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Sökning: AMNE:(NATURVETENSKAP Kemi Miljökemi)

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61.
  • van Hees, Patrick A. W., et al. (författare)
  • The biogeochemical impact of ectomycorrhizal conifers on major soil elements (Al, Fe, K and Si)
  • 2006
  • Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 136:1-2, s. 364-377
  • Tidskriftsartikel (refereegranskat)abstract
    • Mobilisation of nutrients and dissolution of minerals are of key importance for plant growth and soil formation, as well as long term ecosystem sustainability. The effects of Pinus sylvestris seedlings, ectomycorrhizal colonisation and potassium supply on the mobilisation of Al, Fe, K and Si were studied in a soil column experiment. Budgets were constructed considering amounts in drainage water, accumulation in plants and changes in the pools of exchangeable ions (BaCl2 extractions). Drainage was the most important sink under the experimental conditions imposed, but the other two pools were also of quantitative significance. Plants had a significant positive effect on the total quantities of all elements mobilized. Mycorrhizal colonisation had limited quantitative impact on the mobilization, probably because the chosen mycorrhizal fungi did not cause any growth promotion in this experiment. Despite this, a multivariate analysis (PCA) showed a clear separate grouping of mycorrhizal, non-mycorrhizal and no-plant treatments, and in particular Si and K mobilization was related to soil biological variables which in turn were affected by the presence of mycorrhiza. When K was omitted from the watering solution, plants were able to mobilise significantly more K, which was reflected in plant uptake and a potential replenishment of the exchangeable pool. Up-scaling of total Al, K and Si mobilization to field conditions resulted in rates between equal to and up to 10 times higher than the average historical weathering rate.
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62.
  • van Leeuwen, Stefan P. J., et al. (författare)
  • Struggle for quality in determination of perfluorinated contaminants in environmental and human samples
  • 2006
  • Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 40:24, s. 7854-7860
  • Tidskriftsartikel (refereegranskat)abstract
    • The first worldwide interlaboratory study on the analyses of 13 perfluorinated compounds (PFCs) in three environmental and two human samples indicates a varying degree of accuracy in relation to the matrix or analyte determined. The ability of 38 participating laboratories from 13 countries to determine the analytes in the various matrices was evaluated by calculation of z-scores according to the Cofino model. The PFCs which were reported most frequently by the laboratories, and assessed with the most satisfactory agreement, were perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). In general, the level of agreement between the participating laboratories decreased in the following order: PFC standard solution (76% satisfactory z-scores of <[2]1 for PFOS) < human blood (67%) < human plasma (63%) < fish liver extract (55%) < water (31%) < fish tissue (17%). This shows that relative good agreement between laboratories was obtained for the study of standard and human matrices. For the fish extract, most laboratories underestimated the actual PFOS concentration due to matrix effects. The results for the fish tissue and water are also poor, indicating that the extraction and cleanup steps require further improvement. It was concluded that the PFC determinations in various matrices are not yet fully mastered.
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63.
