The ability of Helianthus annuus L. and Brassica juncea to uptake and translocate natural uranium and 226Ra under different milieu conditions

Seedlings of Helianthus annuus L. (HA) and Brassica juncea (BJ) were used to test the effect of the pH, the presence of phosphates, and the addition of ethylene-diamine-tetraacetic acid (EDTA) or citrate on the uptake and the translocation of uranium isotopes ((238)U, (235)U, and (234)U) and (226)Ra. The results indicated that the presence of phosphates generally reduces the uptake and transfer of uranium from the roots to the shoots of HA. In the case of BJ, while phosphate enhanced the retention of uranium by roots, the translocation was poorer. Likewise, for (226)Ra, the best translocation was in the absence of phosphates for both species. The addition of citrate increased the translocation of uranium for both species, but had no clear effect on the transfer of (226)Ra. The effect of EDTA was much more moderate both for uranium and for (226)Ra, and for both plant species. Only noticeable was a slightly better uptake of (226)Ra by BJ at neutral pH, although the translocation was lower.     

Single-walled carbon nanotube behavior in representative mature leachate

Escalating production and subsequent incorporation of engineered nanomaterials in consumer products increases the likelihood of nanomaterials being discarded in landfills. Although direct measurement of particle disposal has not yet occurred, life cycle assessments suggest that over 50% of nanomaterials produced will eventually reside in landfills. Laboratory-scale experiments were conducted to evaluate how organics (humic acid: 20-800 mg/L), ionic strength (100-400 mM NaCl), and pH (6-8) typical of mature leachates influence carbon nanotube surface charge, relative stability, and mobility through representative solid waste environments. Results from the batch experiments suggest that the presence of high molecular weight organics, such as humic acid, acts to stabilize carbon nanotubes present in leachate, even at high ionic strengths (>100 mM NaCl). These results also suggest that in mature landfill leachate, as long as humic acid is present, ionic strength (when represented as NaCl) will be a dominant factor influencing nanomaterial stability. Column experiment results indicate the carbon nanotubes may be mobile through solid waste, suggesting particle placement within landfills needs to be examined more closely.     

Microbiological characterization and specific methanogenic activity of anaerobe sludges used in urban solid waste treatment

This study presents the microbiological characterization of the anaerobic sludge used in a two-stage anaerobic reactor for the treatment of organic fraction of urban solid waste (OFUSW). This treatment is one alternative for reducing solid waste in landfills at the same time producing a biogas (CH(4) and CO(2)) and an effluent that can be used as biofertilizer. The system was inoculated with sludge from a wastewater treatment plant (WWTP) (Río Frío Plant in Bucaramanga-Colombia) and a methanogenic anaerobic digester for the treatment of pig manure (Mesa de los Santos in Santander). Bacterial populations were evaluated by counting groups related to oxygen sensitivity, while metabolic groups were determined by most probable number (MPN) technique. Specific methanogenic activity (SMA) for acetate, formate, methanol and ethanol substrates was also determined. In the acidogenic reactor (R1), volatile fatty acids (VFA) reached values of 25,000 mg L(-1) and a concentration of CO(2) of 90%. In this reactor, the fermentative population was predominant (10(5)-10(6)MPN mL(-1)). The acetogenic population was (10(5)MPN mL(-1)) and the sulphate-reducing population was (10(4)-10(5)MPN mL(-1)). In the methanogenic reactor (R2), levels of CH(4) (70%) were higher than CO(2) (25%), whereas the VFA values were lower than 4000 mg L(-1). Substrate competition between sulphate-reducing (10(4)-10(5)MPN mL(-1)) and methanogenic bacteria (10(5)MPN mL(-1)) was not detected. From the SMA results obtained, acetoclastic (2.39 g COD-CH(4)g(-1)VSS(-1)day(-1)) and hydrogenophilic (0.94 g COD-CH(4)g(-1)VSS(-1)day(-1)) transformations as possible metabolic pathways used by methanogenic bacteria is suggested from the SMA results obtained. Methanotrix sp., Methanosarcina sp., Methanoccocus sp. and Methanobacterium sp. were identified.     

PCB and PCT levels in cultivated and free‐living mussels of galicia (North west Spain)

PCB and PCT residues were measured in free‐living (FM) and cultivated mussels (CM) from ten sites in Galicia by gas chromatography with electron capture detector and capillary column. The level of PCB₁₂₆₀ and PCT₅₄₆₀ in FMs increases going from Muros‐Noya to Vigo estuarine bay. There was a trend of increase from north to south.     

Fractionation of natural radionuclides in soils from a uranium mineralized area in the south-west of Spain

A new version of a classical method was applied to study the distribution of natural radionuclides (238U, 230Th, and 226Ra) in the soil fractions obtained by a sequential extraction procedure. The potential significance of the fractions obtained with this method was tested on two very similar soils but with very different contents of the three radionuclides, collected in the proximity of a disused uranium mine located in the Extremadura region in the south-west of Spain. The results confirmed that, if only non-residual fractions are considered, the sequential method applied shows a characteristic speciation pattern of these natural radionuclides in this soil matrix, i.e., the distribution of each of the three radionuclides was very similar for the two soil samples.     

Fate of Triclosan and Methyltriclosan in soil from biosolids application

This study investigates the persistence of Triclosan (TCS), and its degradation product, Methyltriclosan (MeTCS), after land application of biosolids to an experimental agricultural plot under both till and no till. Surface soil samples (n = 40) were collected several times over a three years period and sieved to remove biosolids. Concentration of TCS in the soil gradually increased with maximum levels of 63.7 ± 14.1 ng g(-1) dry wt., far below the predicted maximum concentration of 307.5 ng g(-1) dry wt. TCS disappearance corresponded with MeTCS appearance, suggesting in situ formation. Our results suggest that soil incorporation and degradation processes are taking place simultaneously and that TCS background levels are achieved within two years. TCS half-life (t(0.5)) was determined as 104 d and MeTCS t(0.5), which was more persistent than TCS, was estimated at 443 d.     

Eco-Efficiency of Electric and Electronic Appliances: A Data Envelopment Analysis (DEA)

Several papers have studied the eco-efficiency of manufacturing systems to address strategic socioeconomic issues in the context of sustainability analysis. Their goal has been to take into account not only environmental impact aspects throughout the whole life cycle but also to incorporate the associated economic value as well, thus, giving a comprehensive vision of both factors. This paper focuses on different commonplace household electric appliances, comparing their eco-efficiency computed using a data envelopment analysis model. We consider the retail price as a measure of the product’s economic value and the ecopoint LCA score as the assessment of its environmental impact. We conclude that cell phones and the bulky analyzed appliances have the highest eco-efficiency scores, whereas the rest would require a more environmentally friendly redesign and/or an increase in their perceived value to improve their eco-efficiency.