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.

Previous research demonstrated that nutrient treatment in conventionally drained bioretention cells is dependent upon temperature and varying wetting and drying regimes in the media. This study examines the influence that previous events have on outflow concentrations by analyzing flow-weighted composite samples from four to six consecutive events during three different seasons for two sets of field-monitored bioretention cells in Nashville, NC. The bioretention cells had different media depths (0.6-m versus 0.9-m). As a means to analyze performance from consecutive events, the evolution of cumulative pollutant loads was presented by plotting cumulative load versus cumulative volume. This method of presenting water quality data allows for the direct analysis of event mean concentrations, load reduction, and volume reduction with one graph, as well as describing the seasonal impacts and impacts from consecutive events. Runoff and outflow concentrations were also correlated to media temperature and rainfall characteristics. The overall results of this study showed that conventionally drained bioretention cells mainly convert organic nitrogen, the predominant source of nitrogen in runoff, into nitrate in the aerobic environment present in the media. Nitrate is then exported from the media during subsequent events. The greatest export occurred during the warmer months because higher media temperatures increased microbial activity. Pollen and leaf litter were identified as organic nitrogen and total phosphorus sources because of elevated runoff concentrations that occurred in the spring and autumn. Based on these results, future bioretention studies should strongly consider monitoring consecutive events and this method of data analysis, as they reveal internal processes and allow researchers to draw conclusions that independent event monitoring could not.

This study investigates the potential impact of OSPW (oil sands processed water) in terms of naphthenic acids (NAs) in the event that OSPW which contain NAs were discharged to a stretch of the Athabasca River of Alberta, Canada. A one-dimensional model WASP7 (water quality analysis simulation programme) was hydro-dynamically calibrated and validated for the data 1999-2008. The model represented the field data quite well except frozen seasons. The sensitivity analysis showed that the concentrations of NAs in the Athabasca River due to OSPW discharged to the river will be most sensitive to changes in the discharge rate of OSPW and concentrations of NAs in the OSPW. The WASP7 was applied to investigate how to achieve acceptable concentrations of NAs (≤0.15 mg/L) along the river, assuming NAs are degraded by natural dilution, biodegradation, sorption, photodegradation or combinations of these processes. If only the dilution effect is considered for an OSPW discharged at 1.5, 3.0 and 4.5 m 3/s (initial NAs concentration of 120 mg/L) to the river, respectively, all the NAs concentrations simulated would exceed an allowable limit of ≤0.15 mg/L, which indicates that dilution effect alone is not sufficient to decrease the concentration of NAs in the river. Similarly, by only considering a photodegradation rate of 0.005/day, the concentrations of NAs would decrease by approximately 0.1-3 %. However, by only considering a maximum biodegradation rate of 0.4/day, NAs discharged to the river can be decreased by 5-90 %. If a more moderate biodegradation rate of 0.2/day is assumed but photodegradation is also considered at 0.0025/day, then for the same three discharge rates of OSPW to the river, the allowable OSPW NAs have to be limited to 8.02, 4.09 and 2.77 mg/L to limit NAs at 0.15 mg/L. This implies that high biodegradation itself is more effective than a combination of moderate biodegradation and photodegradation in degrading NAs. Through multiple numerical experiments with WASP7, it seems that to limit the concentrations of the final NAs in the Athabasca River within 0.15 mg/L, it will be crucial to limit the OSPW NAs and the OSPW discharge rate to the river. © 2013 Springer Science+Business Media Dordrecht.

