Fluorescence fingerprints and Cu2+-complexing ability of individual molecular size fractions in soil- and waste-borne DOM

Land spreading of organic materials introduces large amounts of dissolved organic matter (DOM) into the soil. DOM has the ability to form stable complexes with heavy metals and can facilitate their transport towards the groundwater. The effects on soil processes are difficult to assess, because different DOM components might react differently towards metal ions. The objective of this study was to investigate the fluorescence signature and the Cu2+-binding capacity of individual molecular size fractions of DOM from various sources. DOM extracted from leaf compost, chicken manure, sugar cane vinasse and a fulvic hypercalcaric cambisol was fractionated by the means of dialysis into four molecular size classes: MW<500, 50012000-14000 Da. Vinasse and leaf compost contained around 80% and 70%, respectively, of the total organic carbon in the fractions with low molecular weight (MW<3500 Da); in chicken manure and soil these fractions accounted for 40% and 50% only. Fluorescence was highest in the fraction MW>12000 Da for leaf compost, chicken manure and soil. The opposite result was obtained for vinasse, where the fractions with low molecular weight showed highest fluorescence intensities, distinguishing it from all other samples. Vinasse showed the greatest ability to bind Cu2+ with a resulting complex concentration of 6.31mgl(-1) while in contact with an excess of Cu2+. Leaf compost, soil and chicken manure followed with 2.69, 1.12, and 0.85mgl(-1), respectively. Within vinasse, the fraction MW<500 Da was able to form the most DOM-Cu complexes, indicating the importance of low molecular weight fractions in metal binding.     

Revisiting the plant hyperaccumulation criteria to rare plants and earth abundant elements

The several established criteria to define a hyperaccumulator plant were applied to a rare and endangered species, Plantago almogravensis, and to the 3rd most abundant element in the earth crust, Al. Using the most common criteria, P. almogravensis undoubtedly is an Al hyperaccumulator plant. If the recent proposed requirements were considered, most of them matching those for a plant to be used in phytoextraction, it can only be considered an unusual accumulator of Al. A discussion is made concerning the several criteria of a hyperaccumulator plant in order to include rare and endemic ones and abundant elements. In ecological terms, the enrichment in Al and Fe observed may account for the differences in the vegetation pattern. Due to the rarity and endangered nature of this plant, the contribution of this work is also relevant for the ecological understanding and the development of conservation options of this endemic species.     

Validation and global uncertainty of a gas chromatographic with mass spectrometry method for fenamidone analysis in grapes and wines

Fenamidone is an imidazolinone fungicide recently introduced in viticulture practices. This work reports the validation and assessment of global uncertainty of a gas chromatographic with mass spectrometry method to analyze fenamidone in grapes and wines. This method consists in a simple and fast liquid-liquid extraction step followed by chromatographic determination. Limits of detection for fenamidone in grapes and wines were, respectively, 0.05 mg/kg and 0.06 mg/L, precision was below 9.4% and average recovery was 89 +/- 5%. In the concentration range from 0.05 to 1.00 mg/kg (or mg/L) of fenamidone, global uncertainty calculated following the EURACHEM/CITAC rules, and also by the Horwitz function, was below 25%. The EURACHEM/CITAC global uncertainty budget used gave lower estimates than those obtained from the Horwitz function.     

Structure of Mn-Zr mixed oxides catalysts and their catalytic performance in the gas-phase oxidation of chlorocarbons

The catalytic activity and selectivity of manganese zirconia mixed oxides were evaluated for the oxidation of two common chlorinated pollutants found in waste streams, namely 1,2-dichloroethane (DCE) and trichloroethylene (TCE). Mixed oxides with varying Mn-Zr content were prepared by coprecipitation via nitrates, and subsequent calcination at 600 degrees C for 4 h in air. These catalysts were characterised by means of several techniques such as atomic emission spectrometry, N2 adsorption-desorption, powder X-ray diffraction, temperature-programmed desorption of ammonia, pyridine adsorption followed by diffuse reflectance infrared spectroscopy and temperature-programmed reduction with hydrogen. The active catalytic behaviour of Mn-Zr mixed oxides was ascribed to a substantial surface acidity combined with readily accessible active oxygen species. Hence, the mixed oxide with 40 mol% manganese content was found to be an optimum catalyst for the combustion of both chlorocarbons with a T50 value around 305 and 315 degrees C for DCE and TCE oxidation, respectively. The major oxidation products were carbon dioxide, hydrogen chloride and chlorine. It was observed that the formation of both CO2 and Cl2 was promoted with Mn loading.     

