Chapter 2 - Sources and occurrence of microplastics and nanoplastics in the environment

Abstract

The extensive usage and mismanagement of plastics have contributed to the predominance of microplastics (MPs) and nanoplastics (NPs) in the environment. The primary sources of MPs and NPs for marine ecosystems are land-based, accounting for 80% of MPs in marine environments. Rivers and human activities are major pathways through which MPs and NPs get into larger water bodies like seas and oceans. Also, wind and natural events such as storms and hurricanes contribute to the mobility of MPs and NPs. The distribution patterns of MPs and NPs in marine ecosystems are influenced by the shape, density, biofouling, adsorption, and location. In marine ecosystems, MPs and NPs are transported vertically or horizontally based on the properties and features of the plastics as well as the ocean geometry and conditions. MPs have been detected in the sediments and surface waters of various countries in abundances ranging from 0.1MPsKg−1 dry weight (dw) of sediments in Brazil to 5000MPsKg−1dw of sediments in Canada. The concentration of MPs in sediments varies based on the sources or how MPs are cycled. Because of the toxicity and abundance of MPs and NPs, it is imperative to understand their fate, interaction, transport, and impact on the environment; their tiny sizes ranging from 0.1μm to 5mm allow MPs and NPs to be easily transported through oceans, trophic levels, and animal tissues. MPs and NPs are ubiquitous in the marine environment and can adversely affect aquatic animals and instigate inflammation, starvation, chemical intoxication, reduced fertility, and even death. MP and NP pollution will likely increase in the future because of the high demand and production of plastic products. Therefore further research is needed to understand the fate, transport, and environmental impacts of NPs and MPs. In addition, because of the growing rate of plastic pollution in the environment and the adverse effect of MPs and NPs on biota and the environment, preventive measures are needed to reduce the abundance of MPs and NPs.