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Microfauna Community as an Indicator of Effluent Quality and Operational Parameters in an Activated Sludge System for Treating Piggery Wastewater Full text
2009
Puigagut Juárez, Jaume | García, Joan | Salvadó, Humbert
In order to study the potential use of microfauna as an indicator of effluent quality and operational parameters in an activated sludge system for treating piggery wastewater, an experimental sequencing batch reactor was set up and evaluated by biological and physical-chemical analyses for 12 months. Results show that microfauna (and specifically ciliate protozoa) are a good parameter for assessing effluent quality in terms of both chemical oxygen demand (COD) and ammonia and for assessing the organic and nitrogen load of the system. Specifically, the abundance of ciliates decreases from 20,000 individuals·mL⁻¹ to ca. 2,500 individuals·mL⁻¹ and from ca. 10,000 individuals mL⁻¹ to ca. 200 individuals mL⁻¹ when effluent concentration is between 550 and 750 mg L⁻¹ and above 100 mg L⁻¹ to the COD and ammonia concentrations, respectively. Furthermore, microfauna abundance is reduced from ca. 18,000 individuals mL⁻¹ (organic load between 0.1 and 0.2 mg COD mg total suspended solids (TSS)⁻¹ day⁻¹) to ca. 500 individuals mL⁻¹ (organic load between 0.3 and 04 mg COD mg TSS⁻¹ day⁻¹). Microfauna abundance also decreases as nitrogen loading increases. Nitrogen loading in the range of 5-60 mg NH₄-N g TSS⁻¹ day⁻¹ does not have any significant effect on microfauna abundance. However, ammonia loading from 60 to 120 mg NH₄-N g TSS⁻¹ day⁻¹ reduces microfauna abundance ca. 6-fold. Ciliate protozoa were the largest microfauna group during the whole period of study, representing ca. 75% of the total microfauna abundance. The largest group in the ciliate community was that of the free-swimming ciliates. This was followed by the group of attached and crawling ciliates. Specifically, the dominant ciliate species during the whole study period were Uronema nigricans, Vorticella microstoma-complex, Epistylis coronata, and Acineria uncinata.
Show more [+] Less [-]Degradation Kinetics of an Aged Hydrocarbon-Contaminated Soil Full text
2009
Maletić, Snežana | Dalmacija, Božo | Rončević, Srđan | Agbaba, Jasmina | Petrović, Olgica
This work presents kinetic parameters for the degradation of petroleum hydrocarbons, under field conditions found in a biopile created for the remediation of soil which has been heavily polluted with aged oil and oil derivatives (27,600 mg kg⁻¹ of mineral oil, 41,400 mg kg⁻¹ total hydrocarbons and 3.57 mg kg⁻¹ of total polycyclic aromatic hydrocarbon, (PAH)). The kinetics of the biodegradation process can be described by two equations: [graphic removed] (1) and [graphic removed] (2). According to Eq. 1, biodegradation kinetics constant rates were in the range from 0.58 x 10⁻³ to 1.32 x 10⁻³ day⁻¹ for mineral oil and total hydrocarbons and 6.7 x 10⁻³ to 8.8 x 10⁻³ day⁻¹ for PAHs. According to Eq. 2, biodegradation kinetics constant rates were in the range from 1.6 x 10⁻² to 3.0 x 10⁻² day⁻⁰.⁵ for mineral oil and total hydrocarbons and 0.92 x 10⁻¹ to 1.3 x 10⁻¹ day⁻⁰.⁵ for PAHs.
Show more [+] Less [-]Comparison Between New Wild Plant Trifolium repens and Vicia faba on their Sensitivity in Detecting the Genotoxic Potential of Heavy Metal Solutions and Heavy Metal-Contaminated Soils Full text
2009
Manier, Nicolas | Deram, Annabelle | Le Curieux, Frank | Marzin, Daniel
The DNA damage and cytotoxicity induced by CdCl₂ solutions and soils anthropogenically contaminated with heavy metals were studied using the micronucleus (MN) test. Vicia faba, a plant model widely used in liquid exposure assays, was adapted for direct exposure to a solid phase. In addition, the MN assay was adapted to a new wild plant system, the white clover (Trifolium repens). The results obtained after exposure to CdCl₂ solutions confirmed that V. faba root cells were a sensitive model and revealed that T. repens root cells were not appropriate for the detection of micronuclei (although they were highly sensitive to the cytotoxic effect of CdCl₂). Concerning the results observed after direct exposure to contaminated soils (solid-phase exposure), the MN frequency scores in V. faba root cells were increased in a statistically significant and dose-related manner compared to the control plants. Regarding T. repens root cells, this solid phase exposure confirmed that this model is not appropriate for use in the micronucleus assay.
