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Assessing the Effect of Saltwater Intrusion on Petroleum Hydrocarbons Plumes Via Numerical Modelling
2012
Mastrocicco, M. | Colombani, N. | Sbarbati, C. | Petitta, M.
A contamination by petroleum hydrocarbons was detected in a sandy aquifer below a petrochemical plant in Southern Italy. The site is located near the coastline and bordered by canals which, together with pumping wells, control submarine groundwater discharge toward the sea and seawater intrusion (SWI) inland. In this study, a three-dimensional flow and transport model was developed using SEAWAT-4.0 to simulate the density-dependent groundwater flow system. Equivalent freshwater heads from 246 piezometers were employed to calibrate the flow simulation, while salinity in 193 piezometers was used to calibrate the conservative transport. A second dissolved species, total petroleum hydrocarbons (TPH), was included in the numerical model to simulate the plumes originating from light non-aqueous-phase liquid. A detailed field investigation was performed in order to determine the fate of dissolved hydrocarbons. Fifteen depth profiles obtained from multilevel samplers (MLS) were used to improve the conceptual model, originally built using a standard monitoring technique with integrated depth sampling (IDS) of salinity and TPH concentrations. The calibrated simulation emphasises that density-dependent flow has a great influence on the migration pattern of the hydrocarbons plume. This study confirms that calibration of density-dependent models in sites affected by SWI can be successfully reached only with MLS data, while standard IDS data can lead to misleading results. Thus, it is recommended to include MLS in the characterization protocols of contaminated sites affected by SWI, in order to properly manage environmental pollution problems of coastal zones.
Afficher plus [+] Moins [-]Hydraulic Loading Rate Effect on Removal Rates in a BioSand Filter: A Pilot Study of Three Conditions
2012
Kennedy, T. J. | Hernandez, E. A. | Morse, A. N. | Anderson, T. A.
Safe drinking water is a luxury to approximately 800 million people worldwide. The number of people without access to clean water has been reduced, thanks to technologies like the biosand filter (BSF), an intermittently operated household scale slow sand filter. The BSF outlet (control diameter 0.5â³) was modified in this study by reducing the outlet diameter (0.37â³ and 0.25â³) to determine the effects of hydraulic retention time on removal rates. Filters were dosed with 20Â L of spiked lake water daily and observed for pH, dissolved oxygen (DO), fecal coliforms (FC), turbidity, nitrate, nitrite, sulfate, and ammonia until initial flow rates dropped below 0.2Â L/min. Consistent with previous studies, the average turbidity was reduced to below 1Â NTU; the average DO was reduced by 45Â %. No significant difference was observed between the modified BSFs and the control BSF. Removal efficiency of FC was not significantly different between the modified BSFs (93.3Â % and 91.9Â %) and the control BSF (89.6Â %). Mean FC reduction during the startup period (17Â days) was significantly greater in the modified 0.25â³ BSF when compared with the control during the same time period. After the first 17Â days of the experiment, the average reduction efficiency of all filters was >97Â %. While source water was below guideline values for nitrate, nitrite, ammonia, and sulfate during the course of the experiment, total nitrogen reduction was observed. The reduction indicates that the plastic BSF is capable of accomplishing limited denitrification during the filtering process.
Afficher plus [+] Moins [-]Evaluation of Non-Conventional Coagulants to Remove Turbidity from Water
2012
Devesa-Rey, R. | Bustos, G. | Cruz, J. M. | Moldes, A. B.
Coagulation and flocculation are basic chemical engineering operations employed to remove suspended solids from water. The growing concern for environmental and ecological issues warrants the use of the biodegradable flocculants in wastewater and industrial effluent treatment. In this work, unconventional coagulant, namely lactic acid, calcium lactate, sodium lactate, and citric acid were studied in comparison with AlCl3, a usual coagulant widely employed to remove water turbidity. It was observed that lactic acid and calcium lactate were able to reduce the water turbidity similarly to AlCl3. This fact can be very interesting because lactic acid salts can be produced by biotechnological process, and contrarily to aluminium salts, they are biodegradable, reducing the risk for human and animal’s health.
