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Träfflista för sökning "AMNE:(NATURAL SCIENCES Earth and Related Environmental Sciences Geochemistry) "

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1.
  • Wang, Y. J., et al. (författare)
  • The formation of nitro-aromatic compounds under high NOx and anthropogenic VOC conditions in urban Beijing, China
  • 2019
  • Ingår i: Atmospheric Chemistry and Physics. - 1680-7316. ; 19:11, s. 7649-7665
  • Tidskriftsartikel (refereegranskat)abstract
    • Nitro-aromatic compounds (NACs), as important contributors to the light absorption by brown carbon, have been widely observed in various ambient atmospheres; however, their formation in the urban atmosphere was little studied. In this work, we report an intensive field study of NACs in summer 2016 at an urban Beijing site, characterized by both high-NO(x)and anthropogenic VOC dominated conditions. We investigated the factors that influence NAC formation (e.g., NO2, VOC precursors, RH and photolysis) through quantification of eight NACs, along with major components in fine particulate matter, selected volatile organic compounds, and gases. The average total concentration of the quantified NACs was 6.63 ng m(-3), higher than those reported in other summertime studies (0.14-6.44 ng m(-3)). 4-Nitrophenol (4NP, 32.4 %) and 4-nitrocatechol (4NC, 28.5 %) were the top two most abundant NACs, followed by methyl-nitrocatechol (MNC), methyl-nitrophenol (MNP), and dimethyl-nitrophenol (DMNP). The oxidation of toluene and benzene in the presence of NOx was found to be a more dominant source of NACs than primary biomass burning emissions. The NO2 concentration level was found to be an important factor influencing the secondary formation of NACs. A transition from low- to high-NOx regimes coincided with a shift from organic- to inorganic-dominated oxidation products. The transition thresholds were NO2 similar to 20 ppb for daytime and NO2 similar to 25 ppb for nighttime conditions. Under low-NOx conditions, NACs increased with NO2, while the NO3 concentrations and (NO3-)/NACs ratios were lower, implying organic-dominated products. Under high-NOx conditions, NAC concentrations did not further increase with NO2, while the NO3- concentrations and (NO3-)/NACs ratios showed increasing trends, signaling a shift from organic- to inorganic-dominated products. Nighttime enhancements were observed for 3M4NC and 4M5NC, while daytime enhancements were noted for 4NP, 2M4NP, and DMNP, indicating different formation pathways for these two groups of NACs. Our analysis suggested that the aqueous-phase oxidation was likely the major formation pathway of 4M5NC and 3M5NC, while photo-oxidation of toluene and benzene in the presence of NO2 could be more important for the formation of nitrophenol and its derivatives. Using the (3M4NC+4M5NC) / 4NP ratios as an indicator of the relative contribution of aqueous-phase and gas-phase oxidation pathways to NAC formation, we observed that the relative contribution of aqueous-phase pathways increased at elevated ambient RH and remained constant at RH > 30 %. We also found that the concentrations of VOC precursors (e.g., toluene and benzene) and aerosol surface area acted as important factors in promoting NAC formation, and photolysis as an important loss pathway for nitrophenols.
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2.
  • Sonesten, Lars (författare)
  • Miljöövervakning av Sveriges sjöar och vattendrag : representativiteten av den kontrollerande miljöövervakningen
  • 2013
  • Rapport (övrigt vetenskapligt)abstract
    • Rapporten presenterar en sammanställning och analys av miljöövervakningen i svenska sjöar och vattendrag 2011-2012. Rapporten ger en sammanställning av pågående övervakningsprogram och hur stationer och parametrar fördelar sig i sjöar och vattendrag. Rapporten utgör en grund för det fortsatta arbetet med övervakningsprogrammens syfte och hur man skall kunna utforma optimerade och kostnadseffektiva övervakningsprogram för förvaltningssyfte. Resultaten från projektets olika delar skall användas inom den pågående revideringen av den nationella och regionala miljöövervakningen.
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3.
