Chitosan/Hydrophilic Plasticizer-Based Films: Preparation,Physicochemical and Antimicrobial Properties

The addition of plasticizers to biopolymer films is a good method for improving their physicochemical properties. The aim of this study was to evaluate the effect of chitosan (CHI) blended with two hydrophilic plasticizers glycerol (GLY) and sorbitol (SOR), at two concentrations (20 and 40 wt%) on their mechanical, thermal, barrier, structural, morphological and antimicrobial properties. The chitosan was prepared through the alkaline deacetylation of chitin obtained from fermented lactic from shrimp heads. The obtained chitosan had a degree of deacetylation (DA) of 84 ± 2.7 and a molecular weight of 136 kDa, which indicated that a good film had formed. The films composed of CHI and GLY (20 wt%) exhibited the best mechanical properties compared to the neat chitosan film. The percentage of elongation at break increase to over 700 % in the films that contained 40 % GLY, and these films also exhibited the highest values for the water vapor transmission rate (WVTR) of 79.6 ± 1.9 g m² h^?1 and a yellow color (b _o  = 17.9 ± 2.0) compared to the neat chitosan films (b _o  = 8.8 ± 0.8). For the structural properties, the Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analyses revealed an interaction in the acetamide group and changes in the crystallinity of plasticized films. The scanning electron micrographs revealed that all formulations of the chitosan films were smooth, and that they did not contain aggregations, pores or microphase separation. The thermal analysis using differential scanning calorimetry (DSC) revealed a glass transition temperature (Tg) of 130 °C for neat chitosan film, but the addition of SOR or GLY elicited a decrease in the temperature of the peak (120 °C). In addition, the antimicrobial activity of the chitosan films was evaluated against Listeria monocytogenes, and reached a reduction of 2 log after 24 h. The plasticizer concentration of 20 % GLY is sufficient for obtaining flexible chitosan films with good mechanical properties, and it could serve as an alternative as a packaging material to reduce environmental problems associated with synthetic packaging films.     

Advances in the recycling of plastic wastes for metallurgical coke production

This paper aims to provide useful knowledge on the use of plastic wastes as additives to coking blends for the production of metallurgical coke. It focuses on the influence that the composition of plastic wastes has upon the development of coal fluidity, the generation of pressure during the coking process and the quality of the cokes produced in a semipilot oven. Several plastic mixtures of two types of thermoplastics, polyolefins (HDPE, LDPE and PP) and aromatic polymers such as PET, were used. The overall addition rate of plastics to a medium-fluid coal blend was 2 wt%. It is shown that polyolefins, weaker modifiers of coal fluidity, may be employed to maintain coke quality but that they have a negative effect on the generation of coking pressure, while plastics of the aromatic type such as PET, a strong modifier of coal fluidity, can be used to counteract the generation of coking pressure. From the results, it is deduced that the protocol developed is useful for determining the optimum amount of each type of polymer (polyolefins and aromatic polymers) that is needed in order to counteract the generation of pressure during the coking process and to maintain the quality of the cokes.     

Mortality due to haematological cancer in cities close to petroleum refineries in Spain

Controversy exists as to whether working or living in the vicinity of a petroleum refinery (RF) increases the risk of haematological cancer (HC). The European Pollutant Release and Transfer Register obliges petroleum refineries to notify their emissions of toxic substances which include carcinogenic substances. Our objective is to determine if living in the proximity of an RF is associated with a greater risk of mortality due to HC in the census tracts (CTs) of the Spanish cities of Bilbao, Cartagena, Castellón, La Coruña, Huelva, and Santa Cruz de Tenerife. This is an ecological study of mortality in the years 1996–2007 which includes 968 CTs with 1,263,371 inhabitants. Exposure has been measured as the distance from the centroid of each CT to the RF. The Besag–York–Mollié autoregressive spatial model has been fitted by R-INLA to estimate the relative risk (RR) and 95 % credible intervals (95 % CrI) for distance in quintiles. The most distant quintile has been taken as the reference. A total of 2,574 persons died of HC. The distances from the CTs to RFs ranged from 0.5 to 22.5 km (median?=?7.6 km). All of the RRs for the quintiles of distances in Huelva were greater than 1. Statistically significant excess risk was shown in Cartagena in the nearest CT (1.8 to 6.8 km; RR?=?1.43, 95 % CrI 1.02 to 2.02). Radial effects have not been detected between the CT of residence and the petroleum RF in mortality due to HC in any of the cities.     

