Affiner votre recherche
Résultats 1041-1050 de 1,273
Airborne Volatile Organic Compounds and Their Potential Health Impact on the Vicinity of Petrochemical Industrial Complex
2011
Thepanondh, Sarawut | Varoonphan, Jarupun | Sarutichart, Panukorn | Makkasap, Thagoon
The aggregate potential health impact due to ambient volatile organic compounds on the population living in the area nearby the petrochemical industrial complex in Thailand was evaluated using measured air contaminants concentration. Airborne volatile organic compounds were collected using canisters and were analyzed by gas chromatography/mass spectrophotometer following the US.EPA TO 15 procedure. Composite samples taken over a 24-h period were collected monthly. Concentrations of volatile organic compounds (VOCs) were analyzed for a suite of 24 compounds covering both carcinogenic and non-carcinogenic substances. Results were determined and analyzed in order to evaluate their spatial variability and their potential health risk. Comparison of data from each monitoring site indicated that patterns of VOCs across sites were different from their major species and their concentrations which might be influenced by nearest potential emission sources. Carcinogenic VOCs such as benzene, 1,3butadiene, and 1,2 dichloroethane were found to be higher than their annual national standards. A potential cancer risk map was drawn based on benzene concentration in order to illustrate the zone of impact and the number in the population likely to be exposed. Results indicated that 82% of the total area, and 89.6% of the total population were within the impact area. It was suspected that high concentrations of benzene and 1,3 butadiene might be attributed by both the mobile source and the point source of emissions while 1,2 dichloroethane was suspected to be emitted from factories located upwind from the monitoring sites. Hazard quotients and hazard indexes were applied to determine chronic health effects with non-cancer endpoints. Calculated values of hazard indexes for each of the target organ systems were lower than 1, which indicated that the non-cancer chronic risk due to level of volatile organic compounds in the study area was less.
Afficher plus [+] Moins [-]Tracing Organic Footprints from Industrial Effluent Discharge in Recalcitrant Riverine Chromophoric Dissolved Organic Matter
2011
Borisover, Mikhail | Laor, Yael | Saadi, Ibrahim | Lado, Marcos | Bukhanovsky, Nadezhda
Excitation–emission matrix fluorescence spectroscopy, combined with parallel factor analysis and measurements of UV absorption and dissolved organic carbon (DOC) concentrations, was used to trace the footprints of industrial effluents discharged into the lower Kishon River (Israel). The lower Kishon River typifies streams that are affected by seawater tidal intrusion and represents an extreme case of severe long-term pollution caused mainly by a variety of industrial effluents. The industrial effluents may contribute about 90%, in terms of biochemical oxygen demand, of the total organic carbon discharged into the lower Kishon River. Water samples were collected along the river, including the points of effluent discharge from industrial plants, between November 2005 and September 2006. Two types of fluorescent components characterized the fluorescence of the lower Kishon River water: component I corresponded to humic-like matter and component II spectrally resembled material known to be associated with biological productivity, but different from typical tryptophan-like fluorophore. These fluorescent components and other substances that absorbed light at 254 nm contributed to the DOC pool that resisted riverine microbial degradation under laboratory conditions, and that constitutes up to 70% of the overall riverine DOC. The variations in DOC concentration, absorbance at 254 nm, and concentration of humic-like matter (characterized by component I) correlated with the distance from the sea and the water electrical conductivity, and were linked to seawater tidal intrusion. The increased concentration of component II, as well as its enlarged fraction in the overall riverine DOC pool, was found to be associated with the location of major inputs of the industrial effluents. These findings support the use of this fluorescent component as an indicator of industrial pollution in such severely contaminated riverine systems.
Afficher plus [+] Moins [-]A Comparison of Inorganic Solid Wastes as Adsorbents of Heavy Metal Cations in Aqueous Solution and Their Capacity for Desorption and Regeneration
2011
Zhou, Ya-Feng | Haynes, R. J.
