A new bacterial strain mediating As oxidation in the Fe-rich biofilm naturally growing in a groundwater Fe treatment pilot unit

A bacterial strain B2 that oxidizes arsenite into arsenate was isolated from the biofilm growing in a biological groundwater treatment process used for Fe removal. This strain is phylogenetically and morphologically different from the genus Leptothrix commonly encountered in biological iron oxidation processes. T-RFLP fingerprint of the biofilm revealed that this isolated strain B2 corresponds to the major population of the bacterial community in the biofilm. Therefore, it is probably one of the major contributors to arsenic removal in the treatment process.     

Antioxidant defense gene analysis in <Emphasis Type="Italic">Brassica oleracea</Emphasis> and <Emphasis Type="Italic">Trifolium repens</Emphasis> exposed to Cd and/or Pb

This study focused on the expression analysis of antioxidant defense genes in Brassica oleracea and in Trifolium repens. Plants were exposed for 3, 10, and 56 days in microcosms to a field-collected suburban soil spiked by low concentrations of cadmium and/or lead. In both species, metal accumulations and expression levels of genes encoding proteins involved and/or related to antioxidant defense systems (glutathione transferases, peroxidases, catalases, metallothioneins) were quantified in leaves in order to better understand the detoxification processes involved following exposure to metals. It appeared that strongest gene expression variations in T. repens were observed when plants are exposed to Cd (metallothionein and ascorbate peroxidase upregulations) whereas strongest variations in B. oleracea were observed in case of Cd/Pb co-exposures (metallothionein, glutathione transferase, and peroxidase upregulations). Results also suggest that there is a benefit to use complementary species in order to better apprehend the biological effects in ecotoxicology.     

Studies on atmospheric degradation of diazinon in the EUPHORE simulation chamber

The gas phase atmospheric degradation of diazinon has been investigated at the large outdoor European Photoreactor (EUPHORE) in Valencia, Spain. The rate constant for reaction of diazinon with OH radicals was measured using a conventional relative rate method with di-n-buthylether as reference compound being k = (3.5 ± 1.2) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ at 302 ± 10 K and atmospheric pressure. The available evidence indicates that tropospheric degradation of diazinon is mainly controlled by reaction with OH radicals, and that the tropospheric lifetime with respect to the OH reaction is estimated to be around 4 h whereas its lifetime with respect to the photolysis is higher than 1 d under our conditions. Significant aerosol formation was observed following the reaction of diazinon with OH radicals, and the main carbon-containing products detected in the particle phase were hydroxydiazinon, hydroxydiazoxon and 2-isopropyl-6-methyl-pyrimidinyl-4-ol.     

Effectiveness of control strategies against Botrytis cinerea in vineyard and evaluation of the residual fungicide concentrations

This investigation was undertaken to test different control strategies against Botrytis cinerea vineyards. Two commercial vineyards, “Barbera” and “Moscato,” located in Piedmont (Northern Italy) were divided into seven plots and treated with different combinations of fungicides including fenhexamid, pyrimethanil, fludioxonil + cyprodinil, iprodione, and boscalid, a new carboxamide compound. An integrated strategy including a chemical (pyrimethanil) and a biocontrol agent (Trichoderma spp. t2/4ph1) was also included. At harvest, the percentage of bunches and berries attacked by B. cinerea and the concentration of the chemical fungicides were determined. All the pesticide residues at harvest were below the maximum residue level (MRL), except when two applications of pyrimethanil per season were applied. Boscalid was the most effective active ingredient against B. cinerea among the tested chemicals. When boscalid application was followed by a treatment with pyrimethanil, its efficacy was similar to that shown by two treatments of pyrimethanil. However, this second strategy was not feasible due to the risks of resistance development in the pathogen and to the residue accumulation as indicated by the analysis.     

Spatial Trends of Trace-Element Contamination in Recently Deposited Lake Sediment Around the Ni–Cu Smelter at Nikel, Kola Peninsula, Russian Arctic

A large copper–nickel smelter complex is located at the Kole Penninsula, Russia, close to the Norwegian border. Trace-element concentrations in surface sediments (0–0.5 cm) and pre-industrial sediments from 45 lakes in the region were used to uncover spatial deposition patterns and contamination factor of sediments. Elevated concentrations were found, especially for Ni and Cu, but also for Pb, Co, Hg, As, and Cd. Highest concentrations were found up to 20 km from the smelter, but the concentrations decreased exponentially with distance from the smelter. Increasing Ni, Cu, As, and Hg concentrations from sub-surface to surface sediments were found for lakes at intermediate distances (20–60 km). This may reflect recent changes in atmospheric depositions, as shown in nearby Norwegian areas. However, we cannot rule out that this also may have been caused by diagenetic processes, especially for the most redox-sensitive elements such as As.     

