Plastic and microplastic persistence and breakdown in coastal saltwater systems

Purpose The oceans play a vital role in regulating the Earth’s climate and supporting life, but ocean pollution is increasingly endangering marine ecosystems. The purpose of this study is to address the growing issue of microplastic contamination in oceans, particularly in the Indian Ocean, highlighting its sources, environmental and biological impacts and methods of identification and characterisation. This study also examines the influence of exclusive economic zones (EEZs) on this contamination. Design/methodology/approach This paper comprehensively reviews current literature on microplastic sources and their impacts. It also incorporates experimental investigations that demonstrate polymer fragmentation and degradation in saltwater environments to provide practical insights into the behaviour of microplastics in marine settings. Findings Microplastic contamination is a severe issue with profound implications for marine life and ecosystems. This study identifies key sources of microplastics, such as waste mismanagement and industrial activities, and emphasises the significant contribution of EEZ activities to contamination in the Indian Ocean. Experiments presented in this article reveal important details about the degradation behaviour of polymers in saltwater conditions. Originality/value This paper provides a focused exploration of microplastic contamination in the Indian Ocean, an area often overlooked in global studies. By integrating experimental data with a review of the EEZ’s role, this study offers valuable insights into regional pollution dynamics and practical approaches to understanding microplastic behaviour in marine environments. Unlike most global reviews, this paper uniquely integrates experimental insights on the degradation behaviour of polyamides in saltwater with a policy-oriented discussion of the Indian Ocean’s EEZs. This dual focus on underexplored regional waters and polymer-specific degradation mechanisms makes this study distinctive and valuable for both environmental science and marine policy communities.