Bottom slag and sewage sludge discharged from municipal solid waste incineration and sewage treatment plants were co-sintered for use as a cost-effective adsorbent for phosphate removal from aqueous solutions. The Langmuir isotherm model (which gives a better description of phosphate sorption than the Freundlich model) was adopted to describe the action of the synthesized adsorbent and also for phosphate sorption by either zeolite or ironstone. The model showed that the maximum sorption capacity of the synthesized adsorbent (27,030 mg kg-1) was 38.2 greater than for zeolite and 70.6 times greater than for ironstone. Desorption of phosphate from the synthesized adsorbent at different initial concentrations was about 4.98 %, which was several times lower than for zeolite. The phosphate removal capacity of the synthesized adsorbent remained constant for solution pH values ranging from 3 to 10, which was an improvement on the capacity of the other two adsorbents; its buffering capacity was also superior. The immobilization of phosphate on the synthesized adsorbent might be attributed mainly to complexation with Fe, Al, and Ca ions. Heavy metal ion concentrations in the leachate of the synthesized adsorbent were negligible. © 2013 Springer Science+Business Media Dordrecht.

Adsorption by low-cost adsorbents and biosorbents is recognized as an effective and economic method for low-concentration heavy metal. The purpose of this study was to investigate the possibility of the utilization of N,N′-bis(2, 5-dihydroxybenzylidene)-1, 4-diaminobenzene (DHDB)-immobilized sporopollenin (Schiff base-immobilized sporopollenin, Sp-DHDB) as a sorbent for removal of lead (II) ion from aqueous solution. The effects of different parameters (such as sorbate concentration, sorbent dosage, and pH of the medium) were investigated by differential pulse anodic stripping voltammetry (DPASV) technique. The experimental data were analyzed by the Freundlich, Langmuir, and Dubinin–Radushkevich (D–R) isotherms. Equilibrium data fitted well with the Freundlich model and the procedure developed was successfully applied for the removal of lead ions in aqueous solutions. This investigation reveals a new, simple, environmentally friendly, and cost-effective method for the removal of lead ions from aqueous solutions by a new Sp-DHDB material.

Japan has been receiving increasing levels of atmospheric nitrogenous pollutants from the East Asian continent over the last few decades, so it is critical to evaluate the impact of this increased atmospheric nitrogen (N) deposition on N cycling even in rural forests. This study evaluated the contribution of the current level of atmospheric N deposition to N cycling in a rural forested area. Bulk precipitation and stream water were collected during 2007-2011 at the Shiiba Research Forest (SRF) located in the central Kyushu mountain range of southern Japan. Litterfall was also collected to investigate the contribution of atmospheric N deposition to total N input (litterfall N + atmospheric N deposition). The results showed that atmospheric depositions of both nitrate (NO3 -) and ammonium (NH4 +) were a few times higher during 2009-2011 than in 1991. This could be the result of additional N deposition from the increased long-range transport of nitrogenous pollutants from the East Asian continent. The current level of annual N deposition (9.7 kg N ha-1 year-1) at the SRF was comparable with that at many urban sites and was close to the reported threshold values causing N saturation in forest ecosystems. Although current atmospheric N deposition was an important component (23 %) of total N input (43 kg N ha -1 year-1) at the SRF, the concentrations of NO 3 - in stream water were consistently low (<10 μmol L-1). These results indicate that atmospheric N deposition is currently largely incorporated into forest ecosystems without excess N export from forested watersheds. © 2013 Springer Science+Business Media Dordrecht.

The performance of the Purolite A847 weak basic anion exchanger in the simultaneous removal of the azo dye Lanasyn Navy M-DNL (LNCr) and the phthalocyanine dye Acid Blue 249 (CuPc) from acidic aqueous solutions was studied under dynamic conditions. The comparison of FTIR spectra of unloaded and dye-loaded anion exchangers made it possible to consider suitable sorption mechanisms. The results of dynamic experiments revealed that anion exchanger had a greater dynamic sorption capacity with a longer breakthrough time and a shorter length of mass transfer zone when both dyes LNCr and CuPc were removed from the one-component solution as compared to those of their mixture. Models of Wolborska and Juang were found to be suitable to predict the character of breakthrough curves and to determine the characteristic parameters of the Purolite A847 column useful for process design: the mass transfer coefficient β (1/min) and time at the break point τ (minutes). The result would be useful in the design of wastewater treatment plants for removal of azo and phthalocyanine dyes from aqueous solutions and water recycling.

