AUTHOR=Zhu Xia TITLE=The Plastic Cycle – An Unknown Branch of the Carbon Cycle JOURNAL=Frontiers in Marine Science VOLUME=7 YEAR=2021 URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2020.609243 DOI=10.3389/fmars.2020.609243 ISSN=2296-7745