Affiner votre recherche
Résultats 181-190 de 753
Determination of antibiotics in sewage from hospitals, nursery and slaughter house, wastewater treatment plant and source water in Chongqing region of Three Gorge Reservoir in China Texte intégral
2010
Chang, Xiaosong | Meyer, Michael T. | Liu, Xiaoyun | Zhao, Qing | Chen, Hao | Chen, Ji-an | Qiu, Zhiqun | Yang, Lan | Cao, Jia | Shu, Weiqun
Sewage samples from 4 hospitals, 1 nursery, 1 slaughter house, 1 wastewater treatment plant and 5 source water samples of Chongqing region of Three Gorge Reservoir were analyzed for macrolide, lincosamide, trimethoprim, fluorouinolone, sulfonamide and tetracycline antibiotics by online solid-phase extraction and liquid chromatography-tandem mass spectrometry. Results showed that the concentration of ofloxacin (OFX) in hospital was the highest among all water environments ranged from 1.660 μg/L to 4.240 μg/L and norfloxacin (NOR, 0.136-1.620 μg/L), ciproflaxacin (CIP, ranged from 0.011 μg/L to 0.136 μg/L), trimethoprim (TMP, 0.061-0.174 μg/L) were commonly detected. Removal range of antibiotics in the wastewater treatment plant was 18–100% and the removal ratio of tylosin, oxytetracycline and tetracycline were 100%. Relatively higher removal efficiencies were observed for tylosin (TYL), oxytetracycline (OXY) and tetracycline (TET)(100%), while lower removal efficiencies were observed for Trimethoprim (TMP, 1%), Epi-iso-chlorotetracycline (EICIC, 18%) and Erythromycin-H2O (ERY-H2O, 24%). Antibiotics were removed more efficiently in primary treatment compared with those in secondary treatment.
Afficher plus [+] Moins [-]Chemical fluxes in time through forest ecosystems in the UK - Soil response to pollution recovery Texte intégral
2010
Vanguelova, E.I. | Benham, S. | Pitman, R. | Moffat, A.J. | Broadmeadow, M. | Nisbet, T. | Durrant, D. | Barsoum, N. | Wilkinson, M. | Bochereau, F. | Hutchings, T. | Broadmeadow, S. | Crow, P. | Taylor, P. | Houston, T Durrant
Long term trend analysis of bulk precipitation, throughfall and soil solution elemental fluxes from 12 years monitoring at 10 ICP Level II forest sites in the UK reveal coherent national chemical trends indicating recovery from sulphur deposition and acidification. Soil solution pH increased and sulphate and aluminium decreased at most sites. Trends in nitrogen were variable and dependant on its form. Dissolved organic nitrogen increased in bulk precipitation, throughfall and soil solution at most sites. Nitrate in soil solution declined at sites receiving high nitrogen deposition. Increase in soil dissolved organic carbon was detected - a response to pollution recovery, changes in soil temperature and/or increased microbial activity. An increase of sodium and chloride was evident - a possible result of more frequent storm events at exposed sites. The intensive and integrated nature of monitoring enables the relationships between climate/pollutant exposure and chemical/biological response in forestry to be explored.
Afficher plus [+] Moins [-]Inferring chemical effects on carbon flows in aquatic food webs: Methodology and case study Texte intégral
2010
Laender, Frederik De | Soetaert, K. | Middelburg, J.J.
The majority of ecotoxicological enclosure experiments monitor species abundances at different chemical concentrations. Here, we present a new modelling approach that estimates changes in food web flows from such data and show that population- and food web level effects are revealed that are not apparent from abundance data alone. For the case of cypermethrin in freshwater enclosures, photosynthesis and excretion (d−1) of phytoplankton at 3.643 μg L-1 cypermethrin were 30% lower and 100% higher than in the control, respectively. The ingestion rate of mesozooplankton (d−1) was 6 times higher in the treated enclosures than in the control as food concentration increased with insecticide exposure. With increasing cypermethrin concentrations, nanoflagellates progressively relied on phytoplankton as their main food source, which rendered the food web less stable. We conclude that this tool has excellent potential to analyse the wealth of enclosure data as it only needs species abundance and general constraints.
Afficher plus [+] Moins [-]Relationship between heavy metals pollution and genetic diversity in Mediterranean populations of the sandhopper Talitrus saltator (Montagu) (Crustacea, Amphipoda) Texte intégral
2010
Ungherese, G. | Mengoni, A. | Somigli, S. | Baroni, D. | Focardi, S. | Ugolini, A.