  • Carlsson, Henrik, 1987- (författare)
  • Development of an adductomic approach to identify electrophiles in vivo through their hemoglobin adducts
  • 2016
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Humans are exposed to electrophilically reactive compounds, both formed endogenously and from exogenous exposure. Such compounds could react and form stable reaction products, adducts, at nucleophilic sites in proteins and DNA. The formation of adducts constitutes a risk for effects, such as cancer and contact allergy, and plays a role in ageing processes. Adducts to proteins offer a possibility to measure electrophilic compounds in vivo.Adductomic approaches aim to study the totality of adducts, to specific biomolecules, by mass spectrometric screening. This thesis describes the development and application of an adductomic approach for the screening of unknown adducts to N-terminal valine (Val) in hemoglobin (Hb) by liquid chromatography tandem mass spectrometry (LC/MS/MS).The adductomic approach is based on the FIRE procedure, a modified Edman procedure for the analysis of adducts to N-terminal Val in Hb by LC/MS/MS. The adduct screening was performed by stepwise scanning of precursor ions in small mass increments and monitoring four fragments common for derivatives of detached Val adducts, in the multiple reaction monitoring mode. Samples from 12 smokers/nonsmokers were screened with the adductomic approach, and seven previously identified adducts and 19 unknown adducts were detected. A semiquantitative approach was applied for approximate quantification of adduct levels.A strategy for identifying unknown Hb adducts using adductome LC/MS/MS data was formulated and applied for the identification of unknown adducts. Identifications were based on the observed m/z of precursor ions and retention times combined with databases and Log P calculations. Hypothesized adducts were generated in vitro for comparison and matching with the corresponding unknown adducts. Five identified adducts correspond to the precursor electrophiles ethyl vinyl ketone (EVK), glyoxal, methylglyoxal, acrylic acid, and 1-octen-3-one. These adducts, except the adducts corresponding to glyoxal and methylglyoxal, have not been observed as protein adducts before.  Probable exposure sources to these electrophiles are diet and/or endogenous formation. The observation of these adducts motivate further studies to evaluate possible contributions to health risks, as well as their potential as biomarkers of exposure.The adduct from EVK was quantitatively assessed through different experiments to estimate the daily internal dose (area under the concentration-time-curve, AUC). EVK is about 2 × 103 more reactive than the reference compound acrylamide. The EVK adduct was shown to be unstable, with a relatively short half-life. The daily AUC in humans of EVK was estimated to be about 20 times lower than the corresponding AUC of acrylamide from intake via food.To confirm the observation of the detected unknown adducts and obtain a statistical foundation, analysis of unknown adducts were performed in large sets of blood samples (n = 50–120) from human cohorts. The majority of the previously detected unknown adducts were found in all analyzed samples, and the levels of many adducts showed large variations between individuals. The cause and significance of these observed variations are not yet clarified, but are of importance for the directions of future studies.In conclusion, a new approach for identification of unknown human exposure to electrophiles was developed and successfully applied. 
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64.
  • García García, Sandra, 1977- (författare)
  • Generation, stability and migration of montmorillonite colloids in aqueous systems
  • 2010
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • In Sweden the encapsulated nuclear waste will be surrounded by compacted bentonite in the granitic host rock. In contact with water-bearing fractures the bentonite barrier may release montmorillonite colloids that may be further transported in groundwater. If large amounts of material are eroded from the barrier, the buffer functionality can be compromised. Furthermore, in the scenario of a leaking canister, strongly sorbing radionuclides, can be transported by montmorillonite colloids towards the biosphere. This thesis addresses the effects of groundwater chemistry on the generation, stability, sorption and transport of montmorillonite colloids in water bearing rock fractures. To be able to predict quantities of montmorillonite colloids released from the bentonite barrier in contact with groundwater of varying salinity, generation and sedimentation test were performed. The aim is first to gain understanding on the processes involved in colloid generation from the bentonite barrier. Secondly it is to test if concentration gradients of montmorillonite colloids outside the barrier determined by simple sedimentation experiments are comparable to generation tests. Identical final concentrations and colloid size distributions were achieved in both types of tests. Colloid stability is strongly correlated to the groundwater chemistry. The impact of pH, ionic strength and temperature was studied. Aggregation kinetics experiments revealed that for colloid aggregation rate increased with increasing ionic strength. The aggregation rate decreased with increasing pH. The temperature effect on montmorillonite colloid stability is pH-dependent. At pH≤4, the rate constant for colloid aggregation increased with increasing temperature, regardless of ionic strength. At pH≥10, the aggregation rate constant decreased with increasing temperature. In the intermediate pH interval, the aggregation rate constant decreased with increasing temperature except at the highest ionic strength, where it increased. The relationship between the rate constant and the ionic strength allowed the critical coagulation concentration (CCC) for Na- and Ca-montmorillonite to be determined. In order to distinguish the contribution of physical filtration and sorption to colloid retention in transport, the different retention mechanisms were quantified. Sorption on different representative minerals in granite fractures was measured for latex colloids (50, 100, 200 nm) and montmorillonite colloids as a function of ionic strength and pH. Despite of the negative charge in mineral surfaces and colloids, sorption was detected. The sorption is correlated to the mineral point of zero charge and the zeta potential of the colloids, and increases with increasing ionic strength and decreasing pH. In transport experiments with latex colloids in columns packed with fracture filling material, the retention by sorption could clearly be seen. In particular at low flow rates, when the contact time for colloids with the mineral surfaces were the longest, sorption contributed to retention of the transport significantly. The retention of latex colloids appeared to be irreversible in contrary to the reversible montmorillonite colloid retention. Generation, stability and sorption of the montmorillonite colloids are controlled by electrostatic forces; hence, the results were in qualitative agreement with DLVO.
