The processes affecting adsorption of molybdenum (Mo) in alkaline industrial soils are not well known, as most research on Mo fate and transport has focused on agricultural soils. In this work, we performed studies of soil extraction, as well as sorption studies using both batch and stirred-flow cell approaches. After 60 h of extraction, we observed, even where three extractable fractions were present, 14.1 % of the bound residue was extracted by CaCl 2 solution. This indicates that the procedures recommended by the Commission of European Communities Bureau of Reference, which is targeted to metals cations, not anions due to the use of extractants at acidic pH, are not a suitable approach for assessing mobility and availability of Mo in alkaline soils. Because the observed extent of Mo adsorption onto two Fe minerals, goethite, and amorphous iron hydroxide (HFO) was 2 to 3 orders of magnitude higher than that onto the soil, soils amended with these Fe minerals were found to have a higher Mo adsorption capacity, with HFO yielding stronger sorption than goethite. The additivity principle was successfully used to predict Mo adsorption with the HFO-amended soil but failed to do so for the goethite-amended soil. The best fit sorption isotherms and estimated parameters were slightly different from batch and flow cell experiments. The Kd values of sorption coefficient in our industrial soils and Fe-minerals-amended soils ranged from 0.19 to 1.45 L/kg from both experimental approaches; this low adsorption potential renders it infeasible to immobilize Mo into the soilmatrix and reduce Mo availability by amending the soil with Fe minerals. In the future, materials with potentially high Mo adsorption capacities should be identified, screened, and characterized for permeable reactive barriers application. © Springer Science+Business Media Dordrecht 2013.

A comprehensive investigation of polybromodiphenyl ethers (PBDEs) in wastewater was conducted in the second largest international metroplex area along the U.S. and Mexico (MX) border. Concentrations of PBDEs in wastewater and sludge were measured in four wastewater treatment plants (WWTPs) in El Paso, Texas and two WWTPs in Cd. Juarez, Chihuahua, MX. A green approach in sample preparation technique, called stir bar sorptive extraction (SBSE) coupled with thermal desorption and gas chromatography and mass spectrometry, was used which requires minimum amount of organic solvents and has good sensitivity at nanogram-per-liter levels for wastewater samples and nanograms per gram for waste sludge solids. Concentrations of PBDEs ranged from 30.2 to 342 ng L⁻¹ in wastewater influents, from not detected to 209 ng L⁻¹ in effluents, and from not detected to 1,303 ng g⁻¹ in sludge. Among 27 PBDEs studied, BDE-47, BDE-99, and BDE-100 were the most commonly detected congeners in all samples. Further evaluation showed that secondary and tertiary treatments are highly effective at removing PBDEs from wastewater with percent removals ranging from 84 % to 100 %, while advanced primary treatment only removed 41–73 % of PBDEs. As a complement, the ambient air temperature change on PBDEs concentrations was evaluated finding that this factor did not have an influence on the PBDEs concentrations in WWTPs. The incomplete removal of PBDEs in WWTPs implicates a potential impact on the environmental and public health as a result of the continuous release of PBDEs from the WWTPs to the Rio Grande River and irrigation canals.

Although Cd concentrations in uncontaminated soils are usually low, pollution of soils by Cd from different sources of contamination pose problems. The application of soil amendments to increase plant production has been used as a viable alternative for recovery of soils contaminated with Cd. However, emphasis needs to be placed on the nature of Cd sorption processes in order that the amendments can be managed appropriately. A range of materials including vermicompost, sugarcane filter cake, palm kernel pie, lime, phosphate rock, and zeolite were used for the sorption studies. Total and nonspecific Cd sorption was estimated by batch experiments, and specific sorption was obtained by the difference between the former and the latter. Best adsorbents for specific Cd sorption from soil amendments were lime and zeolite. Langmuir adsorption isotherms fitted reasonably well in the experimental data, and their constants were evaluated, with R ² values from 0.80 to 0.99. The maximum adsorption capacity of Cd(II) was higher for mineral amendments than for organic amendments and ranged from 0.89 to 10.86 g kg⁻¹. The small value (0.08 L mg⁻¹) of the constant related to the energy of adsorption indicated that Cd was bound weakly to the palm kernel pie. Thermodynamic parameter, the Gibbs free energy, was calculated for each system, and the negative values obtained confirm that the adsorption processes were spontaneous. The values of separation factor, R L, which has been used to predict affinity between adsorbate and adsorbent were between 0 and 1, indicating that sorption was very favorable for Cd(II).

