Lettuce plants were exposed to different toxic levels of arsenic (As) to induce an oxidative stress response, and the role of nitric oxide (NO) (provided as sodium nitroprusside (SNP)) as an attenuating agent of this stress condition was evaluated. Plants were treated with 50 μM of As with or without 100 μM SNP added to the nutrient solution. The hydrogen peroxide, superoxide anion, and malondialdehyde concentrations and enzymatic activities were measured. The increase in As concentration detected in the leaves was followed by a significant increase in H₂O₂ and malondialdehyde (MDA) concentrations. However, the presence of SPN promoted a reduction in the concentration of these oxidative agents and also reduced the translocation of As to the shoots. The enzymatic activities in the plants exposed to As were increased, which indicates the active participation of these enzymes in the reduction of oxidative stress induced by the metalloid. In the plants exposed to As and SNP, the enzymatic activities were not so high; this result was possibly related to the direct action of NO in scavenging the generated toxic metabolites and with the reduction in the translocation of the pollutant to the shoots. Lettuce and leaves of other vegetables are usually ingested, and this study shows an alternative to avoid human contamination with As.

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.

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.

We need specific and competent adsorbents to remove arsenic and bring it down to permissible levels in drinking water. Therefore, industrial byproducts are extensively applied to produce large amounts of natural adsorbents. Similarly, managing optimum arsenic adsorption with palm oil clinker sand (POCS) is possible through a careful statistical planning of adsorption variables. We plan and perform a minimum number of experiments to (1) obtain optimum arsenic adsorption and (2) provide a new possible application opportunity to the industrial waste managers and future planners. We observed that adsorption of arsenic was dependent on the pH of the system, initial concentration of arsenic (mg L⁻¹), amount (mg) of POCS, and temperature of the bio-adsorption system. A correlation among the study variables was constructed by three-dimensional (3D) response surfaces and two-dimensional (2D) contour plots based on central composite design (CCD) experiments in a batch mode of study. A quadratic model fitted well with the experimental data and better explained the superiority of current bio-adsorption system and efficient removal of arsenic from water samples. We confirmed that the selected variables were experimentally and statistically significant and controlled the overall adsorption response by the batch system. A comparative and thorough analysis of the adsorption process confirmed that selected variables were mutually interacting in a nonlinear fashion in this study. Excellent experimental results and external comparative studies prove the relative importance of the present model and adsorption system for arsenic remediation biotechnology.

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.

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.

The present work studies the remediation of a B20 (20 % biodiesel, 80 % diesel) biodiesel blend-contaminated soil (1,000 mg kg⁻¹) with persulfate activated by iron. Three different sources of iron (Fe(II)), granular zerovalent iron (gZVI), and a slurry of nanoparticles of zerovalent iron (nZVI), without pH adjustment were tested. Besides, the effect of the addition of chelating agents, such as trisodium citrate (SC), or citric acid (CiA), has been also studied. SC promotes pH under near-neutral conditions and reaction takes place at low rate at these experimental conditions. On the other hand, the use of CiA leads to an acidic pH and chelating agent is oxidized at higher rate than total petroleum hydrocarbons (TPH). Therefore, CiA addition does not seem to produce any improvement on the removal efficiency of TPH. Regarding the three different sources of iron used as activators, Fe(II), gZVI and nZVI, in absence of chelating agent, under acidic pH and by adding the same amount of iron, the highest TPH conversion was obtained with ZVI (about 60 %), while a conversion of about 40 % was obtained with the addition of Fe(II). The maximum TPH conversion value was achieved in shorter time using nZVI. Concerning the removal efficiency of each fraction of biodiesel abated, fatty acid methyl esters (FAME) were by far the easiest to oxidize, achieving 100 % of conversion, either by using Fe(II) or nZVI activated persulfate.

Previous studies with bioindicator organisms have used somatic length distributions, i.e., population structure, to understand the effects of management, environment, or a potential contaminant on populations. We describe a statistical approach to separate somatic length classes of Folsomia candida juveniles as an endpoint for the assessment of changes in population structure. Reproduction-survival bioassays were carried out with five different biochars applied at increasing concentrations. Multi-Gaussian models parameterized juvenile size class cohorts, and the biomass of each size class cohort was estimated. Population structure was modified by both material type as well as concentration. Both biomass and population structure were sensitive to effects not reflected in juvenile number, the classic endpoint. Treatments with more size classes and larger individuals were taken to represent favorable conditions, and less size classes and smaller individuals indicated less favorable conditions. This extension of the standardized test provided additional information about the demography of the population.

The textile industry creates environmental problems due to the release of highly polluting effluents containing substances from different stages of dyeing that are resistant to light, water, and various chemicals, and most of them are difficult to decolorize because of its synthetic origin. The biological degradation of dyes is an economical and environmentally friendly alternative. The aim of this work was to use biofilms of basidiomycete fungi isolated from the Peruvian rainforest for the decolorization of synthetic reactive dyes, considering the advantages of these systems which include better contact with the surrounding medium, resistance to chemical and physical stress, and higher metabolic activity. Among several isolates, two were selected for their capacity of rapid decolorization of several dyes and their biofilm-forming ability. These strains were molecularly identified as Trametes polyzona LMB-TM5 and Ceriporia sp. LMB-TM1 and used in biofilm cultivation for the decolorization of six reactive dyes and textile effluents. Azo dyes were moderately decolorized by both strains, but Remazol Brilliant Blue R (anthraquinone) and Synozol Turquoise Blue HF-G (phthalocyanine) were highly decolorized (97 and 80 %, respectively) by T. polyzona LMB-TM5. Degradation products were found by HPLC analysis. Simulated effluents made of a mixture of six dyes were moderately decolorized by both strains, but a real textile effluent was highly (93 %) decolorized by T. polyzona LMB-TM5. In summary, T. polyzona LMB-TM5 was more efficient than Ceriporia sp. LMB-TM1 for the decolorization of textile dyes and effluents at high initial rates enabling the development of in-plant continuous biofilm processes.

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.