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65.
  • Jakobsson, Kristina, et al. (författare)
  • Polybrominated diphenyl ethers in maternal serum, umbilical cord serum, colostrum and mature breast milk : Insights from a pilot study and the literature
  • 2012
  • Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 47, s. 121-130
  • Tidskriftsartikel (refereegranskat)abstract
    • Human serum and mother's milk are frequently used to assess exposure to polybrominated diphenyl ethers (PBDEs), including transplacental transfer to the foetus. However, little is known about the kinetics of PBDEs, especially the highly brominated BDE congeners.In this pilot study, maternal serum samples were collected from 10 women at delivery and five to six weeks post partum. Umbilical serum was also obtained. Milk was donated two to five days, and five to six weeks after delivery. The amount of PBDEs in these samples was determined using liquid–liquid extraction and GC/MS.Low, moderately and highly brominated diphenyl ethers were present in umbilical cord serum, indicating placental transfer. The lipid-adjusted levels of BDE-47, BDE-207 and BDE-209 were similar in maternal and umbilical cord serum, whereas the cord serum levels for the penta- to octa-BDEs quantified were lower than in maternal serum.Marked changes were seen in the congener pattern in breast milk during the first month of lactation, whereas maternal serum levels did not change significantly. The general pattern was an enrichment of low to moderately brominated congeners (i.e. from BDE-17 to BDE-154, with the exception of BDE-28) in colostrum compared with maternal serum. In contrast, more highly brominated congeners were found at similar, or lower levels in colostrum than in maternal serum. After the transition from colostrum to mature milk, the levels of BDE-153 and BDE-209 were substantially reduced, and BDE‐209 was below the limit of detection in 6 out of 9 samples.A literature review on the design and reporting of studies on the transfer of PBDEs from mother to infant revealed a lack of transparency in many cases. The use of the recently published STROBE-ME guidelines is therefore recommended.
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66.
  • Rydén, Andreas, 1981-, et al. (författare)
  • Synthesis of polybrominated diphenyl ethers via unsymmetrical diaryliodonium triflates
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental pollutants due to theirpersistent character and extensive use as additive flame retardants. In order to assess theirbiological effects, fate, environmental concentrations and other parameters related to riskassessment, authentic PBDE congers are needed for research purposes. In the present work anew general method for the preparation of individual PBDE congeners is presented. Themethodology used is based on recent advances in unsymmetrical diaryliodonium saltsynthesis as well as advances in O-arylation of phenols with these types of salts. Accordingly,three brominated diphenyliodonium triflates were prepared i.e. phenyl(2,4,5-tribromophenyl)iodonium triflate, phenyl(2,4,6-tribromophenyl)iodonium triflate andphenyl(2,3,4,6-tetrabromophenyl)iodonium triflate from 1,2,4-tribromo-5-iodobenzene, 1,3,5-tribromo-2-iodobenzene and 1,2,3,5-tetrabromo-4-iodobenzene, respectively. Yields indiaryliodonium salt syntheses ranged from 69-96%. These salts were further used to O-arylatevarious brominated phenols giving individual tetra- to octa-BDE congeners in yields rangingfrom 64-98%. The O-arylation method used was given after a minor optimisation study, regarding reaction time and temperature, which is reported herein. In addition, this O-arylationmethod was also used with two brominated methoxyphenols in the syntheses of twomethoxylated PBDEs.
