Imperata cylindrica leaf was used as raw material to prepare two different adsorbents through chemical modification by using sulfuric acid and phosphoric acid. These two adsorbents, sulfuric acid-modified I. cylindrica leaf-based adsorbent (SIC) and phosphoric acid-modified I. cylindrica leaf-based adsorbent (PIC), were used to adsorb nickel ions (Ni²⁺) from aqueous solutions. The I. cylindrica leaf-based adsorbent and modified I. cylindrica leaf-based adsorbents were characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Different operational parameters such as initial solution pH, adsorbent size, adsorbent dosage, initial Ni²⁺ ion concentration, and temperature were studied. The adsorption isotherm and the adsorption kinetics were studied systematically. Based on the FT-IR spectrum before and after adsorption of Ni²⁺ ions, the adsorption mechanism involved both ion exchange and complexation between Ni²⁺ ions and functional groups on the surface of adsorbents. There was no sulfur and phosphorus detected in the aqueous solutions after adsorption. Therefore, SIC and PIC are effective in adsorbing Ni²⁺ ions and will not cause secondary pollution to the environment.

The use of reclaimed wastewater in agriculture can be a solution for regions with water shortages or low rainfall periods; besides fulfilling the crop's water needs, it would also promote the recycle of nutrients. However, care should be taken regarding soil salinization, especially in closed environments such as greenhouses for the cultivation of ornamental plants. The domestic effluents are rich in sodium which can accumulate on soil and cause soil sealing. This study evaluated the use of effluents from anaerobic filters and intermittent sand filters in the production of rosebushes (Rosa hybrida "Ambiance"). The crop yield of the rosebushes irrigated with reclaimed wastewater exceeded the one obtained with traditional cultivation, reaching a value 31.8 % higher when employing nitrified effluent originated from intermittent sand filters, with no difference in the product quality. The salinity levels are below the critical limits found in the literature; however, there was a significant increase compared to the irrigation with drinking water. © 2013 The Author(s).

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.

Because of the existence of a semi-analytical solution, the Henry saltwater intrusion problem has been widely used for benchmarking non-reactive density-driven flow models. In this work, we extend the semi-analytical solution of Henry to reactive transport in variable-density fluid flow. Accurate semi-analytical solutions are provided for three test cases dealing with saltwater transport including dissolution and degradation reactions. About 6,195 terms are required in the Fourier series to obtain a stable solution for these test cases instead of the 78 initially used by Henry (Sea Water in Coastal Aquifers 1613-C:70–84, 1964) for the non-reactive problem. The resolution of the highly non-linear system is made possible due to the modified Powell hybrid algorithm with an analytical evaluation of the Jacobian. Numerical simulations are performed using different numerical methods and grid sizes to evaluate the benefits of these new test cases for benchmarking reactive density-driven flow models.

The use of peracetic acid (PAA) in the disinfection of sanitary effluents has been proposed by various authors. However, there are still doubts about its influence on the physical-chemical characteristics of the effluent after application. In the present study, it was observed that the composition of PAA leads to an increase in organic material, resulting in an increase of approximately 20 mg/L in the chemical oxygen demand of the effluent for every 10 mg/L of PAA applied. According to the kinetic tests, the degradation of PAA in the effluent was represented by a first-order reaction and its half-life in the effluent was estimated at 79 min. The formation of by-products resulting from degradation of PAA in the effluent was evaluated by considering by-products already detected by other authors in disinfection trials, these being nonanal, decanal, chlorophenols, and 1-methoxy-4-methylbenzene, which were not observed in the effluent being studied after application of PAA at a dosage of 10 mg/L. © 2013 Springer Science+Business Media Dordrecht.

Development of aminopolycarboxylate chelants (APCs) having enhanced biodegradability is gaining increasing focus to replace the EDTA and its homologs with those used widely for the ex situ treatment of contaminated soils and are potential eco-threats. The paper reports the chelant-assisted extraction of the toxic metals (Cd, Cu, Pb, and Zn) from the metal-spiked European reference soils (Eurosoil 1 and Eurosoil 4) using biodegradable APCs, namely EDDS, GLDA, and HIDS. The effects of chelant-to-metal molar ratio, solution pH, and metal/chelant stability constants were evaluated, and compared with that of EDTA. The selectivity aptitude of the biodegradable chelants towards the toxic metals was assumed from the speciation calculations, and a proportionate correlation was observed at neutral pH. Pre- and post-extractive solid phase distributions of the target metals were defined using the sequential extraction procedure and dissolution of metals from the theoretically immobilized fraction was witnessed. The effect of competing species (Al, Ca, Fe, Mg, and Mn) concentrations was proven to be minimized with an excess of chelant in solution. The highlight of the outcomes is the superior decontamination ability of GLDA, a biodegradable APC, at minimum chelant concentration in solution and applicability at a wide range of pH environments.