An experiment in open-top chambers was carried out in summer 2008 in Curno (northern Italy) in order to study the effects of ozone and drought stress on net photosynthesis, growth and stable isotope partitioning on cuttings of an ozone-sensitive poplar clone (Oxford). The biomass (as dry weight) of stems, leaves and roots was assessed five times during the growing season on a set of plants intended for destructive measurements (set 1). Another set of plants (set 2) was used for repeated measurements (net photosynthesis) and then destroyed at the end of the experiment. The dry weight of the stems in set 1 plants was calculated using allometric relations. The results showed that drought stress had a strong effect on all the parameters assessed. Ozone did not have any effect on biomass allocation in woody stems and stable isotope composition but reduced root/shoot ratios and caused loss of leaves during the growing season. The loss of leaves in the lower part of the crown was partly recovered with the emission of new young leaves in the upper part, thus restoring the overall photosynthetic apparatus. We conclude that the metabolic costs suffered to repair damage and support growth, and the reduction in starch reserves in the roots can compromise growth and the capacity to cope with stress factors in subsequent years.

The accumulation of Ag by the marine herbivorous gastropod, Littorina littorea, has been studied in a series of exposures in which the metal was added in aqueous form and as nanoparticles, both in the presence and absence of contaminated algal food (Ulva lactuca). Significant accumulation occurred in the gill, kidney, stomach and visceral mass when the snail was exposed to aqueous Ag in the absence of food. Despite the consumption of U. lactuca that had been previously contaminated by Ag, no accumulation was observed from the dietary route. When added as nanoparticles, accumulation of Ag was only measured in the head and gill and only in the absence of contaminated food. These observations suggest that Ag is most bioavailable to L. littorina when in true solution and that Ag measured in external tissues of the snail following exposure to nanoparticles arises from some physical association that does not result in significant transfer of the metal to internal organs.

The recovery of Tween 80 from a liquid residue, obtained after washing of a contaminated soil with p-Cresol, was studied by selective adsorption of p-Cresol with activated carbons. A modified expression of the Langmuir equation was succesfully used to predict the adsorption isotherms of p-Cresol in the absence and presence of different surfactant concentrations. The presence of surfactant seems to modify the adsorption equilibrium, but it does not produce any significant influence on the adsorption kinetic of p-Cresol. A mathematical model was developed to predict the optimum activated carbon dosage demanded to reduce the p-Cresol concentration as a function of the surfactant concentration, also obtaining the corresponding surfactant loss. The regenerated solution was favorably used as washing solution in a new contaminated soil. These results indicate that this technique can be adequate to recover the surfactant solution, with a relatively minimal loss, for a subsequent application.

The evaluation of the contribution of natural sources to PM₁₀ and PM₂.₅ concentrations is a priority especially for the countries of European south strongly influenced by Saharan dust transport events. Daily PM₂.₅ concentrations and composition were monitored at an urban site at 14 m above ground level, at the National Technical University of Athens campus from February to December 2010. The typical dust constituents Si, Al, Fe, K, Ca, Mg, and Ti were determined by wavelength dispersive X-ray fluorescence spectrometry (WDXRF). Sulfur, a tracer of anthropogenic origin and major constituent of PM₂.₅, was determined by both WDXRF and ionic chromatography. The contribution of dust and sulfates in PM₂.₅ was calculated from the analytical determinations. An annual mean of 20 μg/m³ was calculated from the mean daily PM₂.₅ concentrations data. Twenty-two per cent of daily concentrations of PM₂.₅ reached or exceeded the EU annual target concentration of 25 μg/m³. The exceedances occurred during 13 short periods of 1–4 days. Back-trajectory analysis was performed for these periods in order to identify the air masses origin. From these periods, ten periods were associated to Saharan dust transport events. The most intense dust transport event occurred between February 17th and 20th and was responsible for the highest recorded PM₂.₅ concentration of 100 μg/m³ where the dust contribution in PM₂.₅ reached 96 %. The other dust transport events were less intense and corresponded to less pronounced enhancements of PM₂.₅ concentrations, and their contribution ranged from 15 to 39 % in PM₂.₅ concentrations. Air masses originated from northwest Africa while the influence of central Sahara was quite smaller.