Eriophorum angustifolium and Lolium perenne metabolic adaptations to metals- and metalloids-induced anomalies in the vicinity of a chemical industrial complex

As plants constitute the foundation of the food chain, concerns have been raised about the possibility of toxic concentrations of metals and metalloids being transported from plants to the higher food chain strata. In this perspective, the use of important phytotoxicity endpoints may be of utmost significance in assessing the hazardous nature of metals and metalloids and also in developing ecological soil screening levels. The current study aimed to investigate the role of glutathione (GSH) and its associated enzymes in the metabolic adaptation of two grass species namely Eriophorum angustifolium Honck. and Lolium perenne L. to metals and metalloids stress in the vicinity of a chemical industrial complex (Estarreja, Portugal). Soil and plant samples were collected from contaminated (C) and non-contaminated (reference, R) sites, respectively, near and away from the Estarreja Chemical Complex, Portugal. Soils (from 0 to 10 and 10 to 20 cm depths) were analyzed for pH, organic carbon, and metals and metalloids concentrations. Plant samples were processed fresh for physiological and biochemical estimations, while oven-dried plant samples were used for metals and metalloids determinations following standard methodologies. Both soils and plants from the industrial area exhibited differential concentrations of major metals and metalloids including As, Cu, Hg, Pb, and Zn. In particular, L. perenne shoot displayed significantly higher and lower concentrations of Pb and As, respectively at contaminated site (vs. E. angustifolium). Irrespective of sites, L. perenne shoot exhibited significantly higher total GSH pool, oxidized glutathione (GSSG) and oxidized protein (vs. E. angustifolium). Additionally, severe damages to photosynthetic pigments, proteins, cellular membrane integrity (in terms of electrolyte leakage), and lipid peroxidation were also perceptible in L. perenne shoot. Contrarily, irrespective of the sites, activities of catalase and GSH-regenerating enzyme, GSH reductase, and GSH-metabolizing enzymes such as GSH peroxidase and GSH sulfotransferase were significantly higher in shoot of E. angustifolium. Despite the higher total GSH content, L. perenne is vulnerable to multi-metals-induced stress in comparison to E. angustifolium as depicted by increased GSH- and protein oxidation, low reactive oxygen radical-processing potential (exhibited in terms of low catalase activity) and poor GSH pool utilization efficiency (in terms of lower GSH-associated enzymes activities). The outcome of the present study may be significant for understanding vital GSH-mediated metals and metalloids tolerance mechanisms in plants as well as their unsuitability for animal consumption due to higher metals and metalloids burdens.     

Seasonal variation of pharmaceutically active compounds in surface (Tagus River) and tap water (Central Spain)

Numerous studies have shown the presence of pharmaceutically active compounds (PhACs) in different environmental compartments, for example, in surface water or wastewater ranging from nanograms per litre to micrograms per litre. Likewise, some recent studies have pointed to seasonal variability, thus indicating that PhAcs concentrations in the aquatic environment may depend on the time of year. This work intended to find out (1) whether Tagus fluvial and drinking water were polluted with different groups of PhACs and (2) if their concentrations differed between winter and summer seasons. From the 58 substances analysed, 41 were found belonging to the main therapeutic groups. Statistical differences were seen for antibacterials, antidepressants, anxiolytics, antiepileptics, and cardiovascular drugs, with higher concentrations being detected in winter than in summer. These results might indicate that the PhACs analysed in this study undergo lower environmental degradation in winter than in summer. In order to confirm these initial results, a continuous monitoring should be performed especially on those PhACs that either because of an elevated consumption or an intrinsic chemical persistence are poorly degraded during winter months due to low temperatures and solar irradiation. It is especially important to identify which of these specific PhACs are in order to recommend their substitution by equally effective and safe substances but also environmentally friendly.     

Adverse birth outcomes in the vicinity of industrial installations in Spain 2004–2008

Industrial activity is one of the main sources of ambient pollution in developed countries. However, research analyzing its effect on birth outcomes is inconclusive. We analyzed the association between proximity of mother’s municipality of residence to industries from 24 different activity groups and risk of very (VPTB) and moderate (MPTB) preterm birth, very (VLBW) and moderate (MLBW) low birth weight, and small for gestational age (SGA) in Spain, 2004–2008. An ecological study was defined, and a “near vs. far” analysis (3.5 km threshold) was carried out using Hierarchical Bayesian models implemented via Integrated Nested Laplace Approximation. VPTB risk was higher for mothers living near pharmaceutical companies. Proximity to galvanization and hazardous waste management industries increased the risk of MPTB. Risk of VLBW was higher for mothers residing near pharmaceutical and non-hazardous or animal waste management industries. For MLBW many associations were found, being notable the proximity to mining, biocides and animal waste management plants. The strongest association for SGA was found with proximity to management animal waste plants. These results highlight the importance of further research on the relationship between proximity to industrial sites and the occurrence of adverse birth outcomes especially for the case of pharmaceutical and animal waste management activities.     

