Delineating and preventing plastic waste leakage in the marine and terrestrial environment

A meta-research analysis on the biological impact of plastic litter in the marine biota

Marine litter and more specifically plastic marine litter is nowadays considered a global issue with unprecedented impact and consequences to the entire marine ecosystem and biota. The current situation that has been created worldwide due to the abundance of plastic litter in the Earth's Seas has been characterized as alarming, necessitating the immediate action for an overall reduction of plastic waste, better collection and recycling schemes and beach-shoreline clean-ups. In this article we attempt to delve into the details of the magnitude of the impact that plastic litter have caused to marine biota via a meta-research analysis, by compiling, combining, analysing and presenting data from various relative works, using primarily scientific and, secondarily, grey literature. Apart from the threats that plastic marine litter pose to the marine ecosystem, they present potential threats to humans, as well, via food chain. Aside from understating the risks and uncertainties contained in the hereby collected and presenting information, this study can provide an evidence base for decision and policy makers into implementing the appropriate action plans for reducing and, in time, mitigating this immense problem.

Investigation on the effect of several parameters involved in the biodegradation of polyethylene (PE) and low-density polyethylene (LDPE) under various seawater environments

This work investigates the biodegradation of polyethylene (PE) and low-density polyethylene (LDPE) and the leaching of their harmful additives. Micro/macro-plastics of both types were subjected to different laboratory-controlled conditions for 3 months. Gas Chromatography-Mass Spectroscopy (GC-MS) results revealed that leachate concentrations ranged from 0.40 ± 0.07 μg/L to 96.36 ± 0.11 μg/L. It was concluded that the additives' leaching process was promoted by light. However, light was not the only factor examined; microorganisms, pH, salinity, aeration/mixing and temperature influenced the biodegradation process, too. GC-MS results showed a prodigious impact on the biodegradation process when Pseudomonas aeruginosa was added to the artificial seawater compared to plastics exposed to light/air only. Scanning Electron Microscopy (SEM) micrographs demonstrated a significant alteration in the plastics' morphologies. Similarly, Fourier-Transform Infrared Spectroscopy (FTIR) spectra showed obvious changes in plastics characteristic peaks, especially microplastics. Furthermore, it was shown that PE was more susceptible to degradation/biodegradation than LDPE. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) findings showed that some toxic metals were present in water samples after experiments, with concentrations above the permissible limits. For instance, bio-augmentation/bio-stimulation experiments showed that the concentrations of Pb, Sr, and Zn were 0.59 mg/L, 70.09 mg/L, and 0.17 mg/L, respectively; values above the permissible limits. It is crucial to emphasise that plastics must be meticulously engineered to avoid environmental and human impacts, originated from their degradation by-products. Furthermore, a holistic approach engaging stakeholders, researchers, policymakers, industries and consumers, is essential to effectively tackle the global challenge of marine plastic pollution.

Harvesting marine plastic pollutants-derived renewable energy: A comprehensive review on applied energy and sustainable approach

The inevitable use of plastics in the existing standard of life makes its way to ecosystems, predominantly into the marine ecosystem. Recent research on energy recycling from marine discarded plastics through biological, chemical, and thermal processes is summarized, which degrade plastic debris and transform it into energy-efficient products. In a system-oriented approach, different boundaries like carbon efficiency, global warming potential, cumulative energy demand, and cost of the product have been evaluated. Even these technologies may successfully reduce the yearly volume of marine plastics by up to 89% while reducing greenhouse gas emissions by 30%. Conversely, recycling a ton of marine discarded plastics may save 915 cubic feet of landfill space, 6500 kWh of energy, and barrels of oil. Energy may be recovered up to 79% from waste plastics using various techniques. Up to 84% liquid fuel had been generated, with a maximum calorific power of 45 MJ/kg. It has been shown that in Asian countries, the power generation capacity of throw-away facemask wastes regularly varies from 2256 kWh/day to 18.52 million kWh/day. Hence, the conversion of marine plastics into biofuel, syngas, biochar, hydrocarbons, electricity, and value-added functional materials by various biotechnological and chemical processes like biodegradation, pyrolysis, gasification, methanolysis, and hydrolysis should be improvised as a source of alternative energy in the immediate future. Our review signifies the potential benefits of energy harvesting technologies from marine plastics pollutants to overcome the growing challenge of energy demands and provide a long-term solution to underdeveloped and developing countries as a sustainable source of energy. Endorsing current strategies to harvest energy from marine plastic wastes that enhance power generation technologies will help in building a more sustainable and greener environment that imparts a healthy and circular economy while shielding natural resources.

