The non-biodegradable nature of microplastics (MPs), their ability to adsorb various environmental pollutants, and the subsequent transfer to the food chain make them a serious threat to the ecosystem. Approximately 40% of the total plastic wastes generated (̴ 9.4 million tonnes per annum) are either landfilled, left unnoticed, or littered. These plastic wastes disintegrate to form MPs or nanoplastics and retain them in nature and may create a long-term negative impact on the ecosystem. Recently, microplastic pollution has attracted widespread attention in India. Microplastics have been reported from different coastal environments in India. India has a coastline of 7516.6 Km, and according to a report published by United Nations Environment Programme, India dumps nearly 0.6 million tons of plastic waste into the ocean annually. Microplastics in these environment causes a negative impact on lives thriving here. Therefore, the sources of these materials in the marine environment need to be well-studied. The Environmental Microplastics group at the Department of Civil Engineering, Manipal Institute of Technology (MIT), is concentrating on the impacts of microplastic pollution on rivers, estuaries, lakes, beaches, soils, and mangrove systems in coastal Karnataka and Kerala. The group is trying to assess the abundance, distribution, and degree of degradation of MPs in the various compartments of these environments. This will help in identifying plastic hotspots and develop strategies to control plastic pollution at its starting stage itself

Warrier et al. (2022) investigated the seasonal occurrence and distribution of microplastics in the surface water samples of Lake Manipal in southwest India. The concentration of MPs was found to be higher during the monsoon season (0.423 particles/L) in comparison with the post-monsoon (0.117 particles/L) period. The higher abundance is attributed to the input of storm-water sewers connected to the lake as well as surface runoff during periods of high rainfall. The concentrations of small-sized (0.3–1 mm) microplastics were greater in both seasons. Approximately 96% of the microplastics were fibres, followed by smaller amounts of fragments, pellets, films, and foams. Polyethylene terephthalate (PET) was the principal polymer composition of the microplastics, followed by cellulose. The PET and cellulose fibres were mainly derived from the laundering of clothes in the residential colonies and hostels situated close to the lake. The storm-water sewers were the likely conduit for these PET fibres into the lake. The Pollution Load Index (PLI) data reveals that pollution due to microplastics in Lake Manipal falls within the Level I risk category. The PLI was higher during the monsoon season due to an increased flux of these particles from the nearby region. During the post-monsoon period, the PLI values decreased, suggesting that MPs in the water column may have settled and mixed with the sediments. The baseline data generated in this study is important as different types of birds, amphibians, and other microorganisms are present in the environment of Lake Manipal. We also propose certain policy measures that can be adopted by the regional population to mitigate microplastic pollution in the lake and its vicinity.

Khaleel et al. (2022) reported the occurrence and distribution of MPs present in the beach sediments of Saint Mary's Island (SMI), a geological heritage site located in the southeastern Arabian Sea. The average abundance of MPs on this island was 97.18 particles/kg. Attenuated total reflectance—Fourier transform infrared (ATR-FTIR) spectroscopy revealed that MPs are composed of high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyamide (PA). Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) highlighted the presence of Cr, As, Pb, and Cd (harmful pollutants) on MP surfaces. The MPs in the SMI are largely contributed by the nearby fishing harbour, touristic beaches and estuaries. The results of this study, act as a starting point for continuous environmental monitoring in this unique region of the world.

Publications from the Microplastics Group:

1.       R Khaleel, G Valsan, N Rangel-Buitrago, AK Warrier (2022). Hidden problems in geological heritage sites: The microplastic issue on Saint Mary's Island, India, Southeast Arabian Sea. Marine Pollution Bulletin, 182, 114043, (Impact factor: 7.001; Q1),
https://doi.org/10.1016/j.marpolbul.2022.114043

2.      Warrier, A.K., Bhavani, K., Amrutha, K., Dhanasree J., Gokul V., Prashansa, A. (2022). Seasonal Variations in the Abundance and Distribution of Anthropogenic Particles in the Surface Waters of a Southern Indian Lake. Chemosphere, v. 300, 134556 (IF: 8.943; Q1) https://doi.org/10.1016/j.chemosphere.2022.134556

Fig. 1. Photographs of microplastics (fibres, fragments, foam, and film) found in the beach sediments of St. Mary’s Island.