Novel nanocomposite hydrogels based on wheat bran-g-poly(methacrylic acid) and nano-sized clinoptilolite have been successfully utilized for the removal of Pb(II), Cu(II), Cd(II), and Ni(II) cations from their aqueous solution. The experimental results were investigated using Freundlich, Langmuir, Temkin, and Dubinin–Radushkevich isotherm models. The pseudo-first-order, pseudo-second-order and interparticle diffusion kinetic models were studied in order to analyze the kinetic data. The kinetic data indicated that the rate of cation adsorption on nanocomposite hydrogels was fast that more than 80 % of the equilibrium adsorption capacity occurs within 15 min. The maximum monolayer adsorption capacity of the nanocomposite hydrogel, as obtained from the Langmuir adsorption isotherm, was found to be 166.7, 243.9, 175.4, and 166.6 mg g⁻¹ for Pb(II), Cu(II), Cd(II), and Ni(II), respectively. Thermodynamic parameters such as free energy (ΔG ⁰), enthalpy (ΔH ⁰), and entropy (ΔS ⁰) change were determined; the sorption process was found to be endothermic. The results of five times sequential adsorption–desorption cycle showed high adsorption efficiency and a good degree of desorption.

Adsorption and degradation processes of triclosan (TCS) were studied in the laboratory using field-collected sediments of different physicochemical properties. Batch equilibrium experiment indicated that adsorption isotherms were fitted well to both linear and Freundlich model with linear sorption coefficients (K d) varied from 147 to 1,425 mL μg⁻¹. The sediment with a higher organic carbon content and a lower pH value had the greatest adsorption capability. Degradation experiment showed that triclosan was relatively stable in water with calculated half-life values ranged from 89 to 161 days. No degradation in sterilized water suggested that the loss of triclosan was due to biological processes. Degradation was more rapid in water-sediment system than in water, and the calculated half-life value in water-sediment systems ranged from 32 to 62 days. Methylation of triclosan was observed in all studied sediments, but the amount of methyl-triclosan (M-TCS) accounted for less than 5 % of the degradated TCS.

Polybrominated diphenyl ethers (PBDEs) are a class of global flame retardants whose residues have markedly increased in fish and human tissues during the last decade. They belong to persistent and toxic contaminants which need more attention and toxicological study as their degradation in the environment is not well understood. This study characterizes 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) bioconcentration, elimination and biotransformation in juvenile turbot Psetta maxima, in order to evaluate the risk of its bioaccumulation in the marine environment. During this study, juvenile turbot were exposed to environmentally relevant BDE-47 concentrations from 0.001 to 1 μg/L for 16 days via aqueous exposure. This study found that juvenile turbot bioconcentrated and biotransformed BDE-47. There was no difference in standard length or weight between control and exposed fish. Uptake and elimination of BDE-47 by the turbot during exposure were examined in controlled laboratory experiments. Bioconcentration of BDE-47 was similar in fish from all treatment groups. Bioconcentration was rapid and increased with exposure time, since the bioconcentration factor (BCF) was higher. However, elimination was slower in comparison and low elimination was detected after 10 days in clean water. BDE-47 concentration in water influences the BCF. Half-life ranged between 37 and 108 days and theoretical times t₉₀could range from 120 to 358 days. The present study demonstrates a stepwise debromination of BDE-47 to BDE-28.

Treatment of reverse osmosis concentrate (ROC) has been complicated in terms of feasibility, cost, and most importantly, efficiency in removing contaminants. While adsorbents such as activated carbon, coal, and fly ash can remove organics, they may not be effective in removing nutrient salts that cause algae growth. Moreover, with regards to physical treatment, removing contaminants using adsorbents may not be appropriate, as toxic and non-biodegradable pollutants are not transformed or degraded into non-toxic forms. In this study, a series of processes involving adsorption using activated carbon and oxidation by hydroxyl and sulfate radicals were assessed as a means of treating ROC. The method includes treating water containing organics with an adsorbent, and adding nano-sized zero-valent iron (nZVI) to the water in the presence of oxygen, followed by the addition of persulfate, where the water is oxidized with reactive oxygen species (e.g., hydroxyl radical, peroxide, superoxide anion) produced by the addition of ZVI and persulfate radicals generated from persulfate activated by the addition of nZVI. Removal of non-biodegradable organics (as well as nitrogen and phosphorous) and nutrient salts not readily removed by conventional treatment methods can be effectively accomplished through the physical removal method described, using activated carbon, and by a chemical removal method using radical oxidation.

Effects of perchlorate stress on the growth and physiological characteristics of rice (Oryza sativa L.) were studied in controlled water culture experiments. Perchlorate stress resulted in varied patterns of biomass allocation to O. sativa organs (roots, stems, and leaves). When stressed with higher perchlorate concentrations, the proportion of root biomass was higher, stem biomass was invariant, while leaf biomass was lower. Coefficients of variation in biomass of different organs followed the order leaf > stem > root, indicating that leaf growth has a higher sensitivity to perchlorate. Compared to the control, the chlorophyll and protein content of leaves and root vigor were lower, whereas malondialdehyde (MDA) content and catalase (CAT) activity were higher and related to perchlorate concentration and duration of stress. Superoxide dismutase (SOD) activity was initially high and then decreased markedly during the experiment, while peroxidase (POX) activity in perchlorate-treated rice was always higher than the POX activity of the control. POX was the most sensitive antioxidant enzyme to perchlorate stress. Correlation analysis showed a positive correlation between SOD activity and the fresh weight of the whole plant, and negative correlation with MDA content. The results suggest that perchlorate could induce oxidative stress and oxidative damage may be the main cause of physiological damage and growth inhibition in rice plants under perchlorate stress.

