The risks of exceeding EU limit values for NO2 concentrations have increased in many European cities, and compliance depends strongly on meteorological conditions. This study focuses on meteorological conditions and their influences on urban background NO2 concentrations in the city of Gothenburg for 1999–2008. The relations between observed NO2 concentrations and meteorological conditions are constructed using two modelling approaches: multiple linear regression and synoptic regression. Both approaches assume no trends in emissions over the study period. The multiple linear regression model is established on observed local meteorological variables. The synoptic-regression model first groups days according to synoptic conditions using Lamb Weather Types and then uses linear regression on each group separately. A model comparison shows that linear regression model and synoptic-regression model perform satisfactory. The synoptic-regression model gives higher explained variance (R 2) against observations during the calibration years (1999–2007), in particular for the morning peak and afternoon–evening peak concentrations, but the improvement in the validation period is weak. The annual mean NO2 variations, and their trends during the study period, were assessed using the synoptic-regression model. The synoptic-regression model is able to explain 54%, 42% and 80% of the annual variability of daily mean, morning peak and afternoon–evening peak NO2 concentrations, respectively. The observed and modelled annual means of the daily mean and morning/afternoon–evening peak NO2 concentrations show decreasing trends from 1999 to 2008. All trends, except the trend in annual-average observed morning peak NO2 are statistically significant. The presence of trends in the modelled NO2 concentrations—even though emissions are assumed to be constant—leads us to conclude that weather and climate alone are responsible for a substantial fraction of the recent declines in observed NO2 concentrations in Gothenburg. Favourable meteorological conditions may have mitigated increases in local NO2 emissions during 1999 to 2008.

The polluted site object of our study was located on an island nourished using different materials, including industrial by-products, inside the area of Porto Marghera (Venice Lagoon, Italy). Until the 1970s, this area was one of the most important chemical districts in Italy and was largely subjected to heavy metals and metalloids pollution. In the year 2004, some Populus and Salix spp. had been planted in this polluted site in order to investigate both the hydrological control and the phytoremediation capability of these trees. In the present work, polluted soil was analyzed at different depths for both metals content and culturable microbial communities with the aim to evaluate the establishment of previously planted poplar and willow plants. Bacteria were characterized on the basis of the r/K-strategists distribution since r-strategists (fast-growing bacteria) and K-strategists (slow-growing bacteria) are characteristic for unstable and stable environments, respectively. A better characterization of bacterial communities composition was obtained from colony development and eco-physiological indices. Results appeared to confirm a good establishment of poplar and willow plants in the heavy metal contaminated site.

In this study, microalgae Scenedesmus quadricauda was entrapped in calcium alginate/polyvinyl alcohol composite hydrogel beads by phase-inversion techniques. The composite biosorbents were used for removal of Cu(II) and Cd(II) ions from single component and binary systems using cell-free composite beads as a control system. The effects of the experimental conditions (such as pH, initial metal ions concentrations, temperatures, contact time, and biosorbent concentrations) on Cu(II) and Cd(II) removal efficiencies were studied. The maximum metal ions on the bare and algal biomass immobilized in alginate beads were observed between pH 5.0 and 6.0. The biosorption of metal ions by the bare and composite beads increased as the initial concentration of the metal ions increased in the medium. The biosorption of Cu(II) and Cd(II) on the composite beads appears to be slightly temperature dependent. The maximum biosorptions of metal ions onto microalgae entrapped in composite beads were 0.970 ± 0.028 and 0.682 ± 0.017 mmol/g for Cu(II) and Cd(II) ions, respectively. The equilibrium experimental data for two metallic species fitted well by the Langmuir model. The values of ΔG° at all temperatures are negative, indicating the spontaneous nature of the biosorption process. When the metal ions competed (in the case of the biosorption from their mixture), the amounts of biosorption onto microalgae cells entrapped in beads were 0.857 ± 0.033 mmol/g for Cu(II) and 0.593 ± 0.024 mmol/g for Cd(II). Under noncompetitive and competitive conditions, the affinity order of ions for biosorbents was Cu(II) > Cd(II).

