The degradation of polylactic acid face mask components in different environments.

The disposal of fossil fuel-based plastics poses a huge environmental challenge, leading to increased interest in biodegradable alternatives such as polylactic acid (PLA). This study focuses on the environmental impact and degradation of PLA face mask components under various conditions (UV (Ultraviolet) radiation, DI water, landfill leachate of various ages, seawater, and enzyme). Under UV exposure, notable changes in physicochemical properties were observed in the PLA masks, including increased oxidation over time. Degradation rates varied across environments, with old landfill leachate and enzyme degradation having a notable impact, especially on meltblown layers. Furthermore, it was found that seawater conditions hampered the degradation of PLA masks, likely due to the inhibitory effect of high salt concentrations. The pathways of chemical group changes during degradation were elucidated using 2D-COS (Two-Dimensional Correlation Spectroscopy) maps. The investigation into the release of microparticles and oligomers further revealed the degradation mechanism. Moreover, PLA masks were found to release fewer microparticles when degraded in studied environments when compared to traditional polypropylene masks. Furthermore, correlation analysis highlighted the influence of factors such as carbonyl index and contact angle on degradation rates, underscoring the complex interplay between environmental conditions and PLA degradation. This comprehensive investigation advances the understanding of PLA degradation pathways, which are crucial for mitigating plastic pollution and promoting the development of sustainable products.

An integrated environmental and economic assessment for the disposal of food waste from grocery retail stores towards resource recovery.

Food waste gives rise to many environmental problems. A large amount of food waste is produced by grocery retail stores. It is therefore important to apply efficient food waste treatment technologies with minimal environmental impact and investigate the optimal approach for food waste collection, transportation, and treatment. In the present study, a life cycle impact assessment (LCIA) was conducted to analyze different food waste disposal scenarios, including incineration, landfilling, composting, anaerobic digestion, and bioconversion. The impacts of the five scenarios on the environmental, economic, and social aspects were assessed. The results suggested that the landfilling scenario has the lowest net cost for the treatment of food waste, followed by the incineration scenario. The bioconversion treatment cost has the most significant positive effect on the net cost of the bioconversion scenario, and both the price and yield of compost have a significant negative effect on the net cost. The rankings of the five scenarios are the same under both weight determination methods, with the bioconversion scenario performing the best, followed by the composting scenario. The results of this study can help improve the disposal of food waste in grocery retail stores in the framework of sustainability and the circular economy.

Exploring the glycoprotein washing fluid-assisted cleanup for the restoration of oil-contaminated shorelines with environmental integrity.

Spilled oil in ocean can spread to the shoreline and cause long-term impacts on the shoreline's ecological environment. Therefore, removing oil accumulated on shorelines is crucial. This study proposed an innovative ovalbumin (OVA) fluid-assisted method for the cleanup of oiled shoreline substrates. The oil removal efficiency of OVA fluids was systematically investigated. Higher concentrations of OVA fluids effectively enveloped and immobilized the oil, aiding in its separation from the sand surface. The increased temperature reduced the viscosity of emulsions, facilitating improved flow and oil removal. High salinity promoted the creation of oil particle aggregates molecules and facilitated the release of oil from the sand surface. The factorial analysis demonstrated that a high salt environment significantly enhances the combined impact of temperature and pH on oil removal performance. Different methods for the responsive separation of washing effluents were studied, and the most effective separation method was adjusting the pH of effluents to 4.54 (the isoelectric point of OVA). Separated precipitates exhibited good decomposition efficiency through thermal decomposition and biodegradation. OVA fluids boast advantages, such as low cost, easy recyclability, and non-toxicity, while ensuring high oil removal efficiency and making them a promising eco-friendly technique for the cleanup of oiled shorelines.

Revealing the Freezing-Induced Alteration in Microplastic Behavior and Its Implication for the Microplastics Released from Seasonal Ice.

