Bioremediation of tributyltin contaminated sediment: degradation enhancement and improvement of bioavailability to promote treatment processes

Bioremediation of tributyltin (TBT) contaminated sediment was studied and degradation enhancement and improvement of bioavailability were also investigated. In TBT spiked sediment, the half-life of TBT in the control sample, representing natural attenuation, was 578 d indicating its persistence. In the stimulated sample (pH 7.5, aeration and incubated at 28 °C), the half-life was significantly reduced to 11 d. Further stimulation by nutrient addition (succinate, glycerol and l-arginine) or inoculation with Enterobacter cloacae (∼10⁷ viable cells g⁻¹ of sediment) resulted in half-life reduction to 9 and 10 d, respectively. In non-spiked sediment, the indigenous microorganisms were able to degrade aged TBT, but the extended period of contamination decreased the degradation efficiency. To improve bioavailability, addition of surfactant, adjustment of salinity and sonication were studied. The highest percentage solubilisation of TBT in water was obtained by adjusting salinity to 20 psu, which increased the solubility of TBT from 13% to 33%. Half-lives after bioavailability was improved were 5, 4 and 4 d for stimulation, stimulation w/nutrient addition and stimulation w/inoculation, respectively. However, natural attenuation in the control sample was not enhanced. The results show that providing suitable conditions is important in enhancing TBT biodegradation, and bioavailability improvement additionally increased the rate and degraded amount of TBT. Unfortunately, nutrient addition and inoculation of the degrader did not enhance the degradation appreciably.     

Electrochemical oxidation of bisphenol A. Application to the removal of bisphenol A using a carbon fiber electrode

Leachate samples with a high strength of ammonium-nitrogen (NH4+-N) were collected from a local landfill site in Hong Kong. Two experiments were carried out to study (1) the inhibition of microbial activity of activated sludge by NH4+-N and (2) the chemical precipitation of NH4+-N from leachate as a preliminary treatment prior to the activated sludge process. The experimental results demonstrated that the efficiency of COD removal decreased from 97.7% to 78.1%, and the dehydrogenase activity of activated sludge decreased from 9.29 to 4.93 microg TF/mg MLSS, respectively, when the NH4+-N concentration increased from 53 to 800 mg/l. The experiment also demonstrated that the NH4+-N in the leachate can be quickly precipitated as MgNH4PO4 x 6H2O after addition of MgCl2 x 6H2O + Na2HPO4 x 12H2O. The NH4+-N concentration was reduced from 5618 to 112 mg/l within 15 min when a molar ratio of Mg2+:NH+:PO4(3-) = 1:1:1 was used. The optimum pH to reach the minimum solubility of MgNH4PO4 x 6H2O was found to be in the range of 8.5-9.0. Attention should be given to the high salinity formed in the treated leachate by using MgCl2 x 6H2O + Na2HPO4 x 12H2O, which may affect microbial activity in the following biological treatment processes. Using two other combinations of chemicals [MgO + 85%H3PO4 and Ca(H2PO4)2 x H2O + MgSO4 x 7H2O] could minimise salinity generation after precipitation, while they were less efficient for NH4+-N removal.     

Comparative study of extraction methods for the determination of PAHs from contaminated soils and sediments

The following four methods were compared on the extraction efficiency of 16 EPA (US Environmental Protection Agency) polycyclic aromatic hydrocarbons (PAHs): German method of the Verband Deutscher Landwirtschaftlicher Untersuchungs und Forschungsanstalten (VDLUFA), two methods of the International Organization for Standardization using shaking (ISO A) and Soxhlet extraction (ISO B) and an ultrasonic method. Recovery rates of 16 PAHs were determined in two soils. Extraction efficiency was evaluated in five soils and three sediments. Effect of drying soils and sediments on extraction efficiency was tested using the VDLUFA and the ultrasonic methods. Our study shows that the number of aromatic rings, rather than extraction procedures, significantly influenced recovery rates of individual PAHs. No significant differences in extraction efficiency of the four methods were observed for less polluted samples. For highly polluted soils, extraction efficiency decreased in the following order: VDLUFA method > ISO A > ultrasonic method > ISO B. Influence of soil moisture on extraction efficiency depended to some extent on both solvent used and content of PAHs in samples. A mixture of dichloromethane/acetone (5:1) is recommended for PAH extraction from moist samples when the ultrasonic method is used.     

