Occurrences, Distribution and Composition of Microplastics in the Surface Seawater and Beach Sediments of the Southern Shandong Peninsula, China

The current work provides the detailed analysis about microplastics contamination of the beach sediments and 2 surface seawater. Sediment samples were collected from the high tidal zone at 13 beaches, and surface seawaters 3 of seven stations along the southern Shandong Peninsula. The presence of microplastics was recorded on both 4 beaches and surface seawater. The mean quantity of microplastics was approximately 664 ± 80 microplastics/kg 5 of dry weight (dw) with 0.5~0.125 mm in beach sediments, and 5.62 ± 0.4 microplastics/liter (L) of surface 6 seawater. Predominant microplastics were fibers ( > 97%). While other plastic forms had lower percentage. 7 Microplastics possessed different color with polymer composition including polypropylene, polyethylene, and 8 polystyrene. The accumulation of microplastics on beaches is an alarming issue and provides better understanding 9 about microplastics pollution along the coastal regions of the southern Shandong Peninsula. It would also help to 10 establish better monitoring system for future and evaluate possible risks by microplastics due to rapid economic 11 growth of China.


Introduction 14
The occurrences and distribution of microplastics (<5 mm) is an alarming issue and attracted more attention and 15 concerns in recent years (Sarijan et al. 2021). There is no standard criteria to define microplastics but particles        Gao et al. 2020). This is essential to assess the level, 56 distribution, and detection of microplastics to understand the level of pollution and enlighten the contributing 57 factors of microplastics in the region. Thus, the sand samples collected from thirteen beach sites and surface 58 seawater samples from seven stations, and identified types, color, shape, and chemical composition. All these 59 beach sites are located in the Shandong Province, comprising intense, highly developed and urbanized coastlines.

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For example, more than 200,000 beach visitors were reckoned in the summer season on Golden bathing beach,

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Qingdao 1 . The present study area comprised of thirteen sandy beaches (Error! Reference source not found., E1 − 76 E13), and seven surface seawater stations (Error! Reference source not found., W1 − W7), along the southern 77 coastline of Shandong. This area normally experiences coastal monsoons owing to its warm temperate climate 78 and assigned as top second city in China concerning investments and efficient government (Mako 2006

Sampling of sediments and water 82
Overall, thirteen beaches (one from Rongcheng, two from Huangdao, four from Rizhao region, and six from 83 Qingdao region) were selected to acquire microplastics samples (Error! Reference source not found.). The

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Later, the solution was allowed to settle for 24 hours and finally passed through filter paper of 0.7 μm. Before 112 analysis, the NaCl saturated solution was passed through filter paper (5 μm) to remove the additional 113 contamination of salt crystals. All transferring devices were washed with deionized water several times and, then 114 passed through the same filter paper to minimize loss of microplastics due to adhesion on apparatuses walls.

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Finally, the filter paper was sealed under a cover glass to allow drying overnight for further analysis. In case of 116 surface seawater samples, water samples were passed through sieve of 0.5 mm mesh before laboratory 117 examination. Thus, acquired water samples were preserved at 4 ºC till the analysis on next day (Leslie et al. 2017).

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Moreover, sediment and water samples were subjected to 30% H2O2 to digest organic matter (Tamminga et al.

Quality assurance (QA) and quality control (QC)
154 All apparatus and instruments were washed with Milli Q water before performing the experiment. The sampling 155 and experimental devices were covered with aluminum foil during laboratory work in order to avoid 156 contamination. Therefore, non-textile robe, gloves, non-plastic tolls, and caps were used to minimize the effect of 157 clothes and hairs. The door and windows of laboratory were closed during experiment. The filter paper was 158 covered with glass to protect from air contamination. Moreover, the known sample of sodium and potassium 159 bromide were run before FTIR analysis to ensure the validity of FTIR results. Ethanol was used to clean the 160 germanium crystal of FTIR.

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Peninsula than other beaches elsewhere was challenging task due to diverse anthropogenic and natural factors.

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The average microplastic abundance of sea water was estimated to be 5.6 ± 0.4 microplastics/L which was 273 Importantly, the present study showed that the majority of microplastics was fibers and very few were others in 274 beach sediments and surface seawater. Our findings were underlined with prior outcomes of Caribbean, European,

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In last, the findings of this study will assist to develop a better understanding of microplastics occurrence including 303 source and pathways in marine and coastal zones of the southern Shandong Peninsula. It also facilitates 304 establishing better monitoring system and provides beneficial data to evaluate the possible risk to the coastal zone 305 and marine ecosystems caused by microplastics. A detailed investigation on microplastics would be beneficent 306 regarding marine food-related species including fishes along the southern part of the Yellow Sea to assess possible 307 risk to human health due to the consumption of microplastics via seafood. Moreover, the effect of microplastics 308 on the properties of these beaches is yet unknown. We highly recommend the utilization of different simulation 309 models to conduct field surveys for sake of measuring an actual magnitude of plastic pollution at a global scale 310 considering biological processes, coupled with physical-biological models for marine microplastics. The sampling 311 and analysis method should be globally standardized for better comparison of the microplastic abundance among 312 different regions. We used method which only detect the microplastics with density < 1.17 g/cm 3 . Therefore, we were unable to determine the polymers with high density such as polyethylene terephthalate, rayon, polyvinyl 314 chloride, etc. (density 1.39, 1.56, and 1.53 g per cm 3 ) and so many others due to adaptation of method but we were 315 still capable to segregate the most common polymers which have been identified worldwide.