The processes affecting adsorption of molybdenum (Mo) in alkaline industrial soils are not well known, as most research on Mo fate and transport has focused on agricultural soils. In this work, we performed studies of soil extraction, as well as sorption studies using both batch and stirred-flow cell approaches. After 60 h of extraction, we observed, even where three extractable fractions were present, 14.1 % of the bound residue was extracted by CaCl 2 solution. This indicates that the procedures recommended by the Commission of European Communities Bureau of Reference, which is targeted to metals cations, not anions due to the use of extractants at acidic pH, are not a suitable approach for assessing mobility and availability of Mo in alkaline soils. Because the observed extent of Mo adsorption onto two Fe minerals, goethite, and amorphous iron hydroxide (HFO) was 2 to 3 orders of magnitude higher than that onto the soil, soils amended with these Fe minerals were found to have a higher Mo adsorption capacity, with HFO yielding stronger sorption than goethite. The additivity principle was successfully used to predict Mo adsorption with the HFO-amended soil but failed to do so for the goethite-amended soil. The best fit sorption isotherms and estimated parameters were slightly different from batch and flow cell experiments. The Kd values of sorption coefficient in our industrial soils and Fe-minerals-amended soils ranged from 0.19 to 1.45 L/kg from both experimental approaches; this low adsorption potential renders it infeasible to immobilize Mo into the soilmatrix and reduce Mo availability by amending the soil with Fe minerals. In the future, materials with potentially high Mo adsorption capacities should be identified, screened, and characterized for permeable reactive barriers application. © Springer Science+Business Media Dordrecht 2013.

Spatial accuracy of hydrologic modeling inputs influences the output from hydrologic models. A pertinent question is to know the optimal level of soil sampling or how many soil samples are needed for model input, in order to improve model predictions. In this study, measured soil properties were clustered into five different configurations as inputs to the Soil and Water Assessment Tool (SWAT) simulation of the Castor River watershed (11-km² area) in southern Quebec, Canada. SWAT is a process-based model that predicts the impacts of climate and land use management on water yield, sediment, and nutrient fluxes. SWAT requires geographical information system inputs such as the digital elevation model as well as soil and land use maps. Mean values of soil properties are used in soil polygons (soil series); thus, the spatial variability of these properties is neglected. The primary objective of this study was to quantify the impacts of spatial variability of soil properties on the prediction of runoff, sediment, and total phosphorus using SWAT. The spatial clustering of the measured soil properties was undertaken using the regionalized with dynamically constrained agglomerative clustering and partitioning method. Measured soil data were clustered into 5, 10, 15, 20, and 24 heterogeneous regions. Soil data from the Castor watershed which have been used in previous studies was also set up and termed “Reference”. Overall, there was no significant difference in runoff simulation across the five configurations including the reference. This may be attributable to SWAT's use of the soil conservation service curve number method in flow simulation. Therefore having high spatial resolution inputs for soil data may not necessarily improve predictions when they are used in hydrologic modeling.

Natural palygorskite was used as an adsorbent for the removal of copper, cobalt and nickel from an aqueous solution. All assays were performed under controlled conditions to establish the adsorption capacity of the solid. Initially, the clay was characterized by chemical analysis, XRD, infrared spectroscopy and thermogravimetry. Adsorption experiments for the ions in aqueous solution were carried out by a batch method through which the reaction time, initial concentration of cations, temperature and pH of the aqueous solution were systematically varied. First-order, pseudo-second-order and intraparticle diffusion models were used to describe the kinetic data. The results show that the processes were fitted well by the pseudo-second-order model. Moreover, the equilibrium solid–cation systems followed the Langmuir isotherm model. The results indicate that raw palygorskite could be employed as a low-cost material for the removal of heavy metals from aqueous solution.