Preliminary study of the source apportionment and diversity of microplastics: Taking floating microplastics in the South China Sea as an example.

At present, the study of microplastic sources is in a relatively preliminary stage due to the complexity of microplastic features in the environment. Based on a literature review, we developed a source-specific classification system for the quantitative analysis of microplastic sources. The classification system includes ten types of microplastics based on morphology and composition and can identify their main sources and the associated probabilities. To reflect the complexity of types and sources in the regional combination of microplastics, we first propose a microplastic diversity index (D1-D'(MP)). We use the South China Sea as an example to carry out quantitative source analysis and calculate the diversity index. Eight types of microplastics were found, mainly consisting of maritime coatings (type "Gran_coat") (33.0%) and synthetic fibers (type "Fib_thin") (29.6%). We also found that the diversity increased with offshore distance. In addition, we partitioned surface microplastics globally according to a two-dimensional microplastic abundance-diversity index. We believe that these indicators can effectively reflect pollution status and ultimately lead to different types of control measures. In the future, additional indicators for the characterization of microplastics must be included in the classification system to establish a one-to-one source analysis system for microplastic characteristics and source apportionment. In general, our study may provide new insights into the establishment of more accurate and quantitative source apportionment techniques and effective pollution control.

Microplastics in a wind farm area: A case study at the Rudong Offshore Wind Farm, Yellow Sea, China.

Despite the rapid construction of offshore wind farms, the available information regarding the risks of this type of development in terms of emerging pollutants, particularly microplastics, is scarce. In this study, we quantified the level of microplastic pollution at an offshore wind farm in the Yellow Sea, China, in 2016. The abundance of microplastics was 0.330 ±â€¯0.278 items/m3 in the surface water and 2.58 ±â€¯1.14 items/g (dry) in the sediment. To the best of our knowledge, the level of microplastic pollution in our study area was slightly higher than that in coastal areas around the world. The microplastics detected in the surface waters and sediments were mainly fibrous (75.3% and 68.7%, respectively) and consisted of some granules and films. The microplastics in the samples might originate from garments or ropes via wastewater discharge. The abundance of plastic in the water and sediment samples collected from the wind farm area was lower than that in the samples collected from outside the wind farm area. The anthropogenic hydrodynamic effect was the main factor affecting the local distribution of microplastics. The presence of a wind farm could increase the bed shear stress during ebb tide, disturbing the bed sediment, facilitating its initiation and transport, and ultimately increasing the ease of washing away the microplastics adhered to the sediment. This study will serve as a reference for further studies of the distribution and migration of microplastics in coastal zones subjected to similar marine utilization.