Exploration of Nanosilver Calcium Alginate-Based Multifunctional Polymer Wafers for Wound Healing.

Wound care is an integral part of effective recovery. However, its associated financial burden on national health services globally is significant enough to warrant further research and development in this field. In this study, multifunctional polymer wafers were prepared, which provide antibacterial activity, high cell viability, high swelling capacity and a thermally stable medium which can be used to facilitate the delivery of therapeutic agents. The purpose of this polymer wafer is to facilitate wound healing, by creating nanosilver particles within the polymer matrix itself via a one-pot synthesis method. This study compares the use of two synthetic agents in tandem, detailing the effects on the morphology and size of nanosilver particles. Two synthetic methods with varying parameters were tested, with one method using silver nitrate, calcium chloride and sodium alginate, whilst the other included aloe vera gel as an extra component, which serves as another reductant for nanosilver synthesis. Both methods generated thermally stable alginate matrices with high degrees of swelling capacities (400-900%) coupled with interstitially formed nanosilver of varying shapes and sizes. These matrices exhibited controlled nanosilver release rates which were able to elicit antibacterial activity against MRSA, whilst maintaining an average cell viability value of above 90%. Based on the results of this study, the multifunctional polymer wafers that were created set the standard for future polymeric devices for wound healing. These polymer wafers can then be further modified to suit specific types of wounds, thereby allowing this multifunctional polymer wafer to be applied to different wounding scenarios.

The waste ban in China: what happened next? Assessing the impact of new policies on the waste management sector in China.

The 2017 ban on the waste import and new policies for the waste management sector in mainland China had wide-spread impact. After decades of poor environmental and public health impacts from the sector, a study is needed which focuses on policies updates and waste management. This provides a direction for the survival of local waste management industries and consider similarities with the ban promulgated in China on the restriction of waste import from other countries. We review the waste management situation in China before national legislation prevented the import of waste, highlight the status of landfill mining in China, and review the dynamics of domestic policies before and after the promulgation of the ban in China. The impact of the COVID19 pandemic on the waste management system is starting to emerge, providing both challenges and opportunities for the sector in China. We see the impact of the ban on the range of imported waste and domestically generated materials. The ban results in price increases for domestic recycling that forces companies to introduce more formal recycling processes and to drive the consumption behaviours to more reasonable and environmentally friendly options. The driver in China is to reduce pollution in the environment and improve health, but a negative impact has been from increased landfill mining which has impeded the original aim of the waste ban and requires further technological development. The dynamic of domestic policies in China shows higher level of activity of updates and revisions or introduction of new policies from 2015 onwards and the concept of 'zero waste cities' brings new hope for improvement of the Chinese waste management system. The pandemic also suggests an important step to establish sustainable management systems despite evidence of increased "fly-tipping". The rebound of the waste ban may have stimulated in the short term negative impacts on local environments both in China and internationally.

Exploration of Dual Ionic Cross-Linked Alginate Hydrogels Via Cations of Varying Valences towards Wound Healing.

This study explored the synergistic effects of simultaneously using calcium and gallium cations in the cross-linking of alginate, detailing its effects on the characteristics of alginate compared to its single cation counterparts. The primary goal is to determine if there are any synergistic effects associated with the utilisation of multiple multivalent cations in polymer cross-linking and whether or not it could therefore be used in pharmaceutical applications such as wound healing. Given the fact divalent and trivalent cations have never been utilised together for cross-linking, an explanation for the mode of binding that occurs between the alginate and the cations during the cross-linking process and how it may affect the future applications of the polymer has been investigated. The calcium gallium alginate polymers were able to retain the antibacterial effects of gallium within the confines of the polymer matrix, possessing superior rheological properties, 6 times that of pure calcium and pure gallium, coupled with an improved swelling capacity that is 4 times higher than that of gallium alginate.

The Effect of Substrate on Water Quality in Ornamental Fish Tanks.

Almost all home aquaria contain substrate, either as intentional enrichment or for aesthetic purposes. For fishes, benefits of structural enrichment have been well considered, particularly in research and aquaculture settings. However, our understanding of the impacts of tank substrate as enrichment is limited. While substrate can induce foraging in some species, a major drawback is the potential of substrate to harbour elevated levels of waste and pathogenic bacteria. Here, we considered whether substrate as a form of environmental enrichment significantly altered water quality and bacterial presence in home aquaria. Water quality (temperature, oxygen, pH, TAN, unionised ammonia, nitrate, Ca2+, Na+, Mg2+ and K+) and bacterial presence (Pseudomonas spp.) were measured over two seven-week periods in stand-alone, tropical, freshwater tanks that simulated home aquaria. The following four enrichment conditions were considered: bare tanks, plastic plants, gravel substrate or sand substrate. The addition of both gravel and sand resulted in increased pH, concentrations of total ammonia nitrogen and nitrate. Substrate was also associated with a greater Pseudomonas presence. Decreased pH alongside an increased concentration of ions were also observed depending on the time of year. In conclusion, enrichment type affected the water quality of home aquaria, with further research needed on the role of the tank biome in fish welfare.

