Management of ambient concentrations of Volatile Organic Compounds (VOCs) is essential for maintaining low ozone levels in urban areas where its formation is under a VOC-limited regime. The significant decrease in traffic-induced VOC emissions in many developed countries resulted in relatively comparable shares of traffic and non-traffic VOC emissions in urban airsheds. A key step for urban air quality management is allocating ambient VOC concentrations to their pertinent sources. This study presents an approach that can aid in identifying sources that contribute to observed BTEX concentrations in areas characterized by low BTEX concentrations, where traditional source apportionment techniques are not useful. Analysis of seasonal and diurnal variations of ambient BTEX concentrations from two monitoring stations located in distinct areas reveal the possibility to identify source categories. Specifically, the varying oxidation rates of airborne BTEX compounds are used to allocate contributions of traffic emissions and evaporative sources to observed BTEX concentrations. BTEX sources are identified from temporal variations of ambient concentration.

A 20-month column experiment investigated leaching of Al, Cu, Mn, Ni, Zn, Cd and Pb during sulphide oxidation in mine tailings with and without sewage sludge (SS) amendment. Leachate pH decreased gradually in all columns during the experiment, irrespective of treatment, due to sulphide oxidation. As the degree of sulphide oxidation, and thus the pH trajectory, differed between replicates (n = 3), running data for each column used are reported separately and the relationships between sulphide oxidation, metal leaching and treatment in each column compared. Mean pH in the columns correlated negatively with total amounts of leached SO₄ ²⁻. In the beginning of the experiment the leachate concentrations of Al, Cu, Zn, Ni and Pb were higher in SS-treated columns due to high initial concentrations of dissolved organic carbon. As leaching proceeded, however, the amounts of Al, Cu, Mn and Ni leached from the columns were closely related to the degree of sulphide oxidation in each column, i.e. to its mean pH. There were no statistically significant differences between treatments regarding the total amounts of metals leached and thus addition of sewage sludge to the tailings appeared to play a minor role for metal leaching patterns. Peak concentrations of Al and Cu in the leachate from untreated tailings and of Zn in the leachate from both untreated and SS-treated tailings at pH 4 exceeded national background values for groundwater.

This work describes recent research carried out in an extremely acidic (pH 0.61–0.82) and hypersaline (e.g., 134 g/L SO₄ ²⁻, 74 g/L Fe, 7.5 g/L Al, 3 g/L Mg, 2 g/L Cu, 1 g/L Zn) leachate which seeps from a pyrite pile in San Telmo mine (Huelva, SW Spain) and forms evaporative pools of ultra-concentrated water in which attractive crystals of Zn-rich melanterite (FeᴵᴵSO₄ 7H₂O) are formed. Geochemical modeling with the Pitzer method indicates that the acidic brine was near saturation with respect to melanterite (SIMₑₗ = 0 ± 0.2). The microbiological investigation has revealed a surprisingly high biomass (1.4 × 10⁶ cells mL⁻¹) and an exotic ecosystem composed of acidophilic, Fe-oxidizing archaea (mainly Ferroplasma spp., representing 52% of the microbial population), and minor numbers of acidophilic bacteria (including Leptospirillum spp. (3.2%), Acidithiobacillus spp. (1.6%), and Alphaproteobacteria (2.8%)). The microbial production of Feᴵᴵᴵ allows the oxidative dissolution of pyrite and other sulphides, which results in additional inputs of Feᴵᴵ, SO₄ ²⁻ and acidity to the system. The surfaces of the pyrite crystals show a typical etch-pitted texture, as well as blobs of elemental sulphur, which are both compatible with this indirect, microbially mediated oxidation mechanism. The composition of the acidic leachate seems to result from the combination of several processes which include: (1) formation of melanterite within the pile during relatively dry seasons, (2) subsequent dissolution of melanterite during rainy episodes, (3) microbial oxidation of Feᴵᴵ, (4) sulphide oxidation mediated by Feᴵᴵᴵ, (5) dissolution of chlorite and other aluminosilicates present in the pile, and (6) cooling and/or evaporation of seepage from the pile and consequent melanterite precipitation.

Xenobiotic compounds are widely used in several industries; hence they frequently appear in industrial wastewaters. It is a well-known fact that even the discharge of conventionally treated wastewater may have adverse effects on the receiving water environment. Turkey, a developing EU applicant country, has many industrial sectors producing large amounts of xenobiotic-containing wastewaters. The problem is only enlarged by the lack of monitoring of these substances due to the deficiencies associated with their analysis and detection. Thus, studies in Turkey are based on the use of some collective parameters as a substitute for the xenobiotic itself. Biological, physicochemical, and integrated treatment technologies have been investigated for the removal and/or minimization of the possible adverse effects of xenobiotics in industrial wastewaters. In this respect, this paper provides an overview of the studies conducted on xenobiotic-containing wastewaters from specific industries in Turkey. Although the studies add invaluable information to the scientific background on the subject, new research on the exact biochemical mechanisms of xenobiotic biodegradation will further extend our understanding for improving treatment.

A new approach to vapor phase elemental mercury capture has been explored; this approach exploits an ionic liquid coating layer to oxidize elemental mercury for subsequent immobilization by chelating ligands. The room temperature ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethane sulfonyl)imide (P₁₄) was selected for study based on its oxidation potential window, thermal stability, and low vapor pressure. Tests were also completed in which KMnO₄ was added to P₁₄ to form a new ionic liquid, P₁₄-KMnO₄, with a higher oxidation potential. In room-temperature bulk liquid phase capture experiments, 59% of the elemental mercury in the inlet gas was captured using P₁₄ alone; mercury capture using P₁₄-KMnO₄ was quantitative. P₁₄ and P₁₄-KMnO₄ coatings were successfully applied to mesoporous silica substrates and to silica substrates functionalized with mercury chelating ligands. The coating layers were found to be thermally stable up to 300°C. Fixed-bed tests of nonfunctionalized silica coated with P₁₄ showed an elemental mercury uptake of 2.7 mg/g adsorbent at 160°C; at the same temperature, functionalized silica coated with P₁₄-KMnO₄ showed an elemental mercury capacity of at least 7.2 mg/g adsorbent, several times higher than that of activated carbon. The empty bed gas residence time in these tests was 0.04 s. A chelating adsorbent incorporating P₁₄ in the coating layer, may be capable of simultaneous removal of elemental and oxidized mercury from coal combustion flue gases.

An investigation was made into a novel system aimed at reducing the impact of highly polluting wastewaters, and based on the combined action of catalytic oxidation and microbial biotechnology. The experimental part incorporated the following three schemes: chemical treatment using Fenton's reaction for a single process (stage 1); biological treatment only (stage 2); and chemical oxidation followed by biological treatment (stage 3). Wastewaters with 2-mercaptobenzothiazole (MBT; 7,200-7,400 mg O₂ l⁻¹) were oxidized by stoichiometric amounts of dilute hydrogen peroxide (35%) in the presence of water soluble iron catalysts, either Fe (II) or Fe (III), at concentrations up to 1% w/w and above. As a result, transformation by chemical means of recalcitrant organics to more easily attackable end-products occurs, that can subsequently undergo conventional or advanced (microflora and biomass dispersed or adhered) biological treatments, with 90% of chemical oxygen demand abatement and 95% of MBT.