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Lysosomal enlargement and lysosomal membrane destabilisation in mussel digestive cells measured by an integrative index Texte intégral
2009
Lysosomal responses (enlargement and membrane destabilisation) in mussel digestive cells are well-known environmental stress biomarkers in pollution effects monitoring in marine ecosystems. Presently, in laboratory and field studies, both responses were measured separately (in terms of lysosomal volume density - Vv - and labilisation period -LP) and combined (lysosomal response index - LRI) in order to contribute to their understanding and to develop an index useful for decisions makers. LRI integrates Vv and LP, which are not necessarily dependent lysosomal responses. It is unbiased and more sensitive than Vv and LP alone and diminishes background due to confounding factors. LRI provides a simple numerical index (consensus reference = 0; critical threshold = 1) directly related to the pollution impact degree. Moreover, LRI can be represented in a way that allows the interpretation of lysosomal responses, which is useful for environmental scientists. Lysosomal responses to pollutants measured by an integrative index.
Afficher plus [+] Moins [-]Pulsed gas injection: A minimum effort approach for enhanced natural attenuation of chlorobenzene in contaminated groundwater Texte intégral
2009
Balcke, Gerd Ulrich | Paschke, Heidrun | Vogt, Carsten | Schirmer, Mario
Chlorobenzene-contaminated groundwater was used to assess pulsed gas sparging as a minimum effort aeration strategy to enhance intrinsic natural attenuation. In contrast to existing biosparging operations, oxygen was supplied at minimum rate by reducing the gas injection frequency to 0.33 day⁻¹. Field tests in a model aquifer were conducted in a 12 m long reactor, filled with indigenous aquifer material and continuously recharged with polluted groundwater over 3 years. The closed arrangement allowed yield balances, cost accounting as well as the investigation of spatial distributions of parameters which are sensitive to the biodegradation process. Depending on the injection frequency and on the gas chosen for injection (pure oxygen or air) oxygen-deficient conditions prevailed in the aquifer. Despite the limiting availability of dissolved oxygen in the groundwater, chlorobenzene degradation under oxygen-deficient conditions proved to be more effective than under conditions with dissolved oxygen being available in high concentrations. Minimum rate gas sparging resulted in sustained biodegradation of chlorobenzene in a polluted groundwater aquifer.
Afficher plus [+] Moins [-]Environmental-geochemical characteristics of Cu in the soil and water in copper-rich deposit area of southeastern Hubei Province, along the middle Yangtze River, Central China Texte intégral
2009
Zhang, Ling | Wang, Lu | Yin, Kedong | Lv, Ying | Zhang, Derong
In this study, the natural Cu background concentration and Cu natural and anthropogenic contamination in soil, water and crop were investigated systematically in Huangshi area. The results show that regional geology is the dominant factor controlling the natural Cu background concentration in soil and water, and that pH is important to control the vertical distribution of Cu in soil under the same geographical and climatic conditions. The mineralization of rock bodies causes the natural Cu increase in soil and water, whereas, a large number of mining-smelting plants and chemical works are the main sources of Cu anthropogenic contamination. Cu in naturally and anthropogenically polluted soil displays differences in total and available contents, vertical distribution patterns and physico-chemical properties, the same happens in water. Consider the rock-soil-water-crop as a system to study the geochemical activities and environmental pollution of copper.
Afficher plus [+] Moins [-]Rising trends of dissolved organic matter in drinking-water reservoirs as a result of recovery from acidification in the Ore Mts., Czech Republic Texte intégral
2009
Oulehle, Filip | Hruška, Jakub
The concentration of chemical oxygen demand (COD), a common proxy for dissolved organic matter (DOM), was measured at seven drinking-water reservoirs and four streams between 1969 and 2006. Nine of them showed significant DOM increases (median COD change +0.08 mg L−1 yr−1). Several potential drivers of these trends were considered, including air temperature, rainfall, land-use and water sulfate concentration. Temperature and precipitation influenced inter-annual variations, but not long-term trends. The long-term DOM increase was significantly associated with declines of acidic deposition, especially sulfur deposition. Surface water sulfate concentrations decreased from a median of 62 mg L−1–27 mg L−1 since 1980. The magnitude of DOM increase was positively correlated with average DOM concentration (R2 = 0.79, p < 0.001). Simultaneously, DOM concentration was positively correlated with the proportion of Histosols within the catchments (R2 = 0.79, p < 0.001). A focus on the direct removal of DOM by water treatment procedures rather than catchment remediation is needed. Rising DOM levels in surface waters are due to changes in soil chemistry caused by a reduction of acidic deposition.
