George Kehayias

Little is known about the vertical distribution of microplastics (MPs) in deep stratified lakes. This study investigates the MPs in the large and deep Lake Trichonis during the thermal stratification period, using two nets of different porosity (50 μm and 200 μm) in three depth strata. Fibers dominated over fragments with an average abundance of 10.63 ± 1.00 items m⁻³ and 3.10 ± 0.52 items m⁻³ respectively in the samples of the 50 μm net in the entire water column, while the respective values for the 200 μm net were 1.4 and 7.4 times greater. Fibers had the highest abundance within the thermocline, and most of them were blue with a length 1–2 mm. There were only abundance differences between the two nets and no qualitative disparities concerning color, size, shape and polymer types. There was a strong positive correlation between the abundance of fibers and the adults of the dominant copepod Eudiaptomus drieschi, which also accumulated within the thermocline. Considering that the adults of E. drieschi are among the preferred prey of Atherina boyeri, the most important commercial fish, certain issues arise concerning possible fiber bioaccumulation on the food web. The study highlights the importance of investigating MPs in connection with biotic elements.

Little is known about the vertical distribution of microplastics (MPs) in deep stratified lakes. This study investigates the MPs in the large and deep Lake Trichonis during the thermal stratification period, using two nets of different porosity (50 μm and 200 μm) in three depth strata. Fibers dominated upon fragments having an average abundance of 10.63 ± 1.00 items/m³ and 3.10 ± 0.52 items/m³ respectively in the samples of the 50 μm net in the entire water column, while the respective values for the 200 μm net were 1.4 and 7.4 times greater. Fibers had highest abundance within the thermocline, and most of them were blue having length 12 mm. There were only abundance differences between the two nets and no qualitative disparities concerning color, size, shape and polymer types. There was strong positive correlation between the abundance of fibers and the adults of the dominant copepod Eudiaptomus drieschi, which accumulated also within the thermocline. Considering that the adults of E. drieschi are among the preferred prey of Atherina boyeri, the most important commercial fish, certain issues arise concerning possible fibers’ bioaccumulation on the food web. The study highlights the importance of investigating MPs in connection with biotic elements.

The widespread dispersion of microplastics (MPs) has been recognized as a pervasive and persistent environmental contaminant in worldwide freshwater ecosystems, and although relative studies have skyrocketed, there are still significant knowledge gaps in areas like southern Europe. This study assesses the microplastic pollution in seven Greek inland aquatic ecosystems which vary in morphology, trophic status, and anthropogenic pressure. Surface and vertical samples were taken with 200 μm plankton nets. MPs were present in all samples, with fibers being the dominant form, having an abundance range between 0.47 and 149.4 items/m³ with fragments between 0.08 and 9.17 items/m³. Fibers and fragments had greater abundance in the vertical than in the surface samples. There were no significant abundance differences between lakes and lagoons, and among the sampling sites in each ecosystem. Blue and transparent were the colors that prevailed, and most of the fibers and fragments were smaller than 1 mm. Four types of MPs were recorded, with PET (polyethylene terephthalate) being the most frequent. The use of the novel Relative Anthropogenic Pressure (RAP) index resulted in positive correlations between certain sociological parameters and the microplastics’ abundance, efficiently reflecting the impingement of human populations on the inland aquatic ecosystems.

The widespread dispersion of microplastics (MPs) has been recognized as a pervasive and per-sistent environmental contaminant in worldwide freshwater ecosystems and although relative studies skyrocketed, there are still knowledge gaps from areas like southern Europe. This study assesses the microplastic pollution in seven Greek inland aquatic ecosystems which vary in morphology, trophic status, and anthropogenic pressure. Surface and vertical samples were taken with 200 μm plankton nets. MPs were present in all samples with fibers being the dominant form having an abundance range between 0.60 and 159.7 n/m3, while fragments between 0.08 and 9.17 n/m3. Fibers and fragments had greater abundance in the vertical than in the surface samples. There were no significant abundance differences between lakes and lagoons, and among the sampling sites in each ecosystem. Blue and transparent were the colors that prevailed while most of the fibers and fragments were smaller than 1 mm. Five types of MPs were recorded with PET being the most frequent among fibers. The use of the novel Relative Anthropogenic Pressure (RAP) index resulted in the highest positive correlations between morphometrical and sociological parameters and the microplastic’s abundance reflecting better the impingement of the human populations on the inland aquatic ecosystems.