Afficher plus [+] Moins [-]Evaluation of the Impacts of Marine Salts and Asian Dust on the Forested Yakushima Island Ecosystem, a World Natural Heritage Site in Japan
2012
Nakano, Takanori | Yokoo, Yoriko | Okumura, Masao | Jean, Seo-Ryong | Satake, Kenichi
To elucidate the influence of airborne materials on the ecosystem of Japan’s Yakushima Island, we determined the elemental compositions and Sr and Nd isotope ratios in streamwater, soils, vegetation, and rocks. Streamwater had high Na and Cl contents, low Ca and HCO₃ contents, and Na/Cl and Mg/Cl ratios close to those of seawater, but it had low pH (5.4 to 7.1), a higher Ca/Cl ratio than seawater, and distinct ⁸⁷Sr/⁸⁶Sr ratios that depended on the bedrock type. The proportions of rain-derived cations in streamwater, estimated by assuming that Cl was derived from sea salt aerosols, averaged 81 % for Na, 83 % for Mg, 36 % for K, 32 % for Ca, and 33 % for Sr. The Sr value was comparable to the 28 % estimated by comparing Sr isotope ratios between rain and granite bedrock. The soils are depleted in Ca, Na, P, and Sr compared with the parent materials. At Yotsuse in the northwestern side, plants and the soil pool have ⁸⁷Sr/⁸⁶Sr ratios similar to that of rainwater with a high sea salt component. In contrast, the Sr and Nd isotope ratios of soil minerals in the A and B horizons approach those of silicate minerals in northern China’s loess soils. The soil Ca and P depletion results largely from chemical weathering of plagioclase and of small amounts of apatite and calcite in granitic rocks. This suggests that Yakushima’s ecosystem is affected by large amounts of acidic precipitation with a high sea salt component, which leaches Ca and its proxy (Sr) from bedrock into streams, and by Asian dust-derived apatite, which is an important source of P in base cation-depleted soils.
Afficher plus [+] Moins [-]Status of Fish and Macroinvertebrate Communities in a Watershed Experiencing High Rates of Fossil Fuel Extraction: Tenmile Creek, a Major Monongahela River Tributary
2012
Kimmel, William G. | Argent, David G.
Over the summer and fall seasons, 2006–2010, we surveyed the fish and macroinvertebrate communities of the Tenmile Creek basin in southwestern Pennsylvania, an area undergoing accelerated extraction of energy resources—historically coal and more recently natural gas associated with the Marcellus formation. Tenmile Creek, its major South Fork (SF), and numerous tributaries drain a basin of 875 km². The drainage network is characterized as warm-water, low-gradient, and net alkaline. The purpose was to provide synoptic baseline data on water quality and the resident aquatic communities in terms of species richness, stress tolerance, and trophic structure. Overall, we sampled 20 stations on the 2 main branches and 1 on each of the 12 tributaries. We collected 26,375 fishes representing nine families and 54 species/hybrids along with 989 macroinvertebrates from 25 separate taxa. The parameter which defines water quality here is specific conductance which ranges from natural background levels of about 400 μS/cm on the minimally impaired Tenmile mainstem to 4,500 μS/cm on its SF. Diverse fish and macroinvertebrate communities were documented at levels of specific conductance exceeding 1,000 μS/cm, well above the 300 μS/cm criterion to protect aquatic life proposed by the US Environmental Protection Agency for streams in the Central Appalachian Region. South Fork fish communities exhibit impairment at levels of specific conductance approaching the maximum observed here.
Afficher plus [+] Moins [-]Presence of Cocaine in the Tissues of the European Eel, Anguilla anguilla, Exposed to Environmental Cocaine Concentrations
2012
Capaldo, Anna | Gay, Flaminia | Maddaloni, Massimo | Valiante, Salvatore | De Falco, Maria | Lenzi, Mauro | Laforgia, Vincenza
The presence of illicit drugs and their metabolites in surface waters has to be considered a new type of hazard, still unknown, for the aquatic ecosystem, due to the potent pharmacological activities of all the illicit drugs. Our research was therefore aimed at evaluating the impact of illicit drugs on the aquatic fauna, till now still undervalued. To this aim, we verified the ability of the European eel (Anguilla anguilla), a well-known biomonitor of environmental contamination, to bioaccumulate cocaine, one of the most abundant illicit drugs found in surface waters. Silver eels were exposed to a nominal cocaine concentration of 20 ng/l for 1 month; at the same time, control, carrier, and post-exposure recovery groups were made. Brains, gills, liver, kidney, muscle, gonads, spleen, digestive tract, and sections of dorsal skin were assayed by high-pressure liquid chromatography. Cocaine was found in the tissues of the treated eels and, at low concentrations, in almost all tissues of post-exposure recovery eels. These results indicate that cocaine is able to accumulate into the eel tissues; its presence suggests potential risks for eels since cocaine could affect their physiology and contribute to their decline, and for humans consuming contaminated fish.
Afficher plus [+] Moins [-]Assessing the Use of Magnetic Methods to Monitor Vertical Migration of Metal Pollutants in Soil
2012
Sapkota, Birendra | Cioppa, Maria T.
