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Danielsson, Åsa
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Publications (10 of 45) Show all publications
Shakeri Yekta, S., Skyllberg, U., Danielsson, Å., Björn, A. & Svensson, B. H. (2017). Chemical Speciation of Sulfur and Metals in Biogas Reactors - Implications for Cobalt and Nickel Bio-uptake Processes. Journal of Hazardous Materials, 324, 110-116
Open this publication in new window or tab >>Chemical Speciation of Sulfur and Metals in Biogas Reactors - Implications for Cobalt and Nickel Bio-uptake Processes
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2017 (English)In: Journal of Hazardous Materials, ISSN 0304-3894, Vol. 324, p. 110-116Article in journal (Refereed) Published
Abstract [en]

This article deals with the interrelationship between overall chemical speciation of S, Fe, Co, and Ni in relation to metals bio-uptake processes in continuous stirred tank biogas reactors (CSTBR). To address this topic, laboratory CSTBRs digesting sulfur(S)-rich stillage, as well as full-scale CSTBRs treating sewage sludge and various combinations of organic wastes, termed co-digestion, were targeted. Sulfur speciation was evaluated using acid volatile sulfide extraction and X-ray absorption spectroscopy. Metal speciation was evaluated by chemical fractionation, kinetic and thermodynamic analyses. Relative Fe to S content is identified as a critical factor for chemical speciation and bio-uptake of metals. In reactors treating sewage sludge, quantity of Fe exceeds that of S, inducing Fe-dominated conditions, while sulfide dominates in laboratory and co-digestion reactors due to an excess of S over Fe. Under sulfide-dominated conditions, metals availability for microorganisms is restricted due to formation of metal-sulfide precipitates. However, aqueous concentrations of different Co and Ni species were shown to be sufficient to support metal acquisition by microorganisms under sulfidic conditions. Concentrations of free metal ions and labile metal complexes in aqueous phase, which directly participate in bio-uptake processes, are higher under Fe-dominated conditions. This in turn enhances metal adsorption on cell surfaces and bio-uptake rates.

Keywords
Biogas, Chemical, speciation, Bio-uptake, Sulfur, Iron Cobalt, Nickela
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:liu:diva-127149 (URN)10.1016/j.jhazmat.2015.12.058 (DOI)000390723900014 ()
Available from: 2016-04-15 Created: 2016-04-15 Last updated: 2017-01-26
Shakeri Yekta, S., Lindmark, A., Skyllberg, U., Danielsson, Å. & Svensson, B. (2016). Correction: Importance of reduced sulfur for the equilibrium chemistry and kinetics of Fe(II), Co(II) and Ni(II) supplemented to semi-continuous stirred tank biogas reactors fed with stillage (vol 269, pg 83, 2014). Journal of Hazardous Materials, 303, 182-182
Open this publication in new window or tab >>Correction: Importance of reduced sulfur for the equilibrium chemistry and kinetics of Fe(II), Co(II) and Ni(II) supplemented to semi-continuous stirred tank biogas reactors fed with stillage (vol 269, pg 83, 2014)
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2016 (English)In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 303, p. 182-182Article in journal (Refereed) Published
Abstract [en]

n/a

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2016
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:liu:diva-124078 (URN)10.1016/j.jhazmat.2015.10.068 (DOI)000366954600025 ()
Available from: 2016-02-02 Created: 2016-01-19 Last updated: 2017-11-30
Natchimuthu, S., Sundgren, I., Gålfalk, M., Klemedtsson, L., Crill, P., Danielsson, Å. & Bastviken, D. (2016). Spatio-temporal variability of lake CH4 fluxes and its influence on annual whole lake emission estimates. Limnology and Oceanography, 61, S13-S26
Open this publication in new window or tab >>Spatio-temporal variability of lake CH4 fluxes and its influence on annual whole lake emission estimates
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2016 (English)In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 61, p. S13-S26Article in journal (Refereed) Published
Abstract [en]

Lakes are major sources of methane (CH4) to the atmosphere that contribute significantly to the global budget. Recent studies have shown that diffusive fluxes, ebullition and surface water CH4 concentrations can differ significantly within lakes—spatially and temporally. CH4 fluxes may be affected at longer scales in response to seasons, temperature, lake mixing events, short term weather events like pressure variations, shifting winds and diel cycles. Frequent measurements of fluxes in the same system and integrated assessments of the impacts of the spatio-temporal variability are rare. Thereby, large scale assessments frequently lack information on this variability which can potentially lead to biased estimates. In this study, we analysed the variability of CH4 fluxes and surface water CH4 concentrations across open water areas of lakes in a small catchment in southwest Sweden over two annual cycles. Significant patterns in CH4 concentrations, diffusive fluxes, ebullition and total fluxes were observed in space (between and within lakes) and in time (over diel cycles to years). Differences observed among the lakes can be associated with lake characteristics. The spatial variability within lakes was linked to depth or distance to stream inlets. Temporal variability was observed at diel to seasonal scales and was influenced by weather events. The fluxes increased exponentially with temperature in all three lakes, with stronger temperature dependence with decreasing depth. By comparing subsets of our data with estimates using all data we show that considering the spatio-temporal variability in CH4 fluxes is critical when making whole lake or annual budgets.