Recycling Plastics from WEEE: A Review of the Environmental and Human Health Challenges Associated with Brominated Flame Retardants.

Waste electrical and electronic equipment (WEEE) presents the dual characteristic of containing both hazardous substances and valuable recoverable materials. Mainly found in WEEE plastics, brominated flame retardants (BFRs) are a component of particular interest. Several actions have been taken worldwide to regulate their use and disposal, however, in countries where no regulation is in place, the recovery of highly valuable materials has promoted the development of informal treatment facilities, with serious consequences for the environment and the health of the workers and communities involved. Hence, in this review we examine a wide spectrum of aspects related to WEEE plastic management. A search of legislation and the literature was made to determine the current legal framework by region/country. Additionally, we focused on identifying the most relevant methods of existing industrial processes for determining BFRs and their challenges. BFR occurrence and substitution by novel BFRs (NBFRs) was reviewed. An emphasis was given to review the health and environmental impacts associated with BFR/NBFR presence in waste, consumer products, and WEEE recycling facilities. Knowledge and research gaps of this topic were highlighted. Finally, the discussion on current trends and proposals to attend to this relevant issue were outlined.

Treatment of environmental contamination using sepiolite: current approaches and future potential.

To evaluate the potential of sepiolite-based materials to resolve environmental pollution problems, a study is needed which looks at the whole life cycle of material application, including the residual value of material classified as waste from the exploitation of sepiolite deposits in the region or from its processing and purification. This would also maximize value from the exploitation process and provide new potential for local waste management. We review the geographical distribution of sepiolite, its application in the treatment of potentially toxic elements in soil and across the wider landscape, an assessment of modification and compositional variation of sepiolite-based applications within site remediation and wastewater treatment. The potential of sepiolite-based technologies is widespread and a number of processes utilize sepiolite-derived materials. Along with its intrinsic characteristics, both the long-term durability and the cost-effectiveness of the application need to be considered, making it possible to design ready-to-use products with good market acceptance. From a critical analysis of the literature, the most frequently associated terms associated with sepiolite powder are the use of lime and bentonite, while fly ash ranked in the top ten of the most frequently used material with sepiolite. These add improved performance for the inclusion as a soil or wastewater treatment options, alone or applied in combination with other treatment methods. This approach needs an integrated assessment to establish economic viability and environmental performance. Applications are not commonly evaluated from a cost-benefit perspective, in particular in relation to case studies within geographical regions hosting primary sepiolite deposits and wastes that have the potential for beneficial reuse.

The legacy of industrial pollution in estuarine sediments: spatial and temporal variability implications for ecosystem stress.

The direct impacts of anthropogenic pollution are widely known public and environmental health concerns, and details on the indirect impact of these are starting to emerge, for example affecting the environmental microbiome. Anthropogenic activities throughout history with associated pollution burdens are notable contributors. Focusing on the historically heavily industrialised River Clyde, Scotland, we investigate spatial and temporal contributions to stressful/hostile environments using a geochemical framework, e.g. pH, EC, total organic carbon and potentially toxic elements: As, Co, Cr, Cu, Ni, Pb and Zn and enrichment indicators. With regular breaches of the sediment quality standards in the estuarine system we focused on PTE correlations instead. Multivariate statistical analysis (principle component analysis) identifies two dominant components, PC1: As, Cr, Cu, Pb and Zn, as well as PC2: Ni, Co and total organic carbon. Our assessment confirms hot spots in the Clyde Estuary indicative of localised inputs. In addition, there are sites with high variability indicative of excessive mixing. We demonstrate that industrialised areas are dynamic environmental sites dependant on historical anthropogenic activity with short-scale variation. This work supports the development of 'contamination' mapping to enable an assessment of the impact of historical anthropogenic pollution, identifying specific 'stressors' that can impact the microbiome, neglecting in estuarine recovery dynamics and potentially supporting the emergence of antimicrobial resistance in the environment.

The Potential of Remedial Techniques for Hazard Reduction of Steel Process by Products: Impact on Steel Processing, Waste Management, the Environment and Risk to Human Health.

