Microplastic in marine environment: reworking and optimisation of two analytical protocols for the extraction of microplastics from sediments and oysters

Abstract

Marine sediments and sessile biota (i.e. oysters) are nowadays recognised to be affected by microplastic (MP) pollution. NOAA proposes two distinct MP extraction protocols for sandy and bed sediments, which, however, were already demonstrated to suffer from many limitations. Conversely, to what concern oysters, works already published are usually time consuming, requiring a KOH 24–48 h oxidation step. The aim of this study is to show how iterative adaptation of the NOAA protocol allows to extract MPs, included PET, from marine sediments, regardless their characteristics. The method tested on PE-LD/PET/PA/PE-HD is based on density separation and oxidation treatments which were both carefully tuned, obtaining final recoveries higher than 85% for all the micropolymers (100% for PE and PA). Furthermore, a new protocol for the extraction of MPs from oysters was assessed, highlighting its efficacy (recoveries higher than 84% for all the plastics) and time-saving peculiarity. Finally, both protocols were successfully applied in the MPs extraction from real samples from Atlantic Ocean. The extraction of PE-LD/PET/PA/PE-HD was optimised in sediments (regardless their characteristics) and oysters. For sediments, density separation and oxidation procedures were carefully optimised. For oysters, oxidation times were reduced from 24 to 48 h to 1 h.

Polycyclic Aromatic Hydrocarbons and Polychlorinated Biphenyls in Seawater, Sediment and Biota of Neritic Ecosystems: Occurrence and Partition Study in Southern Ligurian Sea

“…The presence of these congeners could be explained taking into account feeding habits, since it was recently demonstrated that herbivorous copepods could be deceived in their feeding by microplastics and nanoplastics, upon which algae and phytoplankton grow [53]. Such micropolymers have been shown to adsorb organic and inorganic pollutants (such as PAHs and PCBs) [54], thus suggesting that they could be an additional source of PAH congeners once ingested by organisms [55].…”

Extraction efficiency of different microplastic polymers from deep-sea sediments and their quantitative relevance

“…Previous investigations conducted on coastal sediments have revealed that some polymers such as PE and PA were extracted more efficiently than PET (Rivoira et al, 2020) whereas other studies reported a similar extraction efficiency among different Extraction efficiency of microplastics (20-1000 µm) from deep-sea sediments based on two different approaches applied to bulk (BS) and partitioned (PS) sediments.…”

A simple overflow density separation method that recovers >95% of dense microplastics from sediment

“…sample mass, polymers of interest, chemical and equipment availability). Overflow separation methods are effective at isolating microplastics from sediment samples [17] , [18] , [19] , [20] , [21] , [22] , yet detailed procedures are limited and rarely validated with a range of high-density polymers. In addition, overflow separation methods seldom use solutions prepared at high densities that provide a greater recovery of microplastics [2] .…”