Background: Microplastics are among the identified marine pollutants result from disintegration of the larger plastic debris. Due to the long chemical chain, these pieces may stay in the environment for a long period of time. Coastal sediments are the main areas of microplastic particle accumulation in marine environments.
Aim: This study aims to investigate the number, shape, and colour of microplastics as well as their structure along the coastal lines of Bushehr city. Also, different layers of sediments were investigated for the properties of microplastics.
Methodology: Sediment samples were collected from different depth of sediments (surface to 10 cm, 10 to 20 cm, and 20 to30 cm) of the inter-tidal area of six stations including TV Park, Lian Park, Saheli Street, Bandargah, Daneshjo Park and Jofreh dockside. Small plastic pieces less than 5 mm in length were considered as microplastic particless. Potassium hydroxide was used to remove all biological impurity of the sediments. Microplastics were then separated using a solution of concentrated sodium chloride of the density separation method. Obtained particles on the paper filters were examined under a microscope equipped with a digital camera for their number, size, colour and shape. Polymer structure of the microplastics was assessed through Microraman spectroscopy.
Results: No differences were found between the numbers of microplastics in all of the stations. Totally, range number of 20 to 330 microplastic particles was countend per 1 kg of dry sediment (mean±SD: 117.96 ± 97.75 particles). The highest number of microplastics was in the size range of 2 to 5 mm (in average, 42.16% of all size clacess) in which the top layer, 0-10 cm, of the sediment showed higher number of particles (mean: 248.33 particles) than the deeper layers (mean of layers; 10-20 cm, 64.44 particles and 20-30 cm, 41.11 particles). Fibers (48.33%) and segments (32%) were more abundant than the film (12.16%) and pellet (7.5%) forms. In addi