The use of natural raw substances for food preservation could provide a great contribution to food waste reduction, circular economy enhancement, and green process application widening. Recent studies indicated that the use of porous materials as adsorbents for natural essential oils provided nanohybrids with excellent antioxidant and antimicrobial properties. Following this trend in this work, a thymol oil (TEO) rich SBA-15 nanohybrid was prepared and characterized physiochemically with various techniques. This TEO@SBA-15 nanohybrid, along with the pure SBA-15, was extruded with low-density polyethylene (LDPE) to develop novel active packaging films. Results indicated that TEO loading was higher than other porous materials reported recently, and the addition of both pure SBA-15 and TEO@SBA-15 to the LDPE increased the water/oxygen barrier. The film with the higher thyme-oil@SBA-15 nanohybrid content exhibited a slower release kinetic. The antioxidant activity of the final films ignited after 48 h, was in the range of 60–70%, and was almost constant for 7 days. Finally, all tests indicated a sufficient improvement by the addition of thyme-oil@SBA-15 nanohybrids in the pure LDPE matrix and the concentration of wt. 10% of such nanocarriers provided the optimum final LDPE/10TEO@SBE-15 active packaging film. This material could be a potential future product for active packaging applications.

The use of natural raw substances for food preservation could provide a great contribution to food waste reducing, circular economy enhancing, and green processes application widening. Recent studies indicated that natural preservatives release kinetics significantly influenced the food preservation process. The use of porous materials as absorber for natural essential oils provided nanohybrids with excellent antioxidant and antimicrobial properties. In this study the well-known SBA-15 porous material was used to control the release of the natural preservative thyme oil on food surface and to extend the food shelf-life. Results indicated that the thyme oil loading was higher than other porous materials reported recently and the addition of SBA-15 to the LDPE increases the water/oxygen barrier. The film with the higher thyme-oil@SBA-15 nanohybrid content exhibited the slower release kinetic. The antioxidant activity of the final films ignited after 48 hours, was in the range of 60-70%, and was almost constant for 7 days. Finally, all tests indicated a sufficient improvement by the addition of thyme-oil@SBA-15 nanohybrids in the pure LDPE matrix and the concentration of wt. 10% of such nanocarriers provided the optimum final LDPE/10TEO@SBE-15 active packaging film. This material could be a potential future product for active packaging applications.

Carvacrol is well documented for its antibacterial and antioxidant effects. However, its high volatility has directed researchers toward nanoencapsulation technology according to bioeconomy and sustainability trends. This study examined and compared free carvacrol (FC), carvacrol microemulsion (MC), carvacrol microemulsion busted with chitosan (MMC), and carvacrol nanoemulsions (NC) as active coatings on extending minced pork meat shelf life at 4 ± 1 °C for 9 days, focusing on microbiological, physiochemical, and sensory characteristics. The research involved pre-characterizing droplet sizes, evaluating antioxidants, and determining antibacterial efficacy. The results demonstrated that NC with a 21 nm droplet size exhibited the highest antioxidant and antibacterial activity. All coatings succeeded in extending the preservation of fresh minced pork meat in comparison to the free carvacrol sample (FC). The NC coating showed the highest extension of minced pork meat preservation and maintained meat freshness for 9 days, with a lower TBARs of 0.736 mg MDA/Kg, and effectively reduced mesophilic, lactic acid, and psychotrophic bacterial counts more significantly by 1.2, 2, and 1.3 log, respectively, as compared to FC. Sensory assessments confirmed the acceptability of NC and MCC coatings. Overall, the carvacrol-based nanoemulsion can be considered a novel antioxidant and antimicrobial active coating due to its demonstrated higher efficacy in all the examined tests performed.

Carvacrol is well-documented for its antibacterial and antioxidant effects. However, its high volatility has directed researchers towards nanoencapsulation technology according to bioeconomy and sustainability trends. This study examined and compared carvacrol microemulsion (MC), carvacrol microemulsion busted with chitosan (MMC) and carvacrol nanoemulsions as active coatings on extending minced pork meat shelf-life at 4±1 oC for 9 days, focusing on microbiological, physiochemical, and sensory characteristics. The research involved pre-characterizing droplet sizes, evaluating antioxidant, and determining antibacterial efficacy. The results demonstrated that NC with a 21 nm droplet size exhibited the highest antioxidant and antibacterial activity. All coatings succeed to extend the preservation of fresh minced pork meat in comparison to free carvacrol sample (FC). NC coating showed the highest extension of minced pork meat preservation and maintained meat freshness for 9 days, with a lower TBARs of 0.736 mg MDA/Kg, and effectively reduced mesophilic, lactic acid, and psychrotrophic bacterial counts more significantly 1.2, 2, and 1.3 log respectively as compared to FC. Sensory assessments confirmed the acceptability of NC and MCC coatings. Overall, the carvacrol based nanoemulsion can be considered as novel antioxidant and antimicrobial active coating due to its demonstrated higher efficacy in all the examined tests performed.