Electrokinetic remediation of heavy metal-polluted soil faces different challenges in relation to implementation. One challenge is to cope with the nonlinear and transient geochemical changes in the soil and another is to increase the remediation rate. Both these challenges are met when treating the soil in a suspension in an electrodialytic cell. The soil suspension is stirred and uniform during treatment. Previously, it has been shown that a faster remediation can be obtained when remediating a stirred soil suspension compared to a stationary water saturated soil (all other parameters the same). The present work shows that the method for treating stirred suspensions was robust in the sense that in 1-3 weeks, three of four soils were decontaminated from heavy metal concentrations, where the soils must be deposited to concentrations where the soil can be allowed used for some purposes in Denmark. From the fourth soil of the investigation, 92 % Pb was removed during 14 days, but as the initial concentration was very high (33.6 g Pb/kg), the final concentration was still high and the soil maintained classified where there are no reuse options in Denmark, so optimization of the treatment for this soil is necessary to meet the goal. The good results were obtained even without optimization of processing parameters, but the investigation underlined that the optimal parameters are highly soil and pollution specific. © 2013 Springer Science+Business Media Dordrecht.

Pathogens are the leading cause of water quality impairments as defined by the US Environmental Protection Agency and their transport within water bodies is poorly understood. Because of this, watershed-scale, water quality models often have poor bacterial prediction capabilities. To improve the understanding of in-stream bacterial transport, a cow pie was deposited in a recirculating flume with flows ranging from 0.0102 to 0.0176 m³ s⁻¹. Water samples were collected and analyzed for Escherichia coli concentration, E. coli attached fraction, and turbidity. E. coli concentrations ranged from 4.72 × 10³ to 1.70 × 10⁵ CFU 100 mL⁻¹ and turbidity ranged from 1.93 to 369 NTU over both locations and all times. The percentage of E. coli attached to particles ranged from an average of 2.9 to 31 % downstream of the fecal deposition point. Spearman correlation analysis demonstrated that bacteria concentrations were significantly related with water depth (ρ = 0.128, p = 0.018), and the concentration of attached bacteria was significantly correlated with both the total concentration of E. coli (ρ = 0.4081, p = 0.009) and turbidity (ρ = 0.3627, p = 0.0214). This analysis is useful to indicate parameters that should be considered when monitoring or predicting bacteria transport in streams.

Traces of short- and long-lived fallout ¹³⁴Cs and ¹³⁷Cs were found in surface soil (volcanic ash soil) under a cool-temperate deciduous stand at Tomakomai Experimental Forest in Hokkaido, Japan after the Fukushima nuclear accident in March 2011. Most of them were present in the uppermost 5–6 cm of the soil. Mean concentrations of ¹³⁴Cs and ¹³⁷Cs were found to be 2.4 (±0.3) and 89 (±2) Bq Kg⁻¹ in May, and 6.9 (±0.4) and 94 (±2) Bq Kg⁻¹ in November 2011, respectively. A small increase in radiocesium concentration may result from biological activity in the uppermost portion of the soil in which fallout nuclides derived from the Fukushima NPP would not have existed in May. They were supposed to be fallen down on the fresh litter layer in the previous year. The results of a sequential extraction experiment with 1 M CH₃COONH₄ solution showed that desorption of radiocesium from the soil was difficult and not simple ion exchange processes.

Adsorption potentials of native and amine-modified plant biomass of Alyssum caricum for the removal of Reactive Green 19 (RG-19) and Reactive Red 2 (RR-2) dyes from aqueous solutions were studied. The adsorbents were characterized before and after modification process using Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) and potentiometric titration analysis. Modification of the surface of A. caricum biomass with hexamethylenediamine (HMDA) showed an increase of 1.18-fold in its surface area. Batch studies illustrated that dye adsorption were highly dependent on different process variables, pH, initial dye concentration of solution, adsorbent dosage, and temperature. The maximum adsorption capacities of the native and amine-modified adsorbents were 27.6 and 63.4 mg/g adsorbent for RG-19 dye and 16.5 and 36.8 mg/g adsorbent for RR-2 dye, respectively. The adsorption of both dyes on the native and amine-modified plant biomass correlated well with the Langmuir and Temkin isotherm equations as compared to Freundlich and D-R equations. The calculated thermodynamic parameters for both native and amine-modified adsorbents showed that the adsorption was feasible, spontaneous, and exothermic. The information gained from these studies was expected to indicate whether native and amine-modified adsorbents can have potential to be used for the removal of other dyes from wastewaters. © 2013 Springer Science+Business Media Dordrecht.