Ice can serve as a significant temporary repository and conveyance mechanism for microplastics (MPs). MPs present in the water column can become entrapped within developing ice formations, subsequently being sequestered and transported by ice floes. With changing temperatures, MPs stored in ice can be released back into the environment, while freezing conditions can alter the properties of MPs, ultimately affecting the fate of MPs in the environment. Freezing of MPs in freshwater ice results in the aggregation of MP particles due to physical compression, leading to an increase in particle size once the MPs are released from the ice. The freezing-induced aggregation enhances buoyancy effects, accelerating the settling/rising velocity of MPs in water. Additionally, freezing can lead to enhanced surface wetting alterations, thus improving the dispersion of hydrophobic MPs. The presence of salt in the water can mitigate the effect of freezing on MPs due to the formation of a brine network within the ice structure, which reduces the pressure on MPs entrapped by ice. In cold regions, numerous MPs undergo freezing and thawing, re-entering the water column.

Innovations and development of sustainable personal protective equipment: a path to a greener future.

The unprecedented surge in the demand for personal protective equipment (PPE) worldwide during the covid pandemic resulted in a significant increase in PPE consumption and subsequent waste generation. Despite the importance of PPE, its widespread usage and disposal have sparked worries about the environmental impact and its long-term sustainability. The increasing awareness of environmental challenges, resource scarcity, and the urgent need to mitigate climate change necessitates a paradigm shift in the product design, manufacturing process, and waste management of PPE. To address these challenges and have a sustainable PPE future, the development of degradable polymers and natural fibers offers a promising alternative to traditional plastics. Additionally, recycling and upcycling methods can convert the waste into valuable alternate products or energy sources, thereby reducing their environmental impact. Better waste management systems, comprehensive policy frameworks, and international collaborations are essential for the effective PPE waste management and the promotion of sustainable practices. Despite the challenges, collaborative efforts across governments, manufacturers, research institutions, and waste management authorities are crucial for transitioning to a more sustainable PPE industry and a circular economy, ultimately benefiting both the environment and society.

Evaluating Sustainable Practices for Managing Residue Derived from Wheat Straw.

Farm leftovers, particularly crop residues, are a key source of renewable energy in Canada. The nation's robust agricultural industry provides ample biomass, derived from forestry and agriculture resources, for energy generation. Crop residues, such as straws and husks, play a crucial role in this biomass reservoir, contributing to biofuel production and greenhouse gas mitigation efforts. Focusing on supply chains, waste management, and emission reduction, this study evaluates the sustainability of wheat straw, an agricultural biomass by-product. The environmental issues of various approaches to managing agricultural biomass were explored. Following an evaluation of biomass features, conversion methods, and economic and environmental advantages, the results show anaerobic digestion to be the most sustainable approach. Four metrics were examined in relation to social elements, and numerous aspects were considered as inputs in the evaluation of transportation costs. The use of electric trucks versus fuel-based trucks resulted in an 18% reduction in total operating costs and a 58% reduction in consumption costs. This study examined CO2 emissions over four different transportation distances. The data indicate that a significant reduction of 36% in kg CO2 equivalent emissions occurred when the distance was lowered from 100 km to 25 km. These findings offer insights for creating practical plans that should increase the sustainability of agricultural biomass leftovers.

A robust, low-temperature, closed-loop anaerobic system for high-solid mixed farm wastes: advancing agricultural waste management solutions in Canada.