This study investigated pyrene adsorption on two contrasting Brazilian soils: a Kandiudult and a Vertisol. It was found that the time taken to reach thermodynamic equilibrium depended on the soil type. The curves for different pyrene-to-soil mass ratios for Vertisol soil showed significant differences. This is probably related to the presence of 2:1 clays that may increase the adsorption of pyrene due to the resulting interlamellar space. The adsorption of pyrene on the Kandiudult showed, in general, good agreement with the Langmuir isotherm. In the case of the Vertisol, there was good agreement with the linear isotherm. The kinetic model that best explains the adsorption in Kandiudult was the pseudo second-order model. For the Vertisol, the Morris Weber model best explains the behavior of pyrene.

Over the past decades, the global production of petroleum coke, a by-product of the oil sand industry, has increased with the growing importance of oil sands as a source of fossil fuels. A greenhouse study using Triticum aestivum and Deschampsia caespitosa was conducted to assess the growth and physiological effects of coke on plants. The plants were grown in cokes with or without a cap of peat–mineral mix and were compared to plants grown in a peat–mineral mix (control). Our results indicate that the selected plants can survive in coke; however, stress symptoms such as reductions in transpiration (45–91%) and stomatal conductance rates (44–92%) in T. aestivum, biomass in T. aestivum (5–83%) and D. caespitosa (43–90%), photosynthetic pigments in T. aestivum (32–68%) and D. caespitosa (33–44%) and proline concentrations in D. caespitosa (77–97%) were observed. Furthermore, potentially phytotoxic concentrations of nickel (47–69 μg g−1 in D. caespitosa) and vanadium (9.3–18.3 μg g−1 in T. aestivum and 4–27.8 μg g−1 in D. caespitosa) were found in some tissues while molybdenum accumulated in D. caespitosa shoots at concentrations reported, in other studies, to cause molybdenosis in ruminants. These results suggest that the plants growing in coke could experience multiple stresses including water stress, nutrient deficiencies and/or Ni and V toxicity. Capping coke with peat–mineral mix limited the stress symptoms and could improve revegetation success of coke impoundment sites. This study provides baseline data for future long-term field studies essential for developing coke management guidelines.

In this study, the efficiency of chitin and chitosan toward the removal of ethylbenzene from aqueous solutions was investigated. Batch adsorption experiments of ethylbenzene-contaminated waters (5–200 mg/L) were carried out to evaluate the removal performance. Ethylbenzene uptake was determined from the changes in concentration, as the residual concentration was measured by gas chromatography with mass spectroscopy. The results indicated that the adsorption of ethylbenzene by chitin and chitosan were in agreement with the Langmuir isotherm, for two parameters model, and Redlich–Peterson isotherm, for three parameters model. A maximum removal percentage of 65% of ethylbenzene can be achieved using chitosan as adsorbent material. The adsorption capacity of ethylbenzene followed the order chitosan > chitin. The pseudo-second order rate model described best the adsorption kinetics of ethylbenzene for the two selected adsorbents. The kinetic studies also revealed that the pore diffusion is not the only rate controlling step in the removal of ethylbenzene. Overall, the study demonstrated that chitosan is a potential adsorbent for the removal of ethylbenzene at concentrations as high as 200 mg/L.

A rhizospheric biotest, consisting of a thin layer of substratum in close contact with roots of Lolium multiflorum, was used on two contrasting contaminated soils (Cabezo and Brunita) issued from a former mining area in La Union (Spain). On top of this biotest, soil characterisation, including CaCl2 selective extractions, was performed. Total heavy metal concentrations were the highest in the soil from Cabezo, but CaCl2 extractions indicated higher heavy metal mobilities in Brunita soil. On the base of heavy metal concentrations and biomass production in L. multiflorum seedlings, availability assessed by the rhizospheric biotest was higher than the values obtained from CaCl2 extraction, except for Mn and Pb. Rhizospheric biotest also revealed higher heavy metal bioavailability for Cabezo. The low pH of Brunita (3.47) could explain the high CaCl2-extractable heavy metal concentrations as well as the high transfer factor found for Cu, Mn and Zn in this substrate. Cu, Mn and Zn toxicities were also detected for shoot tissues. Transpiration rates were clearly lower for seedlings exposed to Brunita than for those exposed to Cabezo, while water use efficiency was higher for the former (4.8 mg DW ml−1) than for the latter (3.8 mg DW ml−1). Iron nutrition was found to interfere with heavy metal root absorption, mainly through negative interactions during root absorption. It is concluded that rhizospheric test offers the advantage to consider the root–soil interactions in a dynamic perspective and constitutes a useful tool for the assessment of heavy metal availability on contaminated soils. Heavy metal bioavailability assessment should not be based on only one measure alone, but on different and complementary approaches.

