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Sökning: AMNE:(NATURAL SCIENCES Chemistry Environmental chemistry) > Övrigt vetenskapligt/konstnärligt > Engelska > (2015-2017)

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1.
  • Gerlee, Philip, 1980, et al. (författare)
  • Scientific Models : Red Atoms, White Lies and Black Boxes in a Yellow Book
  • 2016
  • Bok (övrigt vetenskapligt/konstnärligt)abstract
    • A zebrafish, the hull of a miniature ship, a mathematical equation and a food chain - what do these things have in common? They are examples of models used by scientists to isolate and study particular aspects of the world around us. This book begins by introducing the concept of a scientific model from an intuitive perspective, drawing parallels to mental models and artistic representations. It then recounts the history of modelling from the 16th century up until the present day. The iterative process of model building is described and discussed in the context of complex models with high predictive accuracy versus simpler models that provide more of a conceptual understanding. To illustrate the diversity of opinions within the scientific community, we also present the results of an interview study, in which ten scientists from different disciplines describe their views on modelling and how models feature in their work. Lastly, it includes a number of worked examples that span different modelling approaches and techniques. It provides a comprehensive introduction to scientific models and shows how models are constructed and used in modern science. It also addresses the approach to, and the culture surrounding modelling in different scientific disciplines. It serves as an inspiration for model building and also facilitates interdisciplinary collaborations by showing how models are used in different scientific fields. The book is aimed primarily at students in the sciences and engineering, as well as students at teacher training colleges but will also appeal to interested readers wanting to get an overview of scientific modelling in general and different modelling approaches in particular.
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2.
  • Gerlee, Philip, 1980, et al. (författare)
  • Scientific Models
  • 2016
  • Bok (övrigt vetenskapligt/konstnärligt)abstract
    • A zebrafish, the hull of a miniature ship, a mathematical equation and a food chain - what do these things have in common? They are examples of models used by scientists to isolate and study particular aspects of the world around us. This book begins by introducing the concept of a scientific model from an intuitive perspective, drawing parallels to mental models and artistic representations. It then recounts the history of modelling from the 16th century up until the present day. The iterative process of model building is described and discussed in the context of complex models with high predictive accuracy versus simpler models that provide more of a conceptual understanding. To illustrate the diversity of opinions within the scientific community, we also present the results of an interview study, in which ten scientists from different disciplines describe their views on modelling and how models feature in their work. Lastly, it includes a number of worked examples that span different modelling approaches and techniques. It provides a comprehensive introduction to scientific models and shows how models are constructed and used in modern science. It also addresses the approach to, and the culture surrounding modelling in different scientific disciplines. It serves as an inspiration for model building and also facilitates interdisciplinary collaborations by showing how models are used in different scientific fields. The book is aimed primarily at students in the sciences and engineering, as well as students at teacher training colleges but will also appeal to interested readers wanting to get an overview of scientific modelling in general and different modelling approaches in particular.
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3.
  • 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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4.
  • Ericson Jogsten, Ingrid, 1980-, et al. (författare)
  • Analysis of ultra-short chain perfluoroalkyl substances in Swedish environmental waters
  • 2017
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • The purpose of this study was to investigate the environmental occurrence of ultra-short chain perfluoroalkyl substances (PFASs) in Swedish water samples. So far established protocols have focused on measuring PFASs with a carbon chain length of four or more carbons. In this study, perfluoroalkyl sulfonates of chain lengths of two, perfluoroethane sulfonate (PFEtS), and three, perfluoropropane sulfonate (PFPrS), carbons have been measured using a newly established instrumental method employing supercritical fluid separation (SFC) coupled to tandem mass spectrometry detection.A total of 26 samples were analysed, including ground water, surface water, rain water and snow. The sample locations included military and civilian airports, a former hard chromium plating facility, the vicinity of a hazardous waste management facility and background areas (lake surface water, rain and snow). Results show that both PFPrS and PFEtS could be detected in environmental samples using SFC separation coupled to triple quadrupole detection. Out of the 26 samples analysed, the ultra-short-chain PFPrS could be detected and quantified in 22 samples. The concentrations for PFPrS in all the samples ranged between 0.93 ng/l to 39 000 ng/l. The ultra-short-chain PFPEtS could be quantified in all of the 26 samples, with a concentration range between 0.07 and 5 700 ng/l. The highest concentrations represents highly contaminated ground water samples collected from a military airport. In the samples, PFPrS had a relative contribution to total PFAS concentration of 6 and 10 %, indicating the importance of measuring these compounds in environmental samples.