Kriging interpolation technique is adapted to create the mapping of surface ozone seasonality and trends across Europe during 1997–2006, based on European Monitoring and Evaluation Programme ground measurements. The climatology, the annual and seasonal trends and the altitude above sea level (asl) dependence were studied as well as the relation with the North Atlantic Oscillation (NAO). The mean seasonal cycle amplitude and seasonal maximum display an increasing gradient from northwest to southeast, with high levels in Austria and eastern Mediterranean. Significantly close to 0 positive trends appear in UK, Slovakia, southern Scandinavia and Austria in winter and autumn. In Northern Hemisphere winter (December–February), about 40 % of near-surface ozone variability in the western edge of Europe may be attributed to circulation changes and ozone precursors’ transport related to NAO.

Although degradation data for herbicides are essential in understanding their potential to be contaminants and are indispensable inputs in computer-based modeling of their fate in environment, most available data only concern surface soils. Soil samples, collected at two depths from four representative sites of a 31.4-ha field located in Blue Earth County, MN, USA, were used to determine acetochlor dissipation under laboratory conditions. A field study was also carried out within a 16-ha watershed in Dakota County, MN, USA, where 38 locations were sampled to obtain sample representative of the full range of soil properties found within the watershed. Acetochlor DT50 values ranged from 6.51 to 13.9 days for surface soils and from 20.3 to 26.7 days for subsurface soils. DT90 values were a factor of four times longer than for DT50 values. Field DT50 values for acetochlor dissipation were not significantly different for the 2 years, 5.7 ±2.5 and 7.7±4.5 days. Dissipation was slightly faster in the field as compared to the laboratory; however, the difference seems insignificant in view of the wide range in soil properties inMinnesota. In both studies, acetochlor would be classified as slightly persistent. For acetochlor, laboratory dissipation studies can be considered representative of field dissipation for the soils and climatic conditions in this study. Inclusion of subsoil degradation data in mathematical models used for ground water risk assessment may improve their capability of predicting potential movement of acetochlor to groundwater. © Springer Science+Business Media Dordrecht 2013.

Alpine ecosystems, representing a large proportion of the land area in Europe, are under pressure from changes in climate and land-use. This may also impact the quality of drainage waters. Here, we assess effects of plant communities (snowbed, dwarf shrub heath, and tall herb meadow) on concentrations of dissolved organic carbon and nitrogen (DOC and DON), ammonium (NH₄-N), nitrate (NO₃-N), and phosphorus (tot-P and PO₄-P) in locally derived seepage water in a non-fertilized sub-alpine area of southern Norway. In addition, we investigated effects of two density levels of sheep (no sheep and 80 sheep km⁻²) on infiltration capacity, pore size distribution and concentrations of nutrients and bacteria in surface runoff. Concentrations of NO₃-N (<0.02–0.03 mg l⁻¹) and NH₄-N (<0.02–0.03 mg l⁻¹) were low in seepage waters with no significant differences associated with plant community. Also, concentrations of DOC and DON were low, in particular in snowbeds, probably due to low productivity and small soil carbon pools. Infiltration rates, which were significantly smaller in snowbeds than in tall herb meadow, were further reduced by grazing. In turn, this caused increased runoff of coliform bacteria, whereas no effect of grazing on NH₄-N, NO₃-N and PO₄-P was observed. Grazing may significantly alter biological water quality but is not likely to affect the productivity of surface waters in non-fertilized alpine areas.