Masteruppsatser, Miljövetenskap / Institutionen för biologi och miljövetenskap
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Item CHARACTERIZATION, SOURCE IDENTIFICATION AND INVESTIGATION OF EFFECT OF WEATHER PARAMETERS ON ATMOSPHERIC TRANSFORMATION OF BLACK CARBON (BC) AND BROWN CARBON (BrC) AT A RURAL SITE IN INDO-GANGETIC PLAINS (IGP) REGION(2025-10-06) Chilkewar, Ashwini Gangaram; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapCarbonaceous aerosols Black Carbon (BC) and Brown Carbon (BrC) have significant impact of radiative forcing and influence climate system. BC can be emitted from combustion of fossil fuels and biofuels while primary source of BrC is biomass burning, and it can be constrained through atmospheric processes. However, how weather parameters like humidity (RH), temperature and solar radiation (SR) influence atmospheric processes of BC, BrC is not fully understood. Indo Gangetic Plains (IGP) region with high population density is a major source region for BC and BrC and have been facing major pollution problems like formation of atmospheric brown carbon. This study investigates sources, characteristics, atmospheric processes of BC and BrC and influence of weather parameters. Study is based on the yearlong data collected at Indo-Gangetic Plains Centre for Air Research and Education (IGP-CARE); monitoring station located in rural part of IGP region. Seasonal variation in BC and BrC was observed with higher concentration during winter and autumn. Monsoon season was characterized by very low BC, BrC most likely attributed to a wash effect. Summer season showed moderated BC and low BrC indicating fossil fuel combustion as source of emission and or long-term transport of particles from traffic emission or industrial emission. Solar radiation during winter and summer showed significant influence on BrC, indicating presence of photosensitive BrC. Nighttime changes of BrC were mostly attributed to the RH along with other atmospheric factors. During study period 10 episodic events of high concentration of BrC were identified and investigated. Evening and morning time peaks of BC and BrC observed indicates the biomass burning and emission of primary BrC along with BC. Freshly emitted BrC from local biomass burning was hyper-photosensitive compared to nighttime aged and atmospherically processed BrC. Study of change in BrC/BC ratio indicated influence of RH on atmospheric processes of BrC and likely, it negatively influenced the photosensitivity of the atmospheric BrC. Future studies should focus on the analysing effect of RH, temperature, and solar radiation on aging of BC, BrC along with different source materials, to better understand atmospheric processes of BC, BrC.Item EXAMINING DAILY AND DRY SEASON CAPACITIVE WATER RELEASE OF AFRICAN TROPICAL TREES IN A CHANGING CLIMATE(2025-06-30) Crawford, Cecilia; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapTropical forests are vital to the global carbon budget, regional water cycling and biodiversity, but face major threats in a changing climate. Tree die-off due to drought is a concern of increasing magnitude. Understanding how tropical trees manage their water economy under varying environmental conditions is critical for predicting forest resilience during warming and drought. Hydraulic capacitance, the ability of wood tissues to release stored water, plays a key role in buffering short-term water deficits and sustaining physiological function during drought, but is not well understood in tropical trees. In this study, we measured branch wood capacitance at both diurnal (between predawn and midday) and seasonal (between predawn and drought conditions) scales across six tropical tree species planted along an elevation gradient in Rwanda. We investigated how capacitance varies among species and along the climatic gradient, and how it relates to functional traits such as wood density and volumetric water content. It was found that capacitance varies among species and climates, suggesting that it is a trait which can respond to environmental variation, but is ultimately highly dependent on species-specific hydraulic strategies. Capacitance was lowest among all species in the warmest and driest site, while capacitance was similar between the intermediate and wettest and coldest site. We observed indications of correlations between capacitance and volumetric water content and wood density, suggesting that the ability to release water can be dependent on these traits also in tropical trees. Our findings highlight that while capacitance can be functionally important, there is a need to integrate it with information on other physiological and anatomical traits that control tree water uptake, storage and loss to get a more wholistic understanding of tree water economy under heat and drought.Item PFAS in Drinking Water: Institutional Responsibilities and Regulatory Gaps caused the Ronneby incident?