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Cite This: Environ. Sci. Technol. XXXX, XXX, XXX−XXX
Microplastic Disguising As Soil Carbon Storage Matthias C. Rillig*,†,‡ †
Freie Universität Berlin, Institut für Biologie, Berlin, Germany Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
‡
R
urban soils will likely have microplastic-C contents somewhere in between. Microplastic in soil could thus be a unique case of an environmental pollutant posing as an ecosystem service, that is, soil carbon storage, a hallmark of sustainable soil management. As a consequence, we should re-evaluate what constitutes “true” carbon storage: the mere presence of carbon-containing organic molecules may simply no longer suffice. Contributions to soil carbon made by microplastic (and potentially other pollutants, including soot) should be subtracted to arrive at a fair estimate of carbon sequestration. Alternatively, are we prepared to accept microplastic as a non-natural portion of soil carbon? After all, this material will likely be in our soils for the foreseeable future and does represent organic C. We should not, since this material is likely not functionally similar to soil organic matter, probably interacts differently with soil microbes, and it reflects a completely different production path and carbon origin. Either way, we should know its contribution to soil carbon, and this means: investing into methods for quantifying microplastic, and microplastic-carbon in soils globally; understanding its persistence and behavior in soil; and reaching a consensus toward adjusting established standard soil science methods to account for microplastic-derived carbon in the future (perhaps similar to current protocols for removing carbonate). An important driver of such actions could be policy actions to exclude microplastic-derived carbon as a portion of soil carbon.
esearch on microplastic pollution has been an established research topic in marine ecology for well over a decade,1 with the potential implications for sustainability of our oceans becoming increasingly clear. Microplastics, that is pieces of plastic