  • Baresel, Christian, et al. (författare)
  • Uncertainty-Accounting Environmental Policy and Management of Water Systems
  • 2007
  • Ingår i: Environmental Science & Technology. ; 41:10, s. 3653–3659
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Environmental policies for water quality and ecosystem</p><p>management do not commonly require explicit stochastic</p><p>accounts of uncertainty and risk associated with the</p><p>quantification and prediction of waterborne pollutant loads</p><p>and abatement effects. In this study, we formulate and</p><p>investigate a possible environmental policy that does require</p><p>an explicit stochastic uncertainty account. We compare</p><p>both the environmental and economic resource allocation</p><p>performance of such an uncertainty-accounting environmental</p><p>policy with that of deterministic, risk-prone and riskaverse</p><p>environmental policies under a range of different</p><p>hypothetical, yet still possible, scenarios. The comparison</p><p>indicates that a stochastic uncertainty-accounting</p><p>policy may perform better than deterministic policies over</p><p>a range of different scenarios. Even in the absence of</p><p>reliable site-specific data, reported literature values appear</p><p>to be useful for such a stochastic account of uncertainty.</p>
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4.
  • Sonesten, Lars (författare)
  • Miljöövervakningen i sjöar och vattendrag kartlagd
  • 2014
  • Ingår i: Sötvatten 2014: om miljötillståndet i Sveriges sjöar, vattendrag och grundvatten. - Havs- och vattenmyndigheten. - 978-91-87025-63-1 ; s. 8-12
  • Bokkapitel (övrigt vetenskapligt)
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6.
  • Sonesten, Lars (författare)
  • Deformiteter hos oligochaeter i Vänern
  • 2014
  • Rapport (övrigt vetenskapligt)abstract
    • Bottenlevande slamr&ouml;rmaskar, oligochaeter, &auml;r k&auml;nsliga milj&ouml;indikatorer i alla typerav vatten. I en retrospektiv studie har deformiteter hos oligochaeter fr&aring;n treolika nordliga V&auml;nervikar j&auml;mf&ouml;rts under en period med minskad antropogen belastningmed avseende p&aring; n&auml;rings&auml;mnen och olika metaller. Stora m&auml;ngder av milj&ouml;farliga&auml;mnen finns dock lagrade i de sediment som oligochaeterna lever i.Resultaten fr&aring;n unders&ouml;kningen visar p&aring; att de allra gr&ouml;vsta deformitetsformerna,dvs. groteskt f&ouml;r&auml;ndrade ventrala borst, med tiden generellt sett har minskat i omfattning.Det finns d&auml;remot inga tecken p&aring; att l&auml;ttare deformiteter har minskatn&auml;mnv&auml;rt annat &auml;n lokalt. Ut&ouml;ver de skador som noterades p&aring; ventrala borst vidtidigare unders&ouml;kningar s&aring; noterades i denna unders&ouml;kning &auml;ven att deformiteterhos b&aring;de dorsala och ventrala borst har tillkommit hos arten Potamothrix hammoniensisi samtliga tre fj&auml;rdar. Deformiteterna sp&auml;nner mellan l&auml;ttare och mergrava skador, d&auml;r de l&auml;tta dominerar. Liknande skador hos dorsala borst har endastundantagsvis setts i tidigare material fr&aring;n V&auml;nern.&Auml;ven om f&ouml;rekomsten av de mest grava deformiteterna har minskat, s&aring; visar resultatenp&aring; att de l&auml;ttare skadorna inte har minskat noterbart under den unders&ouml;ktaperioden annat &auml;n p&aring; vissa provplatser. Detta skulle kunna tyda p&aring; att oligochaeternafortfarande p&aring;verkas av upplagrade milj&ouml;gifter i sedimenten.
7.
  • Ritter, Camila, et al. (författare)
  • High-throughput metabarcoding reveals the effect of physicochemical soil properties on soil and litter biodiversity and community turnover across Amazonia.