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67.
  • Winnberg, Ulrika, et al. (författare)
  • Novel Octabrominated Phenolic Diphenyl Ether Identified in Blue Mussels from the Swedish West Coast
  • 2014
  • Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 48:6, s. 3319-3326
  • Tidskriftsartikel (refereegranskat)abstract
    • Hydroxylated (OH−) and methoxylated (MeO−) polybrominated diphenyl ethers (PBDEs) are compounds present in the marine environment and OH–PBDEs are of toxicological concern and are therefore of interest to monitor in the environment. A phenolic octaBDE was tentatively identified in the phenolic fraction of previously analyzed mussel samples after methylation of the halogenated phenolic compounds (HPCs). The aim of the present study was to confirm the identity of this compound in blue mussels and investigate whether the analyte is diOH– and/or OH–MeO–octaBDE. Two reference standards, 6,6′-dimethoxy-2,2′,3,3′,4,4′,5,5′-octabromodiphenyl ether (6,6′-diMeO–BDE194) and 6-ethoxy-6′-methoxy-2,2′,3,3′,4,4′,5,5′-octabromodiphenyl ether (6-EtO-6′-MeO–BDE194) were prepared via O-arylation of 2,3,4,5-tetrabromo-6-methoxyphenol and 2,3,4,5-tetrabromo-6-ethoxyphenol, respectively, with a novel unsymmetrical diaryliodonium salt, 2,3,4,5-tetrabromo-6-methoxydiphenyliodonium triflate. The GC retention time and GC/MS spectrum of the synthesized 6,6′-diMeO–BDE194 correspond well with the analyte in the methylated phenolic fraction of a mussel extract from a previous study. Structural analysis performed in this study indicate that the synthesized 6,6′-diMeO–BDE194 and 6-EtO-6′-MeO–BDE194 correspond well with 6-hydroxy-6′-methoxy-2,2′,3,3′,4,4′,5,5′-octabromodiphenyl ether (6-OH–6′-MeO–BDE194) after methylation and ethylation, respectively, of the HPCs in the mussel extracts. The compound 6-OH–6′-MeO–BDE194 was identified and quantified in new mussels, sampled in 2012 from two locations on the Swedish west coast, with geometric mean concentrations of 3700 and 410 ng/g fat, respectively.
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68.
  • Yin, Ge, 1987- (författare)
  • Organohalogen contaminants in wildlife from the Yangtze River Delta : Development of methods and assessments of legacy and emerging persistent organic pollutants
  • 2016
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Rapid economic development has occurred during the past few decades in China with the Yangtze River Delta (YRD) area as one of the most progressive areas. The urbanization, industrialization, agricultural and aquaculture activities result in extensive production and application of chemicals. Organohalogen contaminants (OHCs) have been widely used as i.e. pesticides, flame retardants and plasticizers. They are persistent, bioaccumulative and pose a potential threat to ecosystem and human health. However, limited research has been conducted in the YRD with respect to chemicals environmental exposure.The main objective of this thesis is to investigate the contamination level, distribution pattern and sources of OHCs in the YRD. Wildlife from different habitats are used to indicate the environmental pollution situation, and evaluate selected matrices for use in long term biomonitoring to determine the environmental stress the contamination may cause. In addition, a method is developed for dicofol analysis. Moreover, a specific effort is made to introduce statistic power analysis to assist in optimal sampling design.The thesis results show extensive contamination of OHCs in wildlife in the YRD. The occurrences of high concentrations of chlorinated paraffins (CPs) are reported in wildlife, in particular in terrestrial species, (i.e. short-tailed mamushi snake and peregrine falcon). Impurities and byproducts of pentachlorophenol products, i.e. polychlorinated diphenyl ethers (PCDEs) and hydroxylated polychlorinated diphenyl ethers (OH-PCDEs) are identified and reported for the first time in eggs from black-crowned night heron and whiskered tern. High concentrations of octachlorodibenzo-p-dioxin (OCDD) are determined