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A Survey of Organotin Compounds in the Northern Adriatic Sea
2009
Milivojevič Nemanič, Tadeja | Milačič, Radmila | Ščančar, Janez
The extent of pollution with organotin compounds was investigated in water, sediment and bivalve mussels (Mytilus galloprovincialis) from the Northern Adriatic Sea. Butyl-, phenyl- and octyltin species were quantified after extraction and derivatisation by gas chromatography-mass spectrometry in a total of 99 samples from the period from 2000 to 2006. The accuracies of the analytical procedures were checked by spiking of unpolluted water samples and by the analysis of standard reference materials (harbour sediment PACS-2 and mussel tissue ERM-CE 477). Among organotin species analysed in samples butyltins were the predominant. Tributyltin was found to be present in the highest concentrations, suggesting its recent input into the marine environment. Butyltins were detected at all sites surveyed (sum of butyltins was up to 718 ng Sn L⁻¹, 3,552 ng Sn g⁻¹ d.w. and 9,991 ng Sn g⁻¹ d.w. in water, sediment and mussel samples, respectively), phenytins in much lower concentrations (up to 31 ng Sn L⁻¹, 326 ng Sn g⁻¹ d.w. and 442 ng Sn g⁻¹ d.w. in water, sediment and mussel samples) and to a much smaller extent, while octyltins were not detected at any location. The spatial distribution of tributyltin was closely related to boating, with the highest concentrations found in marinas (up to 586 ng Sn L⁻¹ for water samples, 1,995 ng Sn g⁻¹ d.w. for sediment and 6,434 ng Sn g⁻¹ d.w. for mussel samples). The temporal distribution clearly indicates a decrease of organotin pollution at all sites.
Afficher plus [+] Moins [-]The Role of Mucus in Mytella falcata (Orbigny 1842) Gills from Polluted Environments
2009
David, José Augusto de Oliveira | Fontanetti, Carmem S.
Bivalve mussels can concentrate pollutants which, in high amounts, can cause cellular, physiological and behavioral changes. The gill mucus is essential for many metabolic and behavioral procedures on marine mussels including the response to environmental pollution. The present work analyzed the mucous cell number in Mytella falcata gill filaments from three sites of Santos estuary (Brazil) with different levels of sediment contamination named as sites A, B, and C. Site A is located at a low impacted region of the estuary, and sites B and C are under influence of port activities, domestic sewage, and industries like a still mill located in front of site C (the most contaminated area with high amounts of polycyclic aromatic hydrocarbons). An increase in mucous cell number was detected in animals from sites B and C, when compared to site A; this increase occurred preferentially in the frontal zone and was related to sediment contamination. Mucous cell analysis can be used as an efficient biomarker. It is suggested that mucus produced in lateral and abfrontal zones is responsible for eliminating pollutants previously absorbed and mucus produced in frontal zone is responsible for pollutant arrest and elimination as pseudofeces.
Afficher plus [+] Moins [-]An Analysis of the Indoor Air Quality and Mould Growth in a Multi-zone Building
2009
Chowdhury, Ashfaque Ahmed | Rasul, M. G | Khan, M. M. K
The effects of poor indoor air quality and mould growth in working environment are major problems in built environment, and there is a need to look for improvement of the health, comfort and productivity of the building occupants. Airborne mould sampling studies were conducted in a reference building located in Rockhampton, Central Queensland, Australia. Both indoor culturable and mould spore levels were observed. It was found through the indoor-outdoor ratios of the species that indoor concentrations are mostly related to the outdoor mould levels. The moulds differ in their relative humidity and temperature requirements to support surface growth. Indoor humidity has a significant effect on occupants comfort, perceived air quality, occupants' health, building durability, emissions and energy efficiency. Practical hygrothermal simulation models are employed to analyse the combined heat and moisture behaviour within the built environment. A review of the current modelling options available to predict building performance based on energy and mass transport simulation is presented, and then a case study is presented with the assessment of indoor built environment to avoid mould problem.
Afficher plus [+] Moins [-]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.
Afficher plus [+] Moins [-]Microfauna Community as an Indicator of Effluent Quality and Operational Parameters in an Activated Sludge System for Treating Piggery Wastewater
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.
Afficher plus [+] Moins [-]Fecal Sterol and Bile Acid Biomarkers: Runoff Concentrations in Animal Waste-Amended Pastures
2009
Tyagi, Punam | Edwards, Dwayne R. | Coyne, Mark S.
Nonpoint source pollution is the leading remaining cause of water quality problems. The extent of NPS pollution is often more difficult or expensive to monitor at the point(s) of origin, as compared to monitoring of point sources. This study evaluated the hypothesis that animal manure (chicken, cow, horse, and pig) applied to pasture contribute fecal sterols and bile acids to runoff. The study also assessed the potential benefit of fecal sterols and bile acids as biomarkers in distinguishing fecal pollution and its sources. Fecal sterol and bile acid concentrations were determined in flow-weighted composite runoff samples collected from 2.4 x 6.1 m plots (n = 3) amended with manure. Runoff was generated from simulated rainfall (152 mm.h⁻¹). Runoff samples from manure-amended plots showed high concentrations of fecal sterol (ranged from 13 ± 1 to 1,287 ± 183) and bile acid (ranged from 24 ± 1 to 2,251 ± 248) biomarkers. The profiles of fecal sterols and bile acids in runoff samples were similar to those of fresh manure for all selected animals. For runoff and fresh manure, chenodeoxycholic acid, deoxycholic acid, epicoprostanol, and hyodeoxycholic acid were consistent biomarkers for chicken, cow, horse, and pig, respectively, suggesting that sterols and bile acids can be used to identify sources and occurrence of fecal matter in water and sediments.