(2025-06-27) Eriksson Lilja, Emmie; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapPFAS (per- and polyfluorinated alkyl substances) are a collective name for over 10,000 synthetic chemicals. They are characterized by their persistence, bioaccumulation, and high mobility in aquatic environments, and their hydrophobic and lipophobic properties make them useful in firefighting foam. On December 16, 2013, extremely high levels of PFAS were found in the drinking water from the Brantafors waterworks. The source could be traced back to a fire training site at Blekinge air base (F17), where the Swedish Armed Forces had used firefighting foam containing PFAS since the 1980s. The study shows that international knowledge of PFAS risks existed long before 2013. Even early indications of similar contamination cases in Sweden, such as in Tullinge (2011) and Halmstad (2009), did not lead to coordinated national measures or changed guidelines. The Ronneby case identifies several actors who had the opportunity and, in some cases, the obligation to act preventively, but where lack of communication, insufficient regulatory compliance, or limited mandates contributed to passivity. These actors include manufacturers (who knew the risks but withheld information), the Swedish Armed Forces (which failed to conduct self-control and risk assessment despite internal knowledge), Ronneby Miljö & Teknik AB (which was responsible for the drinking water supply but relied on limited government directives), and national authorities such as the Swedish Chemicals Agency, the Swedish Environmental Protection Agency and the Swedish Food Agency, whose knowledge was not effectively communicated to the municipal level. The precautionary principle and Ch 26 § 19 in the Swedish environmental code were not followed through, and the fragmented chemicals regulation under the REACH Regulation has proven insufficient, mainly since PFAS regulation was carried out on a substance-by-substance basis for a long time. The late introduction of limit values for PFAS in the EU Drinking Water Directive also contributed to delayed action. The PFAS contamination in Ronneby illustrates a systematic failure characterized by unclear mandates, fragmented responsibilities, poor communication, and regulatory weaknesses. Actors who acted independently of each other, and several warning signs were ignored. The Ronneby case is, therefore, not an isolated exception but follows a recurring pattern from previous environmental toxics crises, such as with DDT and PCB, and underlines the need for better knowledge transfer between authorities and the local level, a more proactive risk assessment and better regulatory framework for the management of persistent chemicals.Item BARK AND FOLIAR WATER UPTAKE CAPACITY OF TROPICAL TREE SPECIES IN RWANDA(2025-06-26) Valfridsson, Simon; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapWater is essential for tree function and survival, yet climate warming poses increasing threats to tree health, particularly in tropical regions where droughts are intensifying. While foliar water uptake (FWU) and bark water uptake (BWU), described as the direct uptake of water through leaf and bark surfaces, are increasingly recognized as important supplementary water sources, both processes remain understudied— especially in tropical forests. Here, we investigate species- and climate-related variation in foliar and bark water uptake capacity in 11 tropical tree species (8 for BWU) growing along an elevational gradient in Rwanda. All trees were subjected to a standardized wetting treatment, where stems segments and leaves were fully submerged in water for two hours under controlled conditions. Ten species demonstrated the capacity to absorb water through foliage and all eight species through bark, with substantial interspecific variation. In addition, we examined the influence of a range of physical traits on water uptake. The ability to retain water on surfaces—especially via trichomes on leaves and rough bark on stems—emerged as key factors influencing bark and foliar water uptake. This is the first study, to our knowledge, to assess bark and foliar water uptake in African trees as well as simultaneously on the same individual plants, offering novel insights into the role of external water uptake in tropical tree ecophysiology.Item A Comparative Study of Air Quality and Urban Development in Sri Lankan Cities (1980-2024)(2025-06-26) Amarapathi Saluwadana Mudiyanse Ralahamilage, Nadeeka Chandima Kumari Ambanwela; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapThe aim of this study is to investigate the long -term relationship between urbanization and air quality in four Sri Lankan cities, Colombo, Kandy, Anuradhapura, and Jaffna from 1980 to 2024. As rapid urbanization and economic growth change Sri Lanka's cities through accelerated urbanization, fine particulate matter (PM₂.₅) has emerged as a significant environmental and public health concern. This study employs satellite-derived data from NASA's MERRA-2 and Washington University and ground-based measurements at the U.S. Embassy in Colombo to assess PM₂.₅ and component concentrations, including black carbon (BC), organic carbon (OC), sulfate (SO₄²⁻), dust, and sea salt (SS). Urbanization metrics of population growth, land use change, and household energy consumption were assessed against PM₂.₅ concentrations through time series and comparative analyses. The findings exhibit distinct spatial and temporal pollution trends: while cities like Colombo and Anuradhapura experience stable trends of pollutants, Kandy experiences noticeable increases in PM₂.