Nitrogen significantly regulated (p < 0.05) the effects of spiramycin on the growth and antioxidant responses of Microcystis aeruginosa as well as the biodegradation of spiramycin by M. aeruginosa during a 7-day exposure test. At a nitrogen level of 0.5 mg L⁻¹, the activities of superoxide dismutase and catalase were stimulated by 100–400 ng L⁻¹of spiramycin to protect algal cells from oxidative damage, resulting in alleviated toxicity of spiramycin and low malondialdehyde content in M. aeruginosa. The catalase activity was inhibited by 400 ng L⁻¹of spiramycin at higher nitrogen levels of 5–50 mg L⁻¹, leading to significant growth inhibition (p < 0.05) and higher malondialdehyde content through accumulation of hydrogen peroxide. Stimulated glutathione content and glutathione S-transferase activity were coupled to the biodegradation of spiramycin in M. aeruginosa. The 7-day biodegradation percentage of spiramycin varied from 8.9 to 29.6 %, which was enhanced by increased nitrogen concentration and decreased spiramycin concentration. Due to the regulation of algal growth, the toxicity of M. aeruginosa were significantly enhanced (p < 0.05) by 100 ng L⁻¹of spiramycin at a nitrogen concentration of 0.5 mg L⁻¹while significantly reduced (p < 0.05) by 400 ng L⁻¹of spiramycin at nitrogen levels of 5–50 mg L⁻¹, according to the luminescent bacteria test. Low concentration of coexisting spiramycin contaminant should be considered during the control of M. aeruginosa bloom, especially under nitrogen deficient condition.

Fe₂O₃/γ-Al₂O₃catalysts were prepared using the wet impregnation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption–desorption. The continuous catalytic wet hydrogen peroxide oxidation of an aqueous phenol solution over Fe₂O₃/γ-Al₂O₃was studied in a fixed-bed reactor. The effects of several factors, such as the weight hourly space velocity (WHSV), particle size, reaction temperature, H₂O₂concentration, and initial pH, were studied to optimize the operation conditions for phenol mineralization. For a 1 g L⁻¹phenolic aqueous solution, the phenol was nearly completely removed and chemical oxygen demand (COD) removal was approximately 92 % at steady-state conditions with a WHSV of 2.4 × 10⁻² gPₕOH h⁻¹ gcₐₜ⁻¹at 80 °C with 5.1 g L⁻¹H₂O₂. The long-term stability of the Fe₂O₃/γ-Al₂O₃catalyst was also investigated for the continuous treatment of phenolic water. The removal of phenol and COD exhibited a slowly decreasing trend, which was primarily due to the complexation of active sites with acid organic compounds and the adsorption of intermediate products. The deposition of organic carbon and Fe leached from the catalyst had a small role in the partial deactivation of the catalyst. The Fe leached from the catalyst partially contributed to the phenol removal during a short run. However, this contribution could be neglected after 36 h because the Fe leached from the catalyst decreased to approximately 5 mg L⁻¹.

Eutrophication is a main cause for impairment of freshwater ecosystems, and diffuse phosphorus (P) loss from agricultural land is usually the main cause for freshwater eutrophication. The P index is a simple and practical tool for estimating the potential P loss risk. In a preceding study, a refined P index scheme was developed and validated. In the current study, the relative importance of the 14 input variables used is assessed in order to determine their relative significance to the final P index value. The backpropagation network with Garson’s algorithm was employed in order to capture the significance of interactions among the input variables. The study clearly shows the source factors, especially the degree of P saturation (DPS), along with management practices regarding application of inorganic P fertilizer and livestock manure, are the most important factors governing the P loss in the very high and high risk areas. Conversely, the transportation factors governed P loss risk in the low and very low risk areas. Recommended management strategies for mitigation of P loss from the different risk zones are proposed based on the relative importance analysis and practical constraints. A scenario analysis, based on a gradient reduction of DPS, through decreased application of both inorganic P fertilizer and P emissions factors from livestock manure, gave a reduction of average P index from 7.3 to 57 %. Moreover, the proportion of high- and very-high-risk area may be reduced from 38 to 23 % and 24 to 13 %, respectively.