Accumulation of arsenic, lead, copper, and zinc, and synthesis of phytochelatins by indigenous plants of a mining impacted area

Several native plants, able to grow in an unconfined mining impacted area that is now in close vicinity with urban areas, were evaluated for their ability to accumulate heavy metals. The main soil contaminants were As, Pb, Cu, and Zn. Sampling of the rhizospheric metal polluted soil showed that Euphorbia prostrata Aiton, Parthenium incanum Kunth, and Zinnia acerosa (DC.) A. Gray were able to grow in the presence of high amounts of mixtures of these elements. The plants accumulated the metals in the above ground parts and increased the synthesis of thiol molecules. E. prostrata showed the highest capacity for accumulation of the mixture of elements (588 μg g DW^?1). Analysis of the thiol-molecules profile showed that these plants synthesized high amounts of long-chain phytochelatins, accompanied by low amounts of monothiol molecules, which may be related to their higher resistance to As and heavy metals. The three plants showed translocation factors from roots to leaves >1 for As, Pb, Cu, and Zn. Thus, by periodically removing aerial parts, these plants could be useful for the phytoremediation of semi-arid and arid mining impacted areas, in which metal hyper-accumulator plants are not able to grow.     

Comparative analysis of selected biomarkers and pesticide sensitivity in juveniles of Solea solea and Solea senegalensis

The common sole, Solea solea (Linneus, 1758), and the Senegalese sole, Solea senegalensis (Kaup, 1858), are two important commercial species that coexist in the NW Mediterranean. In order to assess the species' ability to respond to chemical insults, a comparison of activities on enzymes involved in xenobiotic metabolism was carried out. Juveniles of both species were sampled in winter 2011 from the Ebro Delta region, and activities of selected enzymes such as acetylcholinesterase (AChE), carboxylesterase (CbE), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) were determined in several tissues. Lipid peroxidation (LP) levels in plasma were measured as a sign of oxidative stress. In vitro exposures to selected pesticides were contrasted, analysing AChE and CbE activities in several tissue homogenates. Overall, enzymatic activities were higher in S. solea except for gill GST and CbE and kidney GST, while plasmatic LP levels were similar. In vitro contrasts revealed lower IC50 values for CbE activities in S. solea, suggesting a greater buffer capacity of this enzyme to potentially reduce pesticide toxicity over AChE.     

Trace metal and metalloid levels in surface water of Marcal River before and after the Ajka red mud spill, Hungary

The aim of this study was to compare and assess the dissolved concentrations of trace elements (As, Zn, Hg, Cd, Cr, Ni, Pb and Cu) in surface water of Marcal River before and after the red mud spill that occurred in Ajka, western Hungary, in October 2010. The caustic sludge flooded the surrounding settlements and polluted the nearby Torna Creek, which flows through the Marcal and Raba rivers into the Danube. A total of 92 surface water samples were collected from the Marcal River in the period of 2007–2012 and analysed for dissolved trace metal(loid)s by atomic absorption spectroscopy method. After the spill, the water management authority initially focused on acid dosing of surface waters to lower pH and was effective in lowering both pH and metal(loid) concentrations. Among the dissolved trace metal(loid)s, arsenic and nickel levels were moderately higher in the Marcal River 2 years since the spill compared to that observed in the pre-disaster period. The concentrations of dissolved trace metal(loid)s did not exceed the European water quality standards and the US Environmental Protection Agency aquatic life criteria values (excluding one sample for cadmium).     

Four years of continuous monitoring of the Meirama end-pit lake and its impact in the definition of future uses

Following the technical closure of the brown lignite Meirama mine (NW Spain) in April 2008, the reclamation of the mined area is being accomplished with the controlled flooding of its large pit. During the first 7 months of flooding, the sequential arrest of the ground water dewatering system led to the growth of an acidic water body of about 2 hm³. Since October 2008, the surface waters from some local streams have been diverted towards the pit so that these have become the major water input in the flooding process. Surface water has promoted a major change in the chemical composition of the lake water so that, at present, its surface has a circum neutral pH, net alkalinity, and low conductivity. At present, the lake has slightly more than one half of its final volume, and it is expected the overflow in 3 to 3.5 years. The lake is meromictic, with a sharp chemocline separating the acidic monimolimnion (pH?≈?3.2, acidity?≈?150 mg CaCO₃/L, κ ₂₅?≈?2.4 mS/cm) from the main water body (pH?≈?6.5, alkalinity?≈?15 mg CaCO₃/L, κ ₂₅?≈?0.3 mS/cm). Oxygen is being depleted at the bottom of the lake so that the monimolimnion became anoxic in January 2011. Above the chemocline, the composition of the lake is similar, but not identical, to that of the flooding stream waters. Close to the surface, some constituents (pH, metals) show strong seasonal variations in coincidence with the phytoplankton growing periods. Those parameters whose limits are legally prescribed comply with the corresponding water quality standards, and they are also consistent with the forecasting results obtained in early modeling. At present, a project considering the construction of an uptake tunnel to exploit the lake is being developed for the emergency water supply of the metropolitan area of A Coruña.