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Long-Term Soil Reaction Changes in a Temperate Beech Forest Subject to Past Alkaline Pollution
2009
Pichler, Viliam | Homolák, Marián | Capuliak, Jozef
Changes in deposition exert effects on forests. Some evidence for a slow recovery of strongly alkalised forest soils after a reduction in alkaline pollution exists, but the recovery rate is little known. The objective of this study was to estimate temporal soil reaction changes. For this purpose, measurements of soil reaction under a beech forest near magnesite works in Central Slovakia were taken in 1991 and 2006, following the alkaline pollution reduction in 1992. As a result, the mean active soil reaction decreased from pH 7.8 to 6.6. Beyond the range of beech stemflow, which amplifies water and acid pollution inputs into soils locally, soil reaction dropped from pH 7.8 to 6.8. The effect of stemflow on local exchangeable reaction minima was detected even before the pollution reduction. The logarithmic function fitted on the pH data indicates considerable differences between neutralisation rates within and outside the stemflow zone.
Show more [+] Less [-]Evaluation of the Combined Cr(VI) Removal Capacity of Sawdust and Sawdust-Immobilized Acinetobacter haemolyticus Supplied with Brown Sugar
2009
Ahmad, Wan Azlina | Zakaria, Zainul Akmar | Razali, Firdausi | Samin, Jefri
The purpose of this study is to evaluate the combined Cr(VI) removal capacities of nonliving (untreated rubber wood sawdust, URWS) and living biomass (URWS-immobilized Acinetobacter haemolyticus) in a continuous laboratory scale downward-flow two column system. Synthetic solutions of Cr(VI) between 237 and 320 mg L⁻¹ were mixed with 1 g L⁻¹ brown sugar in a nonsterile condition. Final Cr(VI) of between 0 and 1.6 mg L⁻¹ indicate a Cr(VI) removal capacity of 99.8-100%. The bacterial Cr(VI) reduction capacity increased with column length. This study shows the feasibility of using the two column system consisting of living (bacteria) and nonliving biomass (URWS) as a useful alternative treatment for Cr(VI) contamination in the aqueous system.
Show more [+] Less [-]Biodegradation of High Concentrations of Benzene and Diesel in a Fixed-Film Reactor
2009
Bravo, Violeta | Spyra, Wolfgang | Antaño-López, René
The degradation of benzene in groundwater at concentrations as high as 2,000 mg L⁻¹ was studied using a four-column trickling-flow fixed-film biological reactor with recirculation. A decrease in the content of benzene was achieved, its concentration falling to 0.55 µg L⁻¹. On the contrary, high levels of diesel fuel were not diminished sufficiently with this mode of operation of the reactor. Thus, a submerged reactor was tested as a modification to the conventional trickling-flow configuration. This modified fixed-film reactor was effective when high loadings of diesel were present as an emulsion. The concentration of diesel was reduced from 2,000 to 0.12 mg L⁻¹ after 8 days of treatment. In both cases, the reactors were packed with a carbonaceous material and were operated in semibatch mode with recirculation. The final concentration of benzene fell below the permissible limit established by Mexican law, and the results for both pollutants also met the concentration limits required by the German law for drinking water, 0.001 mg L⁻¹ for benzene and 0.1 mg L⁻¹ for total hydrocarbons.
Show more [+] Less [-]In Situ Batch Denitrification of Nitrate-Rich Groundwater Using Sawdust as a Carbon Source—Marydale, South Africa
2009
Israel, S. | Engelbrecht, P. | Tredoux, G. | Fey, M. V.
Batch experiments were performed to denitrify groundwater using sawdust as a carbon source at Marydale, South Africa. Alkalinity, pH, electrical conductivity, nitrate, nitrite, ammonia, SO ₄ ²⁻ , heterotrophic plate count (HPC), dissolved organic carbon (DOC), potassium and chloride were monitored. Two soil depths, 75 to 100 and 165 to 200 cm, respectively, from the Marydale area were used as matrix material during denitrification based on contrasting chemical composition with respect to major ion composition and moisture to consider different denitrification rates for varying soil depths. Different N to C ratios were used to evaluate the denitrification efficiency and the least undesirable products, e.g., elevated SO ₄ ²⁻ , H₂S and other reduced compounds. DOC is directly proportional to the N to C ratio used. Nitrite was produced for most of the treatments as incomplete denitrification occurred. The incubation periods were 28 and 43 days, respectively. N to C ratios were 12.6:1, 24:1, 34:1 and 54:1. Longer incubation period and higher N to C ratio resulted in total removal of both nitrate and nitrite. The reaction was carbon-limited for lower N to C ratios. The denitrification rate was proportional to the carbon availability at any time during the experiment. There was no significant difference in denitrification using heterogeneous and homogeneous particle sizes for sawdust. Soil depth of 75-100 cm displayed a greater denitrification rate than 165-200-cm soil depth due to higher initial soil nitrate concentration. The method showed some specificity, as DOC, nitrite, nitrate, alkalinity and HPC were the only parameters that showed a change in concentration over the duration of the denitrification experiment under constant temperature and nitrogen gas atmosphere. DOC and HPC were unacceptable for domestic use, but methods such as boiling or chlorinating water can rid it of bacteria.
