The presence of different kinds of leaf packs (native or alien) and environmental gradients can affect the composition and abundance of macroinvertebrate assemblages in freshwater ecosystems, but little is known about the interactive effects. Here, we investigated (1) how environmental gradients could influence leaf packs macroinvertebrates and (2) which was the chief factor (among water quality, mass loss of leaf packs, and flow regime) affecting macroinvertebrate assemblages in impaired streams. We analyzed leaf packs in six sites in impaired streams, characterized by wastewater discharges and dominated by pollution-tolerant macroinvertebrate species. Using principal component analysis, we defined two environmental gradients as follows: a water quality gradient, related to anthropogenic alteration, and a hydromorphological gradient, mostly related to the catchment features. Our results pointed out that, in the tested conditions, biological metrics, such as functional groups and taxa richness, were chiefly influenced by the water quality gradient, while different leaf types in packs influenced the total taxa richness, but did not cause significant variation in the distribution and abundance of macroinvertebrate functional groups. On the contrary, the mass loss differed for different leaf types and was related to the stream and catchment features (mainly flow). This work showed that, in impaired streams, macroinvertebrate assemblages colonizing leaf packs are more influenced by water quality than by leaf types. Thus, the improvement of water quality should be the priority in restoration programs and should be achieved before any effort to restore native riparian vegetation.

Pot and field experiments were conducted to elucidate the phytostabilization potential of two grass species (Thysanolaena maxima and Vetiveria zizanioides) with respect to lead (Pb) tailing soil. Three fertilizers (Osmocote® fertilizer, cow manure, and organic fertilizer) were used to improve the physicochemical properties of tailing soil. V. zizanioides treated with organic fertilizer and cow manure showed the highest biomass (14.0±2.6 and 10.5±2.6 g per plant, respectively) and the highest Pb uptake in the organic fertilizer treatment (T. maxima, 413.3 μg per plant; V. zizanioides, 519.5 μg per plant) in the pot study, whereas in field trials, T. maxima attained the best performances of dry biomass production (217.0 ±57.9 g per plant) and Pb uptake (32.1mg per plant) in the Osmocote® treatment. In addition, both grasses showed low translocation factor (<1) values and bioconcentration coefficients for root (>1). During a 1-year field trial, T. maxima also produced the longest shoot (103.9±29.7 cm), followed by V. zizanioides (70.6±16.8 cm), in Osmocote® treatment. Both grass species showed potential as excluder plants suitable for phytostabilization applications in Pbcontaminated areas. © Springer Science+Business Media Dordrecht 2013.

Agroindustrial by-products and residues from treatment of sewage sludge have been recently recycled as soil amendments. This study was aimed at assessing toxic potential of biosolid, obtained from a sewage treatment plant (STP), vinasse, a by-product of the sugar cane industry, and a combination of both residues using Allium cepa assay. Bioprocessing of these samples by a terrestrial invertebrate (diplopod Rhinocricus padbergi) was also examined. Bioassay assembly followed standards of the Brazilian legislation for disposal of these residues. After adding residues, 20 diplopods were placed in each terrarium, where they remained for 30 days. Chemical analysis and the A. cepa assay were conducted before and after bioprocessing by diplopods. At the end of the bioassay, there was a decrease in arsenic and mercury. For the remaining metals, accumulation and/or bioavailability varied in all samples but suggested bioprocessing by animals. The A. cepa test revealed genotoxic effects characterized by different chromosome aberrations. Micronuclei and chromosome breaks on meristematic cells and F₁ cells with micronuclei were examined to assess mutagenicity of samples. After 30 days, the genotoxic effects were significantly reduced in the soil + biosolid and soil + biosolid + vinasse groups as well as the mutagenic effects in the soil + biosolid + vinasse group. Similar to vermicomposting, bioprocessing of residues by diplopods can be a feasible alternative and used prior to application in crops to improve degraded soils and/or city dumps. Based on our findings, further studies are needed to adequately dispose of these residues in the environment.