Physiological and biochemical responses to high Mn concentrations in two contrasting Populus cathayana populations

We exposed the cuttings of Populus cathayana to Hoagland's solution containing four different manganese (Mn) concentrations (0, 0.1, 0.5 and 1mM) in a greenhouse to characterize the physiological and biochemical basis of Mn resistance in woody plants. Two contrasting populations of P. cathayana were used in our study, which were from the wet and dry climate regions in western China, respectively. The results showed that Mn treatments significantly decreased chlorophyll content and growth characteristics, including shoot height, basal diameter, biomass accumulation and total leaf area in the two populations. Mn treatments also significantly increased the levels of abscisic acid (ABA), polyamines and free amino acids especially proline (Pro), histidine (His) and phenylalanine (Phe) available for cellular signaling and heavy metal chelation. In addition, high Mn concentrations also caused oxidative stress indicated as the accumulation of hydrogen peroxide (H(2)O(2)) and malondialdehyde (MDA) contents. On the other hand, there were different responses to Mn stress between the two contrasting populations. Compared with the dry climate population, the wet climate population accumulated more Mn in plant tissues especially in leaves; it showed lower tolerance index and more pronounced decrease in growth and chlorophyll contents. The wet climate population not only accumulated less ABA, putrescine and free amino acids, but also exhibited lower activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX), thus suffering from more serious oxidative damage. Therefore, our results showed that the wet climate population was more susceptible to Mn stress than the dry climate population.     

Challenges in quantifying biosphere-atmosphere exchange of nitrogen species

Recent research in nitrogen exchange with the atmosphere has separated research communities according to N form. The integrated perspective needed to quantify the net effect of N on greenhouse-gas balance is being addressed by the NitroEurope Integrated Project (NEU). Recent advances have depended on improved methodologies, while ongoing challenges include gas-aerosol interactions, organic nitrogen and N(2) fluxes. The NEU strategy applies a 3-tier Flux Network together with a Manipulation Network of global-change experiments, linked by common protocols to facilitate model application. Substantial progress has been made in modelling N fluxes, especially for N(2)O, NO and bi-directional NH(3) exchange. Landscape analysis represents an emerging challenge to address the spatial interactions between farms, fields, ecosystems, catchments and air dispersion/deposition. European up-scaling of N fluxes is highly uncertain and a key priority is for better data on agricultural practices. Finally, attention is needed to develop N flux verification procedures to assess compliance with international protocols.     

Polychlorinated biphenyls and DDT in swordfish (Xiphias gladius) and blue shark (Prionace glauca) from Brazilian coast

The polychlorinated biphenyls (PCBs) and DDT may bioaccumulate in the aquatic food web and have been of great concern due to their toxic effects on wildlife and human health. There is evidence showing that fish in the human diet contributes at a significant proportion to the total intake of PCBs and other organochlorine compounds, particularly fish with higher fat levels. This study investigated the concentration of PCBs and DDTs in muscle tissues of samples of the blue shark (Prionace glauca) and a swordfish (Xiphias gladius) from east Brazilian coast and estimate the human exposure to total DDTs through the consumption of both the species. Samples of the each species were caught between August and September 2001. The mean concentration for summation operator PCBs in P. glauca was 3.15 ng/g w.w. and the summation operator DDTs was 0.93 ng/g w.w. The mean concentration of summation operator PCBs in X. gladius was 6.50 ng/g and the mean of summation operator DDTs was 2.47 ng/g. The estimated daily intake of summation operator DDT through X. gladius or P. glauca consumption can be considered safe since it contributes to less than 0.1% of the limit of acceptable daily intake (ADI) of summation operator DDT proposed by WHO.     

