Petrochemical industry as a source for microplastics; abundance and characteristics of pollution in soil, sewage, and bay

Petrochemical industries can potentially be sources of microplastics. This is the first report that studies the abundance and characteristics of microplastics in different parts of a petrochemical site, and process of changes in microplastics from the place of production to reaching open waters. Samples were taken from 10 points. In order to identify the microplastics, NaCl and ZnCl 2 solutions were used for extraction and then H 2 O 2 was used for cleaning and with using different filters, two groups of size were divided. Then, using a stereomicroscope and ATR-FTIR their abundance, color and shape and the type of polymers were determined. The number of microplastics in the soil samples varied from 1483 ± 475 items/Kgdws to 4620 ± 983 items/kgdws, the industrial WWTP sludge, the number of microplastics detected varied from 1233 ± 225 items/L to 1433 ± 372 items/L and in WWTP effluent was determined to be 276 ± 76 items/10 L. on average, 66.38 % and 33.62 % of the detected microplastic particles were in the size range of 0.45μ-20μ and 20μ-2mm, respectively. Also on average, 75.89 % and 24.11 % of the particles were in the density range of 1.2–2 g/cm 3 and less than 1.2 g/cm 3 , respectively. On average, 68.33 %, 14.35 %, 10.55 %, and 6.77 % of the microplastics were in the form of fiber, film, pellet and other, respectively. On average, 29.84 %, 56.27 %, 1.02 %, 2.88 %, 0.97 %, and 8.99 % of the microplastics were black, white, red, blue, green and other respectively. 61 %, 23 %, 8 %, 4 % and 4 % of the investigated particles were classified as PES, PET, PE, PE and unknown, respectively. The results indicate that by moving away from the place of production of PES fibers, microplastics have undergone physical and chemical changes and their nature is changing. Results showed that the petrochemical industries can be potentially a microplastic source. It is a warning that if not taken into consideration will be a serious threat to environmental health. • The petrochemical industry is a source of microplastics in the vicinity of the Gulf. • The most microplastics were identified in the soil in contact with the wastewater effluent. • White PES fibers were the dominant microplastics. • Confirming the physical and chemical change of microplastics with ATR-FTIR and SEM analyses.