Afficher plus [+] Moins [-]Implications of Uncertainty in a Pre-treatment Dataset when Estimating Treatment Effects in Paired Catchment Studies: Phosphorus Loads from Forest Clear-cuts
2009
Laurén, A. | Heinonen, J. | Koivusalo, H. | Sarkkola, S. | Tattari, S. | Mattsson, T. | Ahtiainen, M. | Joensuu, S. | Kokkonen, T. | Finér, L.
Estimates of increased nutrient export caused by forest clear-cuttings are mostly based on long-term paired catchment studies, where the treatment effect is calculated using pre-treatment dataset regression and post-treatment records of nutrient loads. In these studies uncertainty in the regression between the pre-treatment loads from the control and from the treatment catchments is typically neglected, even though it affects determination of the magnitude and duration of the treatment effect. This uncertainty is described in terms of variance in regression coefficients and residuals. The aim was to study how uncertainty in a pre-treatment dataset is propagated to estimates of the treatment effects using two sets of paired catchment data in eastern Finland, where the total phosphorus loads following forest clear-cutting and site preparation were investigated. The results showed that neglecting the uncertainty in the pre-treatment data did not change the conclusions when the treatment effect was strong enough. However, when the treatment effect was small, neglecting the uncertainty in the pre-treatment dataset easily leads to over-interpretation of the results. The uncertainty in a pre-treatment dataset should be taken into account in the paired catchment studies in order to avoid bias in the estimation of management effects on the loads.
Afficher plus [+] Moins [-]Simultaneous SO₂ Removal by Wastewater with NH₃
2009
Ipek, Ubeyde | Ekinci, Mehtap | Arslan, E Isıl | Cuci, Yakup | Hasar, Halil
Sulfur dioxide (SO₂) is basically resulted from emission of fossil fuel. The ammonia washing is of methods used to remove SO₂ from fuel gas. Several wastewaters contain high ammonia concentrations causing the various problems at wastewater treatment or receiving environment. The synthetic wastewater containing NH₃ was sprayed down as flue gas moved up in the scrubber so that it could be a reaction between SO₂ and NH₃. The effect of NH₃ concentration and pH on SO₂ removal was determined. SO₂ was decreased from about 1,000 to 0, 36, 49 and 66 ppm at NH₃ concentrations of 328, 88, 32 and 9 mg l⁻¹, respectively. While SO₂ of 1,000 ppm was completely treated at 328 mg NH₃ l⁻¹, pH was around 7.16 at the end of process. Consequently, it was recognized that this process could be used for both the SO₂ removal and the wastewater neutralization.
Afficher plus [+] Moins [-]A New and Sound Technology for Biogas from Solid Waste and Biomass
2009
Busch, G | Großmann, J | Sieber, M | Burkhardt, M
Organic waste, as a main constituent of municipal solid waste, has as well as solid biomass a high potential for biogas generation. Despite the importance of biogas generation from these materials, the availability of large-scale biogas processes lacks behind the demand. A newly developed double-stage solid-liquid biogas process, consisting of an open hydrolysis stage and a fixed-bed methane reactor, allows the biogas production from almost all biodegradable solid waste and renewable resources like maize, grass, sugar cane, etc. Furthermore, residues from industrial processes, like the glycerine waste water from biodiesel production, can also be converted into biogas successfully. Due to the strong separation of hydrolysis and methanation, the process is extremely stable. No malfunction has been detected so far. The open hydrolysis releases CO₂ and allows oxidation of sulfur. Consequently, the biogas has a high methane (>72%) and low H₂S concentration (<100 ppm). Stirrers or other agitation equipment are not necessary; only liquids are pumped. The biogas generation becomes controllable for the first time; thus, the actual generation can be easily adapted to the consumption.
Afficher plus [+] Moins [-]Atmospheric Transfer and Deposition Mechanisms of ²¹⁰Pb Aerosols onto Forest Soils
2009
Likuku, Alfred S
Activities of ²¹⁰Pb carrier aerosols in an age-graded Sitka spruce conifer, three deciduous (oak, lime and sycamore) foliage and in rain and throughfall samples have been measured during the period of 2001-2002. The ²¹⁰Pb concentrations in the age-graded Sitka leaf needles have shown to accumulate until a steady state between accretion and loss of particulate matter is maintained with time. Similarly, the concentrations of ²¹⁰Pb on deciduous tree leaves increased with time until the leaves began to senesce. The ²¹⁰Pb inventory in bulk precipitation was significantly (r ² = 0.99; P < 0.001) large compared with that in throughfall samples, as indicated by a ratio of 1 to 0.1 of ²¹⁰Pb deposition in bulk precipitation to throughfall. This suggests that ²¹⁰Pb is retained in the Sitka spruce foliage during deposition until transfer to the ground mainly through litterfall. These findings suggest that the presence of woodland is responsible for enhanced ²¹⁰Pb deposition fluxes beneath wooded areas relative to open grassland soils.
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