₅, BC, and SO₄ likely to be influenced by topography and urbanization. Conversely, due to a lack of extensive data availability, population trends in Jaffna were not able to be reasonably evaluated. Seasonal and diurnal analysis also refers to the influence of climatic features like monsoons in defining air quality. This study contributes to the limited body of literature on long-term air quality monitoring in Sri Lanka and makes recommendations for environmental policy and sustainable urban planning. The study also underscores the value of more data collection and integration to guide air quality management in the developing world.Item ESTIMATING LEAF AREA DENSITY (LAD) ACROSS URBAN TREE GENERA USING LIDAR DATA(2025-06-25) Engström, Hanna; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapUrban greenery provides natural processes that benefit human well-being, called ecosystem services, such as climate change mitigation and is an important factor for establishing sustainable cities. Some ecosystem services, such as carbon fixation, providing space for Particulate Matter (PM) deposition, and temperature cooling because of transpiration are partly dependant on the structure of the canopy, which can be investigated by the estimation of leaf area density (LAD (m2 /m3 )). To facilitate urban planning and evaluation of possible effectiveness of ecosystem services, allometric relationships are used to establish correlation between morphological variables such as crown diameter, tree height, diameter at breast height (DBH) and age. The aim of this study was to estimate LAD from LiDAR (Light Detection and Ranging) scanned urban trees situated in the City of Malmö and additionally investigate whether differences between tree genera could be found and if LAD could be correlated to allometric variables (crown diameter, tree age, height and DBH). Investigation of whether allometric relationships for the growth of urban trees could be established was also conducted. Around 2 100 urban trees, scanned by a terrestrial scanner, were analysed. The point clouds for each individual tree were filtered and divided in halves to account for trees only being scanned from one direction, hence keeping the scanned side. The side that had been scanned directly was used in the analysis. The four most prominent genera (Tilia spp., Quercus spp., Sorbus spp., and Acer spp.) were analysed separately. The estimation of LAD was done through the Voxel-based Canopy Profiling (VCP) method. Estimated LAD was correlated against allometric variables, with crown diameter, tree height, DBH, and tree age as the explanatory variables. The allometric variables were also plotted against each other, with DBH and tree age as the explanatory variables. The results indicated that LAD was strongly, negatively and non-linearly correlated to crown diameter (Radj 2 > 0.68) and moderately correlated to tree height (Radj 2 > 0.54). A multiple regression analysis between crown diameter, tree height and LAD resulted in a statistically significant model with Radj 2 = 0.70, indicating that an additional 2 percentage points could be added by tree height in addition to crown diameter to explain LAD variability. No correlation was found between LAD and tree age or DBH. Comparison of LAD between different tree genera showed a slightly higher LAD for Sorbus spp. and slightly lower for Acer spp., however, variation of crown size seemed to be much more important for LAD estimation than the genus of the tree. This might be the result of the pruning of urban trees, resulting in crown diameter not being dependant on age or DBH for its size. Correlation between tree height and crown diameter was found (Radj 2 = 0.60), but no correlation between DBH and crown diameter or tree height could be established. The results indicate that the tree height and crown diameter are more defining parameters than tree genus when estimating LAD, and for future modelling of LAD, establishing a function based on crown diameter and tree height might be useful for estimating LAD without the need for LiDAR scans of the canopy.Item Composition and effect of windmill-derived microplastic(2025-06-25) Ranaweera, Piumi; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapOne readily available and renewable energy that combats global warming and minimizes the use of fossil fuels is wind power. The next generation of power is likely to be more socially reliant on wind power as it is more economical and there are frequent upgrades in technology. Therefore, it is crucial to focus research on potential pollution from wind turbines, especially concerning microplastics (MP) generated by windmills, to boost sustainability and reduce pollution. Wind energy is a sustainable and readily available source that helps decrease reliance on fossil fuels and combat climate change. With continuous technological advancements and improved efficiency, wind power is anticipated to take on a more important role in future energy generation. Consequently, it is essential to direct research toward potential pollution resulting from wind turbines, particularly regarding MP produced by windmills, to enhance sustainability and lessen pollution. The present study was conducted to identify the composition and effect of windmill-derived MP samples. Aiming to analyse the physical and chemical composition of the collected samples. Additionally, use fish as a bioindicator to determine the levels of MP pollution in the lakes near the Markbygden wind farm. Finally, analyse the cytotoxicity of the collected samples using an in vitro assay. In the methodology, two sites were selected, and windmill parts were collected from two different manufacturers. The collected samples were processed to create MP particles using a TissuLyser. The