Distribution of polycyclic aromatic hydrocarbons in agricultural soils in South Korea

The content and type of polycyclic aromatic hydrocarbons (PAH) in soils from paddy fields and upland areas in South Korea were determined using gas chromatography linked to mass spectrometry (GC–MS). The distribution map of total PAH content was obtained as a contour plot using a geographical information system. The overall distribution of PAH was found to be closely related to the pollution sources, the size of city and the type of industry. The average content of total PAH in all samples was 236 μg kg⁻¹, and the range was from 23.3 to 2834 μg kg⁻¹. The highest concentrations were found in soils sampled near iron processing plants. The concentration of PAH decreased in the order fluoroanthene>benzo(b)fluoroanthene>pyrene. Special PAH compound ratios, such as phenanthrene/anthracene and fluoroanthene/pyrene, were calculated to evaluate the origin. The collected data suggested that the pyrogenic origins such as motor vehicle exhaust and heavy industry emission were the dominant source of PAH in Korean soils.     

The sensitivity of surface waters of Great Britain to acidification predicted from catchment characteristics

Using a combination of soil, land use and geological information, a map of Great Britain has been derived which indicates the sensitivity of surface waters to acidification. For the geological information, a slightly modified version of an available map was used which indicated the sensitivity of groundwaters to acidification. For soils, 1-km databases of soil information for England and Wales and for Scotland were employed to map the soil sensitivity as determined by buffering capacity. The derived soils map was modified to take account of agricultural liming in arable and managed grassland areas using the ITE Land Classification. The final map of surface water sensitivity was obtained by using a geographic information system overlay procedure which enabled each combination of soil and geology sensitivity to be uniquely defined. The final sensitivity classification was based upon expert knowledge and the experience of a similar sensitivity mapping exercise for Wales.     

Evaluating the effectiveness of marine actinobacterial extract and its mediated titanium dioxide nanoparticles in the degradation of azo dyes

Aim of the present study was to synthesize titanium dioxide nanoparticles （YiO2 NPs） from marine actinobacteria and to develop an eco-friendly azo-dye degradation method. A total of five actinobacterial isolates were isolated from Chennai marine sediments, Tamilnadu, India and analyzed for the synthesis of TiO2 NPs using titanium hydroxide. Among these, the isolate PSV 3 showed positive results for the synthesis of TiO2 NPs, which was confirmed by UV analysis. Further characterization of the synthesized TiO2 NPs was done using XRD, AFM and FI＇-IR analysis. Actinobacterial crude extract and synthesized TiO2 NPs was found efficient in degrading azo dye such as Acid Red 79 （AR-79） and Acid Red 80 （AR-80）. Degradation percentage was found to be 81% for AR-79, 83% for AR-80 using actinobacterial crude extract and 84% for AR-79, 85% for AR-80 using TiO2 NPs. Immobilized actinobacterial ceils showed 88% for AR-79 and 81% for AR- 80, dye degrading capacity. Degraded components were characterized by FT-IR and GC-MS analysis. The phytotoxicity test with 500 μg/mL of untreated dye showed remarkable phenotypic as well as cellular damage to Tagetes erecta plant. Comparatively no such damage was observed on plants by degraded dye components. In biotoxicity assay, treated dyes showed less toxic effect as compared to the untreated dyes.     

Importance of Sediment–Water Interactions in Coeur d’Alene Lake,Idaho, USA: Management Implications

A field study at Coeur dAlene Lake, Idaho, USA, was conducted between October 1998 and August 2001 to examine the potential importance of sediment–water interactions on contaminant transport and to provide the first direct measurements of the benthic flux of dissolved solutes of environmental concern in this lake. Because of potential ecological effects, dissolved zinc and orthophosphate were the solutes of primary interest. Results from deployments of an in situ flux chamber indicated that benthic fluxes of dissolved Zn and orthophosphate were comparable in magnitude to riverine inputs. Tracer analyses and benthic-community metrics provided evidence that solute benthic flux were diffusion-controlled at the flux-chamber deployment sites. That is, effects of biomixing (or bioturbation) and ground-water interactions did not strongly influence benthic flux. Remediation efforts in the river might not produce desired water-quality effects in the lake because imposed shifts in concentration gradients near the sediment–water interface would generate a benthic feedback response. Therefore, development of water-quality models to justify remediation strategies requires consideration of contaminant flux between the water column and underlying sediment in basins that have been affected by long-term (decadal) anthropogenic activities.     

