In this work, photocatalytic degradation of two reactive dyes, Reactive Yellow 84 (RY 84) and Reactive Black 5 (RB 5), on FeTiO₃/TiO₂ heterojunction in the presence of UV–visible radiation and H₂O₂ has been reported. FeTiO₃/TiO₂ heterojunction has been prepared from ilmenite FeTiO₃ and anatase TiO₂ by employing oxalic acid as an organic linker. FeTiO₃/TiO₂ ratios have been varied from 1 to 5 wt.%, and the materials were characterized by X-ray diffraction, scanning electron microscope and diffused reflectance UV–visible spectroscopic analysis. The photocatalytic activity of FeTiO₃/TiO₂ heterojunction for the degradation of the organic dyes RY 84 and RB 5 in the presence of UV–visible light was found to be higher than that of pure TiO₂. The addition of H₂O₂ increases the rate of degradation of both dyes on FeTiO₃/TiO₂ heterojunction. It facilitates the fast degradation of dye solutions even when their concentration was above 100 mg/l, which is otherwise very slow due to the low transmittance of light by the dye solution. The extent of mineralisation of the reactive dye during photocatalytic degradation was estimated from chemical oxygen demand analysis. FeTiO₃/TiO₂ heterojunction photocatalyst was also found to have good photostability; the material retains almost 97 % of its initial activity even in the fifth cycle.

Although many studies have examined effects of metal mine effluents (MMEs) on receiving environments, few have compared the roles of individual and mixed metals relative to whole effluents. The objective of the present set of studies was to examine whether Cu, Ni, or Se, alone or in a mixture, causes comparable effects to those observed in fathead minnows (Pimephales promelas) exposed to an environmentally relevant MME (45 % process water effluent [PWE]). Metal bioaccumulation, fathead minnow (FHM) morphometrics, and egg production were compared between treatments over a 21-day exposure. FHMs were exposed to similar waterborne concentrations and species of metals in single and mixed metal treatments relative to 45 % PWE. FHMs were also exposed to similar concentrations of metals in single and mixed metal treatments relative to 45 % PWE through the diet (Chironomus dilutus — a representative prey species). However, only FHMs exposed to 45 % PWE had reduced egg production (60–80 % less than controls). Our findings indicate that Cu, Ni, and Se exposures and bioaccumulation did not contribute to decreased reproductive output in FHMs under the conditions that were examined. We also found no evidence to believe that these metals were responsible for decreased egg production in PWE. It is therefore reasonable to suggest that these metals have limited potential to cause reproductive effects in MMEs with similar composition and water chemistry conditions. Overall, this study highlights the importance of examining single and mixed metal exposures prior to suggesting that adverse effects in fish exposed to MMEs occur due to bioaccumulation of metal(s).

In this paper, we report on a field experiment being carried out in a Typic Eutrorthox. The experiment was initiated in the 1997–98 agricultural season as a randomized block design with four treatments (0, 5, 10, and 20 t ha⁻¹) of sewage sludge and five replicates. Compound soil samples were obtained from 20 subsamples collected at depths of 0–0.1 and 0.1–0.2 m. Cu, Fe, Mn, and Zn concentrations were extracted with DTPA pH 7.3; 0.1 mol L⁻¹ HCl, Mehlich-I, Mehlich-III, and 0.01 mol L⁻¹ CaCl₂. Metal concentrations were determined via atomic absorption spectrometry. Diagnostic leaves and the whole above-ground portion of plants were collected to determine Cu, Fe, Mn, and Zn concentrations extracted by nitric–perchloric digestion and later determined via atomic absorption spectrometry. Sewage sludge application caused increases in the concentrations of soil Cu, Fe, and Mn in samples taken from the 0–0.1 m depth evaluated by the extractants Mehlich-I, Mehlich-III, 0.01 mol L⁻¹ HCl and DTPA pH 7.3. None of the extractants provided efficient estimates of changes in Mn concentrations. The acid extractants extracted more Cu, Fe, Mn, and Zn than the saline and chelating solutions. The highest concentrations of Cu, Fe, and Zn were obtained with Mehlich-III, while the highest concentrations of Mn were obtained with HCl. We did not observe a correlation between the extractants and the concentrations of elements in the diagnostic leaves nor in the tissues of the whole maize plant (Zea mays L.).

