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- Mähler, Johan
(författare)
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The adsorption of arsenic oxyacids to iron oxyhydroxide columns : including studies of weakly hydrated ions and molecules in aqueous solution
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The fundamental side of this project includes determination of ionic radii and plausible hydration numbers for the weakly hydrated alkali metal ions in solution, as well as an investigation of the intramolecular bond lengths of arsenic oxyacid species and orthotelluric acid. Experimental methods such as EXAFS, XANES and LAXS have been used for these purposes, as well as thorough screening for relevant structures in crystal structure databases. The improved ionic radius for the sodium ion in six-coordination is of particular interest as current literature data to a large extent is derived from structures not representative for aqueous solutions. The improved larger value is 1.07 Å in six-coordinated crystal structures and increases to 1.09 Å in aqueous solution due to hydration effects. Furthermore it has been discussed how alkali metal ions affect the three-dimensional network of hydrogen bound water molecules in aqueous solution, based on investigations with double difference infrared spectroscopy. Only the lithium ion was found to be a true structure making ion, even though the status of the border-line sodium ion can be discussed. The applied studies have focused on the rapid removal of arsenic from aqueous solution using columns filled with iron oxyhydroxide based adsorbents, complemented with additional batch experiments. Atomic absorption spectrophotometry has been used to determine concentrations of arsenic in the effluent of columns and iron content of the adsorbent material. Experiments have shown that adsorption does occur rapidly and since there is no need for reaching equilibrium in practical water cleaning applications, short empty bed contact times are sufficient for removing practically all arsenic. However, somewhat longer empty bed reaction times are desirable for a more efficient material utilization, as both diffusion into porosities and desorption of competing species are kinetic hindrances. Adsorption capacity in a column is quite dependent on the presence of competitors such as phosphate, hydrogen carbonate and fluoride, as well as on pH, possibly due to desorption kinetics. Scanning electron microscopy as well as XANES and EXAFS have been used to study the structural and chemical status of the adsorbents. The arsenic part of the project can be seen as an initiation of a future project, aiming at developing a simple but efficient adsorption filter for arsenic removal from drinking water in Burkina Faso.
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- Nassazzi, Winnie
(författare)
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Phytoremediation of soil contaminated with per- and polyfluoroalkyl substances (PFAS)
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Per- and polyfluoroalkyl substances (PFAS) are anthropogenic compounds recognised for their persistence, mobility and potential toxicity. This thesis examines the efficacy of phytoremediation as a potential technique for managing PFAS-contaminated soil and groundwater. First, an extraction and clean-up method was developed to measure PFAS in different plant tissues. A solid-liquid extraction method using methanol and ENVICarb cartridge as clean-up showed satisfactory performance and was selected for validation and application. PFAS were then analysed in plants, soil and groundwater at one landfill and three former fire training sites. The aim was to investigate the phytoextraction potential of trees growing at these sites. Plant tissue concentration and composition profiles highly depended on the soil and groundwater fingerprints. Birch and willow showed the highest PFAS concentrations in the field. Furthermore, the phytoextraction potential of five plants (i.e. sunflower, mustard, hemp, willow and poplar) was also investigated in pot experiments. Parameters such as species-specific uptake, bioaccumulation in different plant tissues, duration of PFAS exposure and effects of supplements were assessed. The supplements i.e. fertilizer, microbes and hormones had limited influence on plant concentration in some cases increased plant biomass, which in turn increased total mass PFAS removal by the plants. Willow and sunflower showed the highest PFAS removal efficiency of all investigated plants. The highest PFAS removal obtained was for short chain PFAS (C3 – C6), with up 34% removal by the plants after 90 days of exposure. These results can be useful for field application of phytoremediation. Further work is required to improve the efficiency of the method and to study the fate of PFAS in plant biomass following remediation.