The negative impact from industrial pollution of the environment is still a global occurrence, and as a consequence legislation and subsequent regulation is becoming increasingly stringent in response, in particular, to minimising potential impact on human health. These changes have generated growing pressures for the steel industry to innovate to meet new regulations driving a change to the approach to waste management across the industrial landscape, with increasing focus on the principles of a circular economy. With a knowledge of the compositional profiles of process by-products, we have assessed chemical cleaning to improve environmental performance and minimise disruption to manufacturing processes, demonstrating re-use and recycling capacity. We show that with a knowledge of phase composition, we are able to apply stabilisation methods that can either utilise waste streams directly or allow manipulation, making them suitable for re-use and/or inert disposal. We studied blast furnace slags and Portland cement mixes (50%/50% and 30%/70%) with a variety of other plant wastes (electrostatic precipitator dusts (ESP), blast furnace (BF) sludge and basic oxygen furnace (BOF) sludge) which resulted in up to 90% immobilisation of hazardous constituents. The addition of organic additives i.e., citric acid can liberate or immobilise problematic constituents; in the case of K, both outcomes occurred depending on the waste type; ESP dust BF sludge and BOF fine sludge. Pb and Zn however were liberated with a 50-80% and 50-60% residue reduction respectively, which generates possibilities for alternative uses of materials to reduce environmental and human health impact.

Enhanced characterisation for the management of industrial steel processing by products: potential of sequential chemical extraction.

There is a pressing need for innovative waste management approaches as environmental regulations become more stringent worldwide alongside increasing demand for a more circular economy. Sequential chemical extraction (SE) analysis, which has previously been applied to environmental media such as soils and sediments, offers the potential to provide an understanding of the composition of solid steel processing by products, aiding the waste classification process and improving environmental protection. The definition of seven-phase associations through a SE method evaluated in this study were for (1) water soluble, (2) ion exchangeable, (3) carbonate, (4) amorphous Fe-Mn oxides, (5) crystalline Fe-Mn oxides, (6) sulphides and (7) silicate residues. Steel waste by-products (flue dust and filter cake) were evaluated for both extracted components (ICP analysis) and residual phases (using powder X-ray diffraction, SEM and FTIR), to model the transformations taking place during extraction. The presence and removal of important potentially toxic element (PTE) host solid phases were confirmed during extraction. The SE protocol provides key information, particularly for the association of potentially toxic elements with the first three extracts, which are most sensitive in waste management processes. The water-soluble phase is the most available followed by ion-exchangeable and carbonate fractions, all representing phases more sensitive to environmental change, in particular to pH. This study demonstrates that the distribution of potentially toxic elements such as zinc, lead and copper between sensitive and immobile phases can be reliably obtained in technological process by-products. We demonstrate that despite heterogeneity as a major variable, even for fine particulate matter, SE can provide more refined classification with information to identify reuse potential and ultimately minimise hazardous waste streams.

The toxicity of potentially toxic elements (Cu, Fe, Mn, Zn and Ni) to the cnidarian Hydra attenuata at environmentally relevant concentrations.

The domestic, agricultural, industrial, technological and medical applications of potentially toxic elements (PTEs) have led to global pollution in all environments. In this study, the cnidarian Hydra attenuata was exposed individually and to a mixture of 5 metals (copper, iron, manganese, zinc and nickel) at environmentally relevant concentrations (1×) within the Clyde estuary, Scotland and incremental concentrations ranging from 0.0001× to 1000×. Toxicity was investigated using morphology, attachment, hydranth number and feeding behaviour as endpoints. When exposed individually, Cu, Mn and Fe significantly reduced Hydra morphology, feeding and attachment at environmentally relevant concentrations. Hydra mortality was measured, having an LC50 of 0.045× (for the environmentally relevant mixture of metals) and Cu 0.5 mg/l, Fe 3 mg/l, Mn 2 mg/l, Zn 0.1 mg/l, Ni 0.5 mg/l for each element exposed individually. The PTE mixture incurred a significant decrease (p ≤ 0.05) in morphology at 0.0001×, with 100% mortality at 0.1× (containing a concentration of Cu 0.05 mg/l, Fe 0.3 mg/l, Mn 0.2 mg/l, Zn 0.01 mg/l, Ni 0.05 mg/l) and a toxicity threshold (TT) of 0.000005×. Both copper and iron when exposed individually to the concentration of their respective metals found in the environment resulted in 100% mortality for all Hydra exposed. These results indicate that the PTE mixture (including the individual concentrations of copper, iron, manganese and nickel) could potentially prove significantly toxic to the aquatic environment.

Understanding fungal functional biodiversity during the mitigation of environmentally dispersed pentachlorophenol in cork oak forest soils.