Karst systems harbor large groundwater resources for human consumption and represent an important habitat for rare and unprotected specialized animals, the so-called stygofauna. Due to the highly adapted features towards underground life, together with the geographic isolation provided by the subterranean aquifers, groundwater-dwelling animals may lose the ability to face sudden changes on their ecosystems, and therefore the risk of extinction is remarkably high. A little is known about their sensitiveness, especially linked to contamination pressure in urbanized karst areas. Understanding the impact of contaminants on stygofauna is important for setting groundwater environmental quality and management of karst systems. We have investigated acute toxicity responses in two endemic stygobiont species of the peri-Mediterranean genus Proasellus from two different karst areas and in freshwater standard species Daphnia magna exposed to two contaminants (copper sulfate; potassium dichromate). Groundwater from both sites was characterized in order to depict possible responses resulting from the long-term exposition of organisms to contaminants. Stygobiont Proasellus spp. were remarkably more tolerant than the epigean D. magna. The less groundwater-adapted revealed to be more tolerant to acute exposure to both toxics, suggesting that the degree of adaptation to groundwater life can influence the acute response of Proasellus spp. to pollutants, and that the tolerance to wide environmental conditions could be a key factor in groundwater colonization. This study highlights the worldwide need to use local specimens to infer the effects of pollution in their corresponding karst systems, which is important to define specific environmental quality thresholds for groundwater ecosystems that will certainly contribute for its protection.

This study examined the potential for regrowth of Escherichia coli in laboratory-incubated microcosms spiked with ultraviolet (UV)-disinfected sewage effluent and extracts derived from turfgrass or leaf litter. A second part of the study examined the potential of nutrients for predicting E. coli in two urban streams with point source effluent. Microcosms containing effluent and vegetation extracts were incubated for 72 h, samples were withdrawn over six time periods for measurement of E. coli. Streams were sampled every 2 weeks and E. coli and nutrients measured. E. coli counts in the microcosms exceeded the Texas state secondary contact recreation standard for surface water quality within 12 h for the turfgrass and within 18 h for leaf litter extracts. Univariate analysis of variance found that the interaction between vegetation extract source and concentration was more important than source of vegetation or concentration of extract alone. In the two streams sampled downstream of a point source effluent discharge, between 82 and 92 % of the variance in annual E. coli during high stream flow and between 55 and 57 % of the variance in annual E. coli during low stream flow was described by stream water-dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), NH₄-N, NO₃-N, or PO₄-P. Once effluent is discharged to surface water, particularly during high flow conditions, DOC and DON derived from the landscape and nitrogen and PO₄-P derived from the effluent will provide ideal conditions for E. coli regrowth in surface waters downstream of the point source discharge.

The degradation of sodium p-cumenesulfonate (SCS) by electrochemical, photochemical, and photoelectrochemical methods in aqueous solution of NaClO4, NaCl, and NaClO has been studied. It was found that as a result of NaClO4 electroreduction and photodecomposition, the ions Cl- and ClO3- are formed. These ions undergo transformations into radicals, mainly Cl-center dot, Cl-2(center dot-), ClO center dot, ClO2 center dot, and ClO3 center dot, due to electrochemical and photochemical reactions. It was shown that the interpretation of results of the studies over mineralization processes carried out in the presence of ClO4-cannot be adequate without taking into consideration the reduction of ClO4 to Cl- and ClO3-. Therefore, previous works presented in the literature should be rediscussed on the basis of the new data. Photoelectrochemical mineralization of substrate in NaCl solution at the concentration of 16 mmol L-1 is comparable with the efficiency of the reaction in NaClO4 solution containing more than 8 mmol L-1 of NaClO. Total SCS mineralization was obtained in the photoelectrochemical reactor with a UV immersion lamp with a power 15 W in the period of 135 min and current intensity of 350 mA. In such conditions, the power consumption was about 1.2 kWh per g of TOC removed.