Pollution levels, pollutant distribution and potential source assessments based on multivariate analysis (chemometrics) were made for harbour sediments from two Arctic locations; Hammerfest in Norway and Sisimiut in Greenland. High levels of heavy metals were detected in addition to organic pollutants. Preliminary assessments based on principal component analysis (PCA) revealed different sources and pollutant distribution in the sediments of the two harbours. Tributyltin (TBT) was, however, found to originate from point source(s), and the highest concentrations of TBT in both harbours were found adjacent to the former shipyards. Polyaromatic hydrocarbons (PAH) ratios and PCA plots revealed that the predominant source in both harbours was pyrogenic related to coal/biomass combustion. Comparison of commercial polychlorinated biphenyls (PCB) mixtures with PCB compositions in the sediments indicated relation primarily to German, Russian and American mixtures in Hammerfest; and American, Russian and Japanese mixtures in Sisimiut. PCA was shown to be an important tool for identifying pollutant sources and differences in pollutant composition in relation to sediment characteristics.

Shewanella putrefaciens IBBPₒ₆(KM405339) showed good tolerance to 5 % organic solvents. The growth was higher when S. putrefaciens IBBPₒ₆cells were exposed to n-decane, as compared with the growth of cells exposed to toluene, o-xylene, ethylbenzene, cyclohexane, or n-hexane. Thus, n-decane was less toxic for S. putrefaciens IBBPₒ₆cells, while toluene, o-xylene, ethylbenzene, cyclohexane, and n-hexane were more toxic for this bacterium. The release of nucleic acids was higher when S. putrefaciens IBBPₒ₆cells were exposed to toluene, o-xylene, ethylbenzene, cyclohexane, or n-hexane, as compared with the release of nucleic acids from control cells and n-decane exposed cells. The cell surface hydrophobicity increased when S. putrefaciens IBBPₒ₆cells were exposed to n-decane, while in the presence of toluene, o-xylene, ethylbenzene, cyclohexane, and n-hexane, a decrease in the cell surface hydrophobicity was acquired. The exposure of S. putrefaciens IBBPₒ₆cells to 5 % organic solvents had induced biofilms formation, and their structure differs according to the nature of the hydrophobic substrate. Two secondary metabolites (i.e., biosurfactants, carotenoids) were produced by S. putrefaciens IBBPₒ₆control cells, as well as by the cells exposed to 5 % organic solvents. S. putrefaciens IBBPₒ₆possesses alkB1 and alkM1 catabolic genes and HAE1 transporter gene. A homologue of otsA1 gene was also detected in this bacterium. Some differences between the polymerase chain reaction (PCR) patterns of S. putrefaciens IBBPₒ₆control cells and cells exposed to 5 % organic solvents were observed. Distinct repetitive sequence-based PCR (rep-PCR), random amplification of DNA fragments (RAPD), and amplified ribosomal DNA restriction analysis (ARDRA) patterns were also acquired in S. putrefaciens IBBPₒ₆cells exposed to 5 % organic solvents, compared with the control cells.

In this study, various metal concentrations were determined in environmental samples from rivers in the vicinity of mining areas of the Northwest Province, South Africa. These metal concentrations were also determined in various crustacean organs viz., hepatopancreas, flesh and muscle of the freshwater crab, Potamonautes warreni. The highest metal concentrations obtained in the freshwater samples were Ni (0.022 mg/l), Pb (0.02 mg/l), Cu (0.011 mg/l), Cd (0.009 mg/l), Pt (0.017 μg/l), Pd (0.011 μg/l) and Rh (0.008 μg/l). The highest metal concentrations obtained in the sediment samples were Ni (85.1 mg/kg dry weight (d.wt)), Pb (25.4 mg/kg d.wt), Cu (75.5 mg/kg d.wt), Cd (64.9 mg/kg d.wt), Pt (0.38 ng/g d.wt), Pd (0.74 ng/g d.wt) and Rh (0.23 ng/g d.wt). The results obtained for the bioavailability studies of all the metals investigated in the sediment have revealed no definite patterns for the fractionation results of the metal concentrations. In the case of the crab samples collected in the Elands River, the Pb, Cd, Pt, Pd and Rh concentrations indicate that the mining activities may have had an influence in the uptake of these metals in the crab samples analysed. In the case of the Hex River, the Ni, Cu, Pb, Cd, Pd and Rh concentrations in the crab samples may be attributed to mining activities. The bioaccumulation results indicated that the Ni and Cu concentrations show partly bioaccumulation in the tissues of the crab samples evaluated. For the Pd, Cd, Pt, Pd and Rh concentrations evaluated, definite signs of bioaccumulation were found.

