Transfer of Graphene CVD to Surface of Low Density Polyethylene (LDPE) and Poly(butylene adipate-co-terephthalate) (PBAT) Films: Effect on Biodegradation Process

Here, the influence of graphene as a coating on the biodegradation process for two different polymers is investigated, poly(butylene adipate-co-terephthalate) (PBAT) (biodegradable) and low-density polyethylene (LDPE) (non-biodegradable). Chemical vapor deposition graphene was transferred to the surface of two types of polymers using the Direct Dry Transfer technique. Polymer films, coated and uncoated with graphene, were buried in a maturated soil for up to 180 days. The films were analyzed before and after exposure to microorganisms in order to obtain information about the integrity of the graphene (Raman Spectroscopy), the biodegradation mechanism of the polymer (molecular weight and loss of weight), and surface changes of the films (atomic force microscopy and contact angle). The results prove that the graphene coating acted as a material to control the biodegradation process the PBAT underwent, while the LDPE covered by graphene only had changes in the surface properties of the film due to the accumulation of solid particles. Polymer films coated with graphene may allow the production of a material that can control the microbiological degradation, opening new possibilities in biodegradable polymer packaging. Regarding the possibility of graphene functionalization, the coating can also be selective for specific microorganisms attached to the surface.     

Preparation and Characterization of Xylan Derivatives and Their Blends

Although hemicellulose is found widely in nature, it is currently under-utilized as a raw material for commercial applications. It would be desirable to find new uses for hemicellulose in order to add value to this agro-based material. A common type of hemicellulose is xylan, which is found in a number of wood species and in cotton. In this work we prepared cationic and anionic xylan derivatives and characterized them by ¹³C NMR, FT-IR, size exclusion chromatography (SEC), thermal analysis, and rheology. In particular, the ¹³C NMR spectra of carboxymethyl xylan (CMX) and quaternary ammonium-adducted xylan (QAX) were fully assigned with the help of samples with different degrees of substitution. SEC indicated that the beechwood xylan showed a bimodal molecular weight distribution, but with derivatization the distribution tended to become unimodal. Thermal analysis and rheology studies did not uncover any surprises; the solution of xylan and its derivatives exhibited mostly Newtonian behavior. The blends of CMX and QAX produced a precipitate at almost all ratios, indicating the formation of a polyelectrolyte complex. When cationic and anionic xylan samples were added together to paper, the paper dry strength increased. Thus, the combination of cationic/anionic xylan may be of interest in selected applications.     

Catalytic upgrading pyrolysis of pine sawdust for bio-oil with metal oxides

The catalytic upgrading pyrolysis of pine sawdust was performed at 500 °C with various metal oxides to improve the quality of the bio-oil. The aim of this study was to investigate the potential of the metal oxides instead of traditional zeolites for catalytic upgrading pyrolysis with the analysis of Gas Chromatograph/Mass Spectrometer. In this study, the used catalysts were Calcium-oxide, Magnesium oxide, Titanium dioxide, and Zeolite (Si/Al?=?80). The influence of catalysts on products yields and compositions were investigated. Most metal oxides can enhance the bio-gas with the bio-oil yields decreased. The metal oxides led to a decrease of Acids, Aldehydes, Ketones and an increase of Furfural, Cresols, Catechols in Furans and Phenolics. Among the catalysts, the MgO catalysts was the most effective to convert the high molecular into lights ones (6.65% Cresols) with yield of 20.48% for Furfural. The deoxygenation reaction in bio-oil was suggested to convert oxygenated compounds into the low molecular weight of the materials (6.39% Guaiacols). Thus, the used metal oxides can improve the quality of bio-oil by decreasing undesirable compounds as well as increasing the desirable compounds with low oxygen contents via deoxygenation reaction.     

Long-term dispersion and availability of metals from submarine mine tailing disposal in a fjord in Arctic Norway

Mining of Cu took place in Kvalsund in the Arctic part of Norway in the 1970s, and mine tailings were discharged to the inner part of the fjord, Repparfjorden. Metal speciation analysis was used to assess the historical dispersion of metals as well as their potential bioavailability from the area of the mine tailing disposal. It was revealed that the dispersion of Ba, Cr, Ni, Pb and Zn from the mine tailings has been limited. Dispersion of Cu to the outer fjord has, however, occurred; the amounts released and dispersed from the mine tailing disposal area quantified to be 2.5–10 t, less than 5% of Cu in the original mine tailings. An estimated 80–390 t of Cu still remains in the disposal area from the surface to a depth of 16 cm. Metal partitioning showed that 56–95% of the Cu is bound in the potential bioavailable fractions (exchangeable, reducible and oxidisable) of the sediments, totalling approximately 70–340 t, with potential for continuous release to the pore water and re-precipitation in over- and underlying sediments. Surface sediments in the deposit area were affected by elevated Cu concentrations just above the probable effect level according to the Norwegian sediment quality criteria, with 50–80% Cu bound in the exchangeable, reducible and oxidisable fractions, potentially available for release to the water column and/or for uptake in benthic organisms.     