In order to assess the use of magnetic methods to study vertical migration behavior of metal pollutants in natural soils, a controlled experiment was performed near Belle River, Ontario, Canada. The soil at the site consists primarily of clay-rich glacial till overlain by localized alluvium. Twenty PVC tubes (16″ × 8″) were inserted vertically into the ground as test capsules. Magnetite powder (<5 μm) was distributed on the surface of the soil inside ten tubes (10 grams/tube) to simulate anthropogenic contamination, while the other ten were used as controls. While the surficial magnetic susceptibility (MS) remained fairly stable in controls, decreases of 15–60% were observed in contaminated soil tubes. Post-test MS profiles from soil cores in contaminated tubes show that the magnetic signal is strongest at depths between 4 and 6 cm. Magnetic measurements and chemical analysis (using SEM-EDS) on soil layers with enhanced magnetic signal indicate the presence of iron containing particles, likely magnetite. Overall, the results suggest that magnetite powder migrated vertically downwards at a rate of ∼14 cm/year over the four month period, probably as a result of rainwater infiltration. Such magnetic methods and chemical analytical techniques are useful in the investigation of migration of metal pollutants and the potential depth of soil contamination.
Afficher plus [+] Moins [-]Correlation Study between Land Use, Water Quality, and Heavy Metals (Cd, Pb, and Zn) Content in Water and Green Lipped Mussels Perna viridis (Linnaeus.) at the Johor Strait
2012
Hadibarata, Tony | Abdullah, Faizuan | Yusoff, Abdull Rahim Mohd | Bin Ismail, Razali | Azman, Shamila | Adnan, Norliyana
In order to observe the variation in land use changes, satellite images from the Landsat Thematic Mapper (TM) and the Enhanced Thematic Mapper (ETM) for 1991, 2000, 2005, and 2008 were used to compare the differences between selected water quality parameters, including heavy metal (Cd, Pb, and Zn) content in both water and green mussels or Perna viridis (Linnaeus.) before and after the increase in land use activities beginning from 2006. The samples were collected at 11 points for water and 4 points for green mussels between the Second Link and the Causeway Link at the Johor Strait in 2009 and were analyzed for pH, temperature degrees Celsius), dissolved oxygen, ammoniacal nitrogen, and heavy metal (Cd, Pb, and Zn) content.
Afficher plus [+] Moins [-]Separation and Determination of Three Phenolic Xenoestrogens in Industrial Wastewater by Micellar Electrokinetic Chromatography on Polydimethylsiloxane Microchip
2012
Yang, Huijuan | Zhang, Qianli | Zhao, Jinjin | Tu, Yifeng
The separation on microchip provides the advantages including high efficiency, increased throughput, reduced quantities of hazardous materials, cost saving, relatively facile instrumentation, improved portability, etc. A technique of micellar electrokinetic chromatography (MEKC) coupled with amperometric detection has been actualized on a polydimethylsiloxane microchip for the rapid separation and determination of three phenolic xenoestrogens as octylphenol (OP), 4-nonylphenol (4-NP), and bisphenol A (BPA). The baseline separation of these phenolic xenoestrogens is successfully obtained within 55 s under the optimized MEKC conditions with borate running buffer of pH 8.0 containing sodium dodecyl sulfate and β-cyclodextrin. The linear range for OP, 4-NP, and BPA are 20–1,000, 15–1,000, and 20–1,000 μg/L with the detection limit of 5.0, 4.0, and 3.0 μg/L, respectively. The present method is successfully applied for the determination of these phenolic xenoestrogens in some industrial wastewater samples from mainland of China with the recoveries ranged from 90.2 to 109.4 %.
Afficher plus [+] Moins [-]Mapping Atmospheric Corrosion on Materials of Archaeological Importance in Athens
2012
Kambezidis, Harry D. | Kalliampakos, George
Atmospheric pollution is known to induce corrosion effects on various materials. For Greece, stone deterioration could emerge severe costs in the case of damaging cultural monuments. This work aims to investigate the corrosion process on materials of archaeological importance (marble, limestone, and sandstone) in the Greater Athens Area (GAA) by using sophisticated geoanalytical methods together with dose–response functions for selected materials, in order to derive corrosion maps for GAA in the period 2000–2009. Also, a corrosion trend analysis is performed, which can be a very helpful tool for the prediction of potential risks to monuments of cultural heritage due to atmospheric pollution. The corrosion effects on the selected materials are generally weak. Nevertheless, increasing corrosion trends are found in the eastern regions of GAA for all sheltered materials and in the northern parts of GAA for unsheltered marble. The technique is finally applied to 12 locations in GAA, which include some of the most important archaeological monuments of Athens, and provides comprehensive results for the estimation of the impact of atmospheric corrosion on the structural materials of these archaeological sites.
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