The aim of this study was to compare the pollution levels of risk elements in flooded and non-flooded alluvial soils as a function of inundation frequency and river distance, depth of soil horizon, and pollution origin. Totally, 43 soil profiles of flooded and non-flooded soils were sampled in two layers (topsoil and subsoil). The total contents of As, Cd, Co, Cr, Cu, Mo, Ni, Pb, V, and Zn were measured and grouped according to the assumed geogenic or anthropogenic origin. Flooded soils were classified according to inundation stage/river distance. Concerning the depth gradient, it can be concluded that the content of anthropogenic risk elements decreased with the depth, while geogenic risk elements revealed no trend. The distance from the river had no influence on the distribution of anthropogenic risk elements in soil. On the contrary, geogenic risk elements showed increasing concentrations with increasing distance. These results indicate that frequency of floods has no influence on the risk elements distribution in soil. The process of sedimentation seems to be the main factor influencing the level of pollution, it differs between groups of anthropogenic and geogenic risk elements. The result of this countrywide study shows higher levels of soil contamination in flooded areas even without significant point sources of pollution, than in non-flooded areas in standard agricultural conditions.

To obtain a good catalytic effect of removing refractory organics from water by Fenton process, granular activated carbon (GAC) supported nano-zero valent iron (nZVI) composite (nZVI/GAC) was prepared by adsorption–reduction method, and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS). The catalytic degradation activity of the composite was evaluated to remove nitrobenzene (NB) pollutant via a heterogeneous Fenton-like system, and the initial pH value, nZVI/GAC dosage, and H₂O₂concentration influencing on NB removal were also investigated at room temperature. Experimental results showed that nZVI particle was uniformly dispersed over GAC matrix, and average particle size was 40–100 nm without agglomeration. The nZVI/GAC composite was very efficient in removing NB with average percentage of more than 85 %. However, the removal rate of Fenton-like reaction was highly affected by pH value, H₂O₂concentration, and nZVI/GAC dosage. The optimal reaction conditions were pH 4.0, 40 mg/L NB, 5.0 mmol/L H₂O₂, and 0.4 g/L nZVI/GAC in this study. Stability and repeatability tests as well as mechanism analysis illustrated that GAC improved catalytic action via enhancing nZVI dispersion and accelerating Fe(III)/Fe(II) cycle attributing to internal iron–carbon microelectrolysis in nZVI/GAC composite. Iron utilization efficiency, which played an important role in NB degradation by Fenton-like greatly increased resulting in dissolved iron <0.6 mg/L. This phenomenon strongly implied that the nZVI/GAC Fenton-like process was not only a practical combination of adsorption and Fenton oxidation but also some synergetic effects existing in such an nZVI/GAC composite.

The feasibility of batch and continuous (60, 80, and 100 mL/min) mode photocatalysis systems in real-time livestock wastewater treatment was investigated. The photocatalytic experiments were conducted with two types of photocatalysts namely slurry titanium-dioxide (UV-TiO₂) and granular activated carbon supported TiO₂(GAC-TiO₂). The performance of the systems was compared using economic analysis based on cost and time required to attain maximum efficiency. The photocatalytic reactors operated with GAC-TiO₂was highly effective under both batch (total volatile solids (TVS) removal of 100 % within 6 min and a total operational cost of 0.68 USD per kg of TVS removal) and continuous (at 60 mL/min) (TVS removal of 63 % at a hydraulic retention time (HRT) of 240 min and a total operational cost of 62.16 USD per kg of TVS removal) mode experiments. The economic analyses indicated that cost reduction was a function of optimum time taken for maximum removal efficiency. Subsequently, the experiments were repeated with ultraviolet light (UV) alone, UV-GAC, and GAC alone to quantify effects of adsorption and photolysis. The results confirmed that the effect of GAC in the treatment/degradation of livestock wastewater by adsorption was negligible. However, the presence of GAC in UV systems propelled the rate of biochemical oxygen demand (BOD) and TVS removals. The entire observations reveal that the degradation was mainly by two reaction mechanisms: firstly, adsorption on the GAC surface and secondly by photocatalytic degradation on the GAC-TiO₂surface. Therefore, GAC-TiO₂photocatalysis could be cost-effectively applied for high-rate treatment of industrial wastewaters.

The contents of As, Cu, Cd, Pb, Mn, along with the Pb isotopic ratios ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁶Pb were studied in both soils and tree rings of the marula tree (Sclerocarya birrea) in the vicinity of the Tsumeb deposit (Namibia). Amounts of all the studied metals and As are higher in the immediate vicinity of the Tsumeb Cu-Pb smelter in the soil. The tree rings also have their maximum content of all the studied substances in the vicinity of the smelter (with the exception of Pb). At a more distant site, the maximum concentration of Pb in the soils was 29.8 mg/kg, while the content in the soil in the vicinity of the smelter was as much as 8,174 mg/kg. In the vicinity of the smelter, the maximum Pb content in the tree rings reaches a value of 5.7 mg/kg, compared to a more distant site, where the contents are as high as 9.2 mg/kg. The lower Pb content in the trees on contaminated soil indicates that the composition of the xylem determines the above-ground uptake, rather than the root uptake. Similarly, the above-ground uptake is documented by the isotopic composition of Pb at the distant location, where the tree rings have different contents of Pb isotopes compared to in the soil. The As, Cd, Cu, Pb, and Zn contents are highest in the tree rings from the 1950s (and older), along with those from the 1990s, while the Mn contents were highest in those from the 1960s and 1990s. The contaminant peaks in the 1950s and 1960s could be associated with the roasting of sulfidic ores, while the peak values in the 1990s could have been caused by the start of Cu slag reprocessing in the late 1980s, and culmination of works at the smelter prior to the closing of the mine. The tree rings of the marula tree were found to be a suitable archive for above-ground pollution close to Cu and Pb smelters.

The cyanobacterial bloom in water has adversely affected water quality, local economies, and human health. Therefore, the removal and restricting the growth of harmful algae are of particular interest. In this study, ZnO–montmorillonite that could flocculate and restrict the growth of Microcystis aeruginosa, used as a probe of cyanobacterial, was prepared by hydrothermal solution intercalation method and characterized by means of XRD, IR, and TEM. In ZnO–montmorillonite, ZnO nanoparticles were either embedded in the interlayer space of montmorillonite or dispersed on montmorillonite surface. The determinations of chlorophyll a levels, total soluble protein content, and malondialdehyde concentration demonstrated that ZnO–montmorillonite had stronger flocculation effect on M. aeruginosa compared with natural montmorillonite and ZnO under visible light and had a better photocatalytic degradation effect on M. aeruginosa than ZnO under UV irradiation after 1 h. Under UV, 95 % removal efficiency was achieved for M. aeruginosa in 1 h using 50 mg L⁻¹ZnO–montmorillonite, and the proliferation of M. aeruginosa was totally inhibited due to the high photocatalytic activity and absorption flocculation ability of ZnO–montmorillonite. Furthermore, the cell structure was irreversibly damaged and the cell lysed. The synergy of absorption flocculation and photocatalysis of ZnO–montmorillonite promoted the removal of M. aeruginosa.

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.