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The dominance and persistence of plastic debris in the marine environment are well documented. No information exists in respect to their lifespan in the marine environment. Nevertheless, the degradation potential of plastic litter items remains a critical issue for marine litter research. In the present study, polyethylene terephthalate bottles (PETs) collected from the submarine environment were characterized using ATR-FTIR in respect to their degradation potential attributed to environmental conditions. A temporal indication was used as indicative to the years of presence of the PETs in the environment as debris. PETs seem to remain robust for approximately fifteen years. Afterwards, a significant decrease of the native functional groups was recorded; some even disappear; or new-not typical for PETs-are created. At a later stage, using the PET time series collected from the Saronikos Gulf (Aegean Sea–E. Mediterranean), it was possible to date bottles that were collected from the bottom of the Ionian Sea (W. Greece). It is the first time that such a study has been conducted with samples that were actually degraded in the marine environment.

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Studying plastic characteristics in the marine environment is important to better understand interaction between plastics and the environment. In the present study, high-density polyethylene (HDPE), polyethylene terephalate (PET), and polyvinyl chloride (PVC) samples were collected from the coastal environment in order to study their surface properties. Surface properties such as surface functional groups, surface topography, point of zero charge, and color change are important factors that change during degradation. Eroded HDPE demonstrated an altered surface topography and color and new functional groups. Eroded PET surface was uneven, yellow, and occasionally, colonized by microbes. A decrease in Fourier transform infrared (FTIR) peaks was observed for eroded PET suggesting that degradation had occurred. For eroded PVC, its surface became more lamellar and a new FTIR peak was observed. These surface properties were obtained due to degradation and could be used to explain the interaction between plastics, microbes, and pollutants.

The present study aims at the preparation and characterization of biochars produced from malt spent rootlets (MSR) under different pyrolysis temperatures. The biochars were characterized for their surface area, microporosity, suspension pH, acid–base behavior, and functional groups on their surface. The highest surface area (340 m2/g) and porosity (0.21 cm3/g) were observed for MSR pyrolized at 800 °C. For the same biochar, 67% of the pore volume corresponds to micropores (<2 nm). The high-temperature biochars resulted in highly alkaline suspensions (pH 9.9) compared to MSR suspensions (pH 5.3). The functional groups (e.g., hydroxyl, phosphonic, amine, or carbon-bonded sulfhydryl) found on the MSR surface disappear as the pyrolysis temperature increases without new ones forming. Thus, the surface charge of high-temperature biochars is low. For phenanthrene, the sorption capacity of biochars pyrolyzed at or above 750 °C increases by almost 1 order of magnitude compared to the raw material. For mercury, sorption capacity of biochars increases by a maximum factor of 4 and a factor of 6 for low- (300–500 °C) and high-temperature (750–900 °C) biochars, respectively.