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- Samuelsson, Göran S., 1967-
(författare)
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In situ remediation of contaminated sediments using thin-layer capping : efficiency in contaminant retention and ecological implications
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hydrophobic organic contaminants (HOCs) often reside in sediments sorbed to particles, most tightly to particles with high content of organic carbon. If persistent, such pollutants can accumulate in the sediment for many years and constitute a contamination risk for sediment-living organisms and organisms at higher trophic levels, including humans.Since traditional remediation techniques are associated with complications (e.g. release of contaminants during dredging operations, disturbance of benthic faunal communities), or constraints (handling of large amounts of contaminated sediment and water, limitations due to depth and size of the area, high costs), there is a need for new alternative methods.In situ remediation through thin-layer capping (a few centimeter cover) with a sorbing material such as activated carbon (AC) has been proposed as an alternative remediation method. Compared to traditional remediation techniques, AC amendment in a thin layer means less material handling and lower costs and is assumed to be less disruptive to benthic communities. The objectives of this thesis were to investigate the ecological effects from thin layer capping as well as the efficiency in contaminant retention.Thin layer capping amended with AC proved to reduce availability of HOCs to the tested organisms, the gastropod Nassarius nitidus (Paper II), the clam Abra nitida (Paper III) and to polychaete worms (Paper II and III). The remediation technique also decreased the sediment-to-water fluxes of the contaminants (Paper II and III).However, AC amended thin-layer capping was also found to cause negative biological effects. In laboratory studies with only a few species the negative effects were minor, or difficult to discern with the endpoints used (Paper II and III). In a larger multi-species mesocosm (boxcore) study, on the other hand, the negative effects were more prominent (Paper I) and in a large scale field study the benthic community was found to be profoundly disturbed by the AC amendment, with the effects persisting or even worsening ca one year (14 months) post amendment (Paper IV).
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| 2. |
- Samuelsson, Karl, Doktorand
(författare)
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Making space for resilient urban well-being
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis addresses the need for urban landscapes that provide resilient contributions to inhabitants’ well-being while also limiting impacts on the Earth system. It aims to (1) advance a nuanced understanding of how urban environments relate to urban dwellers’ well-being, and (2) formulate guidelines for planning that supports urban dwellers’ well-being and align with global sustainability. The thesis consists of five empirical studies of Swedish and Danish urban landscapes in which day-to-day experiences and mental disorders were studied as different components of well-being. A variety of spatial and statistical analysis methods were leveraged, including public participation geographic information systems, remote sensing, deep learning, accessibility analysis, and spatial regression.Results convey that urban environments relate to well-being in substantial ways, but these map poorly onto the simplistic urban-nature or urban-rural dichotomies that dominate current discourse. Support of well-being instead seems to depend on spatial conditions comprised of the street network’s topological configuration, the population distribution, and the accessibility of natural settings. Since the 1990s, contrasts have intensified between stressful urban cores that are increasingly full of people and peripheral areas that are “left behind” and high-risk in terms of mental illness. Results show that urban neighbourhoods could contribute to well-being through fulfilment of three guidelines: (1) a balance of residential and daytime populations, (2) no extreme concentration of movement, and (3) accessible natural settings. Strategies in accordance with the guidelines can increase so-called topodiversity, which refers to variation in spatial conditions across an urban landscape that permits support of well-being through different pathways. Increasing topodiversity in both central and peripheral areas
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