Recycling extruded polystyrene by dissolution with suitable solvents

The amount of extruded polystyrene (XPS) waste has increased in recent years due to the increase of its use in the thermal insulation of buildings, transport vehicles, and refrigerators, among others. Dissolution with suitable solvents to achieve a volume reduction of more than 100 times without degradation of polymer chains is one of the cheapest and most efficient methods of recycling XPS. Several environmentally friendly solvents have been tested as dissolution agents for XPS volume reduction; the action of these solvents does not produce any degradation of polymer chains. The solubility of the polymer in such solvents at different temperatures was investigated. The solvent can be easily recycled by distillation, obtaining a high-quality recycled polymer. Chemical Feedstock Recycling & Other Innovative Recycling Techniques 6     

Cs,Co and K uptake by lettuce plants in two distributions of soil contamination

¹³⁷Cs and ⁶⁰Co, two of the radionuclides more representative of discharges from nuclear facilities, are of interest for radiological protections because of their great mobility in biosphere and affinity with biological systems. The aim of the present work is the investigation of the possible influence of the vertical distribution of ¹³⁷Cs and ⁶⁰Co in soil upon their uptake by lettuce as function of plant's growth. An experiment ad hoc has been carried out in field conditions. The results show that (i) the transfer of ¹³⁷Cs and ⁶⁰Co from soil to lettuce is independent by their distribution in soil, (ii) the soil–plant transfer factors of ¹³⁷Cs and ⁶⁰Co show a similar trend vs. growth stage, (iii) the ⁴⁰K transfer factor trend is different from those of anthropogenic radionuclides, and (iv) ¹³⁷Cs and ⁶⁰Co specific activities are about 1 Bq/kg, in the mature vegetable with soil activity from 9 to 21 kBq/m².     

Influence of environment on insulin sensitivity

Genetic and environmental factors influence insulin sensitivity (IS) during one's lifetime. Actually, uterine environment may affect IS at birth and later in life. In particular, various exogenous toxic substances, coupled to a genetic predisposition, may remarkably influence the regulation of the hypothalamus–hypophysis–adrenal gland axis, and the production or the activity of insulin, cerebral incretins, pro-inflammatory cytokines, and placental hormones. Owing to this reaction against environmental injuries, fetal growth and endocrine system development may be impaired, leading to low or large birth weight, or prematurity. Reduced growth in early life has been related to insulin resistance, which can be silent for years and evident in predisposed adults. The incidence of type 2 diabetes mellitus and obesity associated with sedentary lifestyle patterns and inadequate dieting behaviors in children and adolescents has rapidly increased during the last decade.Recent evidences suggest that the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor-? (PPAR-?) gene and the angiotensin converting enzyme (ACE) I/D gene polymorphism combined with environmental factors, such as phthalates interfering with the post receptorial action of insulin, alter insulin-sensible tissues. Therefore, IS, deriving from a complex interaction between genotype and environment, may change during life and depends on previous metabolic control, which is a sort of metabolic memory. The goal for the future is preventing the complications associated with impaired IS through the control of exogenous factors and the use of drugs selectively effective on its pathogenesis.     

Multi-attribute analysis of trophic state and waterfowl management in Ringkøbing Fjord,Denmark

A multi-attribute analysis by means of the general multi-attribute analysis (GMAA) decision support system was performed in order to rank different strategies for good water quality with respect to trophic state, and good conditions for waterfowl, in the lagoon Ringkøbing Fjord, Denmark. The remedial strategies included nutrient abatement and the construction of facilities to increase the water exchange between the lagoon and the sea. The analysis showed that it is essential to keep the mean annual salinity level constant, since a drastic change in salinity may cause massive destruction of the macrophyte belt with large effects on the water quality and waterfowl abundance. It may be cost-effective to build and maintain a saltwater pumping station or a second sluice to increase the seawater inflow. Further nutrient abatement may not be cost-effective, at least not on time-scales shorter than 20 years, but the utility from nutrient abatement increases if a second sluice is built additionally. However, all of the remedial strategies, except decreasing the salinity, were projected to cause rather small changes in the effect variables compared to the no action alternative.     

