Arsenic speciation and mobilization in CCA-contaminated soils: influence of organic matter content

A laboratory incubation experiment was conducted to investigate the influence of organic matter content on arsenic speciation and mobilization in chromated copper arsenate (CCA)-contaminated soils. The study was performed with four synthetic CCA-contaminated soils, with a range of organic matter content (mixture of peat moss and poultry manure) varying between 0.5% and 15% (w/w), under unsaturated and aerobic conditions for 40 days. Changes in water-soluble arsenic speciation (As(V), As(III), MMAA, DMAA) were monitored over time in soil extracts by HPLC-ICP-MS and in the soil solid phase (As(III), As(V)) by a solvent extraction method. Irrespective of organic matter content, As(V) was the predominant soil bound and aqueous phase arsenic species. However, over 40 days, a high soil organic matter content (7.5% and 15%) was able to entail formation of soil bound As(III). Moreover, total water-soluble arsenic was positively correlated with dissolved organic carbon (r(2)=0.88). However, the organic matter content did not influence arsenic speciation in the soluble fraction; neither As(V) reduction nor arsenic biomethylation occurred within 40 days. An increase in dissolved organic carbon content promoted both As(V) and As(III) solubilization in soils. Also, over time, organic matter contents of 7.5% and 15% entailed the persistence of soluble As(V), likely due to the high content of dissolved organic compounds which prevented its sorption onto soil. Based on this data, the environmental risk of aerobic CCA-contaminated soils rich in organic matter may be due to an enhanced availability of soluble As(V) over time, rather than to the formation of the more toxic and more mobile As(III).     

Inhibition vs. enhancement of the nitrate-induced phototransformation of organic substrates by the OH scavengers bicarbonate and carbonate

Contrary to common expectations, the hydroxyl scavengers, carbonate and bicarbonate, are able to enhance the phototransformation by nitrate of a number of substituted phenols. Carbonate and bicarbonate, in addition to modifying the solution pH, are also able to induce a considerable formation of the carbonate radicals upon nitrate photolysis. The higher availability of less-reactive species than the hydroxyl radical would contribute to substantially enhance the photodegradation of the phenols/phenolates that are sufficiently reactive toward the carbonate radical. This phenomenon has a potentially important impact on the fate of the relevant compounds in surface waters. In contrast, the degradation of compounds that are not sufficiently reactive toward CO₃^−• is inhibited by carbonate and bicarbonate because of the scavenging of ^•OH.     

Microwave-Assisted Extraction of Secoisolariciresinol Diglucoside��Method Development

An optimized microwave-assisted extraction (MAE) method was developed for extracting secoisolariciresinol diglucoside (SDG) from flaxseed. This paper presents the optimization of factors for maximizing the extraction yield of SDG. This work was conducted using the experimental domain identified in a previous study by means of screening designs, that is, samples of 1 g defatted flaxseed meal (DFM) were extracted with 50 ml NaOH of concentration of 0.5–1 M, at microwave power levels of 60–360 W, for 3–9 min, with the microwave power applied intermittently (power on 30 s/min) and continuously (power on 60 s/min). The MAE of SDG was maximized when 1 g DFM was extracted with 50 ml 0.5 M NaOH, at 135 W, for 3 min in intermittent power mode (power on 30 s/min). The optimized MAE achieved a 6% increase in the extraction yield (21.45 mg SDG per gram DFM) as opposed to a direct hydrolysis method (20.22 mg SDG per gram DFM). The MAE of SDG was governed by the microwave–NaOH interaction, which had a curvilinear dependence on the microwave power level, and linear dependence on the NaOH concentration. The microwave-induced effects accounted for a 10% increase in the SDG extraction yield (21.45 mg SDG per gram DFM) as opposed to a microwaveless control method (19.45 mg SDG per gram DFM). The optimized MAE method has good repeatability, a 97% recovery of the target compound; it is fast and efficient and can be used for precise quantification of SDG in flaxseed.     

Effects of pH variations on anodic marine consortia in a dual chamber microbial fuel cell

The effect of anodic pH on Microbial fuel cells (MFCs) inoculated with marine consortia was investigated to characterize the microbial community adaptation to possible pH environmental changes and to define the pH extreme boundaries beyond which MFCs do not run properly.Tests were conducted in triplicate using different feeding pH values (pH_feed) ranging from 3 to 13. The MFCs inoculated with marine consortia had a strong self-regulation ability and actively counterbalanced small variations in pH_feed maintaining the pH inside the anodic chamber (pH_anode) close to neutrality.As soon as the pH_anode deviated from neutrality it affected MFCs' performances. Alkaline conditions with pH_anode values between 8 and 10 corresponded to the formation of a denser biofilm together with the best performance in terms of maximum power density (P_max). Conversely, when the pH_anode reached values lower than 5.5 or higher than 10, a sharp drop in MFC performances, as well as a decrease of viable population, were observed. Interestingly, the system was able to survive these extreme conditions and restart working effectively when neutrality was reset.The obtained results underline the high adaptability and recovery ability of anodic marine consortia even in extreme conditions, suggesting the employment of this inoculum for MFC applications as biosensors for on-site seawater monitoring or as power supply units to be installed in remote area.     

