Spatial distribution of microplastics in Persian Gulf marine environments

Microplastics (MPs) are recognized as a significant environmental threat within marine ecosystems. This study examines the spatial distribution of microplastics in seawater, sediments, and fish from the Persian Gulf. A total of 24 seawater samples, 24 sediment samples, and 40 specimens of Pennahia anea were collected from eight locations. Samples were digested, and MPs were filtered, counted, and analyzed using a stereo microscope, Raman spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX). The results revealed the presence of microplastics across all sample types. The total abundance of MPs in seawater ranged from 3 to 15 items/l, in sediments from 10 to 35 items/kg, and in fish from 4 to 18 items/10 g. The study identified a robust positive correlation between microplastic contamination in seawater and fish (r = 0.932, p = 0.001). Similarly, a strong positive correlation was observed between sediment and fish contamination (r = 0.730, p = 0.040). In seawater, sediment, and fish samples, microplastics were predominantly fibers, constituting 98.31%, 100%, and 87.5% of the total microplastic content, respectively. These fibers measured ≤ 250 μm in length, with black being the most prevalent colors. The findings highlight that the northern site, Khor Semaili (K1), was a significant MP hotspot. At the same time, areas such as Khor Zangi (K6) and Khor Ghazaleh (K8) exhibited minimal contamination across all matrices. This research highlights the crucial role of spatial analyses in understanding the distribution of microplastics in marine ecosystems.