Knowledge of the levels of both total metal content and metal bioavailability is critical for understanding the long-term effects of liming on soil chemistry and potential metal uptake by biota. In the present study, the long-term effects of liming on metal bioavailability in soils contaminated by smelter emissions were assessed in eroded and stable uplands in the Sudbury region, Ontario, Canada. Analytical results revealed that total metal and nutrient contents of the soil matrix are not dominantly in forms available for plant uptake for these soils. On average, only 1 and 1.1 % of total copper and nickel, respectively, were phytoavailable. Landscape topography, site stability, and smelter proximity all play an important role in metal accumulation in the surface organic and mineral horizons of regional soils. The levels of total and bioavailable elements for eroded sites were always smaller for stable and reference sites. The pH in limed sites was significantly higher, ranging from 4.12 to 6.75, in the humus form compared to unlimed areas, even 20 to 30 years following applications of the crushed dolostone (liming). No significant differences between limed and unlimed areas were found for total metal and nutrient contents. Interestingly, in the higher pH limed areas, the levels of bioavailable Al, Co, Cu, Fe, K, Mn, Ni, and Sr were lower than on unlimed areas. © 2013 Springer Science+Business Media Dordrecht.

Arsenic (As) toxicity and the effects of nitric oxide (NO), supplied as sodium nitroprusside (SNP), were analyzed in Pistia stratiotes. The plants, which were grown in nutrient solution at pH 6.5, were exposed to four treatments for 24 h: control; SNP (0.1 mg L-1); As (1.5 mg L-1); and As + SNP (1.5 and 0.1 mg L-1). As accumulated primarily in the roots, indicating the low translocation factor of P. stratiotes. The As accumulation triggered a series of changes with increasing production of reactive oxygen intermediates and damage to cell membranes. The application of SNP was able to mitigate the harmful effects of As. This attenuation was probably due to the action of the SNP as an antioxidant, reducing the superoxide anion concentration, and as a signaling agent. Acting as a signal transducer, SNP increased the activity of enzymatic antioxidants (POX, CAT, and APX) in the leaves and stimulated the entire phytochelatins biosynthetic pathway in the roots (increased sulfate uptake and synthesis of amino acids, non-proteinthiols, and phytochelatins). The As also stimulated the phytochelatins biosynthesis, but this effect was limited, probably because plants exposed only to pollutant showed small increments in the sulfate uptake. Thus, NO also may be involved in gene regulation of sulfate carriers. © 2013 Springer Science+Business Media Dordrecht.

In this study, high surface area porous carbons were synthesized by chemical activation using petroleum coke as the precursor and KOH as the activation agent. The pore structure of the as-synthesized activated carbons was characterized by nitrogen adsorption, and their CO₂ sorption capacities were measured by a magnetic suspension balance at 1 and 10 bar, respectively. The effects of activated carbon preparation parameters (preheating temperature, preheating time, activation time, heating rate during the pyrolysis, and particle size of the precursor) on porous texture, CO₂ adsorption capacity, and CO₂/N₂ selectivity of the activated products were investigated. It has been found that at 1 bar, the CO₂ adsorption capacity is determined by the micropore contribution, i.e., the ratio between micropore surface area and Brunauer–Emmett–Teller (BET) surface area of the sorbents, while at 10 bar, CO₂ adsorption capacity is related to the BET surface area of the activated products. The maximum CO₂ adsorption uptake of 15.1 wt% together with CO₂/N₂ selectivity of 9.4 at 1 bar were obtained for a sample activated at 700 °C indicating its high potential in the capture of CO₂.

