Degradable plastic mulch is being used to overcome the negative environmental impacts of burning and landfilling agricultural plastic waste. In this study P. ostreatus was used to model the capacity of a vegetal speci...Degradable plastic mulch is being used to overcome the negative environmental impacts of burning and landfilling agricultural plastic waste. In this study P. ostreatus was used to model the capacity of a vegetal species to degrade conventional and degradable plastic films. Plastics studied were oxo-degradable polyethylene (OXO-PE), UV-irradiated oxo-degradable polyethylene (UV-OXO-PE), polylactic acid (PLA) and conventional polyethylene (C-PE). The cultivation of P. ostreatus resulted in a reduction in the median of weight (78.2% - 80.2%) and volume (56.1% - 60.1%) of the substrate (wheat straw). Degradation of the plastics embodied was evidenced by a reduction in the median of the elongation at break (OXO-PE 475% to 109%, UV-OXO-PE 23% to 8%, PLA 596% to 398% and C-PE 505% to 304%) and an increase in the median of the carbonyl index (OXO-PE 0.062 to 0.114, UV-OXO-PE 0.098 to 0.145 and PLA 0.024 to 0.034). The Kruskal-Wallis test found no statistical difference (p = 0.384) between the medians of the biological efficiency for substrates containing plastics and the substrate without plastic. In conclusion, plastics embodied in the substrates used for cultivation of P. ostreatus are degraded and the degradation of these plastics does not affect the short term growth of P. ostreatus.展开更多
Degradable plastics are used as a way to decrease the environmental impact of these materials when they become waste. However, they can reach natural ecosystems due to littering and bad management. This research asses...Degradable plastics are used as a way to decrease the environmental impact of these materials when they become waste. However, they can reach natural ecosystems due to littering and bad management. This research assesses the performance of oxodegradable and compostable plastics on marine environments through a respirometric lab test. Probes of the plastics, with and without previous simulated weathering, were put in contact for 48 days with a marine inoculum, in a system that guarantees continuous aeration and capture of the produced CO2. After the test, the samples were also assessed in terms of their loss of mechanical properties. The compostable plastic exhibited the higher degree of mineralization (10%), while there was no difference between the polyolefins (2.06% - 2.78%), with or without presence of pro-oxidants or previous abiotic degradation. On the other hand, exposition to UV light promoted a higher loss of elongation at break in the oxodegradables plastic (>68%). The results show that the studied plastics achieve very low biodegradation rates while presenting a higher rate of loss of physical integrity. This combination of phenomena could lead to their fragmentation before significant biodegradation can occur. The risk of microplastics formation must be prevented by avoiding the presence of the materials in marine environments, even if they have shown suitability for some waste management scenarios.展开更多
文摘Degradable plastic mulch is being used to overcome the negative environmental impacts of burning and landfilling agricultural plastic waste. In this study P. ostreatus was used to model the capacity of a vegetal species to degrade conventional and degradable plastic films. Plastics studied were oxo-degradable polyethylene (OXO-PE), UV-irradiated oxo-degradable polyethylene (UV-OXO-PE), polylactic acid (PLA) and conventional polyethylene (C-PE). The cultivation of P. ostreatus resulted in a reduction in the median of weight (78.2% - 80.2%) and volume (56.1% - 60.1%) of the substrate (wheat straw). Degradation of the plastics embodied was evidenced by a reduction in the median of the elongation at break (OXO-PE 475% to 109%, UV-OXO-PE 23% to 8%, PLA 596% to 398% and C-PE 505% to 304%) and an increase in the median of the carbonyl index (OXO-PE 0.062 to 0.114, UV-OXO-PE 0.098 to 0.145 and PLA 0.024 to 0.034). The Kruskal-Wallis test found no statistical difference (p = 0.384) between the medians of the biological efficiency for substrates containing plastics and the substrate without plastic. In conclusion, plastics embodied in the substrates used for cultivation of P. ostreatus are degraded and the degradation of these plastics does not affect the short term growth of P. ostreatus.
文摘Degradable plastics are used as a way to decrease the environmental impact of these materials when they become waste. However, they can reach natural ecosystems due to littering and bad management. This research assesses the performance of oxodegradable and compostable plastics on marine environments through a respirometric lab test. Probes of the plastics, with and without previous simulated weathering, were put in contact for 48 days with a marine inoculum, in a system that guarantees continuous aeration and capture of the produced CO2. After the test, the samples were also assessed in terms of their loss of mechanical properties. The compostable plastic exhibited the higher degree of mineralization (10%), while there was no difference between the polyolefins (2.06% - 2.78%), with or without presence of pro-oxidants or previous abiotic degradation. On the other hand, exposition to UV light promoted a higher loss of elongation at break in the oxodegradables plastic (>68%). The results show that the studied plastics achieve very low biodegradation rates while presenting a higher rate of loss of physical integrity. This combination of phenomena could lead to their fragmentation before significant biodegradation can occur. The risk of microplastics formation must be prevented by avoiding the presence of the materials in marine environments, even if they have shown suitability for some waste management scenarios.