Show more [+] Less [-]Assessment of Bioconcentration Factor of Chromium by Instrumental Neutron Activation Analysis in Argyrodiaptomus falcifer Daday, a Subtropical Freshwater Copepod
2009
Gagneten, Ana María | Plá, Rita R. | Regaldo, Luciana | Paggi, J. C (Juan Cesar)
The objectives of this study were to determine the capacity of the freshwater calanoid copepod Argyrodiaptomus falcifer (Daday, 1905) to accumulate Cr from water, to know the bioconcentration factors in order to evaluate its potential as a biomonitor, and to compare this with data previously obtained with Daphnia magna Straus under identical conditions. By static bioassays using triplicates and a control, a pool of A. falcifer was exposed to three concentrations of Cr (VI): 150 μg/L (T1), 280 μg/L (T2), and 350 μg/L (T3) for 48 h to later determine by Instrumental Neutron Activation Analysis the amount of Cr accumulated. A. falcifer accumulated Cr in all the three concentrations tested. The comparison of T1, T2, and T3 and the control showed significant differences (p < 0.05) but not between the treatments (p > 0.05). On the other hand, A. falcifer accumulated more Cr than D. magna, but these differences were not significant (p > 0.05). Almost no information is available about metal toxicity in freshwater copepods so the reported results are of high importance in order to detect good biomonitors of freshwater Cr-polluted environments.
Show more [+] Less [-]A Peat Profile Record of Recent Environmental Events in the South Pennines (UK)
2009
Hutchinson, Simon M. | Armitage, Richard P.
This study investigates the impact of accidental fires and the record of recent environmental change held within a long peat core taken on Burbage Moor in the south Pennines (UK). The core has been subjected to mineral magnetic, heavy metal (via inductively coupled plasma-optical emission spectroscopy) and radiometric analyses. It may be subdivided into three zones reflecting the infilling of a basin-like depression and reveals pre-industrial conditions and the impact of recent atmospheric particulate pollution. Peak concentrations of heavy metals are relatively high (e.g., peak Pb concentration is 1,124 mg kg⁻¹). However, the mineral magnetic and heavy metal depth profiles may have been affected by post-depositional changes. The core has been influenced by drainage and a number of moor fires. The area was extensively burnt in 1976, though assessing the impact of this event is problematic, due to the perturbed nature of the profile and the inability to provide a reliable chronology.
Show more [+] Less [-]Simulated Summertime Regional Ground-Level Ozone Concentrations over Greece
2009
Poupkou, Anastasia | Melas, Dimitrios | Ziomas, Ioannis | Symeonidis, Panagiotis | Lisaridis, Iraklis | Gerasopoulos, Evangelos | Zerefos, Christos
Ground-level ozone concentrations were estimated for Greece during a summer period of the year 2000 using the regional air quality model UAM-V off-line coupled with the mesoscale meteorological model MM5. An anthropogenic NOx, NMVOCs and CO emission inventory and biogenic NMVOCs emission data were used to support model simulations. The evaluation analysis indicates a quite satisfactory model performance in reproducing ozone levels. The simulated mean ozone concentrations are above the 32-ppb EU phytotoxicity limit over almost all continental and maritime areas of Greece. Over the greater part of the country, the background mean ozone levels range from 40 to 55 ppb. Ozone values higher than the 55-ppb EU human health protection limit reaching 60 ppb dominate part of the southern Aegean Sea that is influenced by the Athens urban plume. In the areas where anthropogenic emission densities are high, the mean ozone levels vary between 20 and 40 ppb. Over the greater part of Greece, the simulated mean daily maximum ozone concentrations range from 50 to 65 ppb. More enhanced maximum ozone concentrations up to 95 ppb mainly dominate over the greater areas of the two largest Greek urban centres (Athens and Thessaloniki) and over the continental and maritime areas south of Athens which are under the influence of the urban plume.
