A comprehensive evaluation of pelagic microplastic pollution in surface water near the Xisha Islands of the South China Sea

Abstract

Pelagic microplastics (MPs) are ubiquitous in seawater worldwide, driven by global ocean currents and atmospheric circulation. A comprehensive evaluation of MP pollution in surface water near Xisha Islands of the South China Sea was conducted using a typical Manta trawl. The results indicated that the average abundance of MPs in this region was 0.61 ± 0.87n/m³, demonstrating significant spatial heterogeneity. MPs were primarily composed of polypropylene (PP) and polyethylene (PE). The average size of MPs was 1.95 ± 1.18 mm and approximately 90 % of all MPs were smaller than 3.80 mm. Additionally, there were significant differences in MP size between different shapes and polymers. The average sizes of MPs in shape of line and polymer of PS were largest. The type and ecological risk level of MP pollution in the water near Xisha Islands were classified as L-L (low MP abundance with low MP diversity) region and minor-risk, respectively, according to the microplastic diversity integrated index (MDII) and potential ecological risk index (PERI). Based on the map of ocean currents, the convergence effect of eddies may be a significant driving force behind the accumulation of MP pollution at individual stations. Our findings have enhanced the understanding of the current status, sources, and ecological risks of MP pollution in the South China Sea, providing valuable data and theoretical support for the promoting of MP pollution control in the region.