Microplastics and their affiliated PAHs in the sea surface connected to the southwest coast of Taiwan

Contamination by microplastics (MPs) and the associated organic pollutants has caused potential threats to the ecological environment of global waters. In this study, MPs were sampled by trawling from the surface waters of the estuary, fishing port entrance and harbor entrance areas connected to the southwestern coast of Taiwan. Moreover, the abundance, morphological characteristics, composition, and associated polycyclic aromatic hydrocarbons (PAHs) of MPs were analyzed. The abundance of MPs was 0.36 ± 0.21 items/m³, which was 6.4 ± 10.7% of the abundance of zooplanktons. The average abundance of MPs was the highest in the estuary area, indicating that river transport was the primary way for MPs to enter the ocean. The most dominant MPs were small (0.33-2 mm; 78.8 ± 8.1%), colored (60.0 ± 12.8%), fragments (66.1 ± 10.6%), comprising PE (52.6 ± 7.6%), and PP (38.7 ± 9.4%). The decomposition of various plastic products and disposable plastic packaging may be the most significant source. The total concentration of PAHs in MPs ranged from 104 to 3595 ng/g dw, with an average of 818 ± 874 ng/g dw. The diagnostic ratios and the results of principal component analysis (PCA) and multiple linear regression of the absolute principal component scores (MLR-APCS) indicated that the PAHs were mainly contributed from sources related to petrogenic (71.4%) and vehicles (28.6%). Most likely due to MPs on the sea surface coming into contact with floating oil spills from ships or floating tar particles.