Temporal trends and spatial distribution of research topics in anthropogenic marine debris study: Topic modelling using latent Dirichlet allocation.

The release of anthropogenic marine debris (AMD) is one of the major environmental challenges of our time. In this study, a topic model called latent Dirichlet allocation (LDA) was used to infer the research topics about AMD to provide the whole picture of the research area. The results of the LDA showed that the AMD research topics are mostly applied topics and belong to interdisciplinary or transdisciplinary research areas. Furthermore, the analysis of the temporal trends of the topics showed that topics related to such as plastic pollution exhibit an upward trend, whereas those dealing with the spatiotemporal dynamics and distribution patterns of marine debris showed a downward trend. The analysis of topic distribution over countries showed that research is scarce in landlocked countries. The findings of this study can be used as a map for the area of AMD study by various stakeholders related to marine debris issues.