Riverine outflow is one of the major pathways for microplastic transportation to coastal environments. Research on the output of microplastics in small- or medium-sized rivers will help accurately understand the status of their marine loads. In this study, we used both trawling and pumping methods to collect microplastics of different sizes in the Jiulong River Estuary and Xiamen Bay. We found that the abundance of small microplastics (44 μm-5.0 mm) was at least 20 times higher than the large particles (0.33-5.0 mm). The abundance of the large particles ranges from 4.96-16.3 particles/m3, and that of the small particles ranged from 82.8-918 particles/m3. Granule was the dominant shape (>60%), and polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) were the most common components. The riverine flux of small microplastics (44 μm-5 mm, 472±230 t/y) was at a medium level and was eight times greater than that of large particles (0.33 mm-5.0 mm, 61.2±2.6 t/y). The behavior of the large microplastics was relatively conservative, whose abundance had a significant correlation with salinity (R2 = 0.927) and was mainly influenced by physical factors. In contrast, results of statistical analysis revealed that more complicated factors influenced the small microplastics.

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Mid-Level Riverine Outflow Matters: A Case of Microplastic Transport in the Jiulong River, China

Distribution pattern and influencing factors for the microplastics in continental shelf, slope, and deep-sea surface sediments from the South China Sea.

The factors influencing the vertical transport of microplastics in marine environment: A review.

The different ways microplastics from the water column and sediment accumulate in fish in Haizhou Bay.

In this study, microplastics were sampled and analyzed from surface water and sediment samples from July to August in 2020, in the Beibu Gulf (the northern South China Sea [SCS]), a gulf with intensive fishery activities while the economy is less developed, compared with other coastal areas of China. The abundances of microplastics in seawater and sediment in the Beibu Gulf were 0.67 items/m3 and 4.33 items/kg of dry weight, respectively. In seawater, the fragments (92.38%) contributed the most, and polystyrene (PS) was the dominant polymer (53.23%). In sediment, the most abundant microplastics were fiber (82.93%) and rayon (RY; 39.54%). The abundances of remarkably higher microplastics were found in the seawater and sediment adjacent to the urban area. The abundances of microplastics in far coastal sediment were only slightly lower than that in the coastal sediment, indicating that microplastics are ready to transport and bury in open area sediment. Significant positive correlations between the microplastic abundance and population density and per capita gross domestic product (GDP) were found in Chinese coastal seawater, with low population density and less developed economy, and the microplastic pollution in the Beibu Gulf was at a low level. This study provides preliminary data of microplastics in the Beibu Gulf, supporting further investigation of transportation fate and management of this emerging pollutant from the coastal zone to the SCS.

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Occurrence of Microplastic Pollution in the Beibu Gulf, the Northern South China Sea

Microplastics in seawater and two sides of the Taiwan Strait: Reflection of the social-economic development.

Impact of intensive mariculture activities on microplastic pollution in a typical semi-enclosed bay: Zhanjiang Bay.

Quantitative assessment of the response of seawater environmental quality to marine protection policies under regional economic development --A case study of Xiamen Bay, China.

Piao Chen

Papers

Microplastics in seawater and two sides of the Taiwan Strait: Reflection of the social-economic development.

Impact of intensive mariculture activities on microplastic pollution in a typical semi-enclosed bay: Zhanjiang Bay.

Quantitative assessment of the response of seawater environmental quality to marine protection policies under regional economic development --A case study of Xiamen Bay, China.