Place, publisher, year, edition, pages
John Wiley & Sons, 2016
National Category
Climate Research Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:liu:diva-126776 (URN)10.1002/lno.10222 (DOI)000388560900002 ()
Note

Funding agencies: Swedish Research Council FORMAS [2009-872, 2009-1692]; Swedish Research Council VR [325-2012-48, 621-2011-3575]; Swedish Nuclear Fuel and Waste Management Company (Svensk Karnbranslehantering AB)

Available from: 2016-04-05 Created: 2016-04-05 Last updated: 2018-10-05Bibliographically approved
Jidesjö, A. & Danielsson, Å. (2016). Student experience and interest in science: Connections and implication for further education. NorDiNa: Nordic Studies in Science Education, 12(1), 36-55
Open this publication in new window or tab >>Student experience and interest in science: Connections and implication for further education
2016 (English)In: NorDiNa: Nordic Studies in Science Education, ISSN 1504-4556, E-ISSN 1894-1257, Vol. 12, no 1, p. 36-55Article in journal (Refereed) Published
Abstract [en]

Students’ problems with learning science in school have been documented for a long time. Differences in student interest in and attitudes towards science due to gender and age are well documented. Fewer studies have focused on the details at a content level. This paper presents a statistical analysis of student interest in specific content areas and combines this with student experience of science and science-related activities outside school. The result shows that interest and experience are significantly linked and influence student choices for upper secondary education. The results are presented on both a detailed content and experience level, and are discussed in relation to the purpose of compulsory science education and in relation to experiences outside school. The study is an important addition to the discussion about establishing a science education curriculum that can both prepare students for future science studies and meet the need for a public understanding of science.

Place, publisher, year, edition, pages
Oslo: Universitetet i Oslo, 2016
Keywords
Students’ interest, experience, science, PCA, cluster analysis
National Category
Other Natural Sciences
Identifiers
urn:nbn:se:liu:diva-78787 (URN)
Available from: 2012-06-20 Created: 2012-06-20 Last updated: 2017-12-07Bibliographically approved
Wiréhn, L., Danielsson, Å. & Neset, T.-S. (2015). Assessment of composite index methods for agricultural vulnerability to climate change. Journal of Environmental Management, 156, 70-80
Open this publication in new window or tab >>Assessment of composite index methods for agricultural vulnerability to climate change
2015 (English)In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 156, p. 70-80Article in journal (Refereed) Published
Abstract [en]

A common way of quantifying and communicating climate vulnerability is to calculate composite indices from indicators, visualizing these as maps. Inherent methodological uncertainties in vulnerability assessments, however, require greater attention. This study examines Swedish agricultural vulnerability to climate change, the aim being to review various indicator approaches for assessing agricultural vulnerability to climate change and to evaluate differences in climate vulnerability depending on the weighting and summarizing methods. The reviewed methods are evaluated by being tested at the municipal level. Three weighting and summarizing methods, representative of climate vulnerability indices in general, are analysed. The results indicate that 34 of 36 method combinations differ signifi- cantly from each other. We argue that representing agricultural vulnerability in a single composite index might be insufficient to guide climate adaptation. We emphasize the need for further research into how to measure and visualize agricultural vulnerability and into how to communicate uncertainties in both data and methods.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
climate vulnerability; composite index; Agriculture; Regression Analysis
National Category
Climate Research Environmental Sciences
Identifiers
urn:nbn:se:liu:diva-116480 (URN)10.1016/j.jenvman.2015.03.020 (DOI)000355036700009 ()
Projects
Nord-Star
Available from: 2015-03-27 Created: 2015-03-27 Last updated: 2017-12-04
Jidesjö, A., Danielsson, Å. & Björn, A. (2015). Interest and Recruitment in Science: A Reform, Gender and Experience Perspective. Paper presented at IOSTE Borneo 2014. Procedia - Social and Behavioral Sciences, 167(0), 211-216
Open this publication in new window or tab >>Interest and Recruitment in Science: A Reform, Gender and Experience Perspective
2015 (English)In: Procedia - Social and Behavioral Sciences, ISSN 1877-0428, E-ISSN 1877-0428, Vol. 167, no 0, p. 211-216Article in journal (Refereed) Published
Abstract [en]