Household water insecurity and its cultural dimensions: preliminary results from Newtok,Alaska

Using a relational approach, I examine several cultural dimensions involved in household water access and use in Newtok, Alaska. I describe the patterns that emerge around domestic water access and use, as well as the subjective lived experiences of water insecurity including risk perceptions, and the daily work and hydro-social relationships involved in accessing water from various sources. I found that Newtok residents haul water in limited amounts from a multitude of sources, both treated and untreated, throughout the year. Household water access is tied to hydro-social relationships predicated on sharing and reciprocity, particularly when the primary treated water access point is unavailable. Older boys and young men are primarily responsible for hauling water, and this role appears to be important to male Yupik identity. Many interviewees described preferring to drink untreated water, a practice that appears related to cultural constructions of natural water sources as pure and self-purifying, as well as concerns about the safety of treated water. Concerns related to the health consequences of low water access appear to differ by gender and age, with women and elders expressing greater concern than men. These preliminary results point to the importance of understanding the cultural dimensions involved in household water access and use. I argue that institutional responses to water insecurity need to incorporate such cultural dimensions into solutions aimed at increasing household access to and use of water.     

Greenlandic water and sanitation systems—identifying system constellation and challenges

A good water supply and wastewater management is essential for a local sustainable community development. This is emphasized in the new global goals of the UN Sustainable Development, where the sixth objective is to: “Ensure availability and sustainable management of water and sanitation for all” (United Nations 2015). This obviously raises the question of how this can be achieved considering the very different conditions and cultures around the globe. This article presents the Greenlandic context and elucidates the current Greenland water supply system and wastewater management system from a socio-technical approach, focusing on the geographic, climatic and cultural challenges. The article identifies a diverse set of system constellations in different parts of Greenland and concludes with a discussion of health and quality of life implications.     

Effect of lower chlorinated hydroxylated-polychlorobiphenyls on development of PC12 cells

Hydroxylated polychlorobiphenyls (OH-PCBs) are major metabolites of PCBs that are widely distributed in the environment. While the effects of penta- to hepta-chlorinated OH-PCBs on neuronal differentiation have been widely reported, those of lower chlorinated OH-PCBs have not been extensively studied. To investigate the effects of lower chlorinated OH-PCBs on neuronal development, we studied the effects of mono- to hexa-chlorinated OH-PCBs on PC12 cells. Morphological changes were examined using an automatic system IN Cell Analyzer. Seventeen of the 20 OH-PCBs investigated promoted neuronal elongation in an OH-PCB concentration-dependent manner, while three OH-PCB congeners suppressed neuronal elongation based on Dunnett’s analysis. In particular, the top five OH-PCBs (4OH-PCB2, 4′OH-PCB3, 4′OH-PCB25, 4′OH-PCB68, and 4′OH-PCB159), which have hydroxyl groups at the para-position and chlorine substitutions at the 2, 4, or 3′ positions, significantly promoted neuronal elongation. Moreover, these neuronal elongations were suppressed by U0126, and phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 was observed in PC12 cells treated with 4OH-PCB2, 4′OH-PCB25, and 4′OH-PCB159. Taken together, our results indicate that the effect of OH-PCB on neuronal development is not dependent on the number of chlorine groups but on the chemical structure, and the mitogen-activated kinase kinase (MEK)-ERK1/2 signaling pathway is involved in this process.     

Water quality and health in northern Canada: stored drinking water and acute gastrointestinal illness in Labrador Inuit