Adsorption and removal of cadmium ions from simulated industrial wastewater using hydrophilic and hydrophobic commercial silica nanoparticles are reported. These results are compared with those obtained using sol–gel silica nanoparticles. Two types of dense commercial pyrogenic silica nanoparticles with different chemical groups on the surface were used to adsorb cadmium ions: Aerosil A130VS and R972. The pore absence in these particles reduces the surface area and, consequently, the concentration of active chemical groups appropriated for adsorption, as compared with the sol–gel particles that are highly porous; this effect is partially compensated by the small sizes available for these commercial particles. The concentration of cadmium ions was reduced: from 109 to 0.01 ppm for A130VS, from 138 to 1.44 ppm for R972, and from 123 to 0.005 ppm for sol–gel. The flocculation kinetics was obtained using dynamic light scattering and the amount of adsorbed cadmium in the sediment using atomic absorption spectroscopy.

Ametryne is an herbicide applied to sugar cane cultures to prevent the emergence of weeds. It is a persistent compound that percolates ground and surface water thus impacting aquatic communities. In this study, we evaluated microbial activity in soil with increased concentrations of ametryne solution and commercial Microgeo biofertilizer. The soil subject to analysis was obtained from a sugar cane cultivation area. The concentration used in the experiment was ametryne 12 μg/L and 1 % of biofertilizer. It was used with the Bartha and Pramer respirometric method to quantify CO₂production and determine microbial activity. Complimentary phytotoxicity tests with Lactuca sativa seeds after respirometry experiments were conducted in the soluble fraction of the soil. According to the results, the addition of biofertilizer promoted microbial activity in the presence of ametryne and reduced ametryne phytotoxicity for Lactuca sativa seeds. Thus, Microgeo biofertilizer can potentially improve biodegradation of ametryne through both bioaugmentation and bioestimulation.

As the popularity and use of soft plastic lures (SPLs) by recreational anglers have increased in recent years, so does the number of anecdotal reports of SPLs being found in aquatic environments and in the digestive tract of a variety of fish species. We used a multistep approach to determine the possible consequences of SPLs on fish and aquatic environments. Field work focussed on lake trout (Salvelinus namaycush) and smallmouth bass (Micropterus dolomeiu) in Charleston Lake in eastern Ontario, a system identified by resource managers and the lake association as potentially having an SPL problem based on numerous anecdotal reports from anglers. Snorkel surveys revealed that the deposition rate of SPLs was potentially as high as ~80 per km of shoreline per year. In the laboratory, eight different types of SPLs were immersed in water at two temperatures (4 and 21 °C) for a 2-year period to evaluate change in SPL size (both swelling and decomposition). Despite SPLs varying by manufacturer and in composition, there was little evidence of decomposition. Indeed, most SPLs swelled and remained that way throughout the study. In cold water, SPLs increased an average of 61 % in weight and 19 % in length, while warm water treatments experienced an increase of 205 % in weight and 39 % in length. A summer creel survey conducted on Charleston Lake revealed that 17.9 % of anglers interviewed reported finding at least one ingested SPL when cleaning lake trout. However, when we sampled lake trout (using gill nets) and smallmouth bass (by rod and reel), we found few ingested SPLs (2.2 and 3.4 %, respectively). Based on the examination of fish that contained SPLs and the near-shore surveys, the most common SPLs were soft stick baits/wacky worms. The most promising approach to address the SPL problem is to educate anglers about the need to rig SPLs in a manner such that they are less likely to be lost during fishing and to always discard SPLs appropriately. Moreover, the tackle industry should continue to investigate SPLs that are less likely to be pulled off by fish and/or that degrade rapidly.

In the present research work, different types of biodiesel were produced by a homogeneous alkali transesterification reaction using soybean oil, pork lard, and castor bean oil as raw materials, to evaluate how their different compositions may affect the biodegradability, namely, in the presence of benzene. Biodiesel was characterized according to the European standard EN 14214. The anaerobic biodegradation of the different types of biodiesel was examined as well as its influence on the biodegradation of benzene. Analyses were performed to determine the volume of methane (directly related to the anaerobic biodegradation of biodiesel), the concentration of benzene over time, and the production of organic acids. The results showed methane production resulting from the anaerobic degradation of all biodiesel types. The differences between the degradation behavior of each fuel were negligible, contrary to what was expected; however, the amount of methane produced was low due to nutrient limitations. This fact was confirmed by the organic acid analysis as well as by the addition of new media. Anaerobic benzene biodegradation was found to be negatively impacted by the presence of all biodiesel types on average; therefore, the results of this study may impact management of sites that contain biodiesel and fuel hydrocarbon contamination.

This work focuses on the effects of two commercial formulations of dispersants on juvenile turbot after 48 h of contamination and 15 days of recovery. Oxidative stress, gill, and immune functions were assessed in seven conditions: exposition to the water-soluble fraction of an oil, mechanical dispersion, two dispersants alone, two types of chemical dispersion and a control group. In the contaminated groups, nominal concentrations of oil and dispersants were 66 and 3.3 mg L⁻¹, respectively. Dispersants alone had weak effects; the soluble fraction induced leucopenia and gill alteration. Chemical and mechanical dispersion induced similar effects. After contamination, a principal component analysis showed two distinct areas: the first one included the control and dispersants groups, the second one dispersion of the oil. After the 15-day recovery period, it was not possible to differentiate the groups. This study shows that, in the experimental conditions tested, the dispersion, either chemical or mechanical, enhances the consequences of exposure to crude oil without long-lasting consequences.