The adsorption capacity of seven inorganic solid wastes [air-cooled blast furnace (BF) slag, water-quenched BF slag, steel furnace slag, coal fly ash, coal bottom ash, water treatment (alum) sludge and seawater-neutralized red mud] for Cd2+, Cu2+, Pb2+, Zn2+ and Cr3+ was determined at two metal concentrations (10 and 100 mgâL−1) and three equilibrium pH values (4.0, 6.0 and 8.0) in batch adsorption experiments. All materials had the ability to remove metal cations from aqueous solution (fly and bottom ash were the least effective), their relative abilities were partially pH dependant and adsorption increased greatly with increasing pH. At equimolar concentrations of added metal, the magnitude of sorption at pH 6.0 followed the general order: Cr3+â≥âPb2+â≥âCu2+â>âZn2+â=âCd2+. The amounts of previously sorbed Pb and Cd desorbed in 0.01 M NaNO3 electrolyte were very small, but those removed with 0.01 M HNO3, and more particularly 0.10 M HNO3, were substantial. Water treatment sludge was shown to maintain its Pb and Cd adsorption capability (pH 6.0) over eight successive cycles of adsorption/regeneration using 0.10 M HNO3 as a regenerating agent. By contrast, for BF slag and red mud, there was a very pronounced decline in adsorption of both Pb and Cd after only one regeneration cycle. A comparison of Pb and Cd adsorption isotherms at pH 6.0 for untreated and acid-pre-treated materials confirmed that for water treatment sludge acid pre-treatment had no significant effect, but for BF slag and red mud, adsorption was greatly reduced. This was explained in terms of residual surface alkalinity being the key factor contributing to the high adsorption capability of the latter two materials, and acid pre-treatment results in neutralization of much of this alkalinity. It was concluded that acid is not a suitable regenerating agent for slags and red mud and that further research and development with water treatment sludge as a metal adsorbent are warranted.
Afficher plus [+] Moins [-]Water Quality, Water Management and the Ranger Uranium Project: Guidelines, Trends and Issues
2011
Ferguson, Briony | Mudd, Gavin M.
This paper explores the regulation of water quality protection downstream from the Ranger Uranium Project in the Alligator Rivers Region, an area of high conservation value which is both World Heritage- and Ramsar-listed. Available historical monitoring data for surface water quality in Magela Creek downstream of Ranger have been compiled and analysed with respect to hydrologic data and the Australian and New Zealand Environment and Conservation Council–Agricultural and Resource Management Council of Australia and New Zealand (ANZECC–ARMCANZ) regulatory guidelines, introduced in late 2000. The paper focuses on the underlying scientific basis for the current approach and examines the complex inter-relationships of minesite water management, hydrology, climate, monitoring design, implementation and interpretation which are used to differentiate between natural variability and potential mine-derived solutes. The research found that the application of the ANZECC–ARMCANZ guidelines has clearly improved the regulation of water quality protection downstream from the Ranger Uranium Project. The scientific basis is more coherent than the previous regulatory regime; however, for U (a key parameter of indigenous Mirarr-Gundjeihmi and public concern), higher downstream concentrations are permitted than those observed through natural variability, leaving open the potential for an influence of mine-derived U loads while still being within regulatory limits. Another improvement that could be made to the current regulatory regime, to provide enhanced protection of the water quality in Magela Creek downstream of Ranger, would be to explicitly link the water quality monitoring regime with hydrologic flow conditions. The paper makes a valuable case study for the application of water quality guidelines, especially for controversial projects such as uranium mining surrounded by a World Heritage- and Ramsar-listed region on indigenous land—a context of clear relevance for many places around the world.
Afficher plus [+] Moins [-]Integral Approach for Improving the Degradation of Recalcitrant Petrohydrocarbons in a Fixed-Film Reactor
2011
Jiménez, Verónica | Bravo, Violeta | Gutierrez, Linda Gonzalez
The degradation of diesel and phenanthrene in waste water was studied in a column combining a submerged trickling-flow with a fixed-film at a determined biofilm thickness with recirculation. Degradation efficiencies were found to be high with the production of a biofilm thickness of 789 μm structured in a package material with proper adsorption and physicochemical properties necessary to reach a stable state condition for the degradation of recalcitrant components in 78% at a retention time of 3 h. Improved degradation rates were reached with a biofilm built from an adapted inoculum that showed the presence of Pseudomonas sp., Klebsiella sp. Enterobacter in a concentration of 6.45â×â109 CFU mL−1. Moreover, the biodegradation rate of the inoculumn was quantified. The diesel kinetic experimental data were well described by Gompertz model which provides a specific grow rate (Kb) of 0.76â±â0.36 h−1 and a correlation of R 2â=â0.93. The integral approach study of the variables of a complex degradation process lead to improve the complete operation of the reactor in comparison with other more specific component-based approaches.