density measurement of the MP samples was conducted using a Bruker chamber with a light microscope (LM). The chemical composition of these MP samples was determined using Fourier Transform Infrared (FTIR) spectroscopy, followed by processing with Spectroscopy Ninja software. Finally, cytotoxicity analysis of aqueous and MeOH extracts from all MP samples was conducted. The viability of RTgill-W1 cells was evaluated after 48 hours of exposure to varying concentrations of aqueous and MeOH extracts using the Alamar Blue and CFDA-AM assays. The control experiment was conducted to determine any possible interference due to the MP particles themselves without RTgill-W1 cells. In the results, from all the samples processed, the MP particles obtained were within the size range of 1-50 μm, with varying densities, and they can be identified as compounds related to epoxy resin featuring a decaying structure. Moreover, for the observations of fish gut analysis, most fish were contaminated with white particles, Fibers, yellow lumps, and black particles, and from those white particles, it can be predicted that they are MP, but the source is unclear. Furthermore, cytotoxicity analysis revealed mild toxicity in the aqueous extract, whereas the unfiltered aqueous extract showed average cytotoxicity. MP particles showed interferences with the fluorescence and the AB assay. The MeOH extract exhibits considerable toxicity, which depends on dilution. The cytotoxicity of the MeOH extract decreases over time, indicating the instability of leachate chemicals.Item EVALUATION OF THE PROTECTIVITY OF ASSESSMENT FACTORS IN THE REACH REGULATION(2025-06-25) Brunner, Lara Milena; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapUnder REACH, a chemical risk assessmentis often conducted tduring the registration if an industrial chemical. In that chemical risk assessment, assessment factors can be used to extrapolate the toxicity of a chemical with a low amount of testing. These assessment factors are responsible to account for four kinds of uncertainty. These uncertainties are laboratory variation, biological variation, acute to chronic extrapolation and lab to field extrapolation. In this thesis, these uncertainties were evaluated based on how they present in databases from ECHA, EFSA and the US EPA. All tests with environmentally relevant effects, commonly used test durations and with algae, crustaceans, fish and molluscs were included in the evaluation. Additionally, the toxicity of industrial chemicals was compared to the toxicity of pharmaceuticals and pesticides. Finally, the tiered system as proposed by the guidance document of ECHA for REACH is evaluated on its ability to account for those uncertainties in the first four tiers. The analysis shows that the biggest uncertainty was the biological variation between species. The median variation between the most sensitive and least sensitive organisms of the same species group was 100. The median acute to chronic ratio was determined as 3.5 for algae and 11 for crustaceans, fish and molluscs. The laboratory variation showed a median variation of 2.2 and the lab to field extrapolation showed a median variation of 1. The median toxicity of Industrial chemicals was lower than that of pesticides and pharmaceuticals. Industrial chemicals, which were also pesticides or pharmaceuticals, show a higher toxicity than chemicals only classified as industrial chemicals. Evaluating the tiered approach with the available data, the first four tiers are more protective than the species sensitivity distribution approach in 22% of the cases.Item HEAT TOLERANCE AND HEAT ACCLIMATION IN POTENTIAL FUTURE URBAN TREE SPECIES IN SWEDEN(2025-06-24) Ruud, Carl; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapThe full effect on urban greenery due to global warming and future increased intensity and frequency of heatwaves is still unclear. Harsh urban conditions, like the urban heat island effect, may require the introduction of new tree species to maintain urban greenery. This study investigated the heat tolerance of five tree species not endemic to Sweden (Koelreuteria paniculata, Liquidambar styraciflua, Liriodendron tulipifera, Magnolia kobus, and Nyssa sylvatica). The research questions were: (1) Will the trees see an increased stress level with increased leaf temperatures? (2) Will the trees acclimate and become more stress-resilient after exposure to heat waves?, and (3) How does the ability to acclimate to heat stress vary among species? During the experiment, trees were exposed to three heat waves. Control treatments were exposed to 23°C in the first two heatwaves, while heat-treated trees were exposed to 33°C. In the third heatwave, both control and heat-treated trees were exposed to 38°C. To evaluate the heat stress tolerance, measurements for net photosynthesis, stomatal conductance, and photosystem II functionality (evaluated as the temperature at which the functionality was reduced 50% of unstressed values, T50) were taken after each heatwave. Additional leaf measurements of leaf temperatures, angles, light intake, and size were also taken for each heatwave. The results show a mixed response between species, indicating species-specific ability to handle heat. No significant results were found to show that trees exposed to multiple heat waves acclimate to become more heat stress resilient. However, trees exposed to repeated heat waves had fewer cases where