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7 Bioremediation of Plastics and Polythene in Marine Water

forms as it has a number of effects ranging from disturbing their food chain to chok-

ing them to death. In addition to the existing problem of macroplastics, which is dis-

cussed, the emergence of micro- and nanoplastics is also posing an emerging threat.

Plastics are now an integral part of the marine ecosystem, but their interaction

with various physical, chemical, and biological processes results in their breaking

up into smaller fragments giving rise to micro- and nanoplastics. The only option

we are left with to manage such issues is bioremediation.

7.2

Plastic Pollution: A Threat to the Marine Ecosystem

More than a dozen species have succumbed to the poison of plastic. This deadly

polymer is taking a heavy toll on the diversity of aquatic life. Around 800 species

are affected worldwide by marine debris, all of which are anthropogenic in origin,

and the plastic litter accounts for 80% of this debris (http://www.pewtrusts.org/

en/research-and-analysis/articles/2018/09/24/plastic-pollution-affects-sea-life-

throughout-the-ocean (accessed 12 September 2020)). Humans, on the other hand,

are also exposed to plastic pollution as a significant fraction of the population

imparts seafood as a part of their daily diet. The incorporation of plastic into the

food chain has exposed nearly all life forms of life, including birds, wildlife, marine

forms, and humans, to the effects of plastic pollution (Figure 7.1).

The presence of plastic disrupts the natural balance and ambiance if the marine

ecosystem by interfering with entire biogeocycles causing all marine life forms to

suffer. Various reports suggest the ingestion of plastic by fishes and other marine

organisms not only cause digestive problems but also may lead to life-threatening

issues such as a blockage in the gut and ulcers in the lining of the gut. Birds, too, got

trapped by the attractive look of the floating plastic debris which chokes them, and

they end up dying due to suffocation. Around 44% of the seabirds, cetaceans, and

sea turtles have been documented to have ingested plastic in one form or another

(http://www.marineinsight.com/environment/how-is-plastic-ruining-the-ocean

(accessed 12 September 2020)).

Disposal of plastic into the water bodies comes with many toxic and hazardous

compounds such as additives, flames retardants, plasticizers, colors, etc. These com-

pounds, when degraded by natural forces in water, consume oxygen resulting in

lowering the concentration of dissolved oxygen in that vary environment. A lower

level of oxygen has a severe impact on marine animals, especially whales, dolphins,

and penguins.

7.3

Micro- and Nanoplastics

The recalcitrant nature of plastics enables them to persist in the environment for

a very long time. This property causes the plastic to fragment naturally, resulting

in mesoplastics (5–40 mm), microplastics (1–5000 μm), and nanoplastics (0.1 μm or

less). The microplastic contamination has emerged as a newer form of pollution