Variation in antioxidant components of tomato during vine and post-harvest ripening

The variation in the antioxidant content (lycopene, β-carotene, ascorbic acid and total phenolics) was evaluated on two tomato genotypes during vine and post-harvest ripening. Tomatoes were sampled and analysed at seven ripening stages according to the colour value. The data indicate that ripening conditions affected both the antioxidant accumulation kinetics and the final content, which was higher in post-harvest-ripened fruits. In particular, lycopene mainly accumulated in the very last period of ripening and its content was not linearly related to colour changes. Antioxidant accumulation and other ripening indexes were not significantly different in the two tomato genotypes. © 1999 Society of Chemical Industry     

High-resolution Orbitrap™-based mass spectrometry for rapid detection of peanuts in nuts

Peanut represents one of the most harmful allergenic foods capable of triggering severe and sometimes lethal reactions in allergic consumers upon ingestion of even small amounts. Several proteins capable of inducing allergic reactions that have been recognised by patients’ IgE antibodies have been identified from this nut source. Methods mainly based on ELISA assays have been developed in order to detect peanuts in several food commodities. In addition LC-MS/MS methods based on different mass analysers have also been devised for tracing peanut contamination in different foods achieving low limits of detection. The applicability of a benchtop high-resolution Exactive? mass spectrometer has never been investigated for the rapid screening of peanut contamination in complex food matrices like mixtures of nuts. We report in this paper the design of suitable peanut markers and the development of an high-resolution Orbitrap? mass spectrometer-based method for peanut detection in a mixture of nuts species. With this aim, different types of samples were prepared: (1) nuts-based powder made up of a mixture of hazelnuts, pistachios, almonds and walnuts; and (2) nuts powder fortified with peanuts. Different levels of fortifications were produced and the applicability of the method was tested. Finally, a subset of six peptides fulfilling specific analytical requirements was chosen to check the suitability of the method tailored to the detection of peanuts in nuts-based products, and two of them, peptides VYD and WLG, were selected as quantitative markers. The method proved to be a suitable screening tool to assess the presence of traces of peanuts in other tree nuts with a limit of detection as low as 4 µg of peanuts proteins or 26 µg of peanuts in 1 g of matrix.     

The perception of risks associated with food-related hazards and the perceived reliability of sources of information

This study aimed to explore, on the one hand, public perception of risks associated with different food‐related hazards and, on the other hand, perception of reliability of various sources providing information on food‐related risks. Some differences were found when consumers compared six food‐related hazards in terms of perceived personal risk and their knowledge of potential food risks. The concern about food risks was found to be statistically significantly dependent on the perception of risk to the individual. As far as the perception of the reliability of information was concerned, a principal component analysis revealed some differences in terms of respondents’ perception when the sources were compared. Furthermore, a regression analysis showed that the perceived amount of information each source contained about food‐related hazards was an important element in perception of reliability, as well as the degree of concern consumers believed the agencies had with protecting their health from food risks.     

Electron transfer from a solid-state electrode assisted by methyl viologen sustains efficient microbial reductive dechlorination of TCE

The ability to transfer electrons, via an extracellular path, to solid surfaces is typically exploited by microorganisms which use insoluble electron acceptors, such as iron-or manganese-oxides or inert electrodes in microbial fuel cells. The reverse process, i.e., the use of solid surfaces or electrodes as electron donors in microbial respirations, although largely unexplored, could potentially have important environmental applications, particularly for the removal of oxidized pollutants from contaminated groundwater or waste streams. Here we show, for the first time, that an electrochemical cell with a solid-state electrode polarized at -500 mV (vs standard hydrogen electrode), in combination with a low-potential redox mediator (methyl viologen), can efficiently transfer electrochemical reducing equivalents to microorganisms which respire using chlorinated solvents. By this approach, the reductive transformation of trichloroethene, a toxic yet common groundwater contaminant, to harmless end-products such as ethene and ethane could be performed. Furthermore, using a methyl-viologen-modified electrode we could even demonstrate that dechlorinating bacteria were able to accept reducing equivalents directly from the modified electrode surface. The innovative concept, based on the stimulation of dechlorination reactions through the use of solid-state electrodes (we propose for this process the acronym BEARD: Bio-Electrochemically Assisted Reductive Dechlorination), holds promise for in situ bioremediation of chlorinated-solvent-contaminated groundwater, and has several potential advantages over traditional approaches based on the subsurface injection of organic compounds. The results of this study raise the possibility that immobilization of selected redox mediators may be a general strategy for stimulating and controlling a range of microbial reactions using insoluble electrodes as electron donors.     

Evaluation of the oxidation state and metal concentration in the adipose tissue of Parma ham

The effect of different dietary fat supplements: A, no added fat; B, 3% added lard and C, 3% added partially hydrogenated lard (PHL), were evaluated in dry cured Parma ham fat by determination of the lipid oxidation indices, R1 and R2, on a total of 30 Italian Landrace×Italian Large White pigs. Furthermore, correlations between lipid oxidation and calcium, magnesium, iron, zinc, copper and nickel concentrations, determined in Parma ham fat, was also investigated. Results highlighted a correlation between the oxidative state of Parma ham fat and the pigs' diet; in particular the addition of 3% PHL led to a more stable depot fat towards lipid oxidation compared to the addition of lard. Finally, Parma ham fat from treatment C showed higher concentrations of Ca (p<0.01) and Mg (p<0.05) compared to those from control, A, and treatment B groups. On the contrary, no significant differences were found for Fe, Zn, Cu and Ni.