Removal of PCDD/F from incinerator flue gases by entrained-phase adsorption

The emission abatement of polychlorinated dioxins and furans (PCDD/F) Issued from municipal solid waste incineration is growing in importance because of more stringent emission standards and general concern about their toxic characteristics. These substances cannot be separated by conventional gas cleanup processes but are successfully removed through adsorption onto carbonaceous materials. The simplest technique is the entrained-phase injection of pulverized adsorbents in the flue gas, followed by fabric filter separation. The various related techniques are briefly reviewed here. Operating conditions and results obtained from Flemish MSWIs are given. The results illustrate the excellent overall removal efficiency. Furans are adsorbed to a slightly higher extent than dioxins. PCDD/F removal by carbonaceous adsorbents is thereafter modeled from first principles for the contribution of both entrained-phase (eta1) and cake filtration (eta2) to the overall efficiency (etaT). Application of the model equations and comparison of measured and predicted overall efficiencies for the Flemish municipal solid waste incinerators (MSWIs) demonstrate that the approach is meaningful and that the dominant parameters are the operating temperature, the dosage and activity of adsorbent, and the fraction of adsorbent in the filter cake. The model equations enable the MSWI operators to predict the adsorption efficiencies for any combination of operating parameters and to assess the sensitivity of the process to varying operating conditions.     

Combination of biodegradable organic matter quantification and XAD-fractionation as effective working parameter for the study of biodegradability in environmental and anthropic samples

The present work proposes to couple quantification of biodegradable organic matter (BOM) with XAD-fractionation. Biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC) analysis were applied to fractions extracted by XAD resin. An examination of mechanisms during consumption of BOM has been carried out, using comparison of biodegradability between the bulk BOM of samples (landfill leachate and surface water) and the sum of BOM contents obtained for the extracted fractions. Results point out that a cometabolism mechanism seems to be involved during the degradation of the surface water fractions. On the other hand, fractions extracted from the leachate seem to be degraded as primary substratum. The more reactive fractions of the leachate (HPO*) and the water (HPI) have been identified as well the less reactive (HPI* and HPO, respectively). The BDOC contents determined for the bulk leachate and surface water are 10+/-2% and 28+/-2%, respectively. The values of AOC are 107+/-18 microg C acetate L(-1) and 163+/-21 microg C acetate L(-1), respectively.     

Effects of the mixture of diquat and a nonylphenol polyethoxylate adjuvant on fecundity and progeny early performances of the pond snail Lymnaea stagnalis in laboratory bioassays and microcosms

Effects of the bipyridylium herbicide diquat and tank-mix adjuvant Agral((R))90 were investigated on various life history traits of the freshwater pulmonate snail Lymnaea stagnalis. Trait expression was measured in simple laboratory bioassays on small size groups of snails, and under more complex, indoor microcosm conditions, on larger groups of snails. Microcosms were provided with sediment, plants, and fish, thus allowing a more complex level of intra and inter-specific interactions to develop. Treatments were performed with substances alone or in mixture, at concentrations ranging from 4.4 to 222.2mugl(-1) for diquat, and from 10 to 500mugl(-1) for Agral 90, under a fixed ratio design. Adult growth was negatively affected by diquat and its mixture with Agral 90 both at the highest concentrations (222.2 and 500mugl(-1), respectively). Fecundity expressed differently in bioassays and microcosms, but no effect of the chemicals could be observed on this trait. Progeny development was impaired by 222.2mugl(-1) diquat and its mixture with 500mugl(-1) Agral 90, as reflected by longer development time and reduced hatching rate of clutches laid by the exposed animals, as compared to the controls. Hatching data suggested that diquat bioavailability was lower in microcosms than under bioassay conditions. Consistently, chemical analysis showed that diquat disappeared more rapidly from the water in microcosms than in bioassays. Moreover, the differential expression of several life history traits under bioassays and microcosms conditions was probably also influenced by the level of intraspecific interaction, which differed among the systems. When significant, the effect of diquat was attenuated by the presence of Agral 90, indicating antagonistic interaction between the two substances. Such a deviation from additivity was partly validated statistically.