Show more [+] Less [-]An Environmental Risk Assessment of Radon in Lantian Karst Cave of Shaanxi, China Full text
2009
Lu, Xinwei | Li, Loretta Y. | Zhang, Xiaolan
The radiation dose and environmental health risk of radon concentration in the Lantian karst cave of China to guides and visitors were estimated based on the continuous radon concentration monitoring. Distinct seasonal variations were observed in the radon concentration of the air inside the cave. The maximum concentration occurred in the summer, whereas the minimum radon concentration occurred during the winter. The annual average radon concentration in the caves investigated is slightly higher than the upper bound of radon action level for underground space used in China and less than the upper bound of radon action level recommended by the International Commission on Radiation Protection (ICRP) for workplaces. The annual effective dose to tour guides working in two investigated caves varies from 4.1 to 16.5mSv, depending on different equilibrium factors together with different dose conversion factors proposed in the literature. The annual maximum time that a tour guide or other worker can safely be inside the cave is estimated to be 1,250 or 2,246h, depending on whether one bases this on the high or mean radon concentration, with an equilibrium factor of one in both cases. Given the synergistic effects of smoking, tour guides who are smokers should be in the cave only 10-20% of these hours. In all cases, the annual effective doses to visitors are well below the 1mSv maximum suggested dose for a member of the public for 1 year.
Show more [+] Less [-]Characterization of Granulometric and Chemical Composition of Sediments of Barigui River Samples and their Capacity to Retain Polycyclic Aromatic Hydrocarbons Full text
2009
Froehner, Sandro | Zeni, Juliandra | Cardoso da Luz, Erissen | Maceno, Marcell
The presence of polylcyclic aromatic hydrocarbons (PAHs) in surface sediments of Barigui River was investigated. PAHs are considered highly toxic and persistent compounds because of their structure. They originate from incomplete combustion of fossil fuels or biomass. The Barigui River crosses the metropolitan region of Curitiba, and some regions are highly polluted and located near the possible sources of pollution. The results showed that concentrations of total PAHs ranged from 44.6 to 880.2 ng g⁻¹, and the highest values were found at the sites previously investigated and identified as critically polluted. At sites located away from the traffic and possible pollution sources, the total PAHs was lower, 44.6 ng g⁻¹. Due to their hydrophobic character, sediments with high silt and clay content retain greater amounts of PAHs. The granulometric composition of the sediments revealed that most of them are composed basically by silt and clay, and those samples showed high concentration of PAHs. The organic carbon content also confirms this observation. The other sites investigated showed a high capacity to adsorb hydrophobic compounds mainly due to the granulometric composition and organic matter that adsorb poorly water soluble compounds. Finally, we found that the main sources of PAHs are petrogenic; however, at some sites, it is hard to confirm this pattern, and possibly, a mixture of the source would be more appropriate.
Show more [+] Less [-]Nitrogen and Phosphorus Remediation by Three Floating Aquatic Macrophytes in Greenhouse-Based Laboratory-Scale Subsurface Constructed Wetlands Full text
2009
Polomski, Robert F. | Taylor, Milton D. | Bielenberg, Douglas G. | Bridges, William C. | Klaine, Stephen J. | Whitwell, Ted
In the greenhouse and container nursery production industry there is potential for runoff of nitrogen (N) and phosphorus (P), which may contaminate surface and groundwater. Since the 1950s constructed wetlands (CWs), as a simple, low-technology method, have been shown to effectively treat agricultural, industrial, and municipal wastewater. We investigated the N and P attenuating potential of three floating hydrophytes planted in a laboratory-scale subsurface flow (SSF) CW system. Over an 8-week period plants were supplied with N and P (0.39 to 36.81 mg·L⁻¹ N and 0.07 to 6.77 mg·L⁻¹ P) that spanned the rates detected in nursery runoff between the discharge and inflow locations of a commercial nursery currently employing CWs. Whole plant dry weight was positively correlated with N and P supplied. Highest N recovery rates were exhibited by water hyacinth (Eichhornia crassipes [Mart.] Solms.) and water lettuce (Pistia stratiotes L.). P recovery rates were similar for water hyacinth, water lettuce, and dwarf redstemmed parrotfeather (Myriophyllum aquaticum [Vell.] Verdc.). These floating hydrophytes can be cultivated in a SSF CW to remediate runoff losses of N and P. The possibility exists for integrating them into a polycultural remediation system that includes emergent aquatic macrophytes for processing and polishing nursery/greenhouse wastewater.
Show more [+] Less [-]Anthropogenic Heavy Metal Pollution in the Surficial Sediments of the Keratsini Harbor, Saronikos Gulf, Greece Full text
2009
Galanopoulou, Stavroula | Vgenopoulos, Andreas | Conispoliatis, Nikolaos
The contents of ten elements [Cd, Pb, W, Zn, Mn, As, Se, Cr, Cu, and organic carbon (Corg)] have been determined in the surficial sediments of Keratsini harbor, Saronikos Gulf, Greece. The contamination of the sediments was assessed on the basis of geoaccumulation index and to corresponding sediment quality guidelines (SQGs) effects range low/effects range median. The results revealed highly elevated Cd, Pb, W, Zn, As, Se, Cr, Cu, and Corg values (Cd, 190-1,763 mg kg⁻¹; Pb, 521-1,263 mg kg⁻¹; W, 38-100 mg kg⁻¹; Zn, 409-6,725 mg kg⁻¹; Mn, 95-1,101 mg kg⁻¹; As, not detectable-1,813 mg kg⁻¹; Se, not detectable-58 mg kg⁻¹; Cr, 264-860 mg kg⁻¹; Cu, 195-518 mg kg⁻¹; and Corg, 0.69-4.41%). The enrichment of metals in the sediments results from the contribution of the central Athens sewage outfall through which the waste of the Attica basin ends up in Keratsini harbor as well as from industrial and ship contaminants.
