as terrestrial ecosystems,
and it is now a well-established fact that MPs are ubiquitously distributed around
the world. The occurrence of MPs has been widely studied in the marine ecosystem,
including estuaries, lagoon, seafloor, etc. (Cole et al. 2011). However, their abundance study and fate analysis in the freshwater system, especially riverine ecosystem,
are still in the infancy stage covering only few major rivers of the world (Klein et al.
2015; Horton et al. 2017; Lebreton et al. 2017; Wang et al. 2017; Sarkar et al. 2019).
It was reported that only 3.7% of the total publications on MPs contains the term
‘freshwater’ (Lambert and Wagner 2018).
4.2 Source and Transport of Microplastics in River
MPs including other plastic fragments enter into the riverine ecosystem through various routes, and it was observed that the routes differ with different geographical
regions. On the basis of source, the MPs can be classified into two categories, viz.
primary MPs and secondary MPs (Fig. 4.1). Primary MPs are produced industrially
and utilised either as pellets for further industrial process or in the cosmetic products, viz. facial scrub, tooth paste, etc. (van Wezel et al. 2016; Kumar 2016). The
amount of MPs beads used in cosmetics for use in European countries during 2012
was estimated to be 4000 ton (Gouin et al. 2015). However, the primary MPs only
represent a little fraction of estimated environmental plastic load, and further, this
fraction can be easily addressed, and their use can be minimised (Lassen et al. 2015).
The main cause of concern is secondary MPs which are produced in the environment
during disintegration of bigger plastic particles in small fragments or debris. The
source of secondary MPs includes improper management of plastic waste, discarded
to the environment directly or disposed in landfills and ultimately reaching aquatic
ecosystem through wind or water-driven transport (Gouin et al. 2015). Further, industrial abrasion process, erosion of synthetic paints and car tyres are important sources
of MPs (Lassen et al. 2015; Patel et al. 2019b). Another most important source of