leaf temperatures exceeded their T50 temperatures. Koelreuteria paniculata stood out as the previously heatwave-exposed individuals managed to maintain higher stomatal conductance and net photosynthesis in heatwave 3, compared to individuals exposed to a single strong heatwave. Another finding was the steady decline of Liriodendron tulipifera throughout the heat waves, as the heat-treated individuals significantly decreased in T50, stomatal conductance, and net photosynthesis over the three heat waves. As a whole, the results indicate that the five tree species may be able to handle moderate heat stress (33°C), but that severe heat stress (38°C) may be too much for them to handle. This suggests that the studied species may not be suitable for planting in the most heat-exposed urban locations.Item EFFECTS OF THE ANTIDEPRESSANT AMITRIPTYLINE ON MARINE MEIOFAUNA With a novel methodology of examining activity(2025-06-24) Stenmark, Rebecka; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapChemical pollution is an increasing problem threatening earth’s ecosystems around the world. One important group of organisms is meiofauna that is often overlooked despite their great ecological importance and diversity. One chemical of emerging concern for meiofauna is the antidepressant Amitriptyline (AMI) that has affinity for sediments and previous studies have observed its ability to negatively affect meiofauna diversity and abundance at environmentally relevant levels. This study aimed to examine the toxic effects of the compound in both long- and short-term exposure on meiofauna communities, assessing effects on community structure and activity by developing and applying the MTT assay. The findings showed that there was no significant toxic effect on the community structure or activity at the tested concentrations (3-30 000 ng/g dw). There was slight indication of possible negative effects on foraminifers and nematodes at the lowest concentration after 30 days. The MTT assay was deemed a successful possible new ecotoxicological tool, with an established experimental design and demonstrated repeatable stable results. Further research is needed to understand the exposure route of AMI in sediments and investigate effects at low concentrations. Additionally, the reproducibility of the MTT assay needs to be tested and verified, by applying it to other meiofauna communities.Item HOW LOGGING RESIDUES IMPACT ECOSYSTEM RESPIRATION AFTER CLEAR-CUT?(2025-06-23) Serafin, Marta; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapDrained peatlands are a source of CO2; to reduce such effect, afforestation is a common mitigation strategy. However, clear-cutting and logging residue retention, along with climate change, alter soil conditions, affect microbial activity, and reduce mitigation efforts. Moreover, lower water table levels, resulting from drainage, and higher soil temperature accelerate decomposition, leading to increased CO2 release, further undermining mitigation efforts. Interestingly, these relationships have not been studied in highly productive hemiboreal drained peatlands, which constitute a vast CO2 reservoir. This thesis investigates the impact of logging residue retention, along with soil temperature and water table level, on ecosystem respiration in hemiboreal drained peatland following the clear-cutting of Norway spruce forest over three years. The site was divided into two plots. At the rewetted plot, logging residues were removed, and later the plot was rewetted; at the other plot, the logging residues were retained, and it was afforested (afforested plot). At both plots, CO2 fluxes were obtained with the eddy covariance method, and soil temperature and water table level were measured with soil sensors. Logging residue biomass was estimated using the Marklund (1988) model. Linear regression models were applied to investigate the direct and moderating effects of soil temperature and water level table. The results reveal that the annual average of CO2 release at the afforested plot (4.55 kg CO2 m-2 yr-1 ) was almost twice as high as CO2 release at the rewetted plot (2.35 kg CO2 m-2 yr-1 ). Logging residue decomposition contributed to nearly 56% at the afforested plot and 26% at the rewetted plot in the first year of measurements. This increase can be attributed to the decomposition of logging residues, which boosts microbial and fungal activity and modifies soil conditions. Furthermore, a strong positive effect of soil temperature on respiration rates was observed at both plots (stand. coef 0.69 & 0.73, p < 0.01). This effect was moderated by water table level (stand. coef -0.043 & -0.104, p < 0.01). These results reveal that although higher soil temperature accelerates decomposition, leading to increased CO2 release, the higher water table level reduces oxygen availability in the soil and limits respiration sensitivity to temperature. These findings show that both substrate availability and environmental controls interact to influence CO2 release. This thesis contributes to a broader understanding of carbon cycling in managed hemiboreal drained peatlands and calls for further research on long-term effects and integrated management strategies.Item MICROPLASTICS IN THE DRINKING WATER TREATMENT PROCESS: A CASE STUDY OF GISLAVED, SWEDEN(2025-06-23) Matthews, Stuart; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapThe production and subsequent pollution of plastics has reached