Data on the influence of substrate composition on the anaerobic degradation of peptone in a bench-scale packed-bed reactor are presented and discussed. The experiments were conducted in a horizontal-flow anaerobic immobilised biomass reactor operated with a hydraulic detention time of 4 h. Peptone was the sole carbon source in the first experiment (E1). In the second experiment (E2), the reactor was fed with peptone and carbohydrates, and in the third experiment (E3), lipids were also added. At end of each experiment, the samples were collected to obtain spatial profiles of the substrates and intermediary metabolites. A modified first-order kinetic expression fits well with the chemical oxygen demand data, allowing kinetic parameter inference in both E1 and E2. The presence of lipids in the E3 influent clearly disturbed the equilibrium of the process, which could be better represented by two first-order kinetic expressions in series. A kinetic model of irreversible first-order reactions (in series and in parallel) with two intermediate products was proposed for representing the entire process. Several modifications of the metabolic routes were clearly represented by the values of the model parameters. It was also possible to conclude that the adsorption of lipids in the fixed bed caused a decrease in the consumption rate of proteins and acetate. Microscopy examinations and fluorescence in situ hybridisation analyses corroborated the conclusions from the kinetic study. The frequencies of the microorganisms changed as the substrate composition was modified, indicating the capability of the microorganisms to adapt.

Two mine soils in southeastern Ohio do not support a luxurious vegetation growth probably because of soil-related constraints. Thus, a laboratory study was conducted to improve the mine soil quality using amendments of zeolite (two grain sizes), flue gas desulfurization gypsum (FGD), fly ash, and biosolids at an application rate of 10 % by weight. The results showed that FGD was the best amendment for increasing soil pH and improving seed germination of lettuce (Lactuca sativa) while biosolids significantly enhanced soil aggregate stability and saturated-water-holding capacity. Specifically, FGD increased soil pH from 3.1 to 5.0, and 4.2 to above 7.0, respectively. Elongation of the lettuce seedlings (shoots) in mine soil solutions was also enhanced by the amendment, from an initial length of 0-1.5 cm to 4.5-9.6 cm. Application of biosolids, on the other hand, increased the mean weight diameter of soil water-stable aggregates by two to four times from initial 0.5-1.6 mm to 2.0-2.9 mm. Saturated-water-holding capacity of both soils was also significantly improved by biosolids. But biosolids did not enhance soil plant-available-water-holding capacity. Neither zeolite nor fly ash significantly improved the mine soil qualities measured in our study. Soil chemical analyses showed that these mine soils neither contained high concentrations of heavy metals nor other toxins in solids or in solutions, suggesting that soil acidity is the only chemical constraint limiting the vegetation establishment and growth besides the nutrients deficiency. © 2013 Springer Science+Business Media Dordrecht.

Sepiolite reveals as a low-cost and efficient adsorbent for the adsorption of caffeine from aqueous solutions. The characterization of this material was carried out by N₂ adsorption–desorption at 77 K, Fourier transform infrared spectroscopy, thermogravimetric analysis, and electronic microscopy. Initially, batch adsorption experiments were developed in order to determine the equilibrium time and the adsorption isotherm of the system. Pseudo–first-order, Elovich equation, pseudo–second-order, and intra-particle diffusion models were applied to the experimental data to determine the adsorption kinetics. In continuous adsorption, the influence of several operation conditions (initial caffeine concentration, volumetric flow rate, and mass of adsorbent) on the shape of breakthrough curves and the mass transfer resistance was evaluated. Experimental data were fitted to the bed-depth service-time model bed-depth service-time (BDST). Through the calculation of the adsorption, parameters as breakthrough time or caffeine removal percentage can be concluded that the removal of this compound from aqueous solutions by adsorption in sepiolite beds is an alternative technique to the current methods, in order to eliminate this micropollutant.

Measurements of solute dispersion in porous media is generally much more time consuming than gas dispersion measurements performed under equivalent conditions. Significant time savings may therefore, be achieved if solute dispersion coefficients can be estimated based on measured gas dispersion data. This paper evaluates the possibility for estimating solute dispersion based on gas dispersion measurements. Breakthrough measurements were carried out at different fluid velocities (covering the same range in Reynolds number), using O₂ and NaCl as gas and solute tracers, respectively. Three different, granular porous materials were used: (1) crushed granite (very angular particles), (2) gravel (particles of intermediate roundness) and (3) Leca® (almost spherical particles). For each material, 21 different particle size fractions were used. Gas and solute dispersion coefficients were determined by fitting the advection–dispersion equation to the measured breakthrough curves and in turn used to calculate gas and solute dispersivities as a function of mean particle size (D ₘ) and particle size range (R) for the 63 particle size fractions considered. The results show that solute and gas dispersivities are related and that their ratio depends on both R and D ₘ. Based on these observations a simple model for predicting the dispersivity ratio from D ₘ and R, was proposed.