Impacts of Micro- and Nano-Plastics on Soil Properties and Plant Production in Agroecosystems: A Mini-Review

Micro- and nano-plastics (MNPs) are tiny plastic particles resulting from plastic product degradation. Soil MNPs have been identified as potential influential factors affecting various soil properties and crop biomass productivity. This mini-review provides a synthesis of recent findings concerning their effects on soil physicochemical properties, microorganisms, organic carbon content, soil nutrients, greenhouse gas emissions, soil fauna, and their impacts on plant ecophysiology, growth, and production. The results indicate that MNPs may markedly impede soil aggregation ability, increase porosity, decrease soil bulk density, enhance water retention capacity, influence soil pH and electrical conductivity, and escalate soil water evaporation. Exposure to MNPs may predominantly induce changes in soil microbial composition, reducing the diversity and complexity of microbial communities and microbial activity while enhancing soil organic carbon stability, influencing soil nutrient dynamics, and stimulating organic carbon decomposition and denitrification processes, leading to elevated soil respiration and methane emissions, and potentially decreasing soil nitrous oxide emission. Additionally, MNPs may adversely affect soil fauna, diminish seed germination rates, promote plant root growth, yet impair plant photosynthetic efficacy and biomass productivity. These findings contribute to a better understanding of the impacts and mechanistic foundations of MNPs. Future research avenues are suggested to further explore the impacts and economic implications.

Microplastics and Nano-Plastics: From Initiation to Termination

Following the advent of the Industrial Revolution, plastic pollution has been a serious environmental issue while micro- and nano-plastics have been a cynosure of researchers’ attention in the twenty-first century. This is due to the improved knowledge of its ecotoxicological effects and the global pushforward towards sustainability. There is a growing concern that the increasing presence of microplastics and nanoplastics (MNPs) in aquatic habitats poses a threat to marine life, and it is predicted that nanoplastics will be just as ubiquitous as macro- and micro-plastics, but far more destructive to living organisms due to their ability to infiltrate cells. Recent research has shown that marine and freshwater biota become entangled with plastic litter, which disrupts the ecosystem. Aquatic creatures are known to absorb and deposit these new pollutants in their digestive systems, as has been documented in several studies. More recent research has also examined their co-occurrence and toxicity with other emerging contaminants, including their prevalence and effects in food, air, and soil. Using articles extracted from a six-year period from Scopus, ACS Publications and Google Scholar, this review explores the origins, fates, occurrence in the food chain, exposure routes, cellular interactions of microplastics and nano-plastics, in addition to the ecotoxicological impacts, analytical methods, and the potential remedies for combating pollution and toxicity. Ultimately, this review is a comprehensive, updated addendum to available reviews on micro- and nano-plastics.

Effects of environmentally relevant concentrations of micro(nano)plastics on aquatic microorganisms:Changes in potential function but not in overall composition

Micro(nano)plastics(MNPs)are a growing problem as persistent environmental pollutants.Here,we investigated the impact of MNPs on microorganisms in aquatic microbial floc exposed to NPs(80 nm)and MPs(8μm)for 35 days.Water quality indicators were tested weekly and microbiological analyses were conducted on Day 7 and 28 after exposure.The results showed that there were significant differences in the levels of total ammonia nitrogen or nitrite between the MNPs groups and the control group,spanning from Day 7 to Day 28.For the microbial response,microbial community richness in the NPs and MPs groups were significantly increased at Day 7.Functional prediction showed that the relative abundances of bacteria associated with the“Forms Biofilms”,“Potentially Pathogenic”,“Plastic Degradation”and nitrogen cycle processes were significantly different after MNPs exposure.The results suggest that MNPs had no significant effect on the microbial diversity of mature microbial flocs.Findings suggest MPs could cause an increase in the relative abundance of potentially pathogenic bacteria,while NPs do not.In addition,stress associated with MNPs affected the nitrogen cycle of microorganisms,and NPs exerted greater impacts than MPs.Findings from this study further our understanding of the impact of MNPs at environmentally relevant concentrations on microorganisms in aquatic ecosystems.

Water-dispersible nano-pollutions reshape microbial metabolism in type-specific manners:A metabolic and bacteriological investigation in Escherichia coli

Incomplete separation and recycling of nanoparticles are causing undesirable nanopollution and thus raising great concerns with regard to nanosafety.Since microorganisms are important regulator of physiological processes in many organisms,the interaction between nanopollution and microbial metabolomics and the resultant impact on the host’s health are important but unclear.To investigate how typical nanopollution perturbs microbial growth and metabolism,Escherichia coli(E.coli)in vitro was treated with six water-dispersible nanomaterials(nanoplastic,nanosilver,nano-TiO 2,nano-ZnO,semiconductor quantum dots(QDs),carbon dots(CDs))at human-/environment-relevant concentration levels.The nanomaterials exhibited type-specific toxic effects on E.coli growth.Global metabolite profiling was used to characterize metabolic disruption patterns in the model microorganism exposed to different nanopollutants.The percentage of significant metabolites(p<0.05,VIP>1)accounted for 6%–38%of the total 293 identified metabolites in each of the nanomaterial-contaminated bacterial groups.Metabolic results also exhibited significant differences between different nanopollutants and dose levels,revealing type-specific and untypical concentration-dependent metabolic responses.Key metabolites responsive to nanopollution exposures were mainly involved in amino acid and purine metabolisms,where 5,4,and 7 significant metabolic features were included in arginine and proline metabolism,phenylalanine metabolism,and purine metabolism,respectively.In conclusion,this study horizontally compared and demonstrated how typical nanopollution perturbs microbial growth and metabolomics in a type-specific manner,which broadens our understanding of the ecotoxicity of nanopollutants on microorganisms.