staggering levels in recent decades, leading to the ubiquitous presence of microplastics in Earth’s environmental systems, including aquatic resources used for drinking water. The consumption of microplastics is a risk to human health and microplastics have been found in a variety of drinking water sources worldwide, including in larger cities in Sweden with complex treatment processes. This study examines a simpler drinking water treatment plant in Gislaved, Sweden which uses the river Nissan as a source and removes contaminants using natural and artificial slow sand filtration in addition to a bioreactor employing polypropylene-based biofilm carriers. The aims are to assess the presence of microplastics in the drinking water produced, the effectiveness of the treatment process, and the possibility of contamination from the plant itself. Samples representing various stages of the treatment process were collected, processed and analyzed using micro-Raman spectrometry, with minimum examined particle size 5µm. Microplastics were found in the drinking water at significantly higher rates than in more advanced drinking water treatment plants in Sweden in all examined size fractions. The full effectiveness of the treatment plant was not possible to assess due to technical and time-related difficulties, but the artificial sand filtration showed an >95% removal rate of microplastic particles in the >50µm range. Contamination from the bioreactor was determined to be likely, with more than half of detected plastic particles in the drinking water showing corresponding Raman spectra to the polypropylene biocarrier material. The results highlight the possible health risks of drinking water from simpler treatment plants, especially those employing plastic components; further research is recommended for a complete assessment of the studied water treatment plant as well as other comparable facilities.Item ASSESSING THE SPRING ATMOSPHERIC CIRCULATION EFFECTS ON GLACIERS IN THE CENTRAL AND SOUTHERN TIBETAN PLATEAU: Insights from observation data and ERA5 reanalysis for surface air temperature, precipitation and precipitation type(2025-06-23) Goovaerts, Elke; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapThe Tibetan Plateau consists of several glacier regions that are subject to many near-surface and atmospheric processes. Therefore, it is important to understand their relationships. Spring is typically the transition phase between sublimation and ablation of the glaciers, but the transition variates strongly between locations and elevations. This study assesses the relationship between springtime atmospheric conditions (500 hPa) and potential glacier melt in the southern and central Tibetan Plateau using in situ observations and ERA5 reanalysis data. Near-surface conditions in the glacier regions are assessed using near-surface air temperature (T2m) and precipitation and their combination is used to determine potential glacier melt. An investigation of precipitation types is necessary to examine their contribution to glacier processes (ablation/sublimation). A classification of wind speeds and geopotential height at 500 hPa is conducted using the Self-Organizing Map (SOM) method and it is used as a framework for the elevation analysis and the composite analysis. Results show that atmospheric circulations have larger influences on T2m and precipitation spatially rather than vertically. Additionally, glacier processes are strongly dependent on T2m and therefore indirectly related to atmospheric conditions. Precipitation types differ strongly across elevations and their contribution to glacier melt/accumulation differs largely between locations.Item ECOTOXICOLOGICAL EFFECTS OF THE ANTI-EPILEPTIC DRUG LAMOTRIGINE ON ZOOPLANKTON COMMUNITIES(2025-06-23) Rigatti, Silvia; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapPharmaceuticals are essential in modern medicine, to ensure physical and mental health. However, after consumption, these chemicals are discharged into the environment through wastewater treatment plants and pose risks to non-target organisms. Knowledge on the chemical occurrence and exposure pathways are essential to produce reliable risk assessments and set guidelines for policies on chemical production and usage. In this framework, the anti-epileptic drug lamotrigine is an example of a knowledge gap, as more data is needed to infer conclusions on the risk it poses on the environment. Lamotrigine is, in fact, detected in freshwater environments, but no data is publicly available on its occurrence in marine environments. Furthermore, ecotoxicological data on this substance is scarce, often not well documented and from sources without peer reviews, such as, safety data sheets from chemical manufacturers. This thesis wants to increase the knowledge on the ecotoxicological effects of lamotrigine on natural zooplankton communities, with a focus on copepod communities. These organisms are keystone species for the marine environment, influencing biogeochemical processes and the biological food web – by being primary consumers, and at the basis of secondary consumers’ diet. Studies on communities are also more ecologically relevant compared to single-species tests. Through several experiments, I analysed lamotrigine toxicity across different life stages of copepods by assessing functional sublethal endpoints (feeding rate, egg production rate, egg hatching, nauplii development