Afficher plus [+] Moins [-]Quantification of activated carbon contents in soils and sediments using chemothermal and wet oxidation methods Texte intégral
2009
Brändli, Rahel C. | Bergsli, Anders | Ghosh, Upal | Hartnik, Thomas | Breedveld, Gijs D. | Cornelissen, Gerard
Activated carbon (AC) strongly sorbs organic pollutants and can be used for remediation of soils and sediments. A method for AC quantification is essential to monitor AC (re)distribution. Since AC is black carbon (BC), two methods for BC quantification were tested for AC mixed in different soils and sediments: i) chemothermal oxidation (CTO) at a range of temperatures and ii) wet-chemical oxidation with a potassium dichromate/sulfuric acid solution. For three soils, the amount of AC was accurately determined by CTO at 375 °C. For two sediments, however, much of the AC disappeared during combustion at 375 °C, which could probably be explained by catalytic effects by sediment constituents. CTO at lower temperatures (325–350 °C) was a feasible alternative for one of the sediments. Wet oxidation effectively functioned for AC quantification in sediments, with almost complete AC recovery (81–92%) and low remaining amounts of native organic carbon (5–16%). Activated carbon quantification is best performed for soils with chemothermal oxidation at 375 °C, and for sediments with wet oxidation with potassium dichromate/sulfuric acid.
Afficher plus [+] Moins [-]Development of a comprehensive analytical method for the determination of chlorinated paraffins in spruce needles applied in passive air sampling Texte intégral
2009
Iozza, Saverio | Schmid, Peter | Oehme, Michael
Conifer needles are used for the monitoring of atmospheric persistent organic pollutants. The objective of the present study was to develop a method for the detection of airborne chlorinated paraffins (CPs) using spruce needles as a passive sampler. The method is based on liquid extraction of the cuticular wax layer followed by chromatographic fractionation and detection of CPs using two different GCMS techniques. Total CP concentrations (sum of short (SCCP), medium (MCCP) and long chain CPs (LCCP)) were determined by EI-MS/MS. SCCP and MCCP levels as well as congener group patterns (n-alkane chain length, chlorine content) could be evaluated using ECNI-LRMS. For the first time, data on environmental airborne CPs on spruce needles taken within the Monitoring Network in the Alpine Region for Persistent and other Organic Pollutants (MONARPOP) are presented providing evidence that spruce needles are a suitable passive sampling system for the monitoring of atmospheric CPs. A developed method for chlorinated paraffins (CPs) provided evidence that spruce needles are a suitable passive sampling system for the monitoring of atmospheric CPs.
Afficher plus [+] Moins [-]Bioaccumulation of organochlorine pollutants in the fish community in Lake Årungen, Norway Texte intégral
2009
Sharma, Chhatra Mani | Rosseland, Bjørn Olav | Almvik, Marit | Eklo, Ole Martin
Organochlorine pollutants in the major fish species (pike Esox lucius, perch Perca fluviatilis, and roach Rutilus rutilus) of Lake Årungen, Norway, were investigated after an extensive removal of large pike in 2004. The organochlorine pollutants detected in fish liver samples in 2005 were dichlorodiphenyltrichloroethane (DDTs), polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and heptachlor epoxide (HCE). DDTs were the dominant among all analyzed OCs. ΣPCB and HCB, detected in fish from two clearly distinct trophic levels (prey and predators), give an indication of biomagnification. All OC concentrations in female pike were significantly lower compared to males, which might be due to the removal of high concentrations of pollutants in roe during spawning. Organochlorine pollutants in fish tissues tend to magnify up the food chain.