in these samples. The toxic equivalents (TEQs) of polychlorinated dibenzo-p-dioxin (PCDDs) and polychlorinated dibenzofurans (PCDFs) are at mean levels of 300 and 520 pg TEQ g-1lw (WHO2005 TEQ) in eggs from the two bird species, respectively. This is two orders of magnitude higher than European Union (EU) regulation limit in chicken eggs. Also, a novel pattern of polychlorinated biphenyls (PCBs) with octa- to decaCBs, contributing to as much as 20% of total PCBs therein, are reported in birds. The legacy POPs shows a common characteristic with relatively high level of organochlorine pesticides (i.e. DDT, hexacyclohexanes (HCHs) and Mirex), indicating historic applications. In contrast, rather low concentrations are shown of industrial chemicals such as PCBs and polybrominated diphenyl ethers (PBDEs).A refined and improved analytical method is developed to separate dicofol from its major decomposition compound, 4,4’-dichlorobenzophenone. Hence dicofol is possible to assess as such. Statistic power analysis demonstrates that sampling of sedentary species should be consistently spread over a larger area to monitor temporal trends of contaminants in a robust manner.The results presented in this thesis show high CPs and OCDD concentrations in wildlife. The levels and patterns of OHCs in YRD differ from other well studied areas of the world. This is likely due to the extensive production and use of chemicals in the YRD. The results strongly signal the need of research biomonitoring programs that meet the current situation of the YRD. Such programs will contribute to the management of chemicals and environment in YRD, with the potential to grow into the human health sector, and to expand to China as a whole.
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69.
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70.
  • Rydén, Andreas, 1981-, et al. (författare)
  • Synthesis and tentative identification of novel polybrominated diphenyl ether metabolites in human blood
  • 2012
  • Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 88:10, s. 1227-1234
  • Tidskriftsartikel (refereegranskat)abstract
    • Hydroxylated polybrominated diphenyl ethers (OH-PDBEs) are exogenous, bioactive compounds that originate, to a large extent, from anthropogenic activities, although they are also naturally produced in the environment. In the present study nine new authentic OH-PBDE reference standards and their corresponding methyl ether derivatives (MeO-PBDEs) were synthesised and characterised by NMR spectroscopy and mass spectrometry. Seven of the authentic reference standards prepared were thereafter tentatively identified in a pooled human blood sample. The tentatively identified OH-PBDEs were 3-hydroxy-2,2',4,4',6-pentabromodiphenyl ether, 3'-hydroxy-2,2',4,4',6-pentabromodiphenyl ether, 3-hydroxy-2,2',4,4',5-pentabromodiphenyl ether, 3-hydroxy-2,2',4,4',5,6'-hexabromodiphenyl ether. 3'-hydroxy-2,2',4,4',5,6'-hexabromodiphenyl ether, 3-hydroxy-2,2',4,4',5,5'-hexabromodiphenyl ether and 4-hydroxy-2,2',3,4',5,5',6-heptabromodiphenyl ether. An additional seven OH-PBDEs were tentatively identified in the pooled human blood sample, of which one OH-PBDE, 4'-hydroxy-2,2',4,5,5'-pentabromodiphenyl ether, has not been identified in human blood before. The identification was performed using gas chromatography-mass spectrometry (GC-MS) recording the bromine ions m/z 79, 81. The tentative identification was supported by the peaks relative retention times (RRTs) compared to authentic references on two GC columns of different polarities for the hexa-, and heptabrominated OH-PBDEs, and three different GC columns for the pentabrominated OH-PBDEs. The OH-PBDE congeners most likely originate from human metabolism of a flame retardant, i.e. polybrominated diphenyl ethers (PBDEs), due to the relatively high concentrations of PBDEs in the same human blood sample and the fact that these PBDEs could form the tentatively identified OH-PBDEs via metabolic direct hydroxylation or via 1,2-shift.
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