Variability in microbial carbon isotope fractionation of tetra- and trichloroethene upon reductive dechlorination

The variability of stable carbon isotope fractionation upon reductive dechlorination of tetra- and trichloroethene by several microbial strains was investigated to examine the uncertainties related to the in situ application of compound specific isotope analysis (CSIA) of chlorinated ethenes. Carbon isotope fractionation was investigated with a set of microorganisms representative for the currently known diversity of dehalorespirers: Dehalococcoides ethenogenes strain 195, Desulfitobacterium sp. strain Viet1, Desulfuromonas michiganensis and Geobacter lovleyi sp. strain SZ and compared to the previous reports using Sulfurospirillum spp. and Desulfitobacterium sp. strain PCE-S. Carbon isotope fractionation of tetrachloroethene (PCE) and trichlorethene (TCE) was highly variable ranging from the absence of significant fractionation to carbon isotope fractionation (epsilonC) of 16.7 and 3.5-18.9 for PCE and TCE, respectively. Fractionation of both compounds by D. ethenogenes strain 195 (PCE: epsilonC=6.0; TCE: epsilonC=13.7) was similar to the literature data for mixed cultures containing Dehalococcoides spp. D. michiganensis (PCE: no significant fractionation; TCE: epsilonC=3.5) and G. lovleyi sp. strain SZ (PCE no significant fractionation; TCE: epsilonC=8.5) generated the lowest fractionation of all studied strains. Desulfitobacterium sp. strain Viet1 (PCE: epsilonC=16.7) gave the highest enrichment factor for PCE.     

Ozon in Waldökosystemen aus atmosphärenchemischer und pflanzenphysiologischer Sicht

The trend of rising ozone concentrations in forest ecosystems and the phytotoxicity of ozone demand a realistic risk assessment according to an internationally accepted and flux-based quality standard. Ozone fluxes within the canopy are influenced by chemical gas-phase reactions with nitrogen oxide and biogenic hydrocarbons and by surface deposition processes. Therefore, a differentiation of the ozone flux within the canopy is needed between stomatal uptake and other transport pathways. The Eddy Covariance technique is the method of choice for the determination of trace gas fluxes relevant for ozone chemistry. This method is also used for stomatal conductance measurements based on evapotranspiration fluxes and for emission measurements of biogenic hydrocarbons by PTR-MS. Although considerably research efforts were directed to canopy measurements in recent years, the underlying processes are not fully understood yet. Thus, major differences occur in the ratios of stomatal ozone uptake, non-stomatal deposition and gas-phase chemistry between different studies. Furthermore, the vertical concentration gradients within the canopy measured at several forest sites are rather inconsistent and the existing deposition models do rarely account for chemical transformation and detoxification processes. Only a simultaneous measurement of all photochemically relevant trace gases, plant physiological parameters at different sites and forest species over entire vegetation periods, and model parameterization according to the measurement results from the experimental sites will contribute to the clarification of the canopy processes and will ensure realistic risk assessments.     

Turner syndrome-omphalocele association: Incidence,karyotype, phenotype and fetal outcome

Objective

Omphalocele is known to be associated with genetic anomalies like trisomy 13, 18 and Beckwith–Wiedemann syndrome, but not with Turner syndrome (TS). Our aim was to assess the incidence of omphalocele in fetuses with TS, the phenotype of this association with other anomalies, their karyotype, and the fetal outcomes.

Method

Retrospective multicenter study of fetuses with confirmed diagnosis of TS. Data were extracted from a detailed questionnaire sent to specialists in prenatal ultrasound.

Results

680 fetuses with TS were included in this analysis. Incidence of small omphalocele in fetuses diagnosed ≥12 weeks was 3.1%. Including fetuses diagnosed before 12 weeks, it was 5.1%. 97.1% (34/35) of the affected fetuses had one or more associated anomalies including increased nuchal translucency (≥3 mm) and/or cystic hygroma (94.3%), hydrops/skin edema (71.1%), and cardiac anomalies (40%). The karyotype was 45,X in all fetuses. Fetal outcomes were poor with only 1 fetus born alive.

Conclusion

TS with 45,X karyotype but not with X chromosome variants is associated with small omphalocele. Most of these fetuses have associated anomalies and a poor prognosis. Our data suggest an association of TS with omphalocele, which is evident from the first trimester.     

Evaluation and comparison of advanced oxidation processes for the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D): a review

Environmental Science and Pollution Research - Organochlorine pesticides have generated public concern worldwide because of their toxicity to human health and the environment, even at low...     