Pentachlorophenol (PCP) is globally dispersed and contamination of soil with this biocide adversely affects its functional biodiversity, particularly of fungi - key colonizers. Their functional role as a community is poorly understood, although a few pathways have been already elucidated in pure cultures. This constitutes here our main challenge - elucidate how fungi influence the pollutant mitigation processes in forest soils. Circumstantial evidence exists that cork oak forests in N. W. Tunisia - economically critical managed forests are likely to be contaminated with PCP, but the scientific evidence has previously been lacking. Our data illustrate significant forest contamination through the detection of undefined active sources of PCP. By solving the taxonomic diversity and the PCP-derived metabolomes of both the cultivable fungi and the fungal community, we demonstrate here that most strains (predominantly penicillia) participate in the pollutant biotic degradation. They form an array of degradation intermediates and by-products, including several hydroquinone, resorcinol and catechol derivatives, either chlorinated or not. The degradation pathway of the fungal community includes uncharacterized derivatives, e.g. tetrachloroguaiacol isomers. Our study highlights fungi key role in the mineralization and short lifetime of PCP in forest soils and provide novel tools to monitor its degradation in other fungi dominated food webs.

Development of a robust chromatographic method for the detection of chlorophenols in cork oak forest soils.

A major concern for the cork and wine industry is 'cork taint' which is associated with chloroanisoles, the microbial degradation metabolites of chlorophenols. The use of chlorophenolic compounds as pesticides within cork forests was prohibited in 1993 in the European Union (EU) following the introduction of industry guidance. However, cork produced outside the EU is still thought to be affected and simple, robust methods for chlorophenol analysis are required for wider environmental assessment by industry and local environmental regulators. Soil samples were collected from three common-use forests in Tunisia and from one privately owned forest in Sardinia, providing examples of varied management practice and degree of human intervention. These provided challenge samples for the optimisation of a HPLC-UV detection method. It produced recoveries consistently >75% against a soil CRM (ERM-CC008) for pentachlorophenol. The optimised method, with ultraviolet (diode array) detection is able to separate and quantify 16 different chlorophenols at field concentrations greater than the limits of detection ranging from 6.5 to 191.3 µg/kg (dry weight). Application to a range of field samples demonstrated the absence of widespread contamination in forest soils at sites sampled in Sardinia and Tunisia.

Screening pentachlorophenol degradation ability by environmental fungal strains belonging to the phyla Ascomycota and Zygomycota.

Pentachlorophenol (PCP) bioremediation by the fungal strains amongst the cork-colonising community has not yet been analysed. In this paper, the co- and direct metabolism of PCP by each of the 17 fungal species selected from this community were studied. Using hierarchical data analysis, the isolates were ranked by their PCP bioremediation potential. Fifteen isolates were able to degrade PCP under co-metabolic conditions, and surprisingly Chrysonilia sitophila, Trichoderma longibrachiatum, Mucor plumbeus, Penicillium janczewskii and P. glandicola were able to directly metabolise PCP, leading to its complete depletion from media. PCP degradation intermediates are preliminarily discussed. Data emphasise the significance of these fungi to have an interesting potential to be used in PCP bioremediation processes.

The environmental behaviour of polychlorinated phenols and its relevance to cork forest ecosystems: a review.

Pentachlorophenol (PCP) has been used as a herbicide, biocide and preservative worldwide since the 1930s and as a result, extensive and prolonged contamination exists. The environmental impact increases when its many degradation products are taken into consideration. A number of chloroanisols and their related chlorophenols have been found in cork slabs collected from Portuguese oak tree forests before stopper manufacturing, and contamination by PCP and polychlorinated anisole (PCA) has been detected in Canadian forests. It is suggested that the use of polychlorinated phenols, in particular PCP, is thought to be a cause of the cork taint problem in wine, a major socio-economic impact not only for industry but on sensitive and highly biodiverse ecosystems. It also highlights particular issues relating to the regional regulation of potentially toxic chemicals and global economics world wide. To fully understand the impact of contamination sources, the mechanisms responsible for the fate and transport of PCP and its degradation products and assessment of their environmental behaviour is required. This review looks at the current state of knowledge of soil sorption, fate and bioavailability and identifies the challenges of degradation product identification and the contradictory evidence from field and laboratory observations. The need for a systematic evaluation of PCP contamination in relation to cork forest ecosystems and transfer of PCP between trophic levels is emphasised by discrepancies in bioaccumulation and toxicity. This is essential to enable long term management of not only transboundary contaminants, but also the sustainable management of socially and economically important forest ecosystems.