  • 2018
  • Ingår i: PeerJ. - 2167-8359. ; 6
  • Tidskriftsartikel (refereegranskat)abstract
    • Background. Knowledge on the globally outstanding Amazonian biodiversity and its environmental determinants stems almost exclusively from aboveground organisms, notably plants. In contrast, the environmental factors and habitat preferences that drive diversity patterns for micro-organisms in the ground remain elusive, despite the fact that micro-organisms constitute the overwhelming majority of life forms in any given location, in terms of both diversity and abundance. Here we address how the diversity and community turnover of operational taxonomic units (OTU) of organisms in soil and litter respond to soil physicochemical properties; whether OTU diversities and community composition in soil and litter are correlated with each other; and whether they respond in a similar way to soil properties. Methods. We used recently inferred OTUs from high-throughput metabarcoding of the 16S (prokaryotes) and 18S (eukaryotes) genes to estimate OTU diversity (OTU richness and effective number of OTUs) and community composition for prokaryotes and eukaryotes in soil and litter across four localities in Brazilian Amazonia. All analyses were run separately for prokaryote and eukaryote OTUs, and for each group using both presence-absence and abundance data. Combining these with novel data on soil chemical and physical properties, we identify abiotic correlates of soil and litter organism diversity and community structure using regression, ordination, and variance partitioning analysis. Results. Soil organic carbon content was the strongest factor explaining OTU diversity (negative correlation) and pH was the strongest factor explaining community turnover for prokaryotes and eukaryotes in both soil and litter. We found significant effects also for other soil variables, including both chemical and physical properties. The correlation between OTU diversity in litter and in soil was non-significant for eukaryotes and weak for prokaryotes. The community compositions of both prokaryotes and eukaryotes were more separated among habitat types (terra-firme, várzea, igapó and campina) than between substrates (soil and litter). Discussion. In spite of the limited sampling (four localities, 39 plots), our results provide a broad-scale view of the physical and chemical correlations of soil and litter biodiversity in a longitudinal transect across the world’s largest rainforest. Our methods help to understand links between soil properties, OTU diversity patterns, and community composition and turnover. The lack of strong correlation between OTU diversity in litter and in soil suggests independence of diversity drives of these substrates and highlights the importance of including both measures in biodiversity assessments. Massive sequencing of soil and litter samples holds the potential to complement traditional biological inventories in advancing our understanding of the factors affecting tropical diversity.
8.
  • Omstedt, Anders, 1949- (författare)
  • The Development of Climate Science of the Baltic Sea Region
  • 2017
  • Ingår i: Oxford Research Encyclopedia of Climate Science. - Oxford University Press.
  • Bokkapitel (övrigt vetenskapligt)abstract
    • Dramatic climate changes have occurred in the Baltic Sea region caused by changes in orbital movement in the earth–sun system and the melting of the Fennoscandian Ice Sheet. Added to these longer-term changes, changes have occurred at all timescales, caused mainly by variations in large-scale atmospheric pressure systems due to competition between the meandering midlatitude low-pressure systems and highpressure systems. Here we follow the development of climate science of the Baltic Sea from when observations began in the 18th century to the early 21st century. The question of why the water level is sinking around the Baltic Sea coasts could not be answered until the ideas of postglacial uplift and the thermal history of the earth were better understood in the 19th century and periodic behavior in climate related time series attracted scientific interest. Herring and sardine fishing successes and failures have led to investigations of fishery and climate change and to the realization that fisheries themselves have strongly negative effects on the marine environment, calling for international assessment efforts. Scientists later introduced the concept of regime shifts when interpreting their data, attributing these to various causes. The increasing amount of anoxic deep water in the Baltic Sea and eutrophication have prompted debate about what is natural and what is anthropogenic, and the scientific outcome of these debates now forms the basis of international management efforts to reduce nutrient leakage from land. The observed increase in atmospheric CO and its effects on global warming have focused the climate debate on trends and generated a series of international and regional assessments and research programs that have greatly improved our understanding of climate and environmental changes, bolstering the efforts of earth system science, in which both climate and environmental factors are analyzed together.
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9.
