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Sökning: AMNE:(NATURAL SCIENCES Chemistry Environmental chemistry) > (2010-2013)

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1.
  • Ericson Jogsten, Ingrid, 1980-, et al. (författare)
  • Per- and polyfluorinated compounds (PFCs) in house dust and indoor air in Catalonia, Spain : implications for human exposure
  • 2012
  • Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 39:1, s. 172-180
  • Tidskriftsartikel (refereegranskat)abstract
    • A total of 27 per- and polyfluorinated compounds (PFCs) were determined in both house dust (n=10) and indoor air (n=10) from selected homes in Catalonia, Spain. Concentrations were found to be similar or lower than those previously reported for household microenvironments in other countries. Ten PFCs were detected in all house dust samples. The highest mean concentrations corresponded to perfluorodecanoic acid (PFDA) and perfluorononanoic acid (PFNA), 10.7 ng/g (median: 1.5 ng/g) and 10.4 ng/g (median: 5.4 ng/g), respectively, while the 8:2 fluorotelomer alcohol (FTOH) was the dominating neutral PFC at a concentration of 0.41 ng/g (median: 0.35 ng/g). The indoor air was dominated by the FTOHs, especially the 8:2 FTOH at a mean (median) concentration of 51 pg/m(3) (median: 42 pg/m(3)). A limited number of ionic PFCs were also detected in the indoor air samples. Daily intakes of PFCs were estimated for average and worst case scenarios of human exposure from indoor sources. For toddlers, this resulted in average intakes of ∑ionic PFCs of 4.9ng/day (0.33 ng/kg(bw)/day for a 15 kg toddlers) and ∑neutral PFCs of 0.072 ng/day (0.005 ng/kg(bw)/day) from house dust. For adults, the average daily intakes of dust were 3.6 and 0.053 ng/day (0.05 and 0.001 ng/kg(bw)/day for a 70 kg adult) for ∑ionic and ∑neutral PFCs, respectively. The average daily inhalation of ∑neutral PFCs was estimated to be 0.9 and 1.3 ng/day (0.06 and 0.02 ng/kg(bw)/day) for toddlers and adults, respectively. For PFOS, the main ionic PFC detected in indoor air samples, the median intakes (based on those samples where PFOS was detected), resulted in indoor exposures of 0.06 and 0.11 ng/day (0.004 and 0.002 ng/kg(bw)/day) for toddlers and adults, respectively. Based on previous studies on dietary intake and drinking water consumption, both house dust and indoor air contribute significantly less to PFC exposure within this population.
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2.
  • Donahue, N. M., et al. (författare)
  • Aging of biogenic secondary organic aerosol via gas-phase OH radical reactions
  • 2012
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 109:34, s. 13503-13508
  • Tidskriftsartikel (refereegranskat)abstract
    • The Multiple Chamber Aerosol Chemical Aging Study (MUCHACHAS) tested the hypothesis that hydroxyl radical (OH) aging significantly increases the concentration of first-generation biogenic secondary organic aerosol (SOA). OH is the dominant atmospheric oxidant, and MUCHACHAS employed environmental chambers of very different designs, using multiple OH sources to explore a range of chemical conditions and potential sources of systematic error. We isolated the effect of OH aging, confirming our hypothesis while observing corresponding changes in SOA properties. The mass increases are consistent with an existing gap between global SOA sources and those predicted in models, and can be described by a mechanism suitable for implementation in those models.
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3.
  • Ericson Jogsten, Ingrid, 1980- (författare)
  • Assessment of human exposure to per- and polyfluorinated compounds (PFCs) : exposure through food, drinking water, house dust and indoor air
  • 2011
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Per- and polyfluorinated compounds (PFCs) are detected in humans worldwide but all sources of human exposure have not been fully characterized. The aim of this thesis was to evaluate the contributions from food, water, air and dust as sources for human PFC exposure in the general population. Per- and polyfluorinated compounds (PFCs) are detected in humans worldwide but all sources of Up to 27 PFCs were determined at trace levels in blood (ng/mL), water (ng/L), foods (ng/g), dust (ng/g) and air (pg/m3) in a selected Catalan population and PFC intake was estimated from the measured PFC concentrations of the different sources of exposure. The major compounds detected in human blood of the studied population were perfluorooctane sulfonate (PFOS; 7.6 ng/mL), perfluorohexane sulfonate (PFHxS; 3.6 ng/mL) and perfluorooctanoic acid (PFOA; 1.8 ng/mL). In general, PFOS was also the major compound detected in most sources of exposure. Food was found to be the dominant pathway for human PFC exposure accounting for more than 70 % of the total intake of both PFOS and PFOA. In the most populated area (the Barcelona Province) where the highest levels were measured, tap water can contribute to the total exposure substantially with more than 50 % for adults. Indoor sources were negligible in the selected area for most PFCs when compared to food and water intake, except for toddlers under a worst case scenario where contribution from dust and food intake were equal (19 %). Pharmacokinetic (PK) modelling resulted in exposure of 103 ng PFOS/day and 33 ng PFOA/day of adults from the internal PFC blood concentrations. This agrees well with the intake estimated from external exposure through food, drinking water, house dust and indoor air of 80 ng PFOS/day and 32 ng PFOA/day and evidently all major exposure sources for the general population were included (in this study).
