Assessment of marine microplastics in floating plastic debris using a fixed sampling device: the example of South Juhu creek, Mumbai coast, India

A new design of sampling device was developed and used for the assessment of microplastics in the floating plastic debris of the water channel flowing from the creek towards the sea. During the intermonsoon period (April to May), the collection using the sampling device showed over 106 microplastic particles with 9.9 g weight during the low tide conditions. A lesser number and amount of microplastic was recorded (95 particles weighing 8.7 g) during the high tide conditions. The collected microplastics were dried, segregated, assessed, and classified into four major categories, namely: plastic fragments, microfibre, microbeads, and foamed plastics. In total, six samplings were carried out in the water channel and it was evident that the maximum number and the maximum weight (g) of microplastics corresponds to low tide (post-high tide) conditions. The present investigation reveals that an insignificant quantity of microplastics is carried to the sea from the landward side. It is concluded that the origin of the microplastics in the oceans is through fragmentation and degradation of macro-and megaplastic transported to the sea through inland water channels connected to the sea. The contribution of microplastics from the landscape surrounding the sea/oceans is negligible. It is emphasized that the magnitude of microplastic in the oceans can be reduced by preventing the entry of macro- and megaplastics from the landward side.