This study investigates the effectiveness of low-temperature (20 ± 1 °C) anaerobic digestion (AD) for two organic multiple farm substrate combinations: Set 1 comprising chicken manure (CM), dairy manure (DM), and waste corn silage (CS) and Set 2 comprising CM, DM, pig manure (PM), and CS. Inoculum adaptation steps were carried out using CM and CM+DM for Set 1 and Set 2, respectively. Over three consecutive operating cycles spanning 245 days with increasing organic loads, 4.3 and 2.8 g VS L-1 d-1 for Sets 1 and 2 during Cycles 1 to 5.1 and 4.6 g VS L-1 d-1for Sets 1 and 2 during Cycle 3, a closed-loop two-stage liquid-solid AD system was employed, with performance assessed via stability ratios of short-chain volatile fatty acids and alkalinity. Results demonstrate that mono-digestion of CM with adapted inoculum yielded the highest biogas production of 424 ± 4 L over 77 days, indicating superior performance by Set 1 during Phase I, whereas a similar performance was observed during Phase 2, where Sets 1 and 2 exhibited highest specific methane yields of 0.233 ± 0.028 and 0.262 ± 0.004 L g-1 VSfed, respectively, over 68 days. Analysis of heavy metal concentrations in digestates revealed a significant decrease compared to initial raw substrate concentrations, highlighting their role as nutrients for microbial growth. This study, the first of its kind, highlights the potential of low-temperature AD systems to manage diverse organic residues/byproducts and offers insights into effective performance monitoring without compromising system integrity.

Assessment of urban greenhouse gas emissions towards reduction planning and low-carbon city: a case study of Montreal, Canada.

Greenhouse gases (GHGs) can be produced from a broad range of anthropogenic activities at different spatial and temporal scales. In particular, emissions from urban area are an import source of GHGs. City is a complicated system consisting of various component and processes. Efforts have been made to reduce urban GHG emissions. However, there is a lack of available methods for effective assessment of such emissions. Many urban sources and factors which can influence the emissions are still unknown. In the present study, the GHG emissions from municipal activities was assessed. A model for the assessment of urban GHG emissions was developed. Based on the collected data, a case study was conducted to evaluate urban GHG emissions. The comprehensive assessment included the emissions from transportation, electricity consumption, natural gas, waste disposal, and wastewater treatment. There was a variation for GHG emissions from these sectors in different years. This study provided a new approach for comprehensive evaluation of urban GHG emissions. The results can help better understand the emission process and identify the major emission sources. Supplementary Information: The online version contains supplementary material available at 10.1186/s40068-024-00341-y.

Navigating the nexus: climate dynamics and microplastics pollution in coastal ecosystems.

Microplastics (MPs) pollution is an emerging environmental health concern, impacting soil, plants, animals, and humans through their entry into the food chain via bioaccumulation. Human activities such as improper solid waste dumping are significant sources that ultimately transport MPs into the water bodies of the coastal areas. Moreover, there is a complex interplay between the coastal climate dynamics, environmental factors, the burgeoning issue of MPs pollution and the complex web of coastal pollution. We embark on a comprehensive journey, synthesizing the latest research across multiple disciplines to provide a holistic understanding of how these inter-connected factors shape and reshape the coastal ecosystems. The comprehensive review also explores the impact of the current climatic patterns on coastal regions, the intricate pathways through which MPs can infiltrate marine environments, and the cascading effects of coastal pollution on ecosystems and human societies in terms of health and socio-economic impacts in coastal regions. The novelty of this review concludes the changes in climate patterns have crucial effects on coastal regions, proceeding MPs as more prevalent, deteriorating coastal ecosystems, and hastening the transfer of MPs. The continuous rising sea levels, ocean acidification, and strong storms result in habitat loss, decline in biodiversity, and economic repercussion. Feedback mechanisms intensify pollution effects, underlying the urgent demand for environmental conservation contribution. In addition, the complex interaction between human, industry, and biodiversity demanding cutting edge strategies, innovative approaches such as remote sensing with artificial intelligence for monitoring, biobased remediation techniques, global cooperation in governance, policies to lessen the negative socioeconomic and environmental effects of coastal pollution.

Effect of nanobubbles on the mobilization of microplastics in shorelines subject to seawater infiltration.