Afficher plus [+] Moins [-]Mercury mass balance study in Wujiangdu and Dongfeng Reservoirs, Guizhou, China Texte intégral
2009
Feng, Xinbin | Jiang, Hongmei | Qiu, Guangle | Yan, Haiyu | Li, Guanghui | Li, Zhonggen
From October 2003 to September 2004, we conducted a detailed study on the mass balance of total mercury (THg) and methylmercury (MeHg) of Dongfeng (DF) and Wujiangdu (WJD) reservoirs, which were constructed in 1992 and 1979, respectively. Both reservoirs were net sinks for THg on an annual scale, absorbing 3319.5 g km⁻² for DF Reservoir, and 489.2 g km⁻² for WJD Reservoirs, respectively. However, both reservoirs were net sources of MeHg to the downstream ecosystems. DF Reservoir provided a source of 32.9 g MeHg km⁻² yr⁻¹, yielding 10.3% of the amount of MeHg that entered the reservoir, and WJD Reservoir provided 140.9 g MeHg km⁻² yr⁻¹, yielding 82.5% of MeHg inputs. Our results implied that water residence time is an important variable affecting Hg methylation rate in the reservoirs. Our study shows that building a series of reservoirs in line along a river changes the riverine system into a natural Hg methylation factory which markedly increases the % MeHg in the downstream reservoirs; in effect magnifying the MeHg buildup problem in reservoirs. Reservoirs are the sink of total mercury but source of methylmercury to the aquatic systems.
Afficher plus [+] Moins [-]Aqueous suspensions of carbon nanotubes: Surface oxidation, colloidal stability and uranium sorption [Erratum: 2009 Oct., v. 157, no. 10, p. 2891.] Texte intégral
2009
Schierz, A. | Zänker, H.
The objective of this study is to obtain information on the behaviour of carbon nanotubes (CNTs) as potential carriers of pollutants in the case of accidental CNT release to the environment and on the properties of CNTs as a potential adsorbent material in water purification. The effects of acid treatment of CNTs on (i) the surface properties, (ii) the colloidal stability and (iii) heavy metal sorption are investigated, the latter being exemplified by uranium(VI) sorption. There is a pronounced influence of surface treatment on the behaviour of the CNTs in aqueous suspension. Results showed that acid treatment increases the amount of acidic surface groups on the CNTs. Therefore, acid treatment has an increasing effect on the colloidal stability of the CNTs and on their adsorption capacity for U(VI). Another way to stabilise colloids of pristine CNTs in aqueous suspension is the addition of humic acid. Acid treatment of carbon nanotubes has an increasing effect on their colloidal stability and on their adsorption capacity for U(VI).
Afficher plus [+] Moins [-]Sorption mechanisms of cephapirin, a veterinary antibiotic, onto quartz and feldspar minerals as detected by Raman spectroscopy Texte intégral
2009
Peterson, Jonathan W. | Seymour, Michael D. | Wang, Wei | Gu, Baohua
Raman spectroscopy was used to investigate sorption mechanisms of cephapirin (CHP), a veterinary antibiotic, onto quartz (SiO₂) and feldspar (KAlSi₃O₈) at different pH. Sorption occurs by electrostatic attraction, monodentate and bidentate complexation. The zwitterion (CHP⁰) adsorbs to a quartz(+) surface by electrostatic attraction of the carboxylate anion group (-COO-) at low pH, but adsorbs to a quartz(-) surface through electrostatic attraction of the pyridinium cation, and possibly COO- bridge complexes, at higher pH. CHP- bonds to quartz(-) surfaces by bidentate complexation between one oxygen of -COO- and oxygen from carbonyl of an acetoxymethyl group. On a feldspar(+/-) surface, CHP⁰ forms monodentate complexes between CO, and possible -COO- bridges and/or electrostatic attachments to localized edge (hydr)oxy-Al surfaces. CHP- adsorbs to feldspar(-) through monodentate CO complexation. Similar mechanisms may operate for other cephalosporins. Results demonstrate, for the first time, that Raman techniques can be effective for evaluating sorption mechanisms of antibiotics. Raman spectroscopy indicates that cephapirin, a veterinary antibiotic, sorbs to quartz and feldspar by electrostatic attraction, and monodentate and bidentate complexation.
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