Monitoring of polychlorinated biphenyl contamination and estrogenic activity in water, commercial feed and farmed seafood

We evaluated the concentration and congener distribution of seven "target" polychlorinated biphenyls (PCBs) present in water collected in different aquaculture farms of the Mediterranean area, commercial feeds, and farmed seafood. PCBs were present in feed and in tissues of all the analysed organisms at levels ranging from 1.96 ng g(-1) to 124.00 ng g(-1) wet weight, and in 10.5% of the water samples, at levels from under detection limit to 33.0 ng l(-1) with total PCB concentrations significantly higher in samples from the Tyrrhenian Sea than the Adriatic Sea. PCB congener distribution in tissues resembled that of feed, suggesting that commercial feed is an important source of PCBs. The estrogenicity of organic extracts of the samples was also evaluated by using an in vitro yeast reporter assay. Estrogenic activity higher than 10% of the activity induced by 10 nM 17 beta-estradiol was observed in 20.0% of seafood samples and 15.8% of water samples. Seafood and water samples from the Tyrrhenian Sea were more frequently estrogenic than the Adriatic ones (16.45 versus 4.08%). A significant correlation of total PCB concentrations on biological activity was observed for sea bass and mussels from the Adriatic Sea (p < 0.045 and p < 0.04, respectively), and for sea bass of the Tyrrhenian Sea (p = 0.05). These results indicate the need of an integral approach in the exposure assessment to potential toxic compounds for human via food.     

Geostatistical analysis to identify hydrogeochemical processes in complex aquifers: a case study (Aguadulce unit, Almeria, SE Spain)

The Aguadulce aquifer unit in southeastern Spain is a complex hydrogeological system because of the varied lithology of the aquifer strata and the variability of the processes that can take place within the unit. Factorial analysis of the data allowed the number of variables to be reduced to 3 factors, which were found to be related to such physico-chemical processes as marine intrusion and leaching of saline deposits. Variographic analysis was applied to these factors, culminating in a study of spatial distribution using ordinary kriging. Mapping of the factors allowed rapid differentiation of some of the processes that affect the waters of the Gador carbonate aquifer within the Aguadulce unit, without the need to recur to purely hydrogeochemical techniques. The results indicate the existence of several factors related to salinity: marine intrusion, paleowaters, and/or leaching of marls and evaporitic deposits. The techniques employed are effective, and the results conform to those obtained using hydrogeochemical methods (vertical records of conductivity and temperature, ion ratios, and others). The findings of this study confirm that the application of such analytical methods can provide a useful assessment of factors affecting groundwater composition.     

A new hybrid system of QSAR models for predicting bioconcentration factors (BCF)

The aim was to develop a reliable and practical quantitative structure-activity relationship (QSAR) model validated by strict conditions for predicting bioconcentration factors (BCF). We built up several QSAR models starting from a large data set of 473 heterogeneous chemicals, based on multiple linear regression (MLR), radial basis function neural network (RBFNN) and support vector machine (SVM) methods. To improve the results, we also applied a hybrid model, which gave better prediction than single models. All models were statistically analysed using strict criteria, including an external test set. The outliers were also examined to understand better in which cases large errors were to be expected and to improve the predictive models. The models offer more robust tools for regulatory purposes, on the basis of the statistical results and the quality check on the input data.     