Afficher plus [+] Moins [-]Assessment the Health Hazard from 222Rn in Old Metalliferous Mines in San Luis, Argentina
2011
da Silva, A. A. R. | Valladares, D. L. | Anjos, R. M. | Velasco, H. | Rizzotto, M. | Yoshimura, E. M.
Radon levels in two old mines in San Luis, Argentina, are reported and analyzed. The radiation dose and environmental health risk of 222Rn concentrations to both guides and visitors were estimated. CR-39 nuclear track detectors were used for this purpose. The values for the 222Rn concentration at each monitoring site ranged from 0.43 ± 0.04 to 1.48 ± 0.12 kBq m−3 in the Los Cóndores wolfram mine and from 1.8 ± 0.1 to 6.0 ± 0.5 kBq·m−3 in the La Carolina gold mine, indicating that, in this mine, the radon levels exceed up to four times the action level of 1.5 kBq m−3 recommended by the International Commission on Radiological Protection. The patterns of the radon transport process revealed that the La Carolina gold mine can be interpreted as a gas confined into a single tube with constant cross-section and air velocity. Patterns of radon activity, taking into account the chimney-effect winds, were used to detect tributary currents of air from shafts or larger fissures along the main adit of the Los Cóndores mine, showing that radon can be used as an important tracer of tributary air currents stream out from fissures and smaller voids in the rock of the mine.
Afficher plus [+] Moins [-]A Synoptic Survey of Nitrogen and Phosphorus in Tributary Streams and Great Rivers of the Upper Mississippi, Missouri, and Ohio River Basins
2011
Hill, Brian H. | Bolgrien, David W. | Herlihy, Alan T. | Jicha, Terri M. | Angradi, Ted R.
We combined stream chemistry and hydrology data from surveys of 436 tributary stream sites and 447 great river sites in the Upper Mississippi, Missouri and Ohio River basins to provide a regional snapshot of baseflow total nitrogen (TN) and total phosphorus (TP) concentrations, and to investigate the relationships between land use and stream chemistry. Catchments in the Upper Mississippi River basin had more land in agricultural uses (51%) than the Missouri or Ohio River basin catchments (25% and 29%, respectively). The difference in agriculture is reflected in the TN concentrations in tributary streams and the great rivers: 5,431 and 2,112 μg L−1 for the Upper Mississippi, 1,751 and 978 μg L−1 for the Missouri, and 1,074 and 1,152 μg L−1 for the Ohio River basins. This agricultural effect was not as evident for tributary stream or great river TP concentrations: 165 and 181 μg L−1 in the Upper Mississippi, 177 and 171 μg L−1 in the Missouri, and 67 and 53 μg L−1 in the Ohio River basins. We set reference thresholds based on the 75th percentile TN and TP concentrations at our least disturbed sites. The TN threshold was exceeded for 50–63% of the tributary stream and 16–55% of great river lengths, with the greatest proportion in the Upper Mississippi River basin. The TP threshold was exceeded in 32–48% of tributary stream and 12–41% of great river lengths. Tributary stream N/P ranged from 67:1 (Ohio) to 210:1 (Upper Mississippi); river N/P ranged from 20:1 (Missouri) to 60:1 (Ohio). N/P indicated that potential N-limitation occurred in 10–21% of total tributary stream length and in 0–46% of great river length; potential P-limitation ranged from 60–83% of cumulative tributary stream length and from 21–98% of cumulative great river length. Total N flux (concentration × discharge) was highest in the Upper Mississippi River basin; TP flux was lowest in the Ohio River basin. River TN yields and TP yields for both tributary streams and great rivers, was not significantly different between the sub-basins. Our study empirically links catchment land use and stream chemistry, and demonstrates using monitoring data for estimating nutrient yields at a large regional scale.
