Occurrence and abundance of microplastics in offshore sediments of the Persian Gulf and Gulf of Oman

Plastic materials are trackable in every corner of our biosphere [۱]. Some of these materials are intentionally designed to be very small and the others gradually break down into what we know as Micro-plastics (MPs). These tiny plastic bits are < ۵ mm in all dimensions, but they are also the most prevalentform of plastic pollution observed on the Earth [۲]. A lot of the MPs finally reach and gradually deposit into the marine sediments. By doing so, the MP bits act like miniature "Trojan horses", delivering toxic chemicals to the aquatic animals because of inadvertent intake [۳]. The Persian Gulf is a young body of water continually supported by the budget of Oceanic waters of the Indian Ocean, entering through the Gulf of Oman. Since the Persian Gulf is a semi enclosed and shallow region, increasing human activities would result in deleterious repercussions. This is a matter of concern especially in the case of marine debris having recalcitrant nature, notably MPs. By now, no valid report from Offshore Micro-plastics in the sediments from ROPME region (The Persian Gulf and the Gulf of Oman) has been published despite an increasing impetus in marine MPs related surveys. It was thus the topic of a widespread sampling, scheduled in marine expedition of the PERSIANGULF Explorer in ۲۰۱۹. In sum, ۵۱ stations were sampled and subjected to further analysis including MPs content (particles Kg-۱), physical features and spatial distribution. The finding demonstrated that the density of MPs varies from stations with minimum number of ۵ to a single station with a maximum number of ۷۵ particles Kg-۱. The dominant shape of extracted MPs was fiber and it was in a good agreement with the findings that the fibrous particles are prevalent form of MPs in the marine environments. According to the results, Black fibers were the dominant colored particles detected and the white ones share a minimal part. The majority of fibers (۳۹%) possessed a size range of ۰.۵ to ۱ millimeter and the size limit detected was something about ۱۰۰ micrometers. Correlation analysis was run to distinguish any possible dependency among density of MPs and grain-size, organic matter and distance of sampling points from the mainland. The analysis revealed that the density of MPs is not a correlate factor of grain size, organic matter and distance from the mainland.