Editorial: New plastic pollution types and novel sources of microplastic pollution in marine systems

Plastic pollution has been extensively studied over the past decades. For instance, it is well known that 13 animals get entangled in discarded plastic (Afonso and Fidelis, 2023) and consume microplastics 14 (plastic particles < 5 mm) while foraging (Ehlers et al., 2021). Examples for microplastic sources 15 comprise everyday single-use items such as plastic packaging material (Tziourrou et al., 2021), lost or 16 discarded plastic fishing gear (Wu et al., 2023) and tire wear (Goßmann et al., 2021). However, novel 17 microplastic sources, such as weathering polymer-based paints, have only recently been identified 18 (Figure 1A). Even though paints are used in various applications on a regular basis, this source has been 19largely neglected in the past (Gaylarde et al., 2021). 20 Furthermore, reports on novel plastic forms, including plasticrusts (plastic encrusting coastal rocks; 21 Figure 1B), pyroplastic (melted plastic with a stone-like appearance; Figure 1C), and plastitar (plastic 22 embedded in crude oil residues; Figure 1D), that derive from geophysical or geochemical interactions 23 are steadily increasing. Such plastic forms differ from regular plastic debris in appearance, chemical 24 composition and environmental fate (Ellrich et al., 2023A). 25The aims of this Research Topic were to increase the awareness of the distribution and abundance of 26 such novel plastic pollution sources and, if possible, their potential environmental effects. By doing so, 27 these sources can be characterized and incorporated into mitigation measures. Further aims were to 28 find out more about the distribution of novel plastic forms and to collect information about their 29 potential sources worldwide. 30 This Research Topic contains three publications focussing on microplastics in deep-sea 31 geomorphological units in the northern South China Sea (Zhang et al., 2022), mechanisms of 32 microplastic release from ship coatings (Tamburri et al., 2022), and the worldwide distribution of 33 plastitar (Ellrich et al., 2023B). It, thereby, contributes to the knowledge of underrepresented 34 microplastic sources in remote locations (Zhang et al., 2022) In conclusion, this Research Topic reports microplastic types from the deep-sea which is very difficult 69 to access (Zhang et al., 2022), contributes to finding a regulation for microplastic release by ship 70 coatings (Tamburri et al., 2022) and expands the knowledge of plastitar distribution and composition 71 (Ellrich et al., 2023B). The authors used state-of-the-art chemical analyses for microplastic 72 identification and crude oil characterization, thereby assuring the quality of their results. 73 74