Mining operations are potential sources of airborne metal and metalloid contaminants through both direct smelter emissions and wind erosion of mine tailings. The warmer, drier conditions predicted for the Southwestern USA by climate models may make contaminated atmospheric dust and aerosols increasingly important, with potential deleterious effects on human health and ecology. Fine particulates such as those resulting from smelting operations may disperse more readily into the environment than coarser tailings dust. Fine particles also penetrate more deeply into the human respiratory system and may become more bioavailable due to their high specific surface area. In this work, we report the size-fractionated chemical characterization of atmospheric aerosols sampled over a period of a year near an active mining and smelting site in Arizona. Aerosols were characterized with a ten-stage (0.054 to 18 μm aerodynamic diameter) multiple orifice uniform deposit impactor (MOUDI), a scanning mobility particle sizer (SMPS), and a total suspended particulate collector. The MOUDI results show that arsenic and lead concentrations follow a bimodal distribution, with maxima centered at approximately 0.3 and 7.0 μm diameter. We hypothesize that the sub-micron arsenic and lead are the product of condensation and coagulation of smelting vapors. In the coarse size, contaminants are thought to originate as Aeolian dust from mine tailings and other sources. Observation of ultrafine particle number concentration (SMPS) show the highest readings when the wind comes from the general direction of the smelting operations site.

In this paper, two Indian fly ashes (from Talcher and Ramagundam) were converted into zeolites and both the raw fly ash and zeolite were used to treat two British acidic mine waters. The results demonstrate that fly ash zeolites are more effective than raw fly ash for treatment of acid mine drainage. Fly ash has been found effective for removal of Pb, but with increased dosing, caused release of Ba, Cr, Sr (both fly ashes) plus Zn, Ni (Talcher), or Fe (Ramagundam) into mine water. In contrast, increased dosing with fly ash zeolite removed 100% Pb, 98.9% Cd, 98.8% Zn, 85.6% Cu, 82.8% Fe, 48.3% Ni, and 44.8% Ba from mine water. Fly ash is amorphous in nature and many metals attached on the surface of the ash particles are easily leached off when ash comes in contact with acidic mine water. However, fly ash zeolite is crystalline in nature and due to its high cation exchange properties, most of the metals present in acid mine water are retained in surface sites.

The destruction of the surfactants, sodium dodecylbenzene sulfonate (DBS) and dodecyl pyridinium chloride (DPC), using an advanced oxidation process is described. The use of zero valent iron (ZVI) and hydrogen peroxide at pH = 2.5 (the advanced Fenton process), with and without, the application of 20 kHz ultrasound leads to extensive mineralisation of both materials as determined by total organic carbon (TOC) measurements. For DBS, merely stirring with ZVI and H2O2 at 20°C leads to a 51% decrease in TOC, but using 20 kHz ultrasound at 40°C, maintaining the pH at 2.5 throughout and adding extra amounts of ZVI and H2O2 during the degradation, then the extent of mineralisation of DBS is substantially increased to 93%. A similar result is seen for DPC where virtually no degradation occurs at 20°C, but if extra amounts of both ZVI and hydrogen peroxide are introduced during the reaction at 40°C and the pH is maintained at 2.5, then an 87% mineralisation of DPC is obtained. The slow latent remediation of both surfactants and the mechanism of degradation are also discussed.