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4.
  • Nilsson, Helena, 1974-, et al. (författare)
  • Inhalation exposure to fluorotelomer alcohols yield perfluorocarboxylates in human blood?
  • 2010
  • Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:19, s. 7717-7722
  • Tidskriftsartikel (refereegranskat)abstract
    • Levels of perfluorinated carboxylates (PFCAs) in different environmental and biological compartments have been known for some time, but the routes of exposure still remain unclear. The opinions are divergent whether the exposure to general populations occurs mainly indirect through precursor compounds or direct via PFCAs. Previous results showed elevated blood levels of PFCAs in ski wax technicians compared to a general population. The objective of this follow-up study was to determine concentrations of PFCAs, perfluorosulfonates (PFSAs), and fluorotelomer alcohols (FTOHs), precursor compounds that are known to degrade to PFCAs, in air collected in the breathing zone of ski wax technicians during work. We collected air samples by using ISOLUTE ENV+ cartridges connected to portable air pumps with an air flow of 2.0 L min(-1). PFCAs C5-C11 and PFSAs C4, C6, C8, and C10 were analyzed using LC-MS/MS and FTOHs 6:2, 8:2, and 10:2 with GC-MS/MS. The results show daily inhalation exposure of 8:2 FTOH in mu g/m(3) air which is up to 800 times higher than levels of PFOA with individual levels ranging between 830-255000 ng/m(3) air. This suggests internal exposure of PFOA through biotransformation of 8:2 FTOH to PFOA and PFNA in humans.
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5.
  • Kylin, Henrik, et al. (författare)
  • Evaluating threats to an endangered species by proxy : air pollution as threat to the blue swallow (Hirundo atrocaerulea) in South Africa
  • 2011
  • Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 18:2, s. 282-290
  • Tidskriftsartikel (refereegranskat)abstract
    • Background, aim, and scope: The blue swallow (Hirundo atrocaerulea) is one of the most threatened bird species in southern Africa. Among terrestrial birds, its plumage is known to be the most water repellent, an adaptation to foraging on the wing in dense fog. Despite this uniqueadaptation, the nesting success of the blue swallow at the Blue Swallow Natural Heritage Site (BSNHS) is lower during years with high incidence of fog. As the phenomenon is not observed at other nesting sites, we hypothesized that this is due to changes in the air chemistry at the BSNHS. In the immediate proximity of the BSNHS, plantations of exotic trees (e.g., pines and eucalypts), rich in volatile organic compounds (VOCs), are dominant features. In addition, air pollution from the Johannesburg area is transported with the surface winds and mix withVOCs released from exotic trees. Together with the high humidity and high elevation, these conditions may result in the formation of sulphonates. Sulphonates are strong detergents, and the presence of these in the fog could lead to decreased water repellence of the plumage. This study was performed in order to determine the occurrence and distribution of sulphonates in the BSNHS and to compare these with sulphonates formed in other locations in South Africa. Because the blue swallow is endangered, pine needles were used as proxy to detect formation of sulphonates.Methods: We sampled pine needles with different exposure to air pollutants, in climates with different humidity, and at different elevation and analyzed these for sulphonates using mass spectrometry.Results: Pine needles from high elevations and the BSNHS, with high humidity, and exposure to air pollution contained significantly higher concentrations of sulphonates than pine needles from low elevations or from high elevations with a dryer climate or a different combination of air pollutants.Conclusions: These findings lead to two conclusions. First, the occurrence and distribution of sulphonates may be explained by chemical reactions between sulphur dioxide and organic compounds in the humid air induced by ultraviolet radiation. Second, elevated concentrations of sulphonates in the fog could affect the water repellence of the blue swallow plumage, possibly decreasing their capacity to forage in the fog. We cannot prove conclusively that this is the reason why the number of blue swallows atthe BSNHS has decreased dramatically, but for endangered species, we may have to rely on proxies to draw conclusions about outside threats. All such information should be valuable in devising protection plans for species under threat.Recommendations and perspectives: The use of proxies to elucidate threats to endangered species should be evaluated in a broad scale. The mist-belt habitat in general is threatened by many human activities. These findings indicate that air pollution and the proximity of volatile organic compound (VOC) sources close to mist-belt habitat refuges may be an unrecognised conservation threat to the animals inhabiting them.
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6.