Trace metals are one of the groups of pollutants that reduce genetic variability in natural populations, causing the phenomenon known as "genetic erosion". In this study we evaluate the relationship between trace metals contamination (Hg, Cd and Cu) and genetic variability, assessed using fluorescent Inter-Simple Sequence Repeats (fISSRs). We used eight populations of a well-established biomonitor of trace metals on sandy beaches: the amphipod Talitrus saltator. The trace metals analysis confirmed the ability of sandhoppers to accumulate Hg, Cd and Cu. Moreover, populations from sites with high Hg availability had the lowest values of genetic diversity. Our results validate the use of fISSR markers in genetic studies in sandhoppers and support the "genetic erosion" hypothesis by showing the negative influence of Hg contamination on sandhopper genetic diversity. Therefore, genetic variability assessed with fISSR markers could be successfully employed as a biomarker of Hg exposure.
Afficher plus [+] Moins [-]Sources and distribution of polycyclic aromatic hydrocarbons in sediments from the Spanish northern continental shelf. Assessment of spatial and temporal trends Texte intégral
2010
Viñas, Lucía | Franco, M Angeles | Soriano, J Antonio | González, J José | Pon, Jordi | Albaigés, Joan
Sources and distribution of polycyclic aromatic hydrocarbons in sediments from the Spanish northern continental shelf. Assessment of spatial and temporal trends Texte intégral
2010
Viñas, Lucía | Franco, M Angeles | Soriano, J Antonio | González, J José | Pon, Jordi | Albaigés, Joan
The distribution of polycyclic aromatic hydrocarbons was determined in surface sediments collected at 36 stations along the Spanish Northern continental shelf in March and September 2003, and February 2005. Concentrations of PAHs (Σ13 parent components) were in the range of 22-47528 μg/kg dw, the highest values corresponding to coastal urban-industrial hotspots and decreasing offshore. Sediment quality guidelines (SQGs) showed that concentrations of total PAHs were below the threshold effect level (TEC) in 27 stations (81%) and above in 7, two of which (Gijon and Bilbao) were above the probable effect concentration (PEC). The detailed study of diagnostic ratios suggested a rather uniform mixture of petrogenic and pyrolytic PAH sources along the continental shelf, with a slight decrease of the latter moving westwards and offshore. In order to assess the incidence of sediment sampling on the variability of the results, selected stations were also monitored in February and September 2004 and September 2005. The average field variance of the values obtained for each station was 31% that decreased to 23% when the values were normalized to TOC.
Afficher plus [+] Moins [-]Sources and distribution of polycyclic aromatic hydrocarbons in sediments from the Spanish northern continental shelf. Assessment of spatial and temporal trends Texte intégral
2010
Viñas, Lucía | Franco, María Ángeles | Soriano, J. A. | González, Juan José | Pon, Jordi
The distribution of polycyclic aromatic hydrocarbons was determined in surface sediments collected at 36 stations along the Spanish Northern continental shelf in March and September 2003, and February 2005. Concentrations of PAHs (Σ13 parent components) were in the range of 22–47528 μg/kg dw, the highest values corresponding to coastal urban-industrial hotspots and decreasing offshore. Sediment quality guidelines (SQGs) showed that concentrations of total PAHs were below the threshold effect level (TEC) in 27 stations (81%) and above in 7, two of which (Gijon and Bilbao) were above the probable effect concentration (PEC). The detailed study of diagnostic ratios suggested a rather uniform mixture of petrogenic and pyrolytic PAH sources along the continental shelf, with a slight decrease of the latter moving westwards and offshore. In order to assess the incidence of sediment sampling on the variability of the results, selected stations were also monitored in February and September 2004 and September 2005. The average field variance of the values obtained for each station was 31% that decreased to 23% when the values were normalized to TOC. | Peer reviewed
Afficher plus [+] Moins [-]Identification and quantification of a novel nitrate-reducing community in sediments of Suquía River basin along a nitrate gradient Texte intégral
2010
Reyna, Luciana | Wunderlin, Daniel Alberto | Genti-Raimondi, Susana
We evaluated the molecular diversity of narG gene from Suquía River sediments to assess the impact of the nitrate concentration and water quality on the composition and structure of the nitrate-reducing bacterial community. To this aim, a library of one of the six monitoring stations corresponding to the highest nitrate concentration was constructed and 118 narG clones were screened. Nucleotide sequences were associated to narG gene from alpha-, beta-, delta-, gammaproteobacteria and Thermus thermophilus. Remarkably, 18% of clones contained narG genes with less than 69% similarity to narG sequences available in databases. Thus, indicating the presence of nitrate-reducing bacteria with novel narG genes, which were quantified by real-time PCR. Results show a variable number of narG copies, ranging from less than 1.0 × 102 to 5.0 × 104 copies per ng of DNA, which were associated with a decreased water quality index monitored along the basin at different times.