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- Al-Azzawi, Zaenab
(författare)
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The role of biological processes in base cation supply in boreal forest podzols
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes experiments designed to improve understanding of biological processes contributing to supply of base cations and other nutrients in boreal forest podzols. We used microcosms containing tree seedlings growing in natural substrates, a combination of direct measurements, modelling, stable Mg isotope analysis, and 13CO2 pulse-labelling. Addition of 13C-labelled fungal necromass to soil resulted in rapid decomposition and active incorporation of 13C into RNA of Burkholderia, Streptacidophilus, Dyella, Herminiimonas, Granulicella and fungal species belonging mainly to the genera Mortierella and Umbelopsis. There was no evidence of 13C incorporation into RNA of ectomycorrhizal fungi supporting the idea that ectomycorrhizal fungi primarily play an active role in organic matter decomposition by releasing N from recalcitrant substrates, but do not use organic matter as a source of metabolic C. Selected ectomycorrhizal and nonmycorrhizal fungi were examined for their capacity to fractionate and assimilate stable Mg isotopes in vitro. Ectomycorrhizal fungi mobilised and accumulated significantly higher concentrations of Mg, K and P than nonmycorrhizal fungi, when grown on granite particles. Mycorrhizal fungi were significantly depleted in heavy isotopes compared with nonmycorrhizal fungi and there was a highly significant statistical relationship between δ26Mg tissue signature and mycelial concentration of Mg. Pinus sylvestris seedlings were grown in compartmentalised microcosms allowing their mycorrhizal mycelium, but not roots, to access different substrates, including granite particles. Root biomass and contents of Ca, K, Mg, and P in plants in granite treatments were significantly higher than in control roots. Carbon allocation by the ectomycorrhizal mycelium to soil solution was significantly and positively correlated with base cation and P content of the plants. A final experiment (using reconstructed boreal forest podzol layers) was conducted in which the relative amounts of organic and mineral substrates were manipulated to simulate different levels of intensification of the removal of organic matter. All plants were deficient in K and P but had above optimal levels of Ca and Mg. Total plant and fungal mycelial biomass was positively related to the amount of organic soil in each treatment. The δ26Mg values of soil solution samples in B horizon soil increased successively with increasing plant and fungal mycelial biomass, suggesting increased uptake of Mg from the B horizon, with discrimination against the heavier isotope resulting in higher enrichment of 26Mg.
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- Dürig, Wiebke
(författare)
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Wide-scope screening for contaminants of emerging concern in archived biota: Method development, suspect prioritisation, and non-target screening in a novel identification tool
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Environmental monitoring of hazardous chemicals in wildlife conventionally uses target screening for selected contaminants, but relatively few contaminants are moni-tored and knowledge of potentially hazardous contaminants of emerging concern (CECs) in wildlife is lacking. In this thesis, a non-target screening (NTS) method com-bined with temporal trend analysis was developed and applied as a prioritisation tool for identification of CECs in top predators, using high-resolution mass spectrometry (HRMS). A multi-residue sample extraction and HRMS screening method was devel-oped and validated for various biota tissue types and species, to capture chemicals with a broad range of physiochemical properties (Paper I). Minimised sample pre-treatment and clean-up resulted in a non-specific extraction method for NTS in biota. A tool for creating suspect lists for screening of CECs in biota was developed based on an exten-sive database of chemicals (Paper II). Systematic ranking of chemicals based on rele-vant physicochemical properties was used to prioritize CECs relevant for biota and water. Finally, a NTS workflow was developed for prioritizing CECs in time series of archived biological tissue of top predators. The samples included time series of muscle tissue from white-tailed sea eagle (Haliaeetus albicilla) (1965-2017) and Eurasian lynx (Lynx lynx) (1969-2017) obtained from the environmental specimen bank (ESB) at the Swedish Museum of Natural History (SMNH). The prioritisation method was validated with an artificial time series using spiked matrix samples of increasing concentrations (Paper III). A total of 14 compounds (six of anthropogenic origin) with increasing time trends were tentatively identified in white-tailed sea eagle samples, while two com-pounds with increasing time trends and one compound with a decreasing time trend were tentatively identified in lynx samples (Paper IV). The tentatively identified com-pounds originated from different chemical categories (pharmaceuticals, personal care products, industrial chemicals, herbicides). These results showed that, despite the high matrix effect and low expected concentrations in terrestrial species (lynx), it was possi-ble to tentatively identify new CECs in wildlife. The novel prioritisation strategy and NTS workflow developed in this thesis can provide a useful tool for future identifica-tion of CECs in biota. The overall findings can help government agencies expand their monitoring programmes for identification of CECs in biota.
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- Malnes, Daniel
(författare)
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Contaminants of Emerging Concern in Swedish Freshwater Environments: Sources, Occurrence, and Impacts
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Contaminants of emerging concern (CECs) is one of several reasons for the deterioration of surface water quality globally, even though the CECs occur in trace concentrations. This thesis produced new CEC data through a oneyear field study for substances which occur in Sweden’s three largest lakes and their associated rivers. The purpose was to investigate mass flows and seasonal variations of CECs, as well as estimate the potential ecotoxicological hazard posed by the CECs’ occurrence. It was found that numerous CECs occurred in all examined rivers, and that a continuous influx of CECs with suspected hazardous properties into the lakes occurred. Total mass loads of the investigated CECs were estimated from 0.51 to 5.6 kg/day in the influx to the lakes, and from 0.12 to 4.3 kg/day in the outflux from the lakes. Seasonal variations were observed in the aquatic environment for both individual and groups of CECs. This could be due to variations in consumption and environmental conditions. Some of the seasonal variations were being reported for the first time in the academic literature. Many of the CECs were suspected to have the combination of the hazardous properties of persistency, mobility, and toxicity (PMT). Of the 71 CECs detected far from any suspected input into the lakes, 20 had previously been suspected of having PMT properties. Within the remaining 51 CECs, multiple others also had suspected PMT properties. The thesis suggests that CECs with suspected PMT properties should be analysed closer with respect to these properties.
