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Sökning: AMNE:(NATURVETENSKAP Geovetenskap och miljövetenskap Geokemi)

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1.
  • 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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2.
  • 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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3.
  • 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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4.
  • Sonesten, Lars (författare)
  • Miljöövervakning av Sveriges sjöar och vattendrag : representativiteten av den kontrollerande miljöövervakningen
  • 2013
  • Rapport (övrigt vetenskapligt)abstract
    • Rapporten presenterar en sammanst&auml;llning och analys av milj&ouml;&ouml;vervakningen i svenska sj&ouml;ar och vattendrag 2011-2012. Rapporten ger en sammanst&auml;llning av p&aring;g&aring;ende &ouml;vervakningsprogram och hur stationer och parametrar f&ouml;rdelar sig i sj&ouml;ar och vattendrag. Rapporten utg&ouml;r en grund f&ouml;r det fortsatta arbetet med &ouml;vervakningsprogrammens syfte och hur man skall kunna utforma optimerade och kostnadseffektiva &ouml;vervakningsprogram f&ouml;r f&ouml;rvaltningssyfte. Resultaten fr&aring;n projektets olika delar skall anv&auml;ndas inom den p&aring;g&aring;ende revideringen av den nationella och regionala milj&ouml;&ouml;vervakningen.
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5.
  • Bobrowski, Nicole, et al. (författare)
  • Multi-component gas emission measurements of the active lava lake of Nyiragongo, DR Congo
  • 2017
  • Ingår i: Journal of African Earth Sciences. - 0899-5362. ; 134, s. 856-865
  • Tidskriftsartikel (refereegranskat)abstract
    • Between 2007 and 2011 four measurement campaigns (June 2007, July 2010, June 2011, and December 2011) were carried out at the crater rim of Nyiragongo volcano, DR Congo. Nyiragongo is one of the most active volcanoes in Africa. The ground-based remote sensing technique Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS), which uses scattered sunlight, the in-situ Multi-Component Gas Analyzer System (Multi-GAS) and alkaline impregnated filter were simultaneously applied during all field trips. The bromine monoxide to sulfur dioxide (BrO/SO2) and carbon dioxide to sulfur dioxide (CO2/SO2) molar ratios were determined, among other ratios. During the different field trips variations of the level of the lava lake up to several tens of meters were observed during intervals of the order of minutes up to days and also between the years. The measured gas ratios presented covariations with the lava lake level changes. BrO/SO2 ratios and CO2/SO2 ratios showed similar behavior. Annual CO2/SO2 and BrO/SO2 average values are generally positively correlated. In June 2011 increased BrO/SO2 as well as increased CO2/SO2 ratios have been observed before a sudden decrease of the lava lake. Overall the Cl/S ratio, determined by filter-pack sampling, shows an increasing trend with time, which is accompanied by a decreasing sulfur dioxide flux, the later measured nearly continuously by automated MAX-DOAS instruments since 2004. Mean gas emission fluxes of CO2, Cl and ‘minimum-BrO’ fluxes are calculated using their ratio to SO2. The first two show an increase with time, in contrast to the SO2 fluxes. A simple conceptual model is proposed which can explain in particular the June 2011 data, but as well our entire data set. The proposed model takes up the idea of convective magma cells inside the conduit and the possible temporary interruption of part of the cycling. We propose than two alternatives to explain the observed gas emission variation: 1. It is assumed that the diffuse and fumarolic degassing could have significant influence on measured gas composition. The measured gas composition might rather represent a gas mixture of plume, diffuse and fumarolic degassing than only representing the volcanic plume. 2. It is proposed that the interruption of the convection has taken place in the upper part of the conduit and deep degassing of CO2 and bromine initially continues while mixing already with gas emissions from an ageing source, which is characterized by an already diminishing sulfur content. These complex process but as well as the gas mixing of different sources, could explain general features of our dataset, but can unfortunately neither be confirmed nor disproven by the data available today.
6.