This paper reports on Swedish results from a worldwide research project concerned with the Interest and Recruitment in Science Education (the IRIS-International study) together with results from a longitudinal national study on girl's views on out of school experience in science and technology in upper secondary education. The studies are framed in the structural situation of the Swedish educational system. The results show that there are reform and policy effects to consider in the discussion of recruiting more students in STEM. Interest in the subject, earlier school experience, achievement and teacher feedback is found to be important for educational choice in STEM. Specifically girls point out societal relevance as important. In addition there are elements outside the school setting with importance for educational choice. Moreover, girls point out visits to a museum and watching films and boys popularized forms of science and computer games. All students consider TV and activities outside school as important for their educational choice in STEM. When trying to implement outside school experience with girls in a longitudinal study in upper secondary education the interplay with school subject teaching is identified as missing. The friction between subject teaching in schools and connections with the surrounding world is proposed as important for future studies.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Interest, recruitment, STEM education, out of school experience
National Category
Other Natural Sciences
Identifiers
urn:nbn:se:liu:diva-113562 (URN)10.1016/j.sbspro.2014.12.664 (DOI)000361493500030 ()
Conference
IOSTE Borneo 2014
Funder
Swedish Energy Agency
Available from: 2015-01-23 Created: 2015-01-23 Last updated: 2017-12-05
Generó, M. M., Juottonen, H., Robroek, B. J. .., Yrjälä, K., Danielsson, Å., Lindgren, P.-E. & Svensson, B. (2015). Nitrogen and methanogen community composition within and among three Sphagnum dominated peatlands in Scandinavia. Soil Biology and Biochemistry, 81, 204-211
Open this publication in new window or tab >>Nitrogen and methanogen community composition within and among three Sphagnum dominated peatlands in Scandinavia
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2015 (English)In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 81, p. 204-211Article in journal (Refereed) Published
Abstract [en]

Ombrotrophic raised bogs are nutrient poor acidic peatlands accumulating organic matter. They are widely spread on northern latitudes and are substantial sources of methane emissions to the atmosphere being of great concern from a climate change perspective. We investigated the methanogen community composition along microtopographic gradients within three bogs in Scandinavia, receiving different amounts of nitrogen precipitation. Methanogenic community analyses by terminal restriction fragment length polymorphism of the mcrA gene showed different profiles among the three sites, while no in- fluence of the microtopographic gradients was observed. Peat temperature and dissolved organic carbon were the major edaphic variables explaining 38% of the variation of the methanogenic community di- versity among the bogs. The family Methanoregulaceae (hydrogenotrophic methanogens) showed the largest relative proportion and highest activity in all three sites. Quantitative PCR of the mcrA gene and transcripts showed that the most northern site, receiving the lowest atmospheric nitrogen load, had significantly lower abundance and activity of methanogens (4.7 106 and 2.4 104 mcrA copies per gram of soil, respectively), compared to the most southern site (8.2 107 and 4.6 105 mcrA copies per gram of soil, respectively), receiving the highest nitrogen load. No patterns of the mcrA gene and tran- script abundances were observed along the microtopography. The results indicated that the difference in occurrence of methanogens is mainly due to geoclimatological conditions rather than site intrinsic microtopographic variation. The study further suggests that environmental changes on the site intrinsic topography will not affect the methanogenic activity, while increasing average temperatures in Scan- dinavian ombrotrophic raised bogs might contribute to an increase of the methanogenic archaeal activity resulting in an increase of methane production. 

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Methanogenic arhcaea, mcrA gene, peatland, microtopography, T-RFLP, qPCR
National Category
Ecology Microbiology Environmental Sciences
Identifiers
urn:nbn:se:liu:diva-113846 (URN)10.1016/j.soilbio.2014.11.016 (DOI)000350524700024 ()
Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2017-12-05Bibliographically approved
Shakeri Yekta, S., Matsson, L., Svensson, B. H., Danielsson, Å. & Skyllberg, U. (2014). Effects of sulfide removal by Fe addition on chemical speciation of Co(II) and Ni(II) during anaerobic digestion of stillage: Implications for microbial metal uptake.
Open this publication in new window or tab >>Effects of sulfide removal by Fe addition on chemical speciation of Co(II) and Ni(II) during anaerobic digestion of stillage: Implications for microbial metal uptake
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2014 (English)Manuscript (preprint) (Other academic)
Abstract [en]

The effects of sulfide removal by addition of Fe on chemical speciation of Co and Ni and how it may affect the microbial metal uptake processes in biogas reactors were assessed. The influent Fe concentration was increased in a semi-continuous stirred tank biogas reactor fed with sulfur-rich stillage. Performance of the reactor, turnover kinetics of volatile carboxylic acids as well as changes in the chemical speciation of Co and Ni were investigated. The results demonstrated that approximately 95% decrease in gaseous hydrogen sulfide content of the biogas, which was caused by addition of Fe, had no apparent effects on methane production and process stability, while it enhanced the short-term turnover time of propionate. Sulfide removal decreased the overall solubility of Co and Ni partially by 1) lowering the formation of the dominant Co- and Ni-sulfide complexes in the aqueous phase and 2) by promoting processes such as adsorption and coprecipitation of Co and Ni with FeS(s). Combination of chemical speciation and bio-uptake models suggested that a higher concentration of free Co and Ni ions is achieved at low sulfide concentrations which favors the active bio-uptake of these metals. However, it was argued that the decrease in soluble metal concentrations, which was induced as a result of the addition of Fe, demotes potential diffusion-driven, passive metal uptake by microorganisms.

