As the use of biodegradable plastics becomes increasingly widespread, their environmental behaviors and impacts warrant attention. Unlike conventional plastics, their degradability predisposes them to fragment into microplastics (MPs) more readily. These MPs subsequently enter the terrestrial environment. The abundant functional groups of biodegradable MPs significantly affect their transport and interactions with other contaminants (e.g., organic contaminants and heavy metals). The intermediates and additives released from depolymerization of biodegradable MPs, as well as coexisting contaminants, induce alterations in soil ecosystems. These processes indicate that the impacts of biodegradable MPs on soil ecosystems might significantly diverge from conventional MPs. However, an exhaustive and timely comparison of the environmental behaviors and effects of biodegradable and conventional MPs within soil ecosystems remains scarce. To address this gap, the Web of Science database and bibliometric software were utilized to identify publications with keywords containing biodegradable MPs and soil. Moreover, this review comprehensively summarizes the transport behavior of biodegradable MPs, their role as contaminant carriers, and the potential risks they pose to soil physicochemical properties, nutrient cycling, biota, and CO2 emissions as compared with conventional MPs. Biodegradable MPs, due to their great transport and adsorption capacity, facilitate the mobility of coexisting contaminants, potentially inducing widespread soil and groundwater contamination. Additionally, these MPs and their depolymerization products can disrupt soil ecosystems by altering physicochemical properties, increasing microbial biomass, decreasing microbial diversity, inhibiting the development of plants and animals, and increasing CO2 emissions. Finally, some perspectives are proposed to outline future research directions. Overall, this study emphasizes the pronounced effects of biodegradable MPs on soil ecosystems relative to their conventional counterparts and contributes to the understanding and management of biodegradable plastic contamination within the terrestrial ecosystem.
Due to the widespread use of engineered nanomaterials (ENMs) for soil remediation and nano-enabled sustainable agriculture, there is a growing concern regarding the behavior and fate of ENMs released into soil systems in the presence of natural root exudates (REs). Herein, we investigate the influence of REs on the fate and ecological effect of ENMs from a comprehensive perspective. We summarize the key roles reported in the literature for REs in physical changes (e.g., adsorption, dispersion/aggregation), chemical changes (e.g., oxidation/redox reactions, and dissolution), and biotransformation of ENMs, which will further determine the ecological risk of ENMs in natural soil systems. Moreover, this review highlights the potential adverse effects of ENMs on different soil organisms (e.g., bacteria, plants, and eisenia foetida) in the presence of REs. The remaining unclear mechanisms (e.g., oxidative stress and DNA damage) of ENMs toxicity at the cellular level influenced by REs are reviewed and presented. Finally, the review concludes by addressing the current knowledge gaps and challenges in this field.
Meat consumption causes major damage to the environment, such as the pollution of air, water, and soil, and contributes significantly to biodiversity loss and climate change. To reach environmental and climate targets, agricultural production methods need to be addressed politically. However, dietary behavior also needs to change. This is especially the case in Western countries with unsustainably high meat consumption, such as Germany. Based on a systematic analysis of the literature of different disciplines, the article examines the following: (a) Factors influencing food behavior; (b) Policy instruments effectively contributing to behavior change; (c) Potential problems with regard to their political feasibility. Using Germany as an example, the analysis shows that only a combination of measures is promising to achieve a reduction in meat consumption-both in terms of effectiveness as well as political feasibility. Instruments need to change contextual conditions in a way that makes sustainable nutritional choices the easier ones. In the longer term, education programs and campaigns can help to change basic influencing factors such as norms or values. And, in the short term, these factors can be activated and become relevant for action in the respective decision-making situations.
Per- and polyfluoroalkyl substances (PFAS) possess distinct properties, such as hydrophobicity, oleophobicity, and thermal and chemical stability, resulting in their wide application in various industrial processes, including electroplating, fire protection, and textile, paper, and leather production. However, due to their propensity for high bioaccumulation, long-distance transport, resistance to degradation, and potential adverse effects on animal and human health, certain PFAS, including legacy perfluorooctanoic acid (PFOA), were listed in Annex A of the Stockholm Convention in 2019, leading to a global ban on their production and usage. Consequently, per- and poly-fluoropolyether carboxylic acids (PFECA), containing ether oxygen bonds in their structure, have emerged as processing-additive substitutes for PFOA in different industries. Recently, with the increasing concern, more and more PFECA have been identified and detected in various environmental matrix and human samples. Epidemiological research and toxicity experiments have also found that some PFECA have health hazards comparable to or even stronger than PFOA. In the present study, we focus on the classification, environmental impacts, and toxic hazards associated with PFECA and summarize recent research regarding non-targeted identification, environmental behavior and fate, biological/human exposure levels, toxic effects, and related molecular mechanisms. The overall aim of this review is to provide a valuable reference for environmental pollution research and biological risk assessment of PFAS alternatives, thereby supporting the regulation and reduction of PFAS alternatives in China. In terms of PFECA recognition, with the rapid development of non-targeted and targeted screening techniques, researchers have identified a series of PFECA with feature structure in various environmental matrix, such as unsaturated PFECA, chlorinated PFECA and homologues of hexafluoropropylene oxide trimer acid (HFPO-TA). However, non-targeted and targeted screening research is still in its infancy, with only 11 reports identifying dozens of PFECA, more and more novel PFECA will definitely be recognized in the future. In terms of quantitative detection, PFECA has been detected in various environmental matrix (including surface water, soil, atmosphere), organisms (including plants, fish and frogs) and even human samples (serum, urine and milk). Among them, there are many reports on water bodies and population samples. Among the existing reports, the PFECA levels in water and human samples accounts for a relatively large proportion. It is worth noting that the detection rate of HFPO-TA homologues in the serum of residents living around fluoride factories exceeds 90%, and the concentration of HFPO-TA ranking the fourth among all the detected PFAS. In terms of the toxic effects, it has been confirmed through several animal exposure experiments that PFECA, such as HFPO-TA, hexafluoropropylene oxide tetramer acids (HFPO-TeA) and perfluoro (3,5,7,9-tetraoxadecanoic) acid (PFO4DA), can cause liver damage, decreased sex hormone levels, metabolic disorders, and developmental abnormalities by interfering with PPAR pathways and metabolic pathways. In addition to in vivo experiments, we also noticed that researchers have carried out in-depth in vitro and in sillico studies on the interaction between PFECA and nuclear receptors or transporters in order to provide a possible explanation for the bioaccumulation and toxic effects of PFECA. Our paper also discusses the challenges, potential risks, and future research directions concerning the application of PFECA. For example, in the development and application of green alternatives, several problems, including unclear information on their structure, physical and chemical properties, and immature quantitative analysis methods, should be addressed to reduce the potential environmental and health hazards caused by the new PFECA at the source. At the same time, developing efficient degradation methods in contaminant treatment is also one of the future research directions. It is also worth paying more attention to combine regulatory, scientific research, and market aspects to provide guarantees for the rational use of novel PFECA.