In this study, 11 plants (legumes, grasses, and crops) were screened for their ability to grow and survive in soil contaminated with 1 % diesel/oil mix (aliphatic hydrocarbons) or 1 % crude oil. Based on emergence, shoot length, root length, and root/shoot biomass ratio in contaminated soil, maize and wheat which showed the highest growth were selected for further investigation: a long-term phytoremediation study to evaluate the effect of maize and wheat on the microbial removal of hydrocarbons (1 % diesel/oil mix). The results showed that the presence of both maize and wheat in hydrocarbon-contaminated soil led to a significant increase in the utilization of total petroleum hydrocarbon (TPH), from 57 % in the control soil to 72 and 66 % in soil planted with maize and wheat, respectively. Microbial community analysis using denaturing gradient gel electrophoresis (DGGE) showed that the presence of a plant rhizosphere resulted in changes in the structure of the soil microbial community. Sequencing of prominent bands revealed the presence of a few hydrocarbonoclastic fungi only in the contaminated soil planted with maize and wheat. In terms of specific hydrocarbonoclastic activity, DGGE analysis based on alkB genes showed that soils with maize and wheat had similar rates of hydrocarbonoclastic activity but distinct microbial communities in some instances. Most probable number quantitative polymerase chain reaction (MPN-qPCR) confirmed that the number of alkB gene copies in soil planted with maize and wheat increased about 20- and 16-fold, respectively, relative to the control soil. This study showed that fungal and alkB bacterial communities contribute to the rhizoremediation of petrogenic hydrocarbons.

Textile industries use large amounts of water in dyeing processes and a wide variety of synthetic dyes. A small concentration of these dyes in the environment can generate highly visible pollution and changes in aquatic ecosystems. Adsorption, biosorption, and biodegradation are the most advantageous dye removal processes. Biodegradation occurs when enzymes produced by certain microorganisms are capable of breaking down the dye molecule. To increase the efficiency of these processes, cell immobilization enables the reuse of the immobilized cells and offers a high degree of mechanical strength, allowing metabolic processes to take place under adverse conditions. The aim of the present study was to investigate the use of Saccharomyces cerevisiae immobilized in activated sugarcane bagasse for the degradation of Acid Black 48 dye in aqueous solutions. For such, sugarcane bagasse was treated with polyethyleneimine (PEI). Concentrations of a 1 % S. cerevisiae suspension were evaluated to determine cell immobilization rates. Once immobilization was established, biodegradation assays for 240 h with free and immobilized yeast in PEI-treated sugarcane bagasse were evaluated by Fourier transform infrared spectrophotometry. The results indicated a probable change in the dye molecule and the possible formation of new metabolites. Thus, S. cerevisiae immobilized in sugarcane bagasse is very attractive for biodegradation processes in the treatment of textile effluents. © 2013 Springer Science+Business Media Dordrecht.

Although degradation data for herbicides are essential in understanding their potential to be contaminants and are indispensable inputs in computer-based modeling of their fate in environment, most available data only concern surface soils. Soil samples, collected at two depths from four representative sites of a 31.4-ha field located in Blue Earth County, MN, USA, were used to determine acetochlor dissipation under laboratory conditions. A field study was also carried out within a 16-ha watershed in Dakota County, MN, USA, where 38 locations were sampled to obtain sample representative of the full range of soil properties found within the watershed. Acetochlor DT50 values ranged from 6.51 to 13.9 days for surface soils and from 20.3 to 26.7 days for subsurface soils. DT90 values were a factor of four times longer than for DT50 values. Field DT50 values for acetochlor dissipation were not significantly different for the 2 years, 5.7 ±2.5 and 7.7±4.5 days. Dissipation was slightly faster in the field as compared to the laboratory; however, the difference seems insignificant in view of the wide range in soil properties inMinnesota. In both studies, acetochlor would be classified as slightly persistent. For acetochlor, laboratory dissipation studies can be considered representative of field dissipation for the soils and climatic conditions in this study. Inclusion of subsoil degradation data in mathematical models used for ground water risk assessment may improve their capability of predicting potential movement of acetochlor to groundwater. © Springer Science+Business Media Dordrecht 2013.

High mercury concentrations in freshwater fish from the Nordic region have been of concern for a long time. Ongoing monitoring of key ecological species occurs in these countries to follow the situation. Here, we investigated spatial and temporal trends in mercury concentrations in European perch (Perca fluviatilis) within the Swedish and Finnish aquatic environments, collated from national monitoring programmes collected between 1974 and 2005 (n = 5,172). Data were length and weight adjusted to remove perch size as a confounding factor. Temporal trend analyses and t tests comparing pre- and post-1996 mercury concentrations for each country (1974-1995; 1996-2005; perch adjusted to 200 g/25 cm), showed a significant decrease in mercury concentration in perch from Sweden (p < 0.001) and a possible increase in mercury concentration in perch from Finland (p < 0.001). No statistically significant geographical trends were seen. Average mercury concentrations exceeded both the current environmental quality standard (EQS) of 20 ng/g wet weight (ww) and a discussed EQS for the Nordic region of 200-250 ng/g ww. Despite large reductions in mercury use and production in these countries, concentrations in perch continue to be higher here than in other European areas, posing a continued environmental risk. © 2013 Springer Science+Business Media Dordrecht.