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| 9. |
- Minh Nguyen, Anh
(författare)
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Legacy and emerging pollutants in pristine and polluted boreal catchments
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Persistent organic pollutants (POPs) are bioaccumulative chemicals that are ubiquitously and globally distributed in the environment. Several species of POPs have been studied extensively and are continuously being monitored in various environmental matrices for decades. However, with the increasing amounts of chemicals produced and made commercially available, potential emerging POPs are receiving more attention. Per- and polyfluoroalkyl substances (PFASs) and polycyclic aromatic compounds (PACs) are two groups of emerging substances that are currently of great concern due to their potential toxicity and high mobility in terrestrial and aquatic ecosystems. The overall objective of this thesis was to improve our understanding on the impact of various pollution sources, environmental pathways, transport and fate of both legacy and emerging PFASs and PACs in pristine and polluted boreal catchments. In Paper I, population density was found to be significantly correlated with PFAS levels in rivers. Ten rivers with distinctly higher ƩPFAS concentrations and with a common compositional profile (higher fraction of perfluoroalkane sulfonic acids) were identified, suggesting a major impact from a similar kind of point source(s) in these rivers. Significant positive relationships between several PFASs and dissolved organic carbon were detected in river and sea water, indicating chemical binding and co-transport in aquatic ecosystems. The findings in Paper II show that levels and compositional profiles of PFASs in river water were highly impacted by point sources and hydrological conditions. Seasonal trends of PFASs were impacted by river flow probably caused by mobilization of PFASs from contaminated soil and groundwater. In Paper III, fluxes of PACs in atmospheric deposition showed that they were higher during the cold season, both for PAHs and PAH-derivatives. The deposited PACs were found to be largely retained in the terrestrial environment of the boreal forest catchment or lost by other processes with <2% of the total deposited amount of ƩPACs exported via the outlet of the headwater on average over a year. During spring flood, the concentrations of PACs were found to be significantly higher than levels during the preceding snow-covered and snow-free seasons (Paper IV). Besides seasonal changes, landscape type (forest or mire) was found to have an impact on terrestrial export of PACs, with higher levels of PACs in a mire stream than in stream water in a forested sub-catchment.
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| 10. |
- Rydh Stenström, Jenny
(författare)
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Mixture toxicity of pesticides and biological effects in agricultural streams : field and laboratory studies
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of this thesis was to examine pesticide mixture toxicity and its effects on aquatic biota in agricultural streams. This was accomplished by (1) calculating the ΣTUs for algae and Daphnia magna and a pesticide toxicity index (PTI) based on water quality standards (WQS) for long-term monitoring data (2002-2010), (2) by performing algal inhibition tests with Pseudokirchneriella subcapitata, using both collected in situ water samples and reconstituted water spiked with field-observed pesticide mixtures, and (3) by studying seasonal changes in macroinvertebrate and diatom communities during 2008 in four agricultural streams and determine a set of community-based metrics such as species richness, diversity, ASPT, SPEAR and IPS. Partial Least Squares (PLS) regression was used to analyse community changes. Long-term data showed that collected stream water samples had peaks of estimated pesticide toxicity, mainly due to herbicides though insecticides and fungicides also contributed. ∑TUalgae, based on weekly average concentrations, exceeded 0.1 on 28 out of 902 occasions, and 8 of these were higher than 0.2. Only one or a few pesticides contributed to a major part of estimated mixture toxicity in the streams. The algal growth inhibition studies in spiked water showed negative effects at pesticide concentrations corresponding to those found in stream water samples, indicating that pesticide effects on algae occur under in situ conditions. The field study also showed effects of pesticides, suggesting diatom diversity as a sensitive indicator of pesticide effects. Macroinvertebrate community changes were primarily explained by physiochemical conditions, though some non-insect invertebrates decreased (Asellus aquaticus) or increased (Oligochaeta) with pesticide exposure. Somewhat surprisingly, the SPEARpesticides index, specifically developed to detect pesticide effects of macro-invertebrate communities in streams, was not related to pesticide toxicity. The SPEAR index may need to be modified to better fit to Swedish conditions. A combination of chemical and biological monitoring is needed to increase our understanding of the relationship between pesticide stress and the biological diversity of agricultural streams. Specific endpoints and analysis methods are also needed to separate effects of pesticides from effects of other stressors.
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