Domestic water is abstracted from its sources in raw form with a high content of dissolved and suspended material. Polydiallyldimethylammonium chloride (polyDADMAC) is a cationic polyelectrolyte used in the initial water clarification process. However, its residues in treated water pose a health risk as they react with chlorine to produce a carcinogenic compound. There is a need to determine the concentration of the polyelectrolyte cations that pass through the flocculation stage before the chlorine disinfection process in water treatment plants to ascertain the safety of water to consumers. The cationic polymer is UV inactive, and previously available methods for determining the concentrations of polyelectrolytes are unsatisfactory due to poor detection limits. This paper describes a UV-Visible (UV-vis) spectrophotometry method for the determination of residual polyDADMAC as an epoxide. The novelty method lies on the epoxidation of polyDADMAC using 20 % sodium hydroxide dissolved in 30 % hydrogen peroxide to produce a UV-Vis active compound. The epoxidation was confirmed by UV-Vis, FTIR and 1H NMR techniques. Dilute solutions of varying concentrations of polyDADMAC (0.2-1.0 mg L-1) were treated with a basic solution of hydrogen peroxide then analysed by UV-Vis spectrophotometry. The wavelength at maximum absorption (λmax) was found to be 313 nm, and a linear calibration curve with a correlation coefficient (R 2) of 0.993 was used for quantification purposes. The detection limit measured as three times the signal of the blank and was found to be 2.1 × 10-4 mg L-1. The method was applied to determine the concentration of polyDADMAC spiked in water samples collected from a pool as a model for environmental matrix. The results obtained agreed with the quantities spiked in the solution, thus qualified the method to be suitable for the determination of polyDADMAC in treated waters at trace levels. The method was also used to investigate the adsorption capacity of polyDADMAC on sand filters. The adsorption method was found to be in accordance with Langmuir with an adsorption capacity of 2.068 mg g-1. © 2013 The Author(s).

Low-grade weirs are innovative management strategies that control surface drainage, slow water velocities, and encourage sedimentation in agricultural drainage ditches. There is little information on how low-grade weirs perform in terms of short-term (0–12 months) sediment retention and associated phosphorus (P) dynamics. This study documents initial results of sediment and P dynamics of low-grade weirs in a drainage system that was built in a two-stage ditch design. Average sediment deposition did not differ significantly among sites (χ ² = 2.42; P = 0.49); however, average water depths behind weir sites were significantly greater (28 ± 10 cm) than the comparison inflow site (6 ± 8 cm; χ ² = 7.67; P = 0.05). Total P concentrations were not significantly different through time, or between sites, but there was a general trend of progressively higher total P retention moving downstream. Bioavailability ratios of P (i.e., the ratio of potentially bioavailable to non-bioavailable P fractions) were similar between all sites through time (χ ² = 2.09; P = 0.55). The only variables correlated significantly with time were found at the inflow site, where water depth significantly decreased with corresponding increases in sediment/water column pH and bioavailability ratios. From best management practice installation to 12 months after construction, there was a lack of significant correlations with any measured variables behind weirs. However, the lack of correlation between variables suggests increasing the hydroperiod, reducing the ephemeral nature of the drainage ditch system, and prolonging inundation, improves conditions for P retention.

In this study, we evaluated the needle anatomy of Norway spruce trees growing on a territory that was exposed to different alkaline dust pollution. The anatomy of the needles of spruce growing on a polluted site in the vicinity of the Kunda cement plant (Northeast Estonia) was compared with the anatomy and physiological state of the needles from an unpolluted site. The needles from polluted sites had a significantly larger average mesophyll area and thicker epidermis. These needles also had significantly smaller average vascular bundles and xylem areas than needles from the unpolluted site. Although in the alkalised growth conditions, the mesophyll area enlarged, the number of damaged mesophyll cells increased, and as a result, the concentration of chlorophylls decreased reducing the photosynthetic potential of trees. Our study indicates that even though cement dust pollution has practically ceased in the area, the alkalised soil is affecting physiological processes in trees for a long time.