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8.
  • Matyskin, Artem, 1989 (författare)
  • On the solubility of radium sulfate and carbonate
  • 2016
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Radium is one of the most toxic elements and its concentration in different human activities and migration from man-made wastes provokes a strong interest in environmental science. To be able to model the migration process, reliable experimental thermodynamic data of radium compounds are needed.In this work details of the safe radium source disassembly which were previously used in brachytherapy are described and different methods for conversion of RaSO4 into aqueous solution are reviewed. The method of choice included three cycles of RaSO4 heating in 1.5 M Na2CO3 up to 85 ºC, cooling and subsequent removal of supernatant. X-ray diffraction studies showed that the method allows the synthesis of amorphous RaCO3, which can be dissolved in mineral acid. Gamma spectrometric measurements showed that most of the initial RaSO4 was converted into solution and that 7 ± 1 % of the initial 210Pb was co-precipitated with RaCO3. Synthesized RaCO3 was dissolved in HCl to prepare a radium stock solution. The radium stock solution was used to determine the solubility of pure RaSO4 and RaCO3 from oversaturation using Na2SO4 and Na2CO3 as a source of sulfate and carbonate ions. The solubility was determined at 25.1 ºC as a function of ionic strength using NaCl media. The concentration of radium was measured by gamma spectrometry after separation of the aqueous phase from the solid phase using ultracentrifugation. The extended specific ion interaction theory was used to extrapolate solubility product constants to zero ionic strength (log10 Ksp° = -10.16 ± 0.05 for RaSO4 and log10 Ksp° = -7.73 ± 0.56 for RaCO3) and to calculate ion interaction coefficients.A comparison of the shapes of the radium solubility curves for both anions with the shapes of corresponding barium solubility curves demonstrates the similarity of the behaviour of radium and barium salts in saline solutions. It can be supposed that due to the similarity of the radium and barium effective ionic radii, and the same charge, these ions undergo similar specific ion interactions in NaCl media.
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9.
  • Nerentorp, Michelle, 1986 (författare)
  • Mercury cycling in the global marine environment
  • 2016
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Mercury is a globally distributed contaminant that exists in the atmosphere in its elemental form as a stable monoatomic gas. Having a residence time of around one year in air allows it to be transported far from emission sources and end up in polar ecosystems. Gaseous elemental mercury (GEM) can in air be oxidized by photo-induced processes which produce water soluble oxidized forms of mercury which are more easily deposited. Deposited mercury can in the environment be transformed to organic and bio-accumulating compounds which are neurotoxic, making mercury a global concern. Deposited oxidized mercury into the sea can be reduced back to the elemental form (GEM) and be re-emitted to air. This re-evasion constitutes of around 30% of the total emissions of mercury to air and originates from both natural and anthropogenic sources. Models have estimated that the yearly mercury emission from global sea surfaces is between 2000 and 3000 tonnes. The mercury flux rate at the interphase between air and water depends on the Henry´s law constant, the concentration gradient and the gas transfer velocity. How to properly account for weather parameters such as wind speed, and how to accurately adjust the flux model to mercury (originally developed for CO2) has been debated in the literature and have resulted in diverse results of mercury flux rates.  In this work, mercury has been measured in air and in seawater during several campaigns in Antarctica, the Mediterranean Sea, the west coast of Sweden, Northern Finland and in the Arctic. From measured concentrations of mercury, the mercury flux rates from the studied areas were calculated using the gas exchange model described in Johnson (2010). Large spatial and seasonal variations of measured mercury concentrations were found which resulted in similar variations in calculated flux rates. In Antarctica and the Arctic, high concentrations of mercury were also measured in the sea ice environment. Seasonal variations in mercury concentrations were found and a correlation between solar radiation and the photo-production of elemental mercury in sea ice was discovered. The sea ice was suggested to affect the global marine cycling of mercury in several ways: acting as a cap preventing elemental mercury to evade from sea surfaces in Polar Regions, acting as barrier against direct atmospheric deposition and being a significant reservoir of mercury. Climate change will likely affect the cycling of mercury in global marine environments due to an increase in temperature, leading to enhanced mercury evasion, and diminishing and melting sea ice causing an increased input of mercury into polar oceans. Results presented in this thesis bring new insights about how mercury is cycling in the global marine environment and the new collected mercury data from remote and inaccessible areas are valuable for future modeling. However, more research is needed to further understand and quantify the accumulation of mercury in vulnerable marine ecosystems.
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