  • Lutz, Anna, 1986-, et al. (författare)
  • Gas to Particle Partitioning of Organic Acids in the Boreal Atmosphere
  • 2019
  • Ingår i: Acs Earth and Space Chemistry. - 2472-3452. ; 3:7, s. 1279-1287
  • Tidskriftsartikel (refereegranskat)abstract
    • Gas to particle partitioning of carboxylic acids was investigated using a high-resolution chemical ionization time-of-flight mass spectrometer (HR-CI-ToF-MS) with the filter inlet for gases and aerosol (FIGAERO). Specifically, the partitioning coefficients of 640 components with unique molecular composition were calculated from an assumed linear relationship between [particle]/[gas] versus the mass of the organic fraction (M-org) according to Raoult's law, i.e., equilibrium phase partitioning. We demonstrate that, using the full data set, most of the compounds do not follow a linear relationship. This is especially the case for low- and high-molecular-weight species. Using a subset of the data, with concurrent low sulfate ambient observations ([SO42- < 0.4 mu g m(-3)), the relationship improved significantly and K-i could be derived from the slope of a linear regression to the data. The 100 species with the highest R-2 (>= 0.7) of this regression are presented. The restrictions during high sulfate conditions can be explained by changes in either the equilibrium conditions (e.g., the activity coeffient, gamma(i)) or uptake kinetics (mass transfer limitation). This study demonstrates that partitioning of compounds in the complex ambient atmosphere follows ideal Raoult's law for some limited conditions and stresses the need for studies also in more polluted environments.
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10.
  • Konn, Cécile, 1981- (författare)
  • Origin of organic compounds in fluids from ultramafic-hosted hydrothermal vents of the Mid-Atlantic Ridge
  • 2009
  • Ingår i: MoMARnet. - Stockholm : Department of Geology and Geochemistry, Stockholm University. - 978-91-7155-913-5
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • <p>Natural gas, primarily methane (CH<sub>4</sub>), is produced in substantial amounts in ultramafic-hosted hydrothermal systems. These systems could also generate oil (heavier hydrocarbons) and the first building blocks of life (prebiotic molecules). In the presence of iron bearing minerals, serpentinisation reactions generate H<sub>2</sub>. Subsequently, CH<sub>4</sub> could be synthesised by Fischer-Tropsch Type (FTT) reaction (4H<sub>2</sub> + CO<sub>2</sub> → CH<sub>4</sub> + 2H<sub>2</sub>O) which is an abiotic process. This has lead to the idea of abiotic formation of larger organic molecules. Both thermodynamics and laboratory work support this idea, yet field data have been lacking. This study focuses on determining the organic content of fluids from ultramafic-hosted hydrothermal systems from the Mid-Atlantic Ridge (MAR) and the origin of the compounds. Fluids were collected from the Lost City, Rainbow, Ashadze and Logatchev vent fields during the EXOMAR (2005), SERPENTINE (2007), MoMARDREAMnaut (2007) and MOMAR08-Leg2 (2008) cruises conducted by IFREMER, France. A SBSE-TD-GC-MS technique was developed and used to extract, concentrate, separate and identify compounds in the fluids. Hydrothermally derived compounds appeared to consist mainly of hydrocarbons and O-bearing molecules. In addition, some amino acids were detected in the fluids by ULPC-ESI-QToF-MS but their origin will need to be determined. The organic content of the Rainbow fluids did not show intra field variability unlike differences could be noted over the years. In order to address the question of the source of the molecules, compound specific carbon isotopic analyses were carried out and completed with a bacterial (<em>Pyrococcus abyssi</em>) hydrothermal degradation experiment. The δ<sup>13</sup>C data fall in the range of -40 to -30‰ (vs. V-PDB), but individual δ<sup>13</sup>C values preclude the identification of a biogenic or abiogenic origin of the compounds. The degradation experiment, however, suggests an abiogenic origin of a portion of saturated hydrocarbons whereas carboxylic acids would be biogenic, and aromatic compounds would be thermogenic.</p>
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