The widespread presence of microplastics (MPs) in the ocean has varying degrees of impact on ecosystems and even human health. Coastal tidal zones are crucial in controlling the movement of MPs, which are influenced by waves and tidal forces. Meanwhile, natural nanobubbles (NBs) in the ocean can affect the hydrodynamic properties of the tidal zone. The mobilization of MPs in coastal tidal zones under the effect of NBs has been less studied. In this study, we explored natural NBs' influence on the mobilization of MPs in shorelines subject to seawater infiltration. Using glass beads as a substrate, a coastal porous environment was constructed through column experiments, and the pump-controlled water flow was used to study the transport of MPs subject to seawater movement within the substrate. The infiltration of MPs under continuous and transient conditions, as well as the upward transport induced by flood tide, were considered. The role of salinity in the interactions between NBs, MPs, and substrates was evaluated. Salinity altered the energy barriers between particles, which in turn affected the movement of MPs within the substrate. In addition, hydrophilic MPs were more likely to infiltrate within the substrate and had different movement patterns under continuous and transient flow conditions. The motion of the MPs within the substrate varied with flow rate, and NBs limited the vertical movement of MPs in the tidal zone. It was also observed that NBs adsorbed readily onto substrates, altering the surface properties of substrates, particularly their ability to attach and detach from other substances.

Spotlight on the vertical migration of aged microplastics in coastal waters.

Coastal waters are complex and dynamic areas with unique environmental attributes that complicate the vertical migration of microplastics (MPs). The MPs that enter coastal waters from diverse sources, including terrestrial, riverine, oceanic, and shoreline inputs undergo various aging pathways. In this study, the variations in the physiochemical characteristics of MPs undergoing various aging pathways and their vertical migration under dynamic conditions subjected to the effects of different MP characteristics and coastal environmental features were comprehensively explored. Opposite effects of aging on the vertical migration of hydrophobic and hydrophilic MPs were observed, with aging appearing to promote the dispersion of hydrophobic MPs but enhance the vertical migration of hydrophilic ones. The positive role of salinity and the negative role of humic acid (HA) concentrations on MP vertical migration were identified, and the mechanisms driving these effects were analyzed. Notably, intense turbulence not only promoted the floating of positively buoyant MPs but also reversed the migration direction of negatively buoyant MPs from downward to upward. Aging-induced changes in MP characteristics had a limited effect on MP vertical migration. The inherent characteristics of MPs and the surrounding environmental features, however, played major roles in their vertical migration dynamics. ENVIRONMENTAL IMPLICATION: Microplastics (MPs) have emerged as a significant global environmental concern and the coastal zones are the hotspots for MP pollution due to their high population density. This study comprehensively investigated the variations in the physiochemical characteristics of MPs undergoing various aging pathways. Their vertical migration patterns under dynamic conditions subjected to the effects of different MP characteristics and coastal environmental features were revealed. The roles of turbulence and MP density in their migration were identified. The findings of this study have important implications for understanding the transport and determining the ecological risks of MPs in coastal waters.

Unveiling the Vertical Migration of Microplastics with Suspended Particulate Matter in the Estuarine Environment: Roles of Salinity, Particle Properties, and Hydrodynamics.

The estuary is an energetic area connecting the inland, river, and ocean. The migration of microplastics (MPs) in this highly complex area is tied to the entire ecosystem. In this study, the effects of cohesive SPM (clay) and noncohesive SPM (sand) on the vertical migration of positively buoyant MPs, polyethylene (PE), and negatively buoyant MPs, polytetrafluoroethylene (PTFE), in the estuarine environment under hydrodynamic disturbances were investigated. The settling of positively buoyant MPs was more reliant on the cohesive SPM compared to the settling of negatively buoyant MPs. Moreover, MPs interacting with the SPM mixture at a clay-to-sand ratio of 1:9 settled more efficiently than those interacting with clay alone. A significant positive correlation was observed between MP settling percentage and the salinity level. MP settling percentage was significantly negatively correlated with fluid shear stress for both types of MPs, meanwhile, negatively buoyant MPs were able to resist greater hydraulic disturbances. In the low-energy mixing state, for both types of MPs, the settling percentage reached about 50% in only 10 min. The resuspension process of MPs under hydrodynamic disturbances was also uncovered. Additionally, the migration and potential sites of MPs were described in the context of prevalent environmental phenomena in estuaries.