The compositional changes of saturates, aromatics, resins and asphaltenes (SARA) fractions in aqueous clay/oil microcosm experiments with a hydrocarbon-degrading microorganism community were analysed using Iatroscan. The clay mineral samples used in this study were organomontmorillonite, acid-activated montmorillonite and K, Ca, Zn and Cr montmorillonites produced by modifying the original montmorillonite sample. The evaluation and quantification of biodegradation and adsorption were carried out using a combination of the Iatroscan and gravimetric analysis. The SARA compositions in the presence of organomontmorillonite and acid-activated montmorillonite after incubation follow the same pattern in which the aromatic fraction is higher than the other fractions unlike in the presence of unmodified, K, Ca and Zn montmorillonites, where the saturates fraction is higher than the other fractions. Changes in SARA fractions due to biodegradation seemed to occur most in the presence of unmodified and calcium montmorillonites; hence, the removal of SARA fractions due to biodegradation was significant and enhanced in the presence of these two clay samples. However, biodegradation in the presence of organomontmorillonite and acid-activated and Cr montmorillonites was hindered. The study indicated that Cr montmorillonite adsorbed resins most, whereas Zn and K montmorillonites adsorbed aromatics most after incubation.

Soils polluted by metals and organic compounds are a major challenge in soil remediation and environmental recovery; however, the technology to efficiently decontaminate soils polluted by both metal and organic pollutants does not yet exist. Most of these soils are disposed of in landfills. This study first evaluates chemical reagents (hydrochloric, nitric, sulfuric and lactic acids and ethanol) for leaching metals from soil. Assays were then conducted to evaluate non-ionic, ionic and amphoteric surfactants for pentachlorophenol (PCP) removal by flotation. Finally, a laboratory-scale leaching/flotation process was applied to treat four soil samples polluted with both organic ([PCP]ᵢ = 2.5–30 mg kg⁻¹) and metals ([As]ᵢ = 50–250 mg kg⁻¹, [Cr]ᵢ = 35–220 mg kg⁻¹, [Cu]ᵢ = 80–350 mg kg⁻¹) compounds. The organic compounds and metals are concentrated in the froth and liquid fractions, respectively. Removal yields of 82–93 %, 30–80 %, 79–90 % and 36–78 % were obtained from As, Cr, Cu and PCP, respectively, under optimized process conditions (H₂SO₄ = 1 N, [cocamidopropyl betaine]ᵢ = 1 % (w w⁻¹), t = 60 min, T = 60 °C, PD = 10 % (w v⁻¹)). The treatment of the produced leachate was also tested by chemical precipitation using different reagents.

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.

Adsorption together with size exclusion and charge attraction/repulsion has to be taken into account when considering removal of pharmaceuticals as emerging contaminants from water by reverse osmosis and nanofiltration membranes. Glucocorticosteroids (hydrocortisone (HYDRO), dexamethasone (DEXA)), anesthetics (procaine, lidocaine) with relatively weak hydrophobicities (1 < log K O/W < 3), and membranes (XLE, LFC–1, CPA3, SWC1, NF90, and NF270) have been investigated in this study. Adsorption was studied by measuring the concentration of compounds in feed and permeate and by monitoring changes in membrane flux in the batch mode operation during 24 h. A decrease in the feed concentrations for HYDRO and DEXA (log K O/W < 2) was observed. The loss of these compounds in feed was associated with irreversible adsorption onto an NF270 and a CPA3 membrane. Therefore, when considering removal of pharmaceuticals with lower hydrophobicity, adsorption has to be particularly taken into account for membranes with bigger pores in the selective layer. Also, a high dipole moment and low water solubility affected adsorption on the membranes. For smaller and slightly more hydrophobic pharmaceuticals (log K O/W > 2), an increase in the feed concentration was obtained. Firstly, these compounds instantly adsorbed to the membrane. Secondly, the compounds diffused through the polymer matrix and desorbed to the permeate side after equilibrium had been reached.