Micro(nano)plastics in commercial foods: A review of their characterization and potential hazards to human health

Micro (nano)plastics (MNPs) are pollutants of worldwide concern for their ubiquitous environmental presence and associated impacts. The higher consumption of MNPs contaminated commercial food can cause potential adverse human health effects. This review highlights the evidence of MNPs in commercial food items and summarizes different sampling, extraction, and digestion techniques for the isolation of MNPs, such as oxidizing digestion, enzymatic digestion, alkaline digestion and acidic digestion. Various methods for the characterization and quantification of microplastics (MPs) are also compared, including μ-Raman spectroscopy, μ-Fourier transform infrared spectroscopy (FTIR), thermal analysis and Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). Finally, we share our concerns about the risks of MNPs to human health through the consumption of commercial seafood. The knowledge of the potential human health impacts at a subcellular or molecular level of consuming mariculture products contaminated with MNPs is still limited. Moreover, MNPs are somewhat limited, hard to measure, and still contentious. Due to the nutritional significance of fish consumption, the risk of exposure to MNPs and the associated health effects are of the utmost importance.

Understanding allochthonous marine litter in a Protected Area in the Amazon Coast

Studies on international waste on the Amazon coast are lacking, leaving a substantial knowledge gap concerning the socioeconomic, cultural, and environmental repercussion of this issue. In this context, the objective of this study is to comprehensively characterize and trace the origins of allochthonous litter discovered on a beach situated within a Protected Area. Given this, the hypothesis of this study is that the international litters comes from vessels operating in the region. A total of 384 containers were collected, originating from 36 countries, with those located in Asia and Africa showing the highest prevalence. Among the bottles with identified expiration dates, 76 % are newly arrived, confirming our hypothesis. The presence of older waste may result from a combination of the absence of beach cleaning public services and local dynamic processes. While international engagement is necessary, local communities, along with the scientific community, have taken proactive measures to address the problem.

An overview of the occurrence, fate, and human risks of the bisphenol-A present in plastic materials, components, and products

With over 95% of bisphenol-A (BPA) used in the production of polycarbonate (PC) and epoxy resins, termed here as BPA-based plastic materials, components, and products (MCPs), an investigation of human exposure to BPA over the whole lifecycle of BPA-based plastic MCPs is necessary. This mini-review unpacks the implications arising from the long-term human exposure to BPA and its potential accumulation across the lifecycle of BPA-based plastics (production, use, and management). This investigation is timely and necessary in promoting a sustainable circular economy model. Restrictions of BPA in the form of bans and safety standards are often specific to products, while safety limits rely on traditional toxicological and biomonitoring methods that may underestimate human health implications and therefore the "safety" of BPA exposure. Controversies in regards to the: (a) dose-response curves; (b) the complexity of sources, release mechanisms, and pathways of exposure; and/or (c) the quality and reliability of toxicological studies, appear to currently stifle progress toward the regulation of BPA-based plastic MCPs. Due to the abundance of BPA in our MCPs production, consumption, and management systems, there is partial and inadequate evidence on the contribution of BPA-based plastic MCPs to human exposure to BPA. Yet, the production, use, and end-of-life management of plastic MCPs constitute the most critical BPA source and potential exposure pathways that require further investigation. Active collaboration among risk assessors, government, policy-makers, and researchers is needed to explore the impacts of BPA in the long term and introduce restrictions to BPA-based MCPs. Integr Environ Assess Manag 2023;19:45-62. © 2022 SETAC.

Ecotoxicity Study of New Composite Materials Based on Epoxy Matrix DER-331 Filled with Biocides Used for Industrial Applications

The impact of fillers in the epoxy oligomer on the test culture of the marine ecosystem was investigated. The content of additive—biocides—was selected based on the complex research using STAT-GRAPHICS^® Centurion XVI. The ecotoxicity of composite surfaces was determined in model systems using methods which are standard in eco-microbiology. The microorganism was identified by studying morphological, cultural, biochemical, and antigenic properties. Studies of the structure and the microrelief of the surfaces of composite materials were conducted using scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy. Based on comprehensive research, it was established that the composition of oxytetracycline with content of q = 1.5 wt% and nanosilver with a content of q = 0.075 wt% per 100 wt% of the DER-331 oligomer and 10 parts by the mass of the TETA hardener ensures the formation of a porous nano-heterogeneous structure of the coating, which leads to the acceleration of the release of silver ions from the surface of the polymer. The rational content of the complex additives of biocides ensures adhesion to the cell wall of bacteria with subsequent penetration into it and subsequent change to the cell membrane, its death, and, therefore, the suppression of the fouling process of metal structures.

