Plastic pollution, especially microplastics (MPs), poses significant environmental challenges, with biodegradable plastics (BPs) often presented as sustainable alternatives. However, incomplete degradation of BPs in s...Plastic pollution, especially microplastics (MPs), poses significant environmental challenges, with biodegradable plastics (BPs) often presented as sustainable alternatives. However, incomplete degradation of BPs in soil environment leads to the creation of biodegradable microplastics (BMPs), whose impacts remain inadequately understood. This systematic review synthesizes findings from 85 publications to assess the effects of BMPs on soil ecosystems, encompassing physical, chemical, and biological properties. BMPs influence soil texture, porosity, nutrient cycling, microbial diversity, and plant growth, with varying impacts depending on polymer type, concentration, and soil conditions. While BMPs can enhance soil organic matter and microbial activity at low concentrations, higher concentrations often alter nutrient availability and soil stability. Soil biota shows differential responses to BMPs, with potential implications for nutrient cycling and soil ecosystem functioning. Contradictory research findings underscore the need for long-term, field-based studies under varied environmental conditions. The insights from this review contribute to a deeper understanding of the ecological ramifications of BMPs in soil ecosystems, highlighting critical research gaps, advocating for multidisciplinary approaches to comprehensively evaluate impacts of BMPs.展开更多
It has been demonstrated that microplastics (MPs) can accumulate heavy metals from the environment and transfer them into organisms via the food chain. However, adsorption and desorption capacities for biodegradable M...It has been demonstrated that microplastics (MPs) can accumulate heavy metals from the environment and transfer them into organisms via the food chain. However, adsorption and desorption capacities for biodegradable MPs relative to those for conventional MPs remain poorly understood. In this study, cadmium (Cd(II)) adsorption and desorption characteristics of polylactic acid (PLA), a typical biodegradable MP, were investigated. Two conventional MPs, i.e., polypropylene (PP) and polyamide (PA) were used for comparison. The maximum Cd(II) adsorption capacities of the MPs studied in the adsorption experiments decreased in the order PA (0.96 ± 0.07 mg/g) > PLA (0.64 ± 0.04 mg/g) > PP (0.22 ± 0.03 mg/g). The Pseudo-second-order kinetic model and Freundlich isothermal model described the Cd(II) adsorption behaviors of PLA MPs well. X-ray photoelectron spectroscopy and two-dimensional Fourier transform infrared correlation spectroscopy analysis indicated that oxygen functional groups were the major and preferential binding sites of PLA MPs, which contributed to their high Cd(II) adsorption capacities. Simulated gastric and intestinal fluids both significantly enhanced the desorption capacities of the examined MPs. Notably, degradation of the PLA MPs during in vitro human digestion made the Cd(II) on the PLA MPs more bioaccessible (19% in the gastric phase and 62% in the intestinal phase) than Cd(II) on the PP and PA MPs. These results indicate the remarkable capacities of biodegradable MPs to accumulate Cd(II) and transfer it to the digestive system and show that biodegradable MPs might pose more severe threats to human health than conventional nonbiodegradable MPs.展开更多
文摘Plastic pollution, especially microplastics (MPs), poses significant environmental challenges, with biodegradable plastics (BPs) often presented as sustainable alternatives. However, incomplete degradation of BPs in soil environment leads to the creation of biodegradable microplastics (BMPs), whose impacts remain inadequately understood. This systematic review synthesizes findings from 85 publications to assess the effects of BMPs on soil ecosystems, encompassing physical, chemical, and biological properties. BMPs influence soil texture, porosity, nutrient cycling, microbial diversity, and plant growth, with varying impacts depending on polymer type, concentration, and soil conditions. While BMPs can enhance soil organic matter and microbial activity at low concentrations, higher concentrations often alter nutrient availability and soil stability. Soil biota shows differential responses to BMPs, with potential implications for nutrient cycling and soil ecosystem functioning. Contradictory research findings underscore the need for long-term, field-based studies under varied environmental conditions. The insights from this review contribute to a deeper understanding of the ecological ramifications of BMPs in soil ecosystems, highlighting critical research gaps, advocating for multidisciplinary approaches to comprehensively evaluate impacts of BMPs.
基金supported by the Hubei Provincial Natural Science Foundation of China(Nos.2021CF349 and 2020CFA042).
文摘It has been demonstrated that microplastics (MPs) can accumulate heavy metals from the environment and transfer them into organisms via the food chain. However, adsorption and desorption capacities for biodegradable MPs relative to those for conventional MPs remain poorly understood. In this study, cadmium (Cd(II)) adsorption and desorption characteristics of polylactic acid (PLA), a typical biodegradable MP, were investigated. Two conventional MPs, i.e., polypropylene (PP) and polyamide (PA) were used for comparison. The maximum Cd(II) adsorption capacities of the MPs studied in the adsorption experiments decreased in the order PA (0.96 ± 0.07 mg/g) > PLA (0.64 ± 0.04 mg/g) > PP (0.22 ± 0.03 mg/g). The Pseudo-second-order kinetic model and Freundlich isothermal model described the Cd(II) adsorption behaviors of PLA MPs well. X-ray photoelectron spectroscopy and two-dimensional Fourier transform infrared correlation spectroscopy analysis indicated that oxygen functional groups were the major and preferential binding sites of PLA MPs, which contributed to their high Cd(II) adsorption capacities. Simulated gastric and intestinal fluids both significantly enhanced the desorption capacities of the examined MPs. Notably, degradation of the PLA MPs during in vitro human digestion made the Cd(II) on the PLA MPs more bioaccessible (19% in the gastric phase and 62% in the intestinal phase) than Cd(II) on the PP and PA MPs. These results indicate the remarkable capacities of biodegradable MPs to accumulate Cd(II) and transfer it to the digestive system and show that biodegradable MPs might pose more severe threats to human health than conventional nonbiodegradable MPs.
