Microplastics and coliforms distribution in distinctive magnetic minerals content beaches of Northwest coast of India under typical metocean conditions

A study of microplastic distribution and magnetic mineral deposition would aid in comprehending the force of interaction between microplastics and magnetic minerals and transport of microplastic as a result of microplastic current. Ambient physical processes such as tide, current, wind, wave should have significant role in the transportation of marine plastic litter and conversion of this plastic waste to microplastic. Two sampling stations viz., Navgaon and Priyadarshini exhibited elevated values of both microplastics (11,000 and 11,600 per kg sediment) and magnetic susceptibility (χlf of 5.8 and 10.9) with relatively lower values of fecal contamination (fecal coliform counting 150, 210 respectively in water and 200, 280 respectively in sediment). However, Awas (χlf of 19.1) shows an increased value of magnetic minerals but a lower value of microplastics which may be attributed to the continuous flow of river water, transporting low-density microplastics downwards to Navgaon where they settle. The covariance of microplastics associated with magnetic minerals and microbial diversity observed in this study is under the dominance of tide-influenced coastal current while the wave action and wind force play a minor role. Versova, Juhu, Mahim, Dadar in addition, were identified maximum values of coliforms that is >110,000 in number (total coliforms and fecal coliforms). Although coliforms enumeration help to identify point and non-point sources of pollution and study of hydrodynamics essential for micro and nano plastic generation from large plastic litters however magnetic susceptibility and microplastic distribution is necessary to identify potential locations for micro and nano plastic mitigation.