One of the highest self-reported incidence rates of acute gastrointestinal illness (AGI) in the global peer-reviewed literature occurs in Inuit communities in the Canadian Arctic. This high incidence of illness could be due, in part, to the consumption of contaminated water, as many northern communities face challenges related to the quality of municipal drinking water. Furthermore, many Inuit store drinking water in containers in the home, which could increase the risk of contamination between source and point-of-use (i.e., water recontamination during storage). To examine this risk, this research characterized drinking water collection and storage practices, identified potential risk factors for water contamination between source and point-of-use, and examined possible associations between drinking water contamination and self-reported AGI in the Inuit community of Rigolet, Canada. The study included a cross-sectional census survey that captured data on types of drinking water used, household practices related to drinking water (e.g., how it was collected and stored), physical characteristics of water storage containers, and self-reported AGI. Additionally, water samples were collected from all identified drinking water containers in homes and analyzed for presence of Escherichia coli and total coliforms. Despite municipally treated tap water being available in all homes, 77.6% of households had alternative sources of drinking water stored in containers, and of these containers, 25.2% tested positive for total coliforms. The use of transfer devices and water dippers (i.e., smaller bowls or measuring cups) for the collection and retrieval of water from containers were both significantly associated with increased odds of total coliform presence in stored water (OR_{transfer device} = 3.4, 95% CI 1.2–11.7; OR_dipper = 13.4, 95% CI 3.8–47.1). Twenty-eight-day period prevalence of self-reported AGI during the month before the survey was 17.2% (95% CI 13.0–22.5), which yielded an annual incidence rate of 2.4 cases per person per year (95% CI 1.8–3.1); no water-related risk factors were significantly associated with AGI. Considering the high prevalence of, and risk factors associated with, indicator bacteria in drinking water stored in containers, potential exposure to waterborne pathogens may be minimized through interventions at the household level.     

Two sampling strategies for an overview of pesticide contamination in an agriculture-extensive headwater stream

Two headwaters located in southwest France were monitored for 3 and 2 years (Auvézère and Aixette watershed, respectively) with two sampling strategies: grab and passive sampling with polar organic chemical integrative sampler (POCIS). These watersheds are rural and characterized by agricultural areas with similar breeding practices, except that the Auvézère watershed contains apple production for agricultural diversification and the downstream portion of the Aixette watershed is in a peri-urban area. The agricultural activities of both are extensive, i.e., with limited supply of fertilizer and pesticides. The sampling strategies used here give specific information: grab samples for higher pesticide content and POCIS for contamination background noise and number of compounds found. Agricultural catchments in small headwater streams are characterized by a background noise of pesticide contamination in the range of 20–70 ng/L, but there may also be transient and high-peak pesticide contamination (2000–3000 ng/L) caused by rain events, poor use of pesticides, and/or the small size of the water body. This study demonstrates that between two specific runoff events, contamination was low; hence the importance of passive sampler use. While the peak pesticide concentrations seen here are a toxicity risk for aquatic life, the pesticide background noise of single compounds do not pose obvious acute nor chronic risks; however, this study did not consider the risk from synergistic “cocktail” effects. Proper tools and sampling strategies may link watershed activities (agricultural, non-agricultural) to pesticides detected in the water, and data from both grab and passive samples can contribute to discussions on environmental effects in headwaters, an area of great importance for biodiversity.     

PCDD/PCDF formation in the chlor-alkali process—laboratory study and comparison with patterns from contaminated sites

Studies on the formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) during the electrolysis of sodium chloride solution (brine) using graphite or titanium electrodes were carried out at a laboratory scale. High concentrations of PCDFs but no PCDDs were formed in tests using graphite electrodes. With titanium electrodes, PCDFs were only formed when tar pitch was added and mainly originated from the dibenzofuran present in the tar. For the first time, a detailed assessment of the formation of mono- to octachlorinated PCDD/PCDF from tar pitch was investigated. The assessment included of the chlorination steps proved that PCDFs were formed by successive lateral chlorinated from dibenzofuran to MonoCDFs, DiCDFs, and TriCDFs to form the typical known “chlorine pattern” of TetraCDF to OctaCDF with a dominance of 1,2,7,8- and 2,3,7,8-TetraCDFs, 1,2,3,7,8-PentaCDF, and 1,2,3,4,7,8-HexaCDF as marker congeners. The final homologue distributions depended on reaction time and reaction temperature. In addition, electrolysis with non-chlorinated dibenzo-p-dioxins, dibenzofuran, and biphenyl was carried out. As a result, PCDDs, PCDFs, and PCB were formed at comparable yields. Congener patterns in soil samples from a PCDD/F-contaminated site where chlor-alkali electrolysis had been operated for decades in Japan had identical isomer distribution demonstrating the source and contamination potential and risk of these processes. Therefore, sites where in the past 120 years chlor-alkali electrolysis has been operated or where residues from chlor-alkali production or other chlorine using industries have been disposed should be assessed for their pollution level and exposure relevance. The assessment of total organohalogen content revealed that PCDF is only a small fraction of organohalogens in the contaminated soils. For an appropriate risk assessment, also other chlorinated aromatic compounds such as PCBs or PCNs need to be considered.