Calmodulin as a modulator of NaCl transport in the posterior salt-transporting gills of the Chinese crab Eriocheir sinensis

The possible involvement of calmodulin-dependent processes in the control of Na⁺ and Cl^- transport pathways has been investigated on isolated, perfused preparations of salt-transporting posterior gills of the euryhaline Chinese crab Eriocheir sinensis (collected near Emden, Germany in autumn 1990). The anti-calmodulin phenothiazine drugs Chlorpromazine and Trifluoperazine induced depolarization of the transepithelial potential only when added to the serosal bathing saline (socalled in). This effect is best interpreted by assuming a disturbance of the conductive Cl^- pathways located at the baso-lateral side of the epithelium. In agreement with that conclusion is the fact that Trifluoperazine inhibits the Cl^- transepithelial influx. Trifluoperazine also induces inhibition of the Na⁺ influx when added either to the incubation (out) or to the perfusion (in) medium. These results indicate inhibitory effects of the anticalmodulin drug on both the Na⁺/K⁺ pump and leak system located at the serosal side and on the Na⁺/H⁺ exchange located at the apical side of the epithelium.     

Downscaling scenarios of future land use and land cover changes using a participatory approach: an application to mountain risk assessment in the Pyrenees (France)

Regional Environmental Change - Better understanding the pathways through which future socioeconomic changes might influence land use and land cover changes (LULCCs) is a crucial step in accurately...     

Fe(III)–EDDS complex in Fenton and photo-Fenton processes: from the radical formation to the degradation of a target compound

The present work compares the efficiency of homogenous Fenton and photo-Fenton processes in the presence of Fe(III)–EDDS complex under different experimental conditions. 4-tert-Butylphenol (4-t-BP), which is one of the endocrine disrupting chemicals, was used as a model pollutant to investigate the Fenton and photo-Fenton application. The efficiency of homogenous photo-Fenton process was significantly much higher than homogenous Fenton process, which is due to the rapid formation of Fe²⁺ under UV irradiation of the iron complex and the photochemical formation of HO^? from the photolysis of the complex Fe(III)–EDDS. Through the degradation of 4-t-BP, the effect of Fe(III)–EDDS concentration, H₂O₂ concentration, pH, and oxygen was investigated in both processes. Such trend was also correlated with pH calculating the polychromatic Fe²⁺ quantum yield formation at pH 4.0, 6.0, and 8.6. The results showed that at high Fe(III)–EDDS and H₂O₂ concentrations, a negative effect was found. By the way, the Fenton process was found to be enhanced at basic pH. These results can be very useful for the use and optimization of such iron complex in water treatment process as function of different physico-chemical conditions.     

Opportunistically collected data from aerial surveys reveal spatio-temporal distribution patterns of marine debris in German waters

Environmental Science and Pollution Research - Marine debris is known for its ubiquitousness and harmful effects on marine life. This study is the first analysis to provide information on the...     

The food-print of Paris: long-term reconstruction of the nitrogen flows imported into the city from its rural hinterland

Between the tenth and twentieth century the population of Paris city increased from a few thousand to near 10 million inhabitants. In response to the growing urban demand during this period, the agrarian systems of the surrounding rural areas tremendously increased their potential for commercial export of agricultural products, made possible by a surplus of agricultural production over local consumption by humans and livestock in these areas. Expressed in terms of nitrogen, the potential for export increased from about 60 kg N/km2/year of rural territory in the Middle Ages, to more than 5,000 kg N/km2/year from modern agriculture. As a result of the balance between urban population growth and rural productivity, the rural area required to supply Paris (i.e. its food-print) did not change substantially for several centuries, remaining at the size of the Seine watershed surrounding the city (around 60,000 km2). The theoretical estimate of the size of the supplying hinterland at the end of the eighteenth century is confirmed by the figures deduced from the analysis of the historical city toll data (octroi). During the second half of the twentieth century, the ‘food-print’ of Paris reduced in size, owing to an unprecedented increase in the potential for commercial export associated with modern agricultural systems based on chemical N fertilization. We argue that analysing the capacity of territories to satisfy the demand for nitrogen-containing food products of local or distant urban population and markets might provide new and useful insights when assessing world food resource allocation in the context of increasing population and urbanization.     