Prolonged drying impedes the detachment of microplastics in unsaturated substrate: Role of flow regimes.

The detachment of microplastics (MPs) from porous media under different moisture conditions and flow regimes has garnered limited attention within the research community. The present study investigates the detachment of MPs from porous media under wet and dry conditions combined with steady and transient flow. For both the wet and dry conditions, the increase in flow rates is found to decrease the detachment of hydrophobic polyethylene of two sizes and of hydrophilic polymethylmethacrylate. Intermittent flow is found to result in effluent peaks and a higher rate of MP detachment compared to steady flow. The ionic strength of inflow drops in a stepwise manner, leading to abrupt peaks followed by a tail corresponding to the arrival of each ionic strength front. Each step increase in flow rate leads to a steep peak followed by slow release over several pore volumes. Although transient flow facilitates the detachment of MPs, drying significantly impedes the detachment of MPs irrespective of flow regime. Ultraviolet weathering of MPs for 60 days weakens the inhibition effect of drying on hydrophilic polymethylmethacrylate, facilitating their detachment. Furthermore, the release of MPs decreases markedly with an increase in air-drying duration from 0 h to 72 h. Hydrus-1D two-site kinetic models are used to successfully simulate time-dependent processes, implying that drying heightens the energy barrier for MPs to detach. Our analysis confirms the significance of moisture in determining the remobilization of MPs, providing valuable insights concerning the fate of MPs in unsaturated substrate under prolonged drought conditions.

A game theoretic approach to contract-based enviro-economic coordination of wood pellet supply chains for bioenergy production.

Wood pellets have gained global attention due to their economic availability and increasing demand for bioenergy as part of sustainable energy solutions. Management of the wood pellet supply chains, from feedstock harvesting to bioenergy conversion, is critical to ensure competitiveness in the energy markets. In this regard, wood pellets supply chain coordination can play a strategic role in enhancing the efficiency and reliability of bioenergy generation. This study proposes a contract-based coordination mechanism for wood pellet supply chains and compares its performance in alternative centralized and decentralized decision-making structures. A bi-level nonlinear game-theoretic approach with two economic and environmental objective functions is developed. It utilizes the concept of life cycle assessment in a Stackelberg leader-follower game to obtain the bioenergy equilibrium solutions. Further, this study examines the case of wood pellet supply chains in three remote Canadian communities. The aim is to showcase the practicality and significance of the proposed approach and interpret the findings. By focusing on these communities, the crucial role of supply chain coordination in fostering sustainable development, particularly, in the context of bioenergy generation is emphasized. The study colludes by advocating a number of avenues for future research.

An insight into the benefits of substituting polypropylene with biodegradable polylactic acid face masks for combating environmental emissions.

Mask waste can affect the natural environment and human health. In this study, the life cycle assessment (LCA) of two types of face masks (Polylactic acid (PLA) and Polypropylene (PP)) was first performed to evaluate the environmental impacts from production to end-of-life, and then, greenhouse gas (GHG) emissions were estimated for each life stage. The GHG emissions for one functional unit of PP and PLA face masks were estimated to be 6.27E+07 and 5.06E+07 kg CO2 eq, respectively. Explicitly, PLA mask production emissions are 37 % lower as compared to those for PP masks. Packaging has been recognized as a major GHG source throughout the product's life cycle. This study may provide a new insight into the environmental benefits of reducing GHG emissions within PLA face mask life cycles. Biodegradable and environmentally friendly materials can be used in the manufacturing and packaging of face masks.

Promoting Cross-Regional Integration of Maritime Emission Management: A Euro-American Linkage of Carbon Markets.