In this study, arsenate removal by apricot stone-based activated carbon (IAC) modified with iron (oxy-hydr)oxides was carried out. For this purpose, hybrid adsorbents based on Fe²⁺-loaded activated carbon (IAC–Fe(II)) and Fe³⁺-loaded activated carbon (IAC–Fe(III)) were synthesized by precipitation method. A three-level, three-factor Box–Behnken experimental design combined with response surface methodology (RSM) was employed to find the optimum combination of process parameters for maximizing the As(V) adsorption capacity of activated carbon-based iron-containing hybrid adsorbent. Three important operation parameters, namely, initial pH of solution (3.0–7.0), temperature (25–65 °C), and initial As(V) concentration (0.5–8.5 mg L⁻¹), were chosen as the independent variables, while the As(V) adsorption capacities of hybrid adsorbents were designated as dependent variables. Lack of fit test showed that the quadratic model provided the best fit to experimental data for both adsorbents with the highest coefficients of determination (R ²), adjusted R ², and p-values for lack of fit. The standardized effects of the independent variables and their interactions were tested by analysis of variance and Pareto chart. The model F-values (F IAC–Fₑ₍II₎=330.39 and F IAC–Fₑ₍III₎=36.19) and R ² values (R ² IAC–Fₑ₍II₎=0.9977 and R ² IAC–Fₑ₍III₎=0.9789) of second-order polynomial regression equations indicated the significance of the regression models. Optimum process conditions for As(V) adsorption onto IAC–Fe(II) were 63.68 °C, pH 3.10, and 8.4 mg L⁻¹ initial arsenic concentration, while 25.22 °C, pH 3.07, and 8.28 mg L⁻¹ initial As(V) concentration were found to be optimum conditions for IAC–Fe(III).

Quality of the essential commodity, water, is being compromised by contaminants originating from anthropogenic sources, industrial activities, agriculture, etc. Water scarcity and severe droughts in many regions of the world also represent a significant challenge to availability of this resource. Domestic rainwater harvesting, which involves collection and storage of water from rooftops and diverse surfaces, is successfully implemented worldwide as a sustainable water supplement. This review focuses on chemical and microbial qualities of domestic rainwater harvesting, with a particular focus on sources of chemical pollution and major pathogens associated with the water source. Incidences of disease linked to consumption and utilization of harvested rainwater are also discussed. In addition, various procedures and methods used for disinfection and treatment of harvested rainwater, such as implementation of filter systems (activated carbon, slow sand filtration, etc.), heat treatment, and chlorination, among others, are also presented.

The successive alkalinity-producing passive system (SAPPS) located in Gangneung, South Korea was designed to treat acid mine drainage. The performance of SAPPS has been monitored intensively for 3 years at the component level (influent, settling pond A, the successive alkalinity-producing system (SAPS), settling pond B, constructed wetland, and effluent). This study evaluated the ability of SAPPS to remove acidity and iron from influents at flow rates ranging from 17 to 160 m3/day. The concentration of soluble Fe total was the highest, and the pH was the lowest at low flow rates (≤61 m3/day). When flow rates were over 80 m3/day, concentrations decreased and Fetotal was removed primarily at the SAPS stage. For flow rates of less than 61 m3/day, Fetotal was removed at the SAPS stage as well as in settling pond B and at the constructed wetland. Hydraulic retention times of 1 and 2 days were found to be appropriate and economical for use with the SAPS stage and for settling pond B and the constructed wetland, respectively The treatment of acid mine drainage by conventional SAPPSs is limited by the availability of alkaline materials. However, the new proposed system can address this weakness through the provisioning of a suitable alkalinity supply. © 2013 Springer Science+Business Media Dordrecht.