Determination of organophosphorus fire retardants and plasticizers in wastewater samples using MAE-SPME with GC-ICPMS and GC-TOFMS detection

Determination of organophosphorus fire retardants and plasticizers at trace levels in wastewater is described. In this work, microwave assisted extraction (MAE) and solid-phase microextraction (SPME) are used for sample preparation to extract and preconcentrate the analytes, followed by analysis by gas chromatography coupled to inductively coupled plasma mass spectrometry (GC-ICP-MS) for phosphorus-specific detection. Gas chromatography coupled to time of flight mass spectrometry (GC-TOF-MS) was used to confirm the organphosphorus fire retardants in wastewater. The detection limits of organophosphorus fire retardants (OPFRs) were 29 ng L(-1) for tri-n-butyl phosphate (TnBP), 45 ng for L(-1) for tris(2-butoxyethyl)phosphate (TBEP), and 50 ng L(-1) for tris(2-ethylhexyl)phosphate (TEHP). Optimized extraction conditions were performed at 65 degrees C for 30 min and with 10% NaCl. Application of MAE during the sample preparation prior to the SPME allowed the detection of tris(2-ethylhexyl) phosphate, which has been difficult to determine in previous work. Application of the method to wastewater samples resulted in detecting 3.1 microg L(-1) P from TnBP, 5.0 microg L(-1) P from TBEP, and 4.0 microg L(-1) P from TEHP. The presence of these compounds were also confirmed by SPME-GC-TOF-MS.     

Spectroscopic and conformational properties of size-fractions separated from a lignite humic acid

A lignite humic acid (HA) was fractionated by preparative high performance size-exclusion chromatography (HPSEC) in seven different size-fractions. The size-fractions were characterized by cross polarization (CP) magic angle spinning (MAS) (13)C NMR spectroscopy and a further analytical HPSEC elution under UV and fluorescence detection. The alkyl hydrophobic components mainly distributed in the largest molecular-size-fraction, whereas the amount of oxidized carbons increased with decreasing size of fractions. Cross polarization time (T(CH)) and proton spin-lattice relaxation time in the rotating frame (T(1rho)(H)) were measured from variable contact time (VCT) experiments. The bulk HA was characterized by the shortest T(CH) values and the longest T(1rho)(H) values which suggested, respectively, one. an aggregation of components in a large conformation that favored a fast H-C cross polarization, and, two. consequent steric hindrances that prevented fast local molecular motions and decreased proton relaxation rates. Conversely, the separated size-fractions showed longer T(CH) values and shorter T(1rho)(H) values than the bulk HA, thereby indicating that they were constituted by a larger number of mobile molecular conformations. The UV and fluorescence absorptions were both low in the large size-fractions that mainly contained alkyl carbons, whereas they increased in the olephinic- and aromatic-rich fractions with intermediate molecular-size, and decreased again in the smaller fractions which were predominantly composed by oxidized carbons. These results support the supramolecular structure of humic substances and indicate that the observed variation in conformational distribution in humic association may be used to explain environmental processes with additional precision.     

Total and inorganic arsenic in Antarctic macroalgae

The Antarctic region offers unparalleled possibilities of investigating the natural distribution of metals and metalloids, such as arsenic. Total and inorganic As were analysed in nine species of Antarctic macroalgae collected during the 2002 summer season in the Potter Cove area at Jubany-Dallmann Station (South Shetland Islands, Argentinian Base). Total As was determined by inductively coupled plasma-optical emission spectrometry after microwave-assisted acid digestion. Inorganic As was determined by acid digestion, solvent extraction, flow injection-hydride generation-atomic absorption spectrometry. Total As ranged from 5.8 microg g(-1) dry weight (dw) (Myriogramme sp.) to 152 microg g(-1)dw (Himantothallus grandifolius). Total As concentrations were higher in Phaeophytes (mean+/-SD: 71+/-44 microg g(-1)dw) than in Rhodophytes (mean+/-SD: 15+/-11 microg g(-1)dw). Inorganic As ranged from 0.12 microg g(-1) (Myriogramme sp.) to 0.84 microg g(-1)dw (Phaeurus antarcticus). The percentage of inorganic As with respect to total As was 0.7 for Phaeophytes, but almost 4 times higher for Rhodophytes (2.6). The work discusses possible causes for the presence of As in marine organisms in that pristine environment.