With the gradual depletion of high-grade copper ore deposits, secondary wastes are gaining importance as a source for metal recovery. However, the alkalinity and low copper concentration in some of these resources underscore the need for selective leaching agents. In this work, indigenous alkaliphiles from a fly ash landfill site with inherent pH tolerance, metal tolerance and copper leaching capability were isolated and investigated. Four isolates, namely Agromyces aurantiacus TRTYP3, Alkalibacterium pelagium TRTYP5, Alkalibacterium sp. TRTYP6 and Bacillus foraminis TRTYP17, each selectively leached about 50 % copper from 1 % (w/v) of fly ash. Mixed culture of these bacteria resulted in higher leaching of copper. The optimal combination was TRTYP3, TRTYP5, TRTYP6 and TRTYP17 in the ratio 1:1:3:1, which leached 88, 81, 78, 76, 70 and 55 % Cu from 1, 2.5, 5, 10, 15 and 20 % (w/v) of fly ash. While Cu and Pb were bioleached into solution, Fe and Zn were precipitated.

The application of biochar as a sustainable material in biofilters to remove volatile compounds from the air provides a lot of advantages in relation to equipment maintenance and efficiency and ensures a zero-emission process. This work has analysed the morphology of biochar produced from birch and pine at different temperatures, its pore structure and changes depending on the type of pollutant and microorganisms used in biofiltrating media. Biochar morphology was investigated by scanning electron microscopy, while biochar pore structure was analysed by mercury intrusion porosimetry and nitrogen absorption at 77 K. Performed tests have shown that the biggest surface area of pores is in the biochar from pine that underwent thermal treatment at 750 °C. It has been determined that the pore volume of pine biochar decreases when acetone, xylene and ammonia pollutants are being removed from air during biofiltration. The biggest changes occurred in the pores with a diameter of 2–20 μm. Meanwhile, after the treatment with the studied volatile compounds, the surface area of pine biochar mesopores with a diameter smaller than 0.05 μm increased.

Sorption is commonly agreed to be the major process underlying the transport and fate of polycyclic aromatic hydrocarbons (PAHs) in soils. However, there is still a scarcity of studies focusing on spatial variability at the field scale in particular. In order to investigate the variation in the field of phenanthrene sorption, bulk topsoil samples were taken in a 15 × 15-m grid from the plough layer in two sandy loam fields with different texture and organic carbon (OC) contents (140 samples in total). Batch experiments were performed using the adsorption method. Values for the partition coefficient Kd(L kg⁻¹) and the organic carbon partition coefficient KOC(L kg⁻¹) agreed with the most frequently used models for PAH partitioning, as OC revealed a higher affinity for sorption. More complex models using different OC compartments, such as non-complexed organic carbon (NCOC) and complexed organic carbon (COC) separately, performed better than single KOCmodels, particularly for a subset including samples with Dexter n < 10 and OC <0.04 kg kg⁻¹. The selected threshold revealed that KOC-based models proved to be applicable for more organic fields, while two-component models proved to be more accurate for the prediction of Kdand retardation factor (R) for less organic soils. Moreover, OC did not fully reflect the changes in phenanthrene retardation in the field with lower OC content (Faardrup). Bulk density and available water content influenced the phenanthrene transport mechanism phenomenon.

Henry’s law constant is an essential parameter for the estimation of the environmental prevalence of pollutants. Here, we present two improved methods for measuring Henry’s law constant deploying inert gas stripping (IGS). The methods are targeted at compounds with high gamma coefficients (activity coefficient at infinite dilution) corresponding to large infinite dilution coefficients, such as monoterpenes and sesquiterpenes. We deploy a highly sensitive PTR-MS (proton transfer reaction-mass spectrometer) (low limit of detection, wide linear range, split-second time resolution) as detector. We use suited off-equilibrium conditions to extrapolate to equilibrium conditions. The first method is based on the observed linear correlation between gas flow and off-equilibrium experimental Henry’s law constant value. The second method is based on the linear dependence of the gas holdup on volumetric flow. We report HLC constants for six monoterpenes, isoprene and even, as a proof of concept, the sesquiterpene farnesene. The new methods allow for measuring HLC of nearly insoluble compounds at a new accuracy and precision.