Afficher plus [+] Moins [-]A Study of Chromium, Cooper, and Lead Distribution from Lignite Fuels Using Cultivated and Non-cultivated Plants as Biological Monitors
2011
Sawidis, Thomas | Metentzoglou, E. | Mitrakas, M. | Vasara, E.
Concentrations of chromium, copper, and lead were determined in soil and plant specimens collected from the area of coal power plant (CPP), A. Dimitrios, the largest CPP in Greece located on the eastern part of Ptolemais basin, Macedonia. Two cultivated plants (Brassica oleracea var. capitata L. and Zea mays L.) and two non-cultivated plants (Rumex acetosa L. and Verbascum phlomoides L.) were chosen. The mean heavy metal content in the soil is described in the descending order of Cr>Pb>Cu, while for the plant material, the order was Cr>Cu>Pb. Stations in the vicinity of the CPP showed a distinctly high load of Cr in the soil, whereas for the other metals, no such correlation has been noted. Unexpectedly, high levels of chromium and copper have been found in plant samples of the control station (Grevena) where there is no significant point source of air pollution by particulate matter. In general, roots revealed a higher metal concentration than that of the other plant organs. This is more obvious in B. oleracea var. capitata for all metals studied. Thus, B. oleracea var. capitata possesses the potential for phytoremediation of soils contaminated by metals since this plant is removable together with its roots from the contaminated soil. The most contaminated leaves showed a variation in surface roughness. In V. phlomoides the non-glandular, branched candelabrum-like trichomes on the leaf epidermis effectively trapped and retained a considerable number of particles. In contrast, the waxy cuticle of R. acetosa, which forms a smooth sheet over the epidermal cells, enabled the fast removal of particles by rain or wind. In the case of Z. mays, seeds accumulated the lowest amount of all metals.
Afficher plus [+] Moins [-]Removal of Cyanide in Ni(II)–Cyanide, Ni(II)–Cyanide–EDTA, and Electroplating Rinse Wastewater by Ferrate(VI)
2011
Osathaphan, Khemarath | Tiyanont, Patarawan | Yngard, Ria A. | Sharma, Virender K.
Cyanide is found as free cyanide and metal–cyanide complexes in metal finishing rinse wastewaters. Experiments were performed to seek removal of cyanide in Ni(II)–cyanide and Ni(II)–cyanide–ethylenediaminetetraacetate (EDTA) solutions by the environmentally friendly oxidant, ferrate(VI) (FeO4 2−, Fe(VI)) as a function of pH (8.0–11.0). Incomplete removal of cyanide in Ni(II)–cyanide solutions (≤60%) was observed at the studied pH range. However, cyanide removal efficiency approached to 100% in Ni(II)–cyanide–EDTA solutions. Formation of Ni(II)–cyanide and Ni(II)–EDTA complexes and relative rates of the reactions of Fe(VI) with various species (water, cyanide, Ni(II)–cyanide, and EDTA) present in solutions were responsible for the variation in removal efficiencies in mixtures at various pH. The oxidation of cyanide by Fe(VI) produced cyanate. Tests using electroplating rinse wastewaters demonstrated that Fe(VI) was highly effective in removing cyanide.
Afficher plus [+] Moins [-]A Review on Ozone Evolution and Its Relationship with Boundary Layer Characteristics in Urban Environments
2011
Tong, Nelson Y. O. | Leung, Dennis Y. C. | Liu, Chun-Ho
This paper reviews the interrelationship among boundary layer, urbanization, and evolution of ozone, with particular emphasis on how boundary layer dynamics and urbanization affects the evolution of ozone under different meteorological and climatological conditions. The aim of this work is not only to provide an exhaustive investigation of individual ozone episodes but to look at the underlying issues and hypotheses that are available for understanding the evolution of ozone. The review concludes with a summary of the current state of knowledge and outlines some of the remaining questions. It is the intention of this paper to serve as an ecumenical reference to the community for reappraising the relation of boundary layer climate to the evolution of ozone in an urban setting, especially on a peculiar feature of ozone dynamic, nocturnal ozone maxima. To date, there is still no overarching consensus on the mechanisms that lead to its formation. The importance of levels of urbanization and advantage of ascertaining the substantial weights of the respective mixing height and emission structure in exploring the relationship between ozone evolutions should not be overlooked.
Afficher plus [+] Moins [-]