‘Emulsion locks’ for the containment of hydrocarbons during surfactant flushing

Reversible double water in oil in water (W/O/W) emulsions were developed to contain subsurface hydrocarbon spills during their remediation using surfactant flushing. Double emulsions were prepared by emulsifying CaCl₂ solutions in canola oil, and subsequently by emulsifying the W/O emulsions in aqueous sodium alginate solutions. The formation of double emulsions was confirmed with confocal and optical microscopy. The double emulsions reversed and gelled when mixed with the surfactants sodium dodecyl sulfate (SDS) and cocamidopropyl betaine (CPB). Gels can act as ‘emulsion locks’ to prevent spreading of the hydrocarbon plume from the areas treated with surfactant flushing, as shown in sand column tests. Shear rheology was used to quantify the viscoelastic moduli increase (gelation) upon mixing the double emulsion with SDS and CPB. SDS was more effective than CPB in gelling the double emulsions. CPB and SDS could adsorb at the interface between water and model hydrocarbons (toluene and motor oil), lowering the interfacial tension and rigidifying the interface (as shown with a Langmuir trough). Bottle tests and optical microscopy showed that SDS and CPB produced W/O and O/W emulsions, with either toluene or motor oil and water. The emulsification of motor oil and toluene in water with SDS and CPB facilitated their flow through sand columns and their recovery. Toluene recovery from sand columns was quantitated using Gas-Chromatography Mass-Spectroscopy (GC-MS). The data show that SDS and CPB can be used both for surfactant flushing and to trigger the gelation of ‘emulsion locks’. Ethanol also gelled the emulsions at 100 mL/L.     

Combined effect of copper and prolonged summer drought on soil microarthropods in the field

Soil microarthropods experience a large range of natural stressors in their natural environment, e.g. variations in temperature and soil moisture, but also anthropogenic stressors such as soil pollutants. In the present study the combined effect of drought stress and copper pollution on microarthropods was investigated in a field study. We hypothesised that microarthropods in copper polluted soil would be more susceptible to drought than animals in control soil. Surprisingly, the abundance of microarthropods in autumn was positively affected by summer drought and copper pollution did not influence the effect of drought in a negative way. The stimulation was mainly seen as an increase of Acari, but also groups of Collembola were positively affected. We suggest that the positive effect of the enforced summer drought could be due to a rapid recovery, which further is accelerated by an increase of food resources (microbes) which have not been utilized during the drought.     

Actors and arenas in hybrid networks: implications for environmental policymaking in the Baltic Sea region

Policymaking within and among states is under pressure for change. One feature of this change is empirically observed as an activation of different network structures in the Baltic Sea Region, especially since the collapse of the Iron Curtain, the initiation of the Rio process, and the enlargement of the European Union. The contemporary theoretical debates about governance highlight the changing conditions for policymaking and implementation on all societal levels. This process of change, especially evident concerning environmental policies, includes new types of networks crossing state borders both at the supranational and the subnational levels. This article illuminates this process of change with empirical data from the project "Governing a Common Sea" (GOVCOM) within the Baltic Sea Research Program (BIREME).     

Long-term dispersion and availability of metals from submarine mine tailing disposal in a fjord in Arctic Norway

Mining of Cu took place in Kvalsund in the Arctic part of Norway in the 1970s, and mine tailings were discharged to the inner part of the fjord, Repparfjorden. Metal speciation analysis was used to assess the historical dispersion of metals as well as their potential bioavailability from the area of the mine tailing disposal. It was revealed that the dispersion of Ba, Cr, Ni, Pb and Zn from the mine tailings has been limited. Dispersion of Cu to the outer fjord has, however, occurred; the amounts released and dispersed from the mine tailing disposal area quantified to be 2.5–10 t, less than 5% of Cu in the original mine tailings. An estimated 80–390 t of Cu still remains in the disposal area from the surface to a depth of 16 cm. Metal partitioning showed that 56–95% of the Cu is bound in the potential bioavailable fractions (exchangeable, reducible and oxidisable) of the sediments, totalling approximately 70–340 t, with potential for continuous release to the pore water and re-precipitation in over- and underlying sediments. Surface sediments in the deposit area were affected by elevated Cu concentrations just above the probable effect level according to the Norwegian sediment quality criteria, with 50–80% Cu bound in the exchangeable, reducible and oxidisable fractions, potentially available for release to the water column and/or for uptake in benthic organisms.     

Photocatalytic degradation of acetaminophen in modified TiO2 under visible irradiation

This study investigated the photocatalytic degradation of acetaminophen (ACT) in synthetic titanium dioxide (TiO₂) solution under a visible light (λ >440 nm). The TiO₂ photocatalyst used in this study was synthesized via sol–gel method and doped with potassium aluminum sulfate (KAl(SO₄)₂) and sodium aluminate (NaAlO₂). The influence of some parameters on the degradation of acetaminophen was examined, such as initial pH, photocatalyst dosage, and initial ACT concentration. The optimal operational conditions were also determined. Results showed that synthetic TiO₂ catalysts presented mainly as anatase phase and no rutile phase was observed. The results of photocatalytic degradation showed that LED alone degraded negligible amount of ACT but with the presence of TiO₂/KAl(SO₄)₂, 95 % removal of 0.10-mM acetaminophen in 540-min irradiation time was achieved. The synthetic TiO₂/KAl(SO₄)₂ presented better photocatalytic degradation of acetaminophen than commercially available Degussa P-25. The weak crystallinity of synthesized TiO₂/NaAlO₂ photocatalyst showed low photocatalytic degradation than TiO₂/KAl(SO₄)₂. The optimal operational conditions were obtained in pH 6.9 with a dose of 1.0 g/L TiO₂/KAl(SO₄)₂ at 30 °C. Kinetic study illustrated that photocatalytic degradation of acetaminophen fits well in the pseudo-first order model. Competitive reactions from intermediates affected the degradation rate of ACT, and were more obvious as the initial ACT concentration increased.