Sources, Mechanisms, and Interactions of Microplastics with Abiotic and Biotic Factors in Aquatic Environment

Microplastic (MP) pollution has become a serious environmental concern that poses threats to the abiotic and biotic communities, particularly in aquatic environments, which are considered as highly biodiverse ecosystems. This chapter discusses the factors affecting the distribution and accumulation of MPs, mechanisms of their interaction with biotic and abiotic factors in aquatic environments, and their resulting ecological threats. Factors like the disintegration of primary MPs, the release of tiny microbeads from plastic products, industrial wastes, and synthetic fibers are mainly responsible for the distribution and accumulation of MPs in aquatic environments. After accumulation, these MPs interact with different biotic and abiotic factors through different mechanisms like adsorption, penetration, trophic transfer, biofilm formation, etc. The biotic community of aquatic environments ingests MPs in their bodies, resulting in physical damage, blocking the digestive system, and reducing feeding efficiency. MPs accumulate in the tissue of one organism, which is transferred to the organism at the upper-tropical level through their food chain, which affects the entire aquatic food web and overall ecosystem. The interactions of MPs with abiotic factors alter water quality, like pH, temperature, salinity, etc. MPs act as carriers, which can carry organic compounds, pathogens, or heavy metals and accumulate to form complex pollutants. These can be distributed and consumed by the biotic community through the mechanisms of adsorption or penetration. Moreover, on the surface of MPs, a biofilm can be produced, which can facilitate microbial colonization and affect the biodiversity in the aquatic environment. These interactions and their impacts change the overall ecosystem dynamics of the aquatic environment. This chapter also highlights some scope for further research in order to understand the long-term complex interactions and their associated human and environmental risks more deeply.