Spatio-temporal evaluation and risk assessment of microplastics in nearshore surface waters post-2018 Kerala deluge along the southwest coast of India

• Published in: Marine pollution bulletin 2023-07, Vol.192, p.115058-115058, Article 115058
• Main Authors: Nikhil, V.G., Ranjeet, K., Varghese, George K.
• Format: Article
• Language: English
• Subjects: coasts; India; Kerala flood; marine pollution; Microplastics; pollution load; polyethylene; polypropylenes; risk; Risk assessment; Seasonal variation; sewage; Surface water; Weathering
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2023.115058

Spatial and temporal distribution of microplastics along the nearshore surface waters of Kerala after the floods of 2018 was studied. Results indicated a seven-fold increase in its mean concentration (7.14 ± 3.03 items/m3) post deluge. The average abundance was highest during pre-monsoon (8.27 ± 3.09 items/m3). Fibres were the dominant group, with blue and black being the most prevalent colours. Polyethylene and polypropylene were the most commonly found polymers, possibly gaining entry through sewage waste or land-based plastic litter. Highest abundance of microplastic was recorded off Kochi categorising it at Hazard Level I under Pollution Load Index assessment. Similarly high levels of Pollution Hazard Index and Potential Ecological Risk Index were also reported due to the presence of hazardous polymers PVC and PU that can cause concern to marine life. The differential weathering pattern and surface morphology analysis suggested microplastics to be relatively old that had undergone substantial mechanical and oxidative weathering. •Seven-fold increase in microplastics from surface waters post Kerala floods•Pollution Hazard Index for all the stations high at level V•Ecological risk high due to the presence of PVC and PU•Surface morphology of microplastics indicates severe weathering.•Increased bioavailability of microplastic post flood increases risk to trophic levels.