Show more [+] Less [-]Enhanced Biodegradation of Naphthalene and Anthracene by Modified Vermiculite Mixed with Soil Full text
2009
Froehner, Sandro | Cardoso da Luz, Erissen | Maceno, Marcell
Hydrophobic modified vermiculite mixed with soil was investigated in biodegradation experiments of naphthalene and anthracene. The experiments had been carried out on mixtures of soil and vermiculite at a proportion of 2%, 10%, and 15% and also in the absence of clay used for control. Biodegradation of the pollutants was followed by the decline of naphthalene and anthracene concentration, measured by CG. Compound mineralization was also proved by the evolution of CO₂. The results showed that in the mixture with a higher proportion of vermiculite biodegradation is enhanced compared to that performed in the absence of vermiculite. In general, when vermiculite proportions are increased, the rate of degradation increases, which may account for the bioavailability of compounds. Bioavailability is an important factor for the degradation of compounds with low solubility. Comparison of biodegradation rates shows that naphthalene is degraded faster than anthracene. The chemical structure could be responsible for this observation. However, although we did not identify the microorganism that was in the soil, we can conclude that vermiculite could be an alternative for the bioavailability of such compounds. Vermiculite in the modified form could also be very useful as a barrier to retain organic pollutants in accidental spills.
Show more [+] Less [-]SO₂ and NOx Emissions from Kuwait Power Stations in Years 2001 and 2004 and Evaluation of the Impact of These Emissions on Air Quality Using Industrial Sources Complex Short-Term (ISCST) Model Full text
2009
Al-Azmi, Bader N. | Nassehi, V. | Khan, A. R.
Comprehensive emission inventories for 2001 and 2004 for Kuwait's main power stations located at Al-Doha and Al-Subyia have been prepared. These inventories are inserted, in conjunction with meteorological data, into the Source Complex model for Short Term Dispersion (ISCST4.5) to predict ambient ground level concentrations of sulphur dioxide (SO₂) and nitrogen oxides (NOx) at selected receptors for years 2001 and 2004. The comparison of the results obtained for these 2 years show the influence of increase in emission rates due to urban and industrial growth. For model validation, computed results are compared with the measured daily average values of SO₂ and NOx collected at a fixed Kuwait Environment Protection Agency air quality monitoring station located at the roof of polyclinic in Rabia. Individual contributions of each power station to the highest predicted values are assessed. The five highest hourly, daily and annual ground level concentration values under prevailing meteorological conditions are compared for 2001 and 2004. It is found that the hourly mean concentrations are strongly influenced by the prevailing meteorological conditions. The effect of meteorological conditions has not been that dominant for the daily and annual mean values and the predicted values for 2004 are higher than 2001, simply corresponding to a high emission rates, especially in summer months. Top 50 daily average values of SO₂ show a slope of 0.806 for 2001 which means that the model predictions are 20% less than the observed levels. However, the predicted slope of SO₂ for 2004 is 0.96 and the model predictions are in very close agreement with the observed data.
Show more [+] Less [-]The Chemistry of Intercepted Clouds in Northern Arizona during the North American Monsoon Season Full text
2009
Hutchings, James W. | Robinson, Marin S. | McIlwraith, Heide | Triplett Kingston, Jennifer | Herckes, Pierre
Cloudwater samples have been collected for the first time at a high-elevation site in the US interior Southwest. Cloud samples were collected at the summit of Mt. Elden near Flagstaff, Arizona. The samples were analyzed for pH, ionic composition, trace metals, organic carbon content, and volatile organic compounds. All of the samples showed high pH values (5.12-6.66), which appear to be the result of soil/crustal acid-neutralizing components. Ammonium and nitrate were the dominant ionic species. Organic carbon concentrations ranged from 3 to 18 mg/l. Volatile aromatic compounds (toluene, ethylbenzene, and xylenes) were detected, although they did not contribute significantly to the dissolved organic matter (<1% of dissolved organic carbon). Still, their aqueous-phase concentrations were substantially higher than equilibrium partitioning from the gas phase would suggest. Metal concentrations were high when compared to other cloud studies in remote areas. Overall, with the exception of pH, the cloud chemistry showed marked inter-event variability. The source of the variability was investigated using NOAA HYSPLIT dispersion calculations. Like the cloud composition, the air mass back trajectories differed widely from event to event, and consistently, air masses that passed over highly urbanized areas had higher trace metal, organic, and ion concentrations than more pristine air masses.
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