Integrative approach to delineate natural attenuation of chlorinated benzenes in anoxic aquifers

Biodegradation of chlorobenzenes was assessed at an anoxic aquifer by combining hydrogeochemistry and stable isotope analyses. In situ microcosm analysis evidenced microbial assimilation of chlorobenzene (MCB) derived carbon and laboratory investigations asserted mineralization of MCB at low rates. Sequential dehalogenation of chlorinated benzenes may affect the isotope signature of single chlorobenzene species due to simultaneous depletion and enrichment of ¹³C, which complicates the evaluation of degradation. Therefore, the compound-specific isotope analysis was interpreted based on an isotope balance. The enrichment of the cumulative isotope composition of all chlorobenzenes indicated in situ biodegradation. Additionally, the relationship between hydrogeochemistry and degradation activity was investigated by principal component analysis underlining variable hydrogeochemical conditions associated with degradation activity at the plume scale. Although the complexity of the field site did not allow straightforward assessment of natural attenuation processes, the application of an integrative approach appeared relevant to characterize the in situ biodegradation potential.     

Intrasexual competition,territoriality and acoustic communication in male strawberry poison frogs (<Emphasis Type="Italic">Oophaga pumilio</Emphasis>)

In many species male reproductive success is limited by access to females. Territoriality is one behavioural strategy which helps to acquire females. In the present study, we investigated the correlation between territory size and (1) female availability and (2) rate of intrusion by conspecific males in strawberry poison frogs, Oophaga pumilio. Males defended smaller territories in areas with a high female density and high rate of intrusion by conspecific males. Only males with high body condition values were able to establish territories in areas of high female density probably due to better fighting abilities. Moreover, dominant calling frequency was lower during agonistic interactions. Because only males with high body condition values were able to produce very low dominant frequencies, the acoustic properties appear to be an honest signal containing information about fighting abilities. Thus, the negative correlation between dominant frequency and mating success of males found in previous studies seems to be in part the result of intrasexual competition between males.     

Assessment of the natural attenuation of chlorinated ethenes in an anaerobic contaminated aquifer in the Bitterfeld/Wolfen area using stable isotope techniques, microcosm studies and molecular biomarkers

The in situ degradation of chlorinated ethenes was assessed in an anaerobic aquifer using stable isotope fractionation approaches, microcosm studies and taxon specific detection of specific dehalogenating groups of bacteria. The aquifer in the Bitterfeld/Wolfen region in Germany contained all chlorinated ethenes, benzene and toluene as contaminants. The concentrations and isotope composition of the chlorinated ethenes indicated biodegradation of the contaminants. Microcosm studies confirmed the presence of in situ microbial communities capable of the complete dechlorination of tetrachloroethene. Taxon specific investigation of the microbial communities indicated the presence of various potential dechlorinating organisms including Dehalococcoides, Desulfuromonas, Desulfitobacterium and Dehalobacter. The integrated approach, using metabolite spectra, molecular marker analysis and isotope studies, provided several lines of evidence for natural attenuation of the chlorinated ethenes.     

Assessing the viability of electro-absorption and photoelectro-absorption for the treatment of gaseous perchloroethylene

Environmental Science and Pollution Research - This work focuses on the development of electro-absorption and photoelectro-absorption technologies to treat gases produced by a synthetic waste...     

Arsenic and lead contamination in urban soils of Villa de la Paz (Mexico) affected by historical mine wastes and its effect on children’s health studied by micronucleated exfoliated cells assay

Environmental geochemical and health studies were carried out in urban areas of Villa de la Paz, S.L.P. (Mexico), where mining activities have been developed for more of 200 years, leading to the pollution of surface soil by arsenic and heavy metals (Pb, Cd, Cu, Zn). The analysis of urban soils to determine total and bioaccessibility concentrations of As and Pb, demonstrated a combined contribution of the natural and anthropogenic concentrations in the site, at levels higher than the environmental guideline values that provoke a human health risk. Contour soil mapping confirmed that historical mine waste deposits without environmental control measures, are the main source of pollution soil by As and Pb in the site. Exposure (Pb in blood and As in urine) and effect (micronucleated exfoliated cells assay) biological monitoring were then carried out in the childhood population of the site and in a control site. The exposure biological monitoring demonstrated that at least 20–30 % of children presented Pb and As exposure values higher than the national and international maximum intervention values. The effect biomonitoring by MEC assay confirmed that there is a genotoxic damage in local childhood population that could be associated with the arsenic exposure in the site.     

Social representations of socioenvironmental dynamics in extractive ecosystems and conservation practices with sustainable development: a bibliometric analysis

Environment, Development and Sustainability - Social representations necessarily originate from the interaction between individuals and groups in a social setting through communication and shared...