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).

This paper addresses the geochemical evolution, volumetric water content, and temperature of porewater when constructing different soil layers to improve the surface acidic conditions on a slope at a closed mine. Three cases were set under different layer systems. Case 1 was solely composed of surface-weathered rocks. A vegetation layer was constructed on the surface rocks in case 2, whereas a top vegetation and bottom low-permeable layers were constructed on the rocks in case 3. In both cases, a soil–cement layer was constructed to prevent landslides. Porewater sampling systems and soil sensors were set at different depths to collect porewater and measure the volumetric water content and temperature. The results showed that, when no layers were applied (case 1), high concentrations of heavy metals and low pH values were observed regardless of the depth and season. When a vegetation layer (case 2) was applied, a dramatic decrease in heavy metal concentrations was observed, similar to the results in case 3. In both cases, pH values were circumneutral. Moreover, the addition of the low-permeable layer reduced the infiltration of rainfall through the layers by considering the changes in volumetric water content. Also, the results of case 1 were compared with those obtained at a flat surface under similar conditions. On the slope, the pH was more acidic, and heavy metal concentrations were higher. These suggest that the dissolution of heavy metals from the weathered rocks into the porewater is enhanced on the sloping surface due to a longer solid–liquid interaction time.

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).

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.

Antiviral drugs have been recently recognized as one of the emerging contaminants in the environment. These are discharged after therapeutic use through human excretion. Effluent containing high concentration of antiviral drugs discharged from production facilities is also a cause of concern to nearby aquatic bodies. There is an increased interest in their removal because they are highly bioactive. Some antiviral drugs are resistant to conventional methods of degradation, and there is a risk of development of antiviral resistance in humans and animals if exposed repeatedly for long periods. To date, the potential human, animal, and ecological risks associated with the discharge of these antiviral compounds to the environment are not well documented. This study presents a brief summary on occurrence, ecotoxicological risks, and physicochemical properties of antiviral drugs in the environment. The needs regarding removal, disposal, and treatment of antiviral drugs are also addressed.

Wetlands in mountain environments provide critical ecosystem services but are increasingly threatened by agricultural land use intensification. This study evaluates agricultural nonpoint source nutrient pollution transport in a wetland–stream–lake complex in a mountain, tussock grassland catchment in the South Island, New Zealand. Flow and water-quality monitoring in the Lake Clearwater catchment during three flow events from May to August 2010 (autumn high flow, winter low flow, and winter high flow) showed high concentrations and exceedances of water quality guidelines for total nitrogen (TN) and total phosphorus (TP) in small ephemeral streams draining agricultural land during high flows. Concentrations were attenuated through the wetlands to below guidelines, with the exception of TN which still remained slightly higher. Most TN was in the organic form above and below the wetland, suggesting N sources from animal waste/agricultural land and organic material and vegetation within the wetland. Most TP was particulate associated with suspended solids during high flows. Dissolved forms of N and P generally were below guidelines. Flows and loads (instantaneous and daily) increased at the lake outlet during winter high flow, indicating unaccounted sources to the lake from groundwater, the wetlands, or the lake sediments, and seasonal N saturation. Infiltration losses to shallow groundwater along the main perennial tributary likely re-appear as discharge to the wetlands and lake downstream. Surface–groundwater interactions play a dominant role in N transport to the wetland complex due to highly permeable soils and glacial alluvial deposits. Loads and unit loads of TN and TP were also elevated in the ephemeral streams. Results show that TN and TP concentrations and unit loads during high flows in ephemeral streams in this mountain grassland catchment are similar to, or higher than, values for impacted lowland pasture catchments. Although impacts to the wetland ecosystem have not been observed to date, the lake is shifting toward a mesotrophic state, and further research is needed to elucidate impacts of nutrient loads and help meet conservation and restoration goals.