| 1. |
- Grubisic, Lorena M., et al.
(författare)
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Effects of stratification depth and dissolved organic matter on brackish bacterioplankton communities
- 2012
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 453, s. 37-48
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Tidskriftsartikel (refereegranskat)abstract
- Bacterioplankton growth is often directly or indirectly controlled by external energy subsidies via organic matter inputs or solar radiation. We carried out a mesocosm experiment to assess how bacterioplankton communities responded to elevated levels of dissolved organic matter (DOM) and experimentally controlled stratification depth. The month-long experiment consisted of 2500 l mesocosms subjected to 4 experimental manipulations in triplicate: the stratification depth was set to either 1.5 or 3.5 m, with or without experimental addition of ambient levels of chromophoric DOM. DOM addition had a significant effect on bacterial community composition as assessed by terminal restriction fragment length polymorphism of amplified 16S rRNA genes. In contrast, there were no effects of the DOM amendment on bacterial biomass or production. Mixing depth and the coupled effective light climate in the photic zone also had a significant effect on bacterial community composition. Furthermore, shallow mixing depth was associated with enhanced primary production, whereas DOM addition had a negative effect on phyto plankton biomass and productivity. Our results suggest that bacterial community composition is coupled to primary production under the studied coastal nutrient regime, and point to a key role of DOM quality in controlling bacterioplankton communities.
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| 2. |
- Kylinger, Martin
(författare)
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Supply chain coordination using optimal transfer pricing to balance co- and byproduct demand within a process industry
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Process industries has for long been important for the development of Swedish industry and society. All industries face different conditions that affect how to best run their operations. This thesis aims to describe some of the conditions that characterize process industries compared to other industries. Further one of these characteristics has been studied more closely.One of the traits of process industries is that they are positioned at the start of the transformation process close to the raw material mixing, separating or forming it into products often used for further transformation. Process industries hence become dependent on the properties of these materials. One of the most prominent characteristics inherent from the raw material properties is the divergent bill of material. The divergent bill of material originates from the fact that a given raw material is made up of different components that will yield several products with different characteristics when processed. When splitting the raw material into the desired products the yielded products from a certain raw material usually have different value to the producer, some more desired than others. These multiple products generated poses a challenge from a planning perspective raising questions like “How should we balance the supply and demand of all the products produced?”, “What shall we do with the excess products produced?”.The first paper in this thesis describe the production planning in four Swedish process industries with the ultimate aim to connect their planning to the supply chain characteristics they face as process industries. The study concludes that the industry specific conditions mainly affect planning at short time ranges when planning becomes more detailed. In general the use of planning or decision support systems is low, stemming from a, warranted or not, belief that general decision support systems do not fit process industries. Another finding is that the case companies mainly operate in niche markets. This study also highlighted that the planning complexity arising from characteristic of co- and by-product generation in combination with the lack of decision support systems requires further studies.The subsequent two papers focus on supply chain planning and coordination with a divergent bill of material. They present a mathematical model over the supply chain planning in a real case company in the specialty oils industry. The second paper investigates transfer pricing as a coordination tool by comparing decentralised supply chain planning with centralized planning in an integrated model. Transfer pricing is found to have a potential positive effect on supply chain planning while simultaneously creating problems in terms of uneven distribution of the contribution margin among supply chain partners.Finally the third paper more closely investigates different ways to set transfer prices and comparing them to the optimal transfer prices. Setting optimal transfer prices with a divergent bill of material has proven to be less straightforward than the case with no dependencies between products. Some optimal transfer prices could even be set lower than the marginal cost for producing them due to the dependency between the products in the divergent bill of material. This indicates that there is an opportunity cost for a product that is dependent on the demand of other products.
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| 3. |
- Larsson, Ulf, et al.
(författare)
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Växtplanktonproduktion : mätningar med problem
- 2010
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Ingår i: Havet. - Stockholm : Naturvårdsverket och Havsmiljöinstitutet. - 9789162012816 ; , s. 26-29
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Nilsson, Jonas, et al.
(författare)
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Havsmiljöns tillstånd : ur ett miljömåls perspektiv
- 2011
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Ingår i: Havet 2011. - Göteborg ; Stockholm : Havs-och vattenmyndigheten, Naturvårdsverket och Havsmiljöinstitutet. - 9789162012885 - 9789163397639 - 9789187025006 ; , s. 6-12
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Nilsson, Jonas, et al.
(författare)
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Havsmiljöns tillstånd ur miljömålsperspektiv
- 2011
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Ingår i: Havet 2011. - : Naturvårdsverket, Havsmiljöinstitutet, Havs- och vattenmyndigheten. - 9789162012885 ; , s. 8-12
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 9. |
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| 10. |
- Nydahl, Anna, 1981-
(författare)
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Coastal microbial respiration in a climate change perspective
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In a climate change perspective increased precipitation and temperature are expected which should influence the coastal microbial food web. Precipitation will have a strong impact on river flow and thereby increase the carbon input to the coastal zone as well as lowering the marine salinity by dilution with freshwater. Simultaneously temperature may increase by 2-5 °C, potentially influencing e.g. metabolic processes. Consequences of this have been evaluated in this thesis with focus on microbial respiration in paper II and IV. A temperature increase of 3 °C will have a marked effect on microbial respiration rates in the coastal zone. The effect of temperature on microbial respiration showed a median Q10 value of 25 with markedly higher values during winter conditions (around 0°C). These Q10 values are several-fold higher than found in oceanic environments. The conclusion was in accordance with a consistent temperature limitation of microbial respiration during an annual field study, however, shifting to DOC limitation at the elevated temperature. Neither bacterial production nor phytoplankton production showed a consistent temperature effect, suggesting that the biomass production at the base of the food web is less sensitive to a temperature increase. Results from both a field study and a fully factorial microcosm experiment supported the conclusion. Our results suggested that areas dealing with hypoxia today will most likely expand in the future, due to increased respiration caused by higher temperatures and larger riverine output of dissolved organic carbon. Pelagic respiration measurements in the sea are relatively scarce in the literature, mainly due to the lack of sufficiently good and user friendly techniques. New methods such as the dynamic luminescence quenching technique for oxygen concentration have been developed. This makes it possible to obtain continuous measurements of oxygen in an enclosed vial. Two different commercially available systems based on the dynamic luminescence quenching technique were evaluated from the aspect of precision, accuracy and detection limit when applied to respiration measurements in natural pelagic samples. The Optode setup in paper III showed a practical detection limit of 0.30 mmol m-3 d-1, which can be applied to measure respiration in productive coastal waters (used in paper IV). This included development of a stopper where the sensor was attached, stringent temperature control, proper stirring and compensation for an observed system drift. For controlled laboratory experiments with organisms smaller than 1 µm the Sensor Dish Reader (paper I) has sufficient detection limit of (4.8 mmol m-3 d-1). This required a stringent temperature control and manual temperature correction. The Sensor Dish Reader gives the opportunity to perform multiple treatments at low cost (used in paper II), but the precision is too low for field studies due to the between ampule variation.
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