Why is the generation of packaging waste from express deliveries a major problem?

The rapid growth of the express delivery industry resulted in the explosion of packaging waste with a wide range of direct and indirect environmental consequences. Until recently, little attention was given to this topic, but e-commerce and the associated growth of packaging waste exploded with the COVID-19 pandemic. Even though the phenomenon is only little to moderately documented, the waste problems in express delivery are recognized and caused by excessive packaging, lack of recyclability of the packaging material, and the low motivation of consumers to recycle. Key research, policy, and educational actions to reduce the environmental impacts of the fast-growing express delivery industry are discussed in this short discussion article.

Material flow analysis of plastic waste in the gulf co-operation countries (GCC) and the Arabian gulf: Focusing on Qatar

Global plastic waste production has increased dramatically in recent years, both globally and regionally, having a multitude of adverse effects on the environment and human health. However, little attention has been directed to this problem in the Arabian Gulf region. This study aims to delineate and map the status of the plastic waste problem in the Gulf Co-operation Countries (GCC), with a focus on Qatar. The study focuses on the plastic waste in the marine environment, depicting the different types, sizes and shapes of plastic particles found in the Arabian Gulf. To depict the flow of plastic waste, a generic material flow diagram was built using a material flow analysis software named STAN, in which transfer coefficients were assigned based on existing scientific literature and estimations built on data from local industries and recycling facilities. The recovery and recycling efforts that have been made by the different GCC countries, in efforts to reduce plastic waste and minimize the risk of plastic on the environment are analyzed, too. Our analyses indicate that approximately 11.9 Mt ± 595.395 Kt of plastic waste is produced annually in the GCC region, of which only 23 ± 15% is recycled, indicating that improvements are yet to be made in the recovery, recycling and treatment of plastics in the region. However, in Qatar, a higher percentage of plastics (40 ± 10%) is recovered-recycled with efforts to treat plastics and reuse it to generate energy.

Enzymatic Degradation of the Most Common Aliphatic Bio-Polyesters and Evaluation of the Mechanisms Involved: An Extended Study

Commercial hydrolytic enzymes belonging to different subclasses (several lipases, proteinase k, cutinase) were investigated for their ability to degrade different aliphatic polyesters, i.e., poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBSA), two poly(caprolactone), having two different molecular weights, poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC). The enzyme screening was first carried out by investigating the capacity of fully degrading the target polymers in 24 h, then weight loss measurements of selected polyesters and target enzymes were performed. Solid residues after enzyme degradation were characterized by proton nuclear magnetic resonance (¹H NMR), gel permeation chromatography (GPC), infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetry (TGA). Liquid fractions were studied via GPC, ¹H NMR and high-performance liquid chromatography (HPLC). PCL and PBSA were found to be the most biodegradable polyesters, under the conditions used in this study. PBS was fully degraded only by cutinase, whereas none of the tested enzymes were able to completely degrade PLA and PPC, in the conditions assessed here. Cutinase exhibited the highest hydrolytic activity on PBSA, while lipase from Candida sp. (CALB) on low molecular weight PCL. Chemical analyses on residual solids showed that the enzymatic degradation occurred homogeneously from the surface through an erosion mechanism and did not significantly affect the macromolecular structure and thermal stability. Cleaving action mode for each enzyme (endo- and/or exo-type) on the different polyesters were also proposed based on the evaluation of the degradation products in the liquid fraction.

Preparation and evaluation of polyphenol derivatives as potent antifouling agents: addition of a side chain affects the biological activity of polyphenols

In this study, eight polyphenol derivatives were prepared to serve as green antifoulants. Polyphenol derivatives, which can hinder the growth of bacteria and algae and decrease the adhesion of some marine organisms, showed good AF activity; in particular, the activities of these derivatives were much higher than those of the corresponding polyphenols. The antibacterial rates of the products (20 μg ml^-1) exceeded 88%. Moreover, the anti-algal rates of compounds a3, b1, b2, b3 and b4 (15 μg ml^-1) were over 57% at 240 h, but these compounds showed low toxicity, and the 120 h EC₅₀ values were > 6.60 μg ml^-1. In addition, there were fewer marine microorganisms on the test panel than on the control. The above results show that some polyphenol derivatives possess relatively high antibacterial, anti-algal, and AF activity; more notably, the addition of chlorine atoms and amide groups can further increase the activity of these derivatives.