Mineralisation of Monuron photoinduced by Fe(III) in aqueous solution

The degradation of Monuron (3-(4-chlorophenyl)-1,1-dimethylurea) photoinduced by Fe(III) in aqueous solution has been investigated. The rate of degradation depends on the concentration of Fe(OH)2+, the most photoreactive species in terms of *OH radical formation. These *OH radicals are able to degrade Monuron until total mineralisation. The primordial role of the speciation of Fe(III)-hydroxy complex in aqueous solution, for the efficiency of the elimination of pollutant, was shown and explained in detail. The formation of Fe(II) in the irradiated solution was monitored and correlated with the total organic carbon evolution. Degradation photoproducts were identified and a mechanism of degradation is proposed.     

Fe(III) promoted LAS (linear alkylbenzenesulfonate) removal from waters

The mechanisms of the interactions between Fe(III) aquacomplexes and surfactants were investigated; three alkylbenzenzsulfonates, two surfactants (octylbenzenesulfonate (OBS) and dodecylbenzenesulfonate (DBS)), and a shorter derivative (ethylbenzenesulfonate (EBS)) were studied. The results with OBS show evidence for three different ways in which Fe(III) interferes with the surfactant: the widely described flocculation process, complexation of Fe(OH)2+ (aquacomplexes) by the surfactant, and a redox reaction. The formation of a weak complex is maximum for a ratio of three between the monomeric aquacomplex [FeOH(H2O)5]2+ and OBS. In the presence of oxygen, an intramolecular redox reaction occurs inside the complex. The interaction between commercial DBS and Fe(III) was also investigated. Immediate precipitation occurred, mainly involving derivatives of higher molecular weights that are contained in the DBS samples. The constituents with the shortest alkyl chain were not affected by the presence of Fe(III) as it was also observed with EBS.     

Structure characterization and thermal stabilities of the isomers of the brominated flame retardant 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane

1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) is used primarily as an additive flame retardant. 1H NMR spectroscopy and an X-ray structure determination have revealed that a technical mixture consists largely of two (of the four possible) diastereomers, rac-(1R,2R)-1,2-dibromo-(4S)-4-((1S)-1,2-dibromoethyl)cyclohexane (alpha-TBECH) and rac-(1R,2R)-1,2-dibromo-(4S)-4-((1R)-1,2-dibromoethyl)cyclohexane (beta-TBECH), in a mole ratio of approximately 1:1. The two other possible isomers, gamma- and delta-TBECH, were not detected in a technical mixture. The TBECH isomers are thermally sensitive and can easily interconvert at temperatures of 125 degrees C. A thermal equilibrium mixture of alpha-, beta-, gamma- and delta-TBECH consists of approximately 33%, 33%, 17% and 17% of these isomers, respectively. Separation of all four TBECH diastereomers, with minimal thermal interconversion of the isomers, was achieved by careful selection of GC-capillary column length and injector temperature. Although technical TBECH does not contain the gamma- and delta-isomers, they may still be relevant environmental contaminants since manufacturing processes utilize thermal processes which may induce their formation.     

Some issues relating to the use of perfluorooctanesulfonate (PFOS) samples as reference standards

Samples of potassium perfluorooctanesulfonate (PFOSK) from three suppliers were analyzed by LC-ESI-MS/MS for purity and by LC-ESI-MS for the percentage of linear isomer present. Our data indicated that the purity ranged from 80% to 98% and the percentages of linear isomer from 67% to 79%. The proportion of branched isomers present in the samples was also estimated using (19)F NMR. These results agreed quite closely with those found by LC-ESI-MS indicating that there is essentially no difference in overall SIM response factor for the branched isomers vs. that of the linear isomer. Several further observations relevant to the use of standards when analyzing for PFOS were encountered during this study. It appears unlikely that matrix effects attributable to the cation (sodium or potassium) present in PFOSNa or PFOSK internal standards is an issue. In seeking potential matrix effects, it was found that the chromatography was improved substantially when the standard was injected as a solution in 80:20 methanol/water rather than 100% methanol. Notably, in concert with the improvement in chromatography, an increase of about 10% in response was observed. In some closely related studies, when (18)O(2) mass-labeled perfluorohexanesulfonate was used as an internal standard, the actual and theoretical concentration ratios matched closely those for related native sulfonates as long as they did not co-elute. However, when they did co-elute, the peak intensities of the native species were enhanced by about 5%, while those of the labeled compound were suppressed by a similar amount. If this effect were not taken into account, the concentration of the native would be inflated by 10%.