into copepodites), lethal endpoints (nauplii and copepodites mortality), and structural endpoints (community composition shifts). After refining the chemical range to test, I was able to conclude that lamotrigine toxicity to marine zooplankton has a non-monotonous trend, with the highest adverse effect observed at a concentration of 1 μg L-1. However, statistical significance was rarely met likely due to the high natural variation that characterize natural communities. The results of my thesis highlights the complexity of assessing pharmaceutical toxic effects on marine zooplankton, and the difficulty in explaining non-monotonous responses when only little data are available. This thesis underlines the need for more environmental occurrence data in the marine environment, to assess if lamotrigine can represent a risk giving the ecotoxicity data I obtained. In addition, to have a comprehensive risk assessment, I suggest that different species and/or communities should be tested to have a clearer understanding of lamotrigine ecotoxicityItem DROUGHT TOLERANCE OF CANDIDATE URBAN TREE SPECIES(2025-06-23) Thapa, Rabina; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapGlobal climate change is increasing the frequency and intensity of extreme events such as drought and the effect is exacerbated in urban environment, threatning urban tree health and survival. In this study, we conducted a pot experiment using 15 candidate urban tree species (267 trees in total) diverse in origin but broadly categorized as native and exotic. Three treatment groups were established: control (regular watering), moderate drought (short-term water withholding followed by rewatering), and extreme drought (water withholding until visible leaf damage, then rewatering). Key physiological parameters were measured every week at regular intervals throughout the experiment: photosynthetic rate, stomatal conductance, chlorophyll fluorescence, and predawn and midday leaf water potentials. We examined whether physiological traits decline in parallel or independently during drought, assessed recovery capacity at different drought intensities, compared drought tolerance between native and exotic species, and identified species-specific drought tolerance characteristics. Results revealed parallel declines in all physiological parameters during both moderate and extreme drought, with decline severity increasing with drought intensity and duration. Recovery patterns exhibited threshold behavior, with physiological functions failing to recover after predawn leaf water potentials dropped below -2.3 Mpa and Fv/Fm below 4, indicating permanent/irreversible damage after the point. Thus, substantial recovery was observed in moderately stressed trees while extremely stressed trees didn’t show any signs of recovery. Native species were less sensitive to moderate drought than exotic species while the opposite was true under extreme drought. Species-specific responses revealed Ostrya carpinifolia (European Hop-hornbeam) as consistently drought-tolerant, while Koelreuteria paniculata (Goldenrain tree) demonstrated remarkable recovery capacity despite intermediate drought sensitivity. Nyssa sylvatica (Black gum) and Acer saccharinum (Silver maple) were consistently the most drought-sensitive species. Our findings highlight the complex, coordinated nature of physiological responses to drought and the importance of considering both drought resistance and recovery capacity when selecting urban tree species for climate resilience, particularly as extreme drought events become more common under climate change.Item Establishment of Long-Term Measurement of Alkali-Containing Particles at The Natrium Air Quality Research Station(2025-06-23) Ahmad, Muhammad Nasrullah; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapMeasurement of alkali-containing aerosol particles over extended periods provides valuable insight into both natural and anthropogenic influences on air quality. This study aimed to establish continuous measurement of alkali-containing particles using a Surface Ionization Detector (SID) at the Natrium Air Quality Research Station in Gothenburg. As a low-cost with high-impact tool, the SID holds strong potential for long-term atmospheric research. The project focused on optimizing SID operational parameters, characterizing the temporal variability of alkali particles, and comparing results with complementary datasets, including EDXRF filter analysis and PM2.5 measurements. In total 40 days of valid data were obtained from a 62-day measurement campaign. SID measurements revealed that alkali particle concentrations were influenced by meteorological conditions and air mass origins. Results from EDXRF analysis shows that on some occasion, EDXRF detected high chlorine levels during a short sampling period in February. However, alkali concentration was low possibly due to incomplete data and different temporal resolution. In contrast, during April, SID concentrations aligned more closely with EDXRF results. These elevated levels were also observed during mild temperatures and periods of high relative humidity, likely associated with sodium from sea salt particles in marine air. Lower concentrations occurred under colder conditions and easterly winds, suggesting potassium-containing particle from inland biomass burning influence. Back trajectory analysis using the HYSPLIT model further supported these findings, showing that the