**4. Microplastics in marine ecosystems**

The pollution of microplastics varies geographically with location because as the consumption of plastic increases, there is increase in production of MP. Marine life is more disturbed by this plastic waste because ocean become a dump yard for running water system either directly via riverine system as river ultimately end up meet up with the ocean or indirectly as waste water treatment plant dispose of their waste directly in the ocean or in river which end up by meeting the marine water body. However, the size of sediment and distribution of MP is influenced by oxidative degradation (either photo- or thermal initiated), friction and biodegradation [39, 40]. The typical shape of microplastics consists of pellets, fibers and fragments but according to literature, majority of microplastics in Oceans are microfibers [41, 42]. Distribution and abundance of microplastics is chiefly determined by environmental [42–44] and anthropogenic factors [45]. Environmental factors include runoff, infiltration, river discharge, wind action, ocean currents, cyclones, river hydrodynamics, wave current, tides and movement/dispersion of animals. On the other hand, anthropogenic activities either they are for industrial or tourism or transport purpose which further led to accumulation of plastic debris in environment. According to literature, these environmental factors play vital role in determining the distribution of microplastics more intensely than anthropogenic activities, however anthropogenic activities are the core source of production of these plastic wastes.

Abundance of microplastics in oceans distribute across various strata of Ocean. In the sediments- water systems, microplastics only sink and accumulate in the sediment when their density exceed seawater (>1.02 g/cm3 ); otherwise it tends to float on the sea surface or in the water column [46], hence low density microplastics float on surface layer of ocean water whereas high density microplastics sinks down to benthos layer [5]. Buoyancy of microplastics can depend on befouling in which former biomass accumulation led to increase in microplastics density and later can decrease microplastics density which is responsible for sinking, neutral or floating action of microplastics. But in case of High density microplastics, there distribution depends on other factors also like change in tidal fronts, high flow rates or larger surface area of High density microplastics.

Beaches are a reservoir of highly fragmented plastic debris that transport microplastics back to costal water and finally to open ocean [47]. It is based on observation of Wang et al. [48] that concentration of microplastics is usually higher in upper layer i.e. epipelagic layer than the immediate lower mesopelagic layer this may be due to preferential flow or animal movement. Even, mesoscale ocean dynamics have impact on distribution of plastic debris at sea surface within subtropical gyres [49]. Usually, sea platforms and marine trafficking are responsible for microplastics in far off Ocean, whereas microplastics in near shore originate mostly from waste water, runoffs, rivers etc. [50, 51]. However terrestrial environment also determines the concentration of microplastics as harbor and industries add huge amount of plastic debris either directly or indirectly which add up to the acumen concentration of microplastics in the ocean. The dire situation of disturbance in aquatic ecosystem is becoming huge day by day as these not only affect flora but fauna as well; even coral beds are not far away from disturbance. This plastic debris also includes mesoplastics accumulation. Use and through plastic items are becoming huge threat to the aquatic organisms hence number of reports are increasing in this area of research which indicate the negative impact of microplastics and is alarming accumulation rate in ecosystem which is also eye catching for researchers and environmentalists.

## **5. Microplastics in freshwater ecosystem**

To understand the impact of microplastics pollution in freshwater environment, various aspects are to be analyzed i.e. source, distribution, type and effect of microplastics. Source of freshwater pollution is usually synthetic textile, personal care products, industrial raw material, whereas the main source of microplastics in riverine system are wastewater discharge which may be industrial or household untreated waste water disposal. Microplastics are of serious concern because their accumulation potential increases with decreasing size [52]. It is also noted that, there may be change of composition of MP as they accumulate with waterborne contaminates which includes metals and persistent, bioaccumulative and toxic compounds this is possible due to larger surface-to-volume ratio. Studies by Engler [53] showed relationship between plastic debris and PBTs (e.g. PCBs and DDT) similarly a number of studies exist for polycyclic aromatic hydrocarbons [54–56]. Since the spectrum of contaminants is different between freshwater and marine system. In stagnant riverine system like ponds and lakes water pollution is more severe problems because of the irresponsible behavior of the inhabitants or by various tourism related activities which disturb the ecosystem due to accumulation of degradable or non- degradable waste. They float in the surface water and stay in the water sink into sediments of lake. For stagnant system rate of accumulation of microplastics is higher, since there is no efflux. Therefore, it can be concluded that there is a direct correlation between distance of contamination source and microplastics pollution levels in sediments [57]. Various studies confirmed the presence of microplastics in drinking water system which makes it a serious issue [58]. Research about river system and watersheds can provide the knowledge to the people to understand the alarming situation of microplastics accumulation in freshwater system [59]. Further the flow of river plays significant role in removal of plastic fragments. It is also observed that after precipitation high amount of MP is observed in sediments and running water [60]. Eventually, freshwater system also contributes to the pollutant content of marine ecosystems because ultimately riverine merge with the ocean resulting merger of mineral, sediments, soil content as well as pollutants. Hence the fact that freshwater system act as strong source of microplastics to marine ecosystem cannot be neglected. Although distribution of microplastics in freshwater system is not uniform, it depends on nearby source of waste water disposal.