Reducing greenhouse gas emissions from maritime transport is an urgent topic. Some regional emissions trading systems (ETSs), buoyed by the globalized market-based measures (MBMs) plan of the International maritime organization, have initially assessed the feasibility of including maritime emissions under compliance obligations. However, including maritime emissions (which are interjurisdictional) in the existing ETSs is controversial, and globalized maritime MBMs remain elusive. Therefore, this study designed a joint bilateral maritime carbon market (BMCM) model based on the European ETS (EU-ETS) and Quebec ETS (QC-ETS). The carbon costs, speed optimization, and marginal abatement costs of three container routes under BMCM were analyzed. The results show that this Euro-American linkage achieves adequate emission coverage on specific routes and generates acceptable carbon costs for charterers. This study yields a positive result for the equal division of ETSs' exercising competence in cross-regional maritime transport and provides evidence for sector-specific ETS links based on quantitative analysis.

Assessment of the infiltration of water-in-oil emulsion into soil after spill incidents.

The issue of inland oil spills exerts an adverse impact on environmental and ecological health. Many cases are concerned with water-in-oil emulsions, especially in the oil production and transport system. To understand the contamination and take an efficient response work after spill, this study investigated the infiltration behavior of water-in-oil emulsions and the influencing factors by measuring the characteristics of different emulsions. The results showed that an increase of water and fine particle content and decrease in temperature would improve the viscosity of emulsions and reduce the infiltration rate, whereas salinity levels had a negligible impact on infiltration if the pour point of emulsion systems was far higher than the freezing point of water droplets. It is worth mentioning that excessive water content at a high temperature may cause demulsification during the infiltration process. The oil concentration in different soil layers was related to the viscosity of emulsion and infiltration depth, and the adopted Green-Ampt model simulated well under low temperature. This study reveals the new features of emulsion infiltration behavior and distribution patterns under different conditions and is helpful for the response work after spill accidents.

Preparation, characteristics, and performance of the microemulsion system in the removal of oil from beach sand.

Oil deposited on shoreline substrates has serious adverse effects on the coastal environment and can persist for a long time. In this study, a green and effective microemulsion (ME) derived from vegetable oil was developed as a washing fluid to remove stranded oil from beach sand. The pseudo-ternary phase diagrams of the castor oil/water (without or without NaCl)/Triton X-100/ethanol were constructed to determine ME regions, and they also demonstrated that the phase behaviors of ME systems were almost independent of salinity. ME-A and ME-B exhibited high oil removal performance, low surfactant residues, and economic benefits, which were determined to be the W/O microstructure. Under optimal operation conditions, the oil removal efficiencies for both ME systems were 84.3 % and 86.8 %, respectively. Moreover, the reusability evaluation showed that the ME system still had over 70 % oil removal rates, even though it was used six times, implying its sustainability and reliability.

Overlooked Role of Bulk Nanobubbles in the Alteration and Motion of Microplastics in the Ocean Environment.

The increasing enrichment of microplastics (MPs) in the shoreline environment poses both ecological and social-economic risks. The alteration and motion of MPs in the ocean under the effect of bulk nanobubbles (NBs) have been less extensively studied. In this study, we explored the behavior and movement of various MPs in the presence of bulk NBs. The role of salinity and external energy in the interactions between NBs and MPs was evaluated, and the mechanism underlying these interactions was analyzed. In the presence of NBs, the binding of MPs and NBs resulted in an increase in the measured average particle size and concentration. Meanwhile, NBs reduced the aggregation between MPs, while the NBs present combined with MPs to make them more stable in suspensions. The velocity of motion of MPs driven by NBs varies under different salinity conditions. The increase in ionic strength reduced the energy barrier between particles and promoted their aggregation. Thus, the binding of NBs and MPs became more stable, which in turn affected the movement of MPs in suspensions. Polyethylene (PE1) with small particle size was mainly affected by Brownian motion, and its rising was limited; therefore, polyethylene (PE2) with large particle size rose faster than PE1 in suspension, especially in the presence of NBs. The rising velocity of poly(tetrafluoroethylene) (PTFE) was higher than that of PE1 and PE2. However, when NBs were present, the trend of the change in velocity was the opposite compared to the absence of NBs for PTFE. Moreover, various types of MPs were found to be affected distinctly by external energy. The presence of NBs had a clear effect on PE under shaking conditions, whereas the effect on PTFE was less obvious.