Influence of water treatment residuals on phosphorus solubility and leaching

Laboratory and greenhouse studies compared the ability of water treatment residuals (WTRs) to alter P solubility and leaching in Immokalee sandy soil (sandy, siliceous, hyperthermic Arenic Alaquod) amended with biosolids and triple superphosphate (TSP). Aluminum sulfate (Al-WTR) and ferric sulfate (Fe-WTR) coagulation residuals, a lime softening residual (Ca-WTR) produced during hardness removal, and pure hematite were examined. In equilibration studies, the ability to reduce soluble P followed the order Al-WTR > Ca-WTR = Fe-WTR > hematite. Differences in the P-fixing capacity of the sesquioxide-dominated materials (Al-WTR, Fe-WTR, hematite) were attributed to their varying reactive Fe- and Al-hydrous oxide contents as measured by oxalate extraction. Leachate P was monitored from greenhouse columns where bahiagrass (Paspalum notatum Flugge) was grown on Immokalee soil amended with biosolids or TSP at an equivalent rate of 224 kg P ha(-1) and WTRs at 2.5% (56 Mg ha(-1)). In the absence of WTRs, 21% of TSP and 11% of Largo cake biosolids total phosphorus (PT) leached over 4 mo. With co-applied WTRs, losses from TSP columns were reduced to 3.5% (Fe-WTR), 2.5% (Ca-WTR), and <1% (Al-WTR) of applied P. For the Largo biosolids treatments all WTRs retarded downward P flux such that leachate P was not statistically different than for control (soil only) columns. The phosphorus saturation index (PSI = [Pox]/ [Al(ox) + Fe(ox)], where Pox, Al, and Fe(ox) are oxalate-extractable P, Al, and Fe, respectively) based on a simple oxalate extraction of the WTR and biosolids is potentially useful for determining WTR application rates for controlled reduction of P in drainage when biosolids are applied to low P-sorbing soils.     

Evaluating Infiltration Requirements for New Development Using Extreme Storm Transposition: A Case Study from Dane County,WI

Changes in land use and extreme rainfall trends can lead to increased flood vulnerability in many parts of the world, especially for urbanized watersheds. This study investigates the performance of existing stormwater management strategies for the Upper Yahara watershed in Dane County, WI to determine whether they are adequate to protect urban and suburban development from an extreme rainfall. Using extreme storm transposition, we model the performance of the stormwater infiltration practices required for new development under current county ordinances. We find during extreme rainfall the volume of post‐development runoff from impervious surfaces from a typical site would increase by over 55% over pre‐development conditions. We recommend the ordinance be strengthened to reduce vulnerability to flooding from future urban expansion and the likely increase in the magnitude and frequency of extreme storms.     

Effects of Acidification and its Mitigation with Lime and Wood Ash on Forest Soil Processes: A Review

Anthropogenic acid deposition causes forest soil acidification and perturbation of the soil forming processes. The impact of soil acidification on tree growth is discussed in view of the role of mycorrhizal fungi in weathering and nutrient uptake. A review has been carried out of experiments involving treatments of forest soil by lime and wood ash, where soil properties and soil solution composition have been investigated. Results from these experiments in Europe and North America are summarized. In general, the content of C in the mor layer decreased as a result of treatment due to higher microbial activity and soil respiration as well as increased leakage of DOC. In addition, the content of N in the mor layer, in general, decreased after treatment and there are occasional peaks of high NO₃concentrations in soil solution. In nearly all reviewed investigations the pH of the deep mineral soil solution decreased and Al, SO₄and NO₃concentrations increased after treatment. These effects are probably due to the high ionic strength and increased microbial activity as a consequence of the treatments. In the soil, pH, CEC and base saturation increased in the upper horizons, but decreases in the upper mineral soil are also reported. In general, there was no increase in tree growth as a result of these treatments. The positive effects of the treatments on soil processes and tree growth are therefore questionable. In view of these conclusions, an investigation was carried out on the soil and soil solution chemistry and the role of mycorrhizal fungi in a spruce stand treated with two doses of lime and another treated with lime/ash in southern Sweden. The results of this investigation is reported in this volume.