Evaluation of methods for sorting CCA-treated wood

Construction and demolition (C&D) wood frequently contains treated wood including wood treated with chromated copper arsenate (CCA). Many recycling options for such wood require that the product be essentially free of preservative chemicals. The objectives of this study were to document the characteristics of the wood waste stream and to evaluate the effectiveness of sorting methods for identifying treated wood. Sorting methods evaluated included visual sorting and visual sorting augmented with the use of PAN indicator stain and/or hand-held X-ray fluorescence (XRF) units. Experiments were conducted on two types of construction and demolition (C&D) wood: source separated loads containing only C&D wood and wood hand-picked from commingled loads of general C&D waste. Results showed that 77% of the treated wood was CCA-treated. For uncontaminated piles (<1% treated wood) of source separated C&D wood, visual sorting was found to effectively remove the small amounts of treated wood present. For piles of source separated wood that were contaminated (approximately 50% treated wood), visual sorts were not accurate and benefited from augmented sorting using PAN indicator stain. The handheld XRF devices were found to be effective for sorting commingled C&D wood, as PAN indicator stain was not as effective due to the excessive amount of surface dirt associated with commingled wood waste. Visual sorting of source separated wood was estimated to cost between US$21 to US$96 per metric ton. These costs depended upon the amount of treated wood and whether or not augmentation with PAN indicator was necessary. Visual sorting augmented with hand-held XRF units was estimated at US$113 per metric ton. The bulk of these costs were associated with labor. Future efforts should focus on reducing labor costs by mounting automated XRF units on conveyor systems.     

Evaluation of commercial landscaping mulch for possible contamination from CCA

Wood treated with chromated copper arsenate (CCA) is found in construction and demolition (C&D) debris, and a common use for wood recycled from C&D debris is the production of mulch. Given the high metals concentrations in CCA-treated wood, a small fraction of CCA-treated wood can increase the metal concentrations in the mulch above regulatory thresholds. The objective of this study was to determine the extent of contamination of CCA-treated wood in consumer landscaping mulch and to determine whether visual methods or rapid X-ray fluorescence (XRF) technology can be used to identify suspect mulch. Samples were collected throughout the State of Florida (USA) and evaluated both visually and chemically. Visual analysis focused on documenting wood-chip size distribution, whether the samples were artificially colored, and whether they contained plywood chips which is an indication that the sample was, in part, made from recycled C&D wood. Chemical analysis included measurements of total recoverable metals, leachable metals as per the standardized synthetic precipitation leaching procedure (SPLP), and XRF analysis. Visual identification methods, such as colorant addition or presence of plywood, were found effective to preliminarily screen suspect mulch. XRF analysis was found to be effective for identifying mulch containing higher than 75 mg/kg arsenic. For mulch samples that were not colored and did not contain evidence of C&D wood, none exceeded leachable metal concentrations of 50 microg/L and only 3% exceeded 10 mg/kg for recoverable metals. The majority of the colored mulch made from recycled C&D wood contained from 1% to 5% CCA-treated wood (15% maximum fraction) resulting in leachable metals in excess of 50 microg/L and total recoverable metals in excess of 10 mg/kg. The maximum arsenic concentration measured in the mulch samples evaluated was 230 mg/kg, which was above the Florida residential direct exposure regulatory guideline of 2.1 mg/kg.     

Estrogenic activity removal of 17beta-estradiol by ozonation and identification of by-products

This work investigated the degradation of a natural estrogen (17beta-estradiol) and the removal of estrogenic activity by the ozonation process in three different pHs (3, 7 and 11). A recombinant yeast assay (YES assay) was employed to determine estrogenic activity of the ozonized samples and of the by-products formed during the ozonation. Ozonation was very efficient for the removal of 17beta-estradiol in aqueous solutions. High removals (>99%) were achieved with low ozone dosages in the three different pHs. Several by-products were formed during the ozonation of 17beta-estradiol. However, only a few compounds could be identified and confirmed. Different by-products are formed at different pHs, which is probably due to different chemical pathways and different oxidants (O(3) and OH radical). The by-products formed at pH 11 were 10epsilon-17beta-dihydroxy-1, 4-estradieno-3-one (DEO) and 2-hydroxyestradiol, which were not formed in pH 3. Only testosterone could be observed in pH 3, whereas at pH 7 all three by-products were found. At pH 7 and 11 the applied ozone dosages were not enough to remove all the estrogenicity from samples, even though the 17beta-estradiol residual concentration for these two pHs was lower than at pH 3. Higher estrogenicity was detected at pH 11. An explanation to this fact may be that oxidation via OH radical forms more by-products with estrogenic activity. Probably, the formation of 2-hydroxyestradiol at pHs 7 and 11 is contributing to the residual estrogenicity of samples ozonized at these pHs. In this work, complete removal of estrogenic activity was only obtained at pH 3.