Suchergebnisse

Sequestration of plastics in sediments is considered the ultimate sink of marine plastic pollution that would justify unexpectedly low loads found in surface waters. Here, we demonstrate that mangroves, generally supporting high sediment accretion rates, efficiently sequester plastics in their sediments. To this end, we extracted microplastics from dated sediment cores of the Red Sea and Arabian Gulf mangrove (Avicennia marina) forests along the Saudi Arabian coast. We found that microplastics <0.5 mm dominated in mangrove sediments, helping explain their scarcity, in surface waters. We estimate that 50 ± 30 and 110 ± 80 metric tons of plastic may have been buried since the 1930s in mangrove sediments across the Red Sea and the Arabian Gulf, respectively. We observed an exponential increase in the plastic burial rate (8.5 ± 1.2% year$^{−1}$) since the 1950s in line with the global plastic production increase, confirming mangrove sediments as long-term sinks for plastics. ; We thank A. Qasem and P. Priahartato, from Saudi Aramco, for support and advice on sampling design; R. Lindo, R. Magalles, P. Bacquiran, S. Ibrahim, and M. Lopez, at the Marine Studies section of the Center for Environment and Water of King Fahd University of Petroleum and Minerals, for contribution in fieldwork sampling in the Arabian Gulf; and Z. Batang and staff from the Coastal and Marine Resources core laboratory at King Abdullah University of Science and Technology (KAUST) for help with sampling in the Red Sea. We thank I. Schulz, N. Geraldi, K. Rowe, S. Roth, M. Ennasri, and D. Prabowo for helping with processing of the cores. We thank the KAUST Workshop for manufacturing the SMI unit. We thank R. al Nahdi for help during plastic extraction. The International Atomic Energy Agency (IAEA) is grateful for the support provided to its Environment Laboratories by the government of the Principality of Monaco. ; This work was supported and funded by KAUST through the baseline funding of C.M.D. and by the Australian Research Council LIEF Project (LE170100219) and the Generalitat de Catalunya (grant 2017 SGR-1588) through the funding provided to P.M. This work is contributing to the ICTA "Unit of Excellence" (MinECo, MDM2015-0552).