  • Rickaby, Rosalind E. M., et al. (författare)
  • Perturbing phytoplankton : response and isotopic fractionation with changing carbonate chemistry in two coccolithophore species
  • 2010
  • Ingår i: Climate of the Past. - : Copernicus Publications on behalf of the European Geosciences Union. - 1814-9324 .- 1814-9332. ; 6, s. 771-785
  • Tidskriftsartikel (refereegranskat)abstract
    • All species of coccolithophore appear to respond to perturbations of carbonate chemistry in a different way. Here, we show that the degree of malformation, growthrate and stable isotopic composition of organic matter and carbonate produced by two contrasting species of coccolithophore (Gephyrocapsa oceanica and Coccolithus pelagicusssp. braarudii) are indicative of differences between their photosynthetic and calcification response to changing DIC levels (ranging from 1100 to 7800 μmol kg−1) at constant pH (8.13±0.02). Gephyrocapsa oceanica thrived under all conditions of DIC, showing evidence of increased growth rates at higher DIC, but C. braarudii was detrimentally affected at high DIC showing signs of malformation, and decreased growth rates. The carbon isotopic fractionation into organic matter and the coccoliths suggests that C. braarudii utilises a common internal pool of carbon for calcification and photosynthesis but G. oceanica relies on independent supplies for each process. All coccolithophores appear to utilize bicarbonate as their ultimate source of carbon for calcification resulting in the release of a proton. But, we suggest that this proton can be harnessed to enhance the supply of CO2(aq) for photosynthesis either from a large internal HCO−3 pool which acts as a pH buffer (C. braarudii), or pumped externally to aid the diffusive supply of CO2 across the membrane from the abundant HCO−3 (G. oceanica), likely mediated by an internal and external carbonic anhydrase respectively. Our simplified hypothetical spectrum of physiologies may provide a context to understand different species response to changing pH and DIC, the species specific Ep and calcite “vital effects”, as well as accounting for geological trends in coccolithophore cell size.
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7.
  • 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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8.
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9.
  • Pathak, Ravi K., et al. (författare)
  • Influence of Ozone and Radical Chemistry on Limonene Organic Aerosol Production and Thermal Characteristics
  • 2012
  • Ingår i: Environmental Science & Technology. - : American Chemical Society. - 0013-936X .- 1520-5851. ; 46:21, s. 11660-11669
  • Tidskriftsartikel (refereegranskat)abstract
    • Limonene has a strong tendency to form secondary organic aerosol (SOA) in the atmosphere and in indoor environments. Initial oxidation occurs mainly via ozone or OH radical chemistry. We studied the effect of O3 concentrations with or without a OH radical scavenger (2-butanol) on the SOA mass and thermal characteristics using the Gothenburg Flow Reactor for Oxidation Studies at Low Temperatures and a volatility tandem differential mobility analyzer. The SOA mass using 15 ppb limonene was strongly dependent on O3 concentrations and the presence of a scavenger. The SOA volatility in the presence of a scavenger decreased with increasing levels of O3, whereas without a scavenger, there was no significant change. A chemical kinetic model was developed to simulate the observations using vapor pressure estimates for compounds that potentially contributed to SOA. The model showed that the product distribution was affected by changes in both OH and ozone concentrations, which partly explained the observed changes in volatility, but was strongly dependent on accurate vapor pressure estimation methods. The model–experiment comparison indicated a need to consider organic peroxides as important SOA constituents. The experimental findings could be explained by secondary condensed-phase ozone chemistry, which competes with OH radicals for the oxidation of primary unsaturated products.
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10.
  • Haug, Line Smastuen, et al. (författare)
  • Levels in food and beverages and daily intake of perfluorinated compounds in Norway
  • 2010
  • Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 80:10, s. 1137-1143
  • Tidskriftsartikel (refereegranskat)abstract
    • Perfluorinated compounds (PFCs) have been determined in 21 samples of selected food and beverages such as meat, fish, bread, vegetables, milk, drinking water and tea from the Norwegian marked. Up to 12 different PFCs were detected in the samples. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were found in concentrations similar to or lower than what has been observed in other studies world-wide. Differences in the relative proportion of PFOA and PFOS between samples of animal origin and samples of non-animal origin were observed and support findings that PFOS has a higher bio-accumulation potential in animals than PFOA. Based on these 21 measurements and consumption data for the general Norwegian population, a rough estimate of the total dietary intake of PFCs was found to be around 100 ng d(-1). PFOA and PFOS contributed to about 50% of the total intake. When dividing the population in gender and age groups, estimated intakes were decreasing with increasing age and were higher in males than females. The estimated intakes of PFOS and PFOA in the present study are lower than what has been reported in studies from Spain, Germany, United Kingdom, Canada and Japan. This study illustrates that by improving the analytical methods for determination of PFC in food samples, a broad range of compounds can be detected, which is important when assessing dietary exposure. (C) 2010 Elsevier Ltd. All rights reserved.
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