Arbuscular mycorrhizal fungi can decrease the uptake of uranium by subterranean clover grown at high levels of uranium in soil

Subterranean clover inoculated or not with the arbuscular mycorrhizal (AM) fungus Glomus intraradices was grown on soil containing six levels of 238U in the range 0-87 mg kg(-1). Increasing U concentration in soil enhanced the U concentration in roots and shoots of both mycorrhizal and nonmycorrhizal plants but had no significant effects on plant dry matter production or root AM colonization. Mycorrhizas increased the shoot dry matter and P concentration in roots and shoots, while in most cases, it decreased the Ca, Mg and K concentrations in plants. The AM fungus influenced U concentration in plants only in the treatment receiving 87 mg U kg(-1) soil. In this case, U concentration in shoots of nonmycorrhizal plants was 1.7 times that of shoots of mycorrhizal plants. These results suggested that mycorrhizal fungi can limit U accumulation by plants exposed to high levels of U in soil.     

Individual PCBs as predictors for concentrations of non and mono-ortho PCBs in human milk

32 Dutch human milk samples were analyzed for PCBs with either HRGC-ECD or HRGC-LRMS in the NCI mode. Samples were collected from three different locations in The Netherlands: Amsterdam, Rotterdam and Groningen. Quantitatively, no differences could be observed between the three localities, while in addition the congener specific pattern showed a striking similarity for all individual samples. Only principal component analysis revealed slight individual differences. Based on similarities in the PCB profiles, linear relationships were calculated between 2,3′4,4′,5-PnCB (#118) or 2,2′4,4′5,5′HxCB (#153) and the most relevantnon andmonoortho PCBs exhibiting dioxinlike activity. These PCBs included 2,3,3′,4,4′-PnCB (#105), 3,3′,4,4′5-PnCB (#126) 2,3,3′,4,4′,5-HxCB (#156), 2,3,3′,4,4′,5′-HxCB (#157), 2,3′,4,4′,5,5′-HxCB (#167) and 3,3′,4,4′,5′5-HxCB (#169). Good linear relationships were observed between individual PCBs. Based on the results of this study, PCB #118 can be used to predict concentrations of the PCBs #105 and #126. PCB #153 can be used as a predictor for the PCBs #156, #157, #167 and #169, but also for the total toxic equivalencies (TEQs) ofnon andmonoortho PCBs present in human milk. This method using certain PCBs as predictors for other toxicological relevant congeners, can be useful and cost effective, e.g. for epidemiological studies. However, before applied a number of conditions should be met. These are:

1. A stable composition of the PCB matrix should be established.
2. A possible time dependent change in composition of the matrix should first be excluded when used over different time periods.

     

Chromosome analysis of multipronuclear human oocytes after in vitro fertilization

Multipronuclear human eggs are frequent after in vitro fertilization. Their chromosome analysis can provide useful information. Before cleavage it can confirm the suspected poly-ploidy. Among the cleaved multipronuclear eggs it provides an estimation of the incidence of the possible return to diploidy. Ninety-four multipronuclear eggs were fixed at the first, second, or third cleavage according to the air-drying method of Tarkowski with or without colchicine exposure: 60 were successfully analysed. Twelve were stopped before cleavage (six without colchicine treatment and six with colchicine treatment). They were polyploid, confirming the cytological observation. Forty-eight eggs cleaved and were stopped by colchicine treatment and karyotyped. Seventeen eggs (35 per cent) had produced diploid embryos. Mosaicism was frequent (15 cases, 31 per cent). Triploidy was not frequent (8 eggs, 17 per cent). Haploidy constituted the remaining cases (8 eggs, 17 per cent). Our data indicate that the initial count of pronuclei is a reliable test. Multipronuclear one-cell oocytes were confirmed to be polyploid. Furthermore, the developmental capacity of the multipronuclear oocytes is variable. Most of them cleaved. However, many multipronuclear oocytes led to diploid cleaving eggs.     

Effect of metals on the adsorption and extractability of 14C-phenanthrene in soils

The fate of polycyclic aromatic hydrocarbons (PAHs) in contaminated soils may be affected by several environmental factors including the presence of co-contaminants. This study was conducted in order to assess the effect of metals on (i) the adsorption of 14C-phenanthrene in soils and (ii) its extractability and ability to form non-extractable residues. The first objective was accomplished using batch adsorption experiments with an uncontaminated agricultural soil spiked with the metals Cd, Cu, Pb, and Zn. Adsorption of phenanthrene was significantly higher after the addition of the metals (Kf = 21.48 vs. 8.55) and the desorption less readily reversible when compared to the unspiked soil. The extractability of phenanthrene was assessed with incubation (4 months, laboratory conditions) and microlysimeter experiments (6 months, natural climatic conditions) on three soils spiked with metals. All the soils were labelled with 14C-phenanthrene. The amount of extractable phenanthrene residues was significantly higher when the metals had been added to the soils. Nevertheless, the quantity of non-extractable residues was non-significantly different between the spiked and unspiked soils. The mechanism leading to increased adsorption and extractability of phenanthrene in the presence of metals is still unknown. In perspective, it would be interesting to assess the bioavailability of PAHs in the presence of metals in further experiments.     