The volatile monoterpene alpha-pinene has been measured in sediments of a selected area at "Carlos Anwandter" Nature Sanctuary, a Ramsar protected wetland located at the northwest of Valdivia City, south-central Chile. The ecosystem was seriously damaged by an uncontrolled liquid emission of a pulp mill (CELCO-Arauco) located about 15 km upstream of Rio Cruces during 2004. Exploratory data analysis was applied to analytical data collected from sediment samples, having found alpha-pinene as a reiterative chemical at relatively high concentrations in some specific areas of the wetland. The decrease of the total concentration of alpha-pinene in the area under study is coincident with a point contamination that occurred during 2004 (12,240 ng g(-1)) showing a decay in 2005 (7,890 ng g(-1)) and middle of 2006 (4,060 ng g(-1)). The following years, last 2006, 2008, and 2009, show a relatively constant concentration with a clear tendency toward baseline levels (2,460-2,640 ng g(-1)). Since the decrease of concentrations of alpha-pinene in sediments in the period 2004-2009 shows an opposite trend as compared to the surface area increase of pine and eucalyptus plantation in Region de Los Rios, and not having found potential sources of alpha-pinene by anthropogenic activities other than the pulp mill in the area under study, it may be finally concluded that this compound did not enter the bodies of water from a gradual and natural process; instead there is a base to sustain anthropogenic input. alpha-Pinene in sediments may be a plausible chemical tracer capable of detecting pollution events over time and its impacts in aquatic ecosystems as well as changes in aquatic ecosystems produced by improperly treated pulp mill liquid emissions that use pine and eucalyptus species.

This study investigated how forest soil acidification is affected by edge proximity. We measured pH(KCl) and exchangeable K, Ca, Mg and Al concentrations of the mineral topsoil (0–30 cm) from the exposed edge to the interior (128 m from the edge) of three deciduous and four coniferous forest stands. From the front edge to the interior of the deciduous stands, the pH(KCl) values decreased at 0–5 cm soil depth (from 3.07 to 2.98) but increased at 5–10 cm (from 3.26 to 3.32) and 10–30 cm (from 3.48 to 3.75) depth. In the coniferous stands, pH(KCl) values declined from edge to interior at all soil depths, i.e. from 3.10 to 2.89, from 3.26 to 3.06 and from 3.54 to 3.31 at 0–5, 5–10 and 10–30 cm, respectively. The concentrations of exchangeable cations decreased from edge to interior, with larger differences in the coniferous (of up to 265 %) than in the deciduous stands (up to 99 %). At forest edges, enhanced soil acidification due to higher potentially acidifying deposition could be counteracted in the upper mineral soil by higher base cation throughfall and litterfall, faster litter decomposition, higher soil organic matter content, lower nitrate leaching from the soil and/or lime fertiliser drift. Nonetheless, deeper in the soil of the deciduous stands, these buffer processes seem unable to counteract soil acidification due to potentially acidifying deposition at the edges. Edge effects on soil acidity are important since they can translate into effects on plant communities, soil biota, nitrogen cycling and carbon sequestration.

Perfluorooctane sulfonate (PFOS), which has numerous uses besides being an ingredient in the formulation of aqueous film-forming foams, is considered as an emerging pollutant of increasing public health and environmental concern due to recent reports of its worldwide distribution, environmental persistence and bioaccumulation potential. In an attempt to recommend a 'risk-based' remediation strategy, this study investigates the removal of PFOS from impacted waters and fixation of PFOS in impacted soils using a novel modified clay adsorbent (MatCARE™, patent number 2009905953). Batch adsorption tests demonstrated a much faster adsorption kinetics (only 60 min to reach equilibrium) and remarkably higher PFOS adsorption capacity (0.09 mmol g-1) of the MatCARE™ compared to a commercial activated carbon (0.07 mmol g -1). Treatability studies, performed by treating the PFOS-contaminated soils with the MatCARE™ (10 % w/w) and then incubating at 25 and 37 C temperatures maintaining 60 % of the maximum water holding capacity of the soils for a period of a year, demonstrated a negligible release (water extractable) of the contaminant (only 0.5 to 0.6 %). The fixation of PFOS in soils by the new adsorbent was exothermic in nature. Soils with higher clay and organic matter content, but lower pH values, retained PFOS to a much greater extent. A cost analyses confirmed that the MatCARETM could be an economically viable option for the 'risk-based' remediation of PFOS in contaminated waters and soils. © 2013 Springer Science+Business Media Dordrecht.

The characterisation of plant responses to metal exposure represents a basic step to select a plant species for phytoremediation. In the present work, 3-week-old Amaranthus paniculatus L. plants were subjected to nickel chloride concentrations of 0 (control), 25, 50, 100 and 150 μM in hydroponic solution for 1 week to evaluate morphophysiological responses, such as biomass production and partitioning, nickel accumulation in plants and nickel removal ability from the polluted solutions. The results showed a progressive decrease in plant organ dry mass with the enhancement of nickel (Ni) concentration in the solution, suggesting a good metal tolerance at 25 μM Ni and a marked sensitivity at 150 μM Ni. The modification of biomass partitioning was particularly appreciated in leaves, analysing the organ mass ratio, the total leaf area and the specific leaf area. Amaranthus plants accumulated a significant amount of Ni in roots exposed to the highest Ni concentrations, while lower metal contents were observed in the aerial organs. The Ni uptake ratio was progressively reduced in plants exposed to increased Ni concentrations. The metal translocation from root to shoots, appreciated by the Ni translocation index, showed a far lower value in Ni-exposed plants than in controls. Moreover, by measuring the daily Ni content of the solutions, a lower Ni removal ability was found in Amaranthus plants at increasing Ni concentrations. Remarkably, plants exposed to 25 μM Ni succeeded in removing almost 60 % of the initial Ni content of the solution showing no stress symptoms. The potential of A. paniculatus for phytoremediation was discussed.