National Category
Environmental Biotechnology
Identifiers
urn:nbn:se:liu:diva-112854 (URN)
Available from: 2014-12-17 Created: 2014-12-17 Last updated: 2014-12-17Bibliographically approved
Shakeri Yekta, S., Lindmark, A., Skyllberg, U., Danielsson, Å. & Svensson, B. (2014). Importance of reduced sulfur for the equilibrium chemistry and kinetics of Fe(II), Co(II) and Ni(II) supplemented to semi-continuous stirred tank biogas reactors fed with stillage. Journal of Hazardous Materials, 269, 83-88
Open this publication in new window or tab >>Importance of reduced sulfur for the equilibrium chemistry and kinetics of Fe(II), Co(II) and Ni(II) supplemented to semi-continuous stirred tank biogas reactors fed with stillage
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2014 (English)In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 269, p. 83-88Article in journal (Refereed) Published
Abstract [en]

The objective of the present study was to assess major chemical reactions and chemical forms contributing to solubility and speciation of Fe(II), Co(II), and Ni(II) during anaerobic digestion of sulfur (S)-rich stillage in semi-continuous stirred tank biogas reactors (SCSTR). These metals are essential supplements for efficient and stable performance of stillage-fed SCSTR. In particular, the influence of reduced inorganic and organic S species on kinetics and thermodynamics of the metals and their partitioning between aqueous and solid phases were investigated. Solid phase S speciation was determined by use of S Kedge X-ray absorption near-edge spectroscopy. Results demonstrated that the solubility and speciation of supplemented Fe were controlled by precipitation of FeS(s) and formation of the aqueous complexes of Fe-sulfide and Fe-thiol. The relatively high solubility of Co (similar to 20% of total Co content) was attributed to the formation of compounds other than Co-sulfide and Co-thiol, presumably of microbial origin. Nickel had lower solubility than Co and its speciation was regulated by interactions with FeS(s) (e.g. co-precipitation, adsorption, and ion substitution) in addition to precipitation/dissolution of discrete NiS(s) phase and formation of aqueous Ni-sulfide complexes.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Biogas; Stillage; Sulfur; Trace metals; Thermodynamics; Kinetics
National Category
Social Sciences
Identifiers
urn:nbn:se:liu:diva-106983 (URN)10.1016/j.jhazmat.2014.01.051 (DOI)000335109100012 ()
Available from: 2014-06-04 Created: 2014-06-02 Last updated: 2017-12-05
Danielsson, Å. (2014). Influence of hypoxia on silicate concentrations in the Baltic Proper (Baltic Sea). Boreal environment research, 19(4), 267-280
Open this publication in new window or tab >>Influence of hypoxia on silicate concentrations in the Baltic Proper (Baltic Sea)
2014 (English)In: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 19, no 4, p. 267-280Article in journal (Refereed) Published
Abstract [en]

Silica (Si) is a key nutrient for diatoms. Over the last century, Si concentrations within the Baltic Sea decreased significantly. This is mainly attributed to ongoing eutrophication, increased production and subsequent deposition and accumulation of organic matter including biogenic silica. As a consequence of the eutrophication, hypoxic and anoxic bottom waters have spread affecting nutrient cycling. This paper looks at the potential impact of oxygen on dissolved silica (DSi). It presents a statistical analysis of the relationship between DSi concentrations and oxygen conditions (O-2) in the deep water of the Baltic Proper. The idea is not new, but this is the first time it is studied in more detail in this area. Regression analysis shows that DSi concentrations decrease significantly with O-2 concentrations, and that the major intrusion of saline water in 1993 strengthened this relationship. Increased hypoxia will significantly affect the cycling of Si in the Baltic Sea.

Place, publisher, year, edition, pages
Finnish Environment Institute, 2014
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:liu:diva-111465 (URN)000342185900002 ()2-s2.0-84905691881 (Scopus ID)
Note

Funding Agencies|BOX-project (SEPA) [NV 08/307 F-255-08]

Available from: 2014-10-21 Created: 2014-10-17 Last updated: 2017-12-05Bibliographically approved
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