It is observed that the condemnation in water is observed higher in riverine near industrial area as compared to the residential area. However waste water treatment

**235**

*Sources, Fate, and Impact of Microplastics in Aquatic Environment*

plants are established by organizations but they remove large plastic waste more efficiently than meso and micro plastic waste, as various technologies are installed to remove large size particle but these are not specified to retain microplastics [61, 62]. Discharge from waste water treatment plant contain may hazardous compounds along with micro –and Nano- plastic particles which enter the food web and cause diverse

The threat of microplastics is rapidly increasing, and as the global plastic production projected to reach an accumulative 25 billion tons by 2050, things are going to be worse [63]. Although these plastic materials are key factors for innovation and development of various fields such as healthcare, energy generation, aerospace, automotive industries, construction, electronics, packaging, textile and many others [64]. However, instead of recycling or incineration or utilizing any other way of removing unused or discarded plastic from environment, these plastic wastes enters the environment from year to year and it is accumulated in Marine, freshwater and terrestrial ecosystem worldwide, even from densely populated countries like India and China to cold desert like Antarctica. And this became a matter of concern for scientists across the world. The reliance on plastic for huge number of consumer products, many of them being single-use, results in continuous entry into

No doubt, with due course of time via biotic and abiotic degradation pathway,

Microplastics are of special concern because they can be ingested throughout the food web more readily than larger particles. It is to be noted that the impact of microplastics on public health and aquatic ecosystems is not yet fully understood, but there is increasing number of reports which indicate negative impact of micro-

With increased focus on microplastics debris, several groups have studied the influence of microplastics uptake by different organisms. As microplastics invasion appear to occur across all ecosystem from terrestrial to marine environment in different trophic level not only invertebrates but vertebrates also seem to be affected by their presence [66, 67]. Organism ingests these microplastics debris while swallowing their food. And with due course of time bioaccumulation of microplastics results in diverse negative impact on various organism like disruption of organ system, rupturing of digestive system, weakening of immune system, impotency, various respiratory and circulatory problems, even failure of organ and in extreme cases led to death of organism [51, 68, 69]. However, continuous accumulation of these deadly microplastics in various systems of the body is possible through food chain via ingestion as well as by accumulation around gill aperture (or around respiratory apertures) and appendages of body by diverse aquatic organisms [70, 71]. However, situation

plastic loose its mechanical integrity but it may take several years to degrade completely. With gradual degradation this immortal plastic emits smaller size particle in environment i.e. macroplastics, mesoplastics and microplastics. Plastic particles <5 mm size are considered Microplastic, although there are efforts to redefine them as <1 mm in size, as recommended by [65]. However minimum size of Microplastics has not yet been specified and it depends on the sampling and processing as well as on the applied method for Microplastics identification.

**7. Effect of microplastics on aquatic biota**

plastics on marine and freshwater biota.

*DOI: http://dx.doi.org/10.5772/intechopen.93805*

effect in biotic ecosystem**.**

**6. Fate of microplastics**

environment.

*Sources, Fate, and Impact of Microplastics in Aquatic Environment DOI: http://dx.doi.org/10.5772/intechopen.93805*

plants are established by organizations but they remove large plastic waste more efficiently than meso and micro plastic waste, as various technologies are installed to remove large size particle but these are not specified to retain microplastics [61, 62]. Discharge from waste water treatment plant contain may hazardous compounds along with micro –and Nano- plastic particles which enter the food web and cause diverse effect in biotic ecosystem**.**