Priming effects on PAH degradation and ecotoxicity during a phytoremediation experiment

An experiment was conducted to distinguish priming effects from the effects of phytoremediation of a creosote-polluted soil. The concentration of 13 polycyclic aromatic hydrocarbons (PAHs), and their combined soil toxicity (using four bioassays), was determined on recently excavated, homogenized soil and on such soil subjected to a time-course phytoremediation experiment with lucerne. The results showed a high priming effect, with minor positive and synergistic effects of planting and fertilization on PAH degradation rates. At the end of the experiment, PAH degradation reached 86% of the initial 519 mg PAHs kg(-1). Two of the four toxicity tests (bioluminescence inhibition and ostracod growth inhibition) corroborated the chemical data for residual PAHs, and indicated a significant reduction in soil toxicity. We conclude that priming effects can easily surpass treatment effects, and that an unintentional pre-incubation that ignores these effects can jeopardize the full quantitative assessment of in situ bioremediation of contaminated soil.     

Flammability of Some Ornamental Species in Wildland–Urban Interfaces in Southeastern France: Laboratory Assessment at Particle Level

Assessment of the flammability of ornamental vegetation (particularly hedges) planted around houses is necessary in light of the increasing urbanization of the wildland–urban interfaces (WUIs) and the high fire occurrence in such areas. The structure and flammability of seven of the species most frequently planted as hedges in Provence (southeastern France) were studied at particle level. Spatial repartition of the different types of fuel particles within plants was assessed by means of the cube method. The leaf flammability was assessed using an epiradiator as a burning device, and measurements of foliar physical characteristics and gross heat of combustion (GHC) helped to explain the results of burning experiments. Co-inertia analysis revealed that species with thin leaves were quick to ignite (Pyracantha coccinea, Phyllostachys sp.) and species with high leaf GHC burned the longest (Pittosporum tobira, Nerium oleander). Species presenting high ignitability (Photinia fraseri, Phyllostachys sp. and Pyracantha coccinea) were characterized by high foliar surface area-to-volume ratio, and species presenting lower ignitability were characterized by high GHC (Pittosporum tobira, Nerium oleander, Cupressus sempervirens). Hierarchical cluster analysis of the flammability variables (ignition frequency, time-to-ignition and flaming duration) categorized the relative flammability of the seven species (including dead Cupressus sempervirens) in five clusters of species from poorly flammable (Pittosporum tobira) to extremely flammable (dead Cupressus sempervirens).This study provides useful information for reducing fire risk in WUIs in the study area.     

Risk assessment of sensory irritants in indoor air--a case study in a French school

Exposure to airborne pollutants can result in adverse health effects. Acute symptoms can for instance comprise of irritation of the eyes or of the respiratory tract (called sensory irritation). In a recent case, health problems were reported in a French school and supposedly attributed to the presence of airborne irritant pollutants. Based on measured concentrations, the risk of developing the described health effects was assessed.Numerous airborne sensory irritants (aldehydes, organic acids, volatile organic compounds (VOCs), SO(2), NH(3)) were identified and quantified in the indoor air by using active and passive sampling and online monitoring techniques. Reference values based on toxicological properties of compounds (sensory irritants) were taken from the literature. If not available, tentative values were specially developed for this purpose. Concentrations of all sensory irritants remain below their corresponding guideline values and are comparable to literature data. It was concluded that the risk of developing sensory irritation due to the presence of the studied compounds is negligible. This holds both for individual compounds and for the mixture of studied compounds. Limitations of the employed sampling strategy, and of existing sampling and analytical techniques, which do not allow for analysing more reactive compounds-which are strong sensory irritants-may play a role. New sampling techniques need to be developed. Psychosocial factors (group behaviour, increased attention to sensory irritation) should also be taken into account when dealing with health complaints on sensory irritation.     

Assessment of heavy metal and organic contaminants levels along the Libyan coast using transplanted mussels (Mytilus galloprovincialis)

Within the framework of the MYTIOR project in 2009, heavy metals and organic compounds contaminations were assessed in transplanted mussels in 16 different stations along the coasts of Libya. These stations were located at miles offshore industrial/urban sources but in open sea providing original results related to the background contamination rather than linked to a specific coastal source of pollutants. Results indicated mercury (Hg, 0.045–0.066 mg/kg dry weight (dw)), lead (Pb, 0.44–0, 71 mg/kg dw) and copper (Cu, 3.56–4.21 mg/kg dw) were in the same range or at lower value than control for all stations. Chromium (Cr) in Meleta (3.08 mg/kg dw) and Bomba (3.80 mg/kg dw) and Cadmium values in all stations (1.21–2.41 mg/kg dw) were above control. Meleta, stations from the gulf of Syrt and the three eastern stations were the most affected stations by nickel (max at 5.83 mg/kg dw in Syrt) when zinc was in the same range (141–197 mg/kg dw) and above the control (92 mg/kg dw) at all stations. Polycyclic aromatic hydrocarbon (PAH) levels were found in the range of 16.8–42.8 mg/kg (dry weight) indicating low levels along the Libyan coast with acenaphthene and benzo (a, b, k) pyrenes detected mainly in western Libya. The study of PAH ratios indicated a mixed petrogenic/pyrolytic origin. The only polychlorinated biphenyls (PCBs) found in Libya were PCB 101 in one location and PCB 153 in Tripoli, Garrapoli, Syrt, Ras Lanuf and Benghazi (1.2–1.9 μg/kg dw). Insecticides were lower than control in all stations except DDT, only detected in Misratah (3.5 μg/kg dw). Overall, the results indicated a low background contamination and a low pollution extent according to the environmental pressure occurring offshore the Libyan coast.