Afficher plus [+] Moins [-]An approach for arsenic in a contaminated soil: Speciation, fractionation, extraction and effluent decontamination Texte intégral
2010
Giacomino, A. | Malandrino, M. | Abollino, O. | Velayutham, M. | Chinnathangavel, T. | Mentasti, E.
The fractionation and speciation of As in a contaminated soil were investigated, and a remediation strategy was tested. Regarding speciation, we found that As(V) prevails over As(III) whereas more than 40% of total arsenic is in organic form. The fractionation of As was investigated with two sequential extraction methods: a low mobility was found. Then we tested the possibility of using phosphoric acid to extract As from the soil and cleaning the washing effluents by sorption onto montmorillonite. The efficiency of the extraction and of the adsorption onto the clay were also investigated for Cr, Cu, Fe, Mn, Ni, Pb and Zn, whose total concentrations and fractionation in the soil are reported here. The extraction percentages for As and metals ranged from 30 to 65%; the residual proportions in the soil are presumably in very unreactive forms. Montmorillonite showed a good uptake capacity towards the investigated pollutants. Arsenic in a contaminated soil was present in different forms and it was extracted by soil washing followed by effluent treatment by sorption onto a natural clay.
Afficher plus [+] Moins [-]Current status of agricultural and rural non-point source Pollution assessment in China Texte intégral
2010
Ongley, E. D. | Xiaolan, Zhang | Tao, Yu
Estimates of non-point source (NPS) contribution to total water pollution in China range up to 81% for nitrogen and to 93% for phosphorus. We believe these values are too high, reflecting (a) misuse of estimation techniques that were developed in America under very different conditions and (b) lack of specificity on what is included as NPS. We compare primary methods used for NPS estimation in China with their use in America. Two observations are especially notable: empirical research is limited and does not provide an adequate basis for calibrating models nor for deriving export coefficients; the Chinese agricultural situation is so different than that of the United States that empirical data produced in America, as a basis for applying estimation techniques to rural NPS in China, often do not apply. We propose a set of national research and policy initiatives for future NPS research in China.
Afficher plus [+] Moins [-]Metal accumulation and performance of nestlings of passerine bird species at an urban brownfield site Texte intégral
2010
Hofer, Charles | Gallagher, Frank J. | Holzapfel, Claus
The use of passerine species as bioindicators of metal bioaccumulation is often underutilized when examining the wildlife habitat value of polluted sites. In this study we tested feathers of nestlings of two common bird species (house wren and American robin) for accumulation of Pb, Zn, As, Cr, Cu, Fe in comparison of a polluted, urban brownfield with a rural, unpolluted site. House wren nestlings at the study site accumulated significantly greater concentrations of all target metals except Zn. At the polluted site we found significant species differences of metal concentrations in feathers, with house wrens accumulating greater concentrations of Pb, Fe, and Zn but slightly lesser accumulations of Cr and Cu than American robins. Although house wren nestlings demonstrated significant accumulation of metals, these concentrations showed little effect on size metrics or fledge rates during the breeding season compared to nestlings from the control site.
Afficher plus [+] Moins [-]Pb isotopes as tracers of mining-related Pb in lichens, seaweed and mussels near a former Pb-Zn mine in West Greenland Texte intégral
2010
Søndergaard, Jens | Asmund, Gert | Johansen, Poul | Elberling, Bo
Identification of mining-related contaminants is important in order to assess the spreading of contaminants from mining as well as for site remediation purposes. This study focuses on lead (Pb) contamination in biota near the abandoned ‘Black Angel Mine’ in West Greenland in the period 1988-2008. Stable Pb isotope ratios and total Pb concentrations were determined in lichens, seaweed and mussels as well as in marine sediments. The results show that natural background Pb (207Pb/206Pb: 0.704-0.767) and Pb originating from the mine ore (207Pb/206Pb: 0.955) have distinct isotopic fingerprints. Total Pb in lichens, seaweed, and mussels was measured at values up to 633, 19 and 1536 mg kg-1 dry weight, respectively, and is shown to be a mixture of natural Pb and ore-Pb. This enables quantification of mining-related Pb and shows that application of Pb isotope data is a valuable tool for monitoring mining pollution.
Afficher plus [+] Moins [-]