Show more [+] Less [-]Amphoteric Surfactants for PAH and Lead Polluted-Soil Treatment Using Flotation
2009
Mouton, Julia | Mercier, Guy | Blais, Jean-François
Polluted soils are a problem of major concern impacting the health of the global environment and human beings. Without any safe technology for polluted soil treatment, most of the contaminated soils go to landfill especially when metals are the pollutants. This research compares the performance of non ionic (Brij 35 and Tween 80) and amphoteric (cocamydopropyl hydroxysultaine (CAS) and coamydopropylbetaine (BW)) surfactants for polycyclic aromatic hydrocarbons (PAHs) and metals (mainly Pb) removal from three contaminated soils. Best removal yields have been obtained using 0.5% (w/w) of CAS surfactant with 46 ± 2% for PAHs and 21 ± 5% for Pb simultaneously removed. Sodium chloride and EDTA have been shown to considerably enhance Pb solubilization (respectively 55 ± 5% and 35 ± 12% for [NaCl] = 5.5 M and [EDTA] = 0.025 M). Flotation technology has been tested as a separating technique of PAHs micelles and Pb from aqueous solution and has given good results for both contaminants (54 ± 7% for both PAH and Pb, using [CAS] = 0.5%, [NaCl] = 5.5 M, pH = 3). Finally, this study proposes a soil washing process using flotation to treat soil polluted with both organic and inorganic compounds. The suggested process concentrates the organic compounds in the froth and the inorganic pollutants in the liquid fraction.
Show more [+] Less [-]Characterizing Uncertainties Associated with Contaminant Transport Modeling through a Coupled Fuzzy-Stochastic Approach
2009
Qin, X. S. | Huang, G. H.
A factorial-design-based fuzzy-stochastic modeling system (FFSMS) was developed in this study to systematically investigate impacts of uncertainties associated with hydrocarbon contaminant transport in subsurface through integration of a compositional model, factorial design method, fuzzy modeling approach and Monte Carlo simulation technique. The goodness of fit of the numerical model was analyzed by means of a pilot-scale experimental system. Once the model was calibrated, it was used in order to predict the contaminant concentration depending on values of several parameters including intrinsic permeability, porosity, and longitudinal dispersivity. These parameters were imprecisely known, and such an imprecision was handled by means of both fuzzy sets and/or stochastic theory. The individual and joint effects of these uncertain parameters were analyzed by modeling the dependence between the prediction and the imprecise parameters (factors) through factorial design analysis. The study results indicated that the uncertainties associated with input parameters had significant impacts on modeling outputs; the degree of influence of each model input varied significantly with the level of its imprecision. The study results demonstrated that proposed FFSMS can efficiently analyze the impact of different uncertainty sources associated with different hydrogeological parameters on the prediction of the hydrocarbon concentrations in groundwater. Such studies would provide strong basis for performing successful risk assessment and efficient remediation design for the management of contaminated site.
Show more [+] Less [-]Reuse of Stormwater for Watering Gardens and Plants Using Green Gully: A New Stormwater Quality Improvement Device (SQID)
2009
Begum, Sharmina | Rasul, M. G
This paper introduces a new stormwater quality improvement device, called the "Green Gully" that collects, purifies, and reuses stormwater throughout an automated system. The working principal of the Green Gully is divided into two parts. Firstly, diverting stormwater from roadways to the diverter channel by filtering litter and secondly, watering the gardens and roadside plants with the stormwater that is collected from diverter channel. Stormwater treatment is an important step before reusing the water for gardening purpose. Different treatment levels (primary, secondary, and tertiary) are applied depending on the application to make water suitable for long-term storage and watering purposes. In this study, stormwater samples from three sites of Rockhampton City have been tested and analyzed to determine the quality of water for reuse. The parameters tested were electrical conductivity, pH, salinity, concentration of oil and grease, total suspended solid, turbidity, alkalinity, sodium, and chloride. The results of on-site stormwater quality tests are compared with the Australian and New Zealand Environment Conservation Council (ANZECC) standards and quality data available in the literature for each parameter suitable for irrigating roadside plants and gardening. Although, the results of this study is comparable with the literature data, a significantly different quality data are found compared to ANZECC standards. However, the samples collected for this study gave a basic understanding of stormwater quality issues for potential inflows to the Green Gully. Further study is recommended in order to establish mathematical link between raw stormwater quality and water quality required for gardening and irrigating roadside plants and for adopting required level of treatment facility with Green Gully for purifying and reusing water through an automated network system.
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