  • Ledesma, Jose, et al. (författare)
  • Aquatic DOC export from subarctic Atlantic blanket bog in Norway is controlled by seasalt deposition, temperature and precipitation
  • 2016
  • Ingår i: Biogeochemistry. - Springer Verlag (Germany). - 0168-2563 .- 1573-515X. ; 127, s. 305-321
  • Tidskriftsartikel (refereegranskat)abstract
    • Comprehensive and credible peatland carbon budgets, needed for global carbon accounting, must include lateral aquatic organic carbon export. Here, we quantify aquatic dissolved organic carbon (DOC) export for an Atlantic bog in subarctic Norway, the And&oslash;ya peatland, and test for sensitivity to climatic drivers. Hydrology, DOC concentrations and DOC export were simulated for 2000&ndash;2013 using the process-based catchment model Integrated Catchments model for Carbon(INCA-C), calibrated to site-specific water chemistry and hydrology (2011&ndash;2014) using readily-available data on temperature, precipitation and seasalt deposition. Measured streamwater DOC declined under seasalt episodes and was strongly positively related to temperature. Model calibrations successfully reproduced the water balance, variation in runoff (R2=0.67; Nash&ndash;Sutcliffe model efficiency NS=0.67) and DOC concentrations (R2=0.85; NS=0.84). The most sensitive model parameters related to temperature-sensitivity of DOC production and DOC (de)sorption sensitivity to seasalts. Model uncertainty related to parameter space was similar to interannual variation in DOC export. Mean annual modelled DOC export was 7.2&plusmn;0.7g C m&minus;2 year&minus;1, roughly 35% of the net land&ndash;atmospheric CO2 exchange at And&oslash;ya from 2009 to 2012 (estimated elsewhere). Current and antecedent mean temperature and precipitation were strong drivers of seasonal modelled DOC export, implying that warmer and wetter summers will lead to more DOC export. Evaluation of similar climate impacts on net peatland carbon accumulation requires additional exploration of the climate-sensitivity of land&ndash;atmosphere fluxes of CO2 and methane. Process-based models are valuable tools to account for lateral DOC exports in carbon balances of northern peatlands, especially where long-term monitoring data are lacking.
7.
  • 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.
8.
  • 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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9.
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10.
  • Arellano, Santiago, 1981- (författare)
  • Studies of Volcanic Plumes with Remote Spectroscopic Sensing Techniques -DOAS and FTIR measurements on volcanoes of the Network for Observation of Volcanic and Atmospheric Change-
  • 2014
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Volcanism is a rich geodynamical process, closely linked to the origin and ongoing evolution of the lithosphere, atmosphere, hydrosphere and biosphere. Humans have benefited from the resources provided by volcanoes but also been threatened by the dangers of volcanic eruptions, which accurate prediction remains elusive. This is partly due to the inherent complexity of volcanic systems and partly because of the difficulty of conducting key observations to characterize them. In particular, since the segregation and escape of magmatic volatiles are essential mechanisms behind volcanic eruptions, monitoring the intensity and composition of the resulting emissions in the atmosphere is essential to characterize the state of volcanic activity; however, their direct measurement is not always feasible.Remote spectroscopic sensing, whereby gas species can be quantified by their spectral signatures in electromagnetic radiation gathered at a prudent distance from the plume, offers the possibility to conduct reliable and sustainable monitoring of volcanic emissions. To expand the remote sensing capabilities of volcanological observatories the Network for Observation of Volcanic and Atmospheric Change (NOVAC) was established in 2005. The central theme of this thesis is the acquisition, analysis and interpretation of measurements of volcanic gas emissions on volcanoes of NOVAC. Measurements of the mass flow rate of SO2 and the molar ratios of SO2 against BrO and HCl were obtained by scanning-Differential Optical Absorption Spectroscopy (DOAS) of scattered solar ultraviolet radiation and by Fourier-Transform Spectroscopy (FTIR) of direct solar infrared radiation. The uncertainty of the measurements is characterized and methods for combining observations from different sensors implemented. Statistical and physical models of degassing are proposed for selected volcanoes of the network. The resulting time-series of emission on 16 volcanoes is one of the more detailed compilations of volcanic degassing in the last decade, particularly from passive emissions which are difficult to detect from satellite platforms. This work aims at advancing our knowledge of volcanic eruptions for a better mitigation of their risks.
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