highest alkali concentrations were linked to Atlantic air masses, while the most frequent easterly inland flows exhibited the lowest concentrations. This emphasises the role of sea salt as a major contributor and highlights the importance of air mass transport in shaping ambient alkali-containing aerosol levels. Overall, this study demonstrates SID’s effectiveness as a selective, sensitive instrument for detecting trace alkali species and offers valuable insights for future aerosol monitoring.Item EFFECTS OF ANTIBIOTICS AND MULTIDRUG RESISTANT E. COLI ON BACTERIAL SEDIMENT COMMUNITIES(2025-06-23) Jyrmark, Oliver; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapThe spread of antibiotic resistance is a global health concern, with growing evidence that environmental reservoirs such as aquatic sediments play a role in antibiotic resistance persistence and dissemination. This study investigates the effects of a mixture of antibiotics and the establishment of a multidrug-resistant strain of Escherichia coli at levels commonly discharged by wastewater treatments plants on freshwater sediment bacterial communities. In addition, the study evaluates how the potential E. coli establishment was affected by the occurrence of antibiotics. To assess the effect and interaction of these two variables, a 10-day static test was performed in microcosm conditions using sediment from Lake Vänern, Sweden. Prior to the full experiment, a pilot study was performed to assess the invasion capacity of E. coli on sediment and how to prepare the inoculation of E.coli in the sediment. Results from the pilot study demonstrated that E.coli was able to survive and establish in the sediment for up to 28 days. In the full experiment an increase of the blaCTX-M gene in the sediment invaded by E.coli was observed after 1, 3, and 7 days after inoculation, indicating potential resistance spread to natural bacterial communities. The occurrence of antibiotic contamination positively affected the spread of antibiotic resistance genes (ARGs) on natural communities. The functions of the community were resilient to both the exposed antibiotic mixture and the invasion of the E.coli, attributed to functional redundancy in the bacteria communities and no-ecological effects of acquiring ARGs. The bacterial communities appear to have a higher carbon metabolism and a higher nitrification over time, attributed to an increasement on their efficiencies in using carbon and ammonium. These findings underscore the potential of invading bacteria carrying ARGs, such as E.coli, to influence the resistome of bacterial communities, and how this is modulated by the occurrence of antibiotic contamination. This study highlights the importance of incorporating environmental dimensions into antibiotic resistance research and supports a One Health approach to managing antimicrobial resistance.Item CHLOROPHYLL A AND MICROCYSTIN VARIATIONS ACROSS WETLANDS LOCATED IN MINERAL AND PEAT SOILS IN SOUTH SWEDEN(2025-06-23) Sanyang, Bakanding; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapConcentrations of chlorophyll a (Chl-a) and cyanobacterial toxins such as microcystin are used as indicators of phytoplankton biomass, water quality and ecological status in surface waters such as wetlands. Although rewetting wetlands for biodiversity restoration is on the political agenda, little is known on how physical characteristics of the wetlands will affect water quality and in turn Chl-a and microcystin concentrations. In this study, it was examined the influence of physical characteristics (i.e. soil type, age, depth) and water quality (i.e. nutrient content, dissolved organic carbon-DOC, light-extinction or pH) on Chl-a and microcystin variations among 41 wetlands in south Sweden. In addition, it was assessed if detected levels of Chl-a and microcystin can pose an impact on ecosystem integrity and the quality for drinking water. Phytoplankton pigments were quantified using spectrophotometric analysis, and microcystin concentrations using ELISA assay. Relationships between variables were investigated through statistical analysis. Results show that the mean Chl-a was higher (25±21 μg/L) in young wetlands (<4 years) than in old wetlands (>4 years; 5±2 μg/L), and especially if the wetlands were located in peat soils. Detected levels of Chl-a were above the threshold for eutrophic state (10 μg/L) in 24% of the wetlands studied and all of them were young (<4 years). Phycocyanin (marker for cyanobacteria) was positively correlated with microcystin, indicating that the highest microcystin concentrations occurred in wetlands with higher phycocyanin concentrations. However, detected levels of microcystin were always below the threshold for human health risk (ie. 1 μg/L; World Health Organization). Wetlands located in peat soils had higher levels of nutrients (Total Nitrogen, NO3 ⁻ , PO43⁻) and DOC, and lower pH and dissolved oxygen (DO), suggesting that the poor water quality in wetlands located in peat soils contributed to the higher Chl-a and microcystin of these wetlands. Altogether, this preliminary study shows that young wetlands in peat soils tend to have a lower water quality (nutrient content and phytoplankton descriptors) than old wetlands or those located in mineral soils, independently of the year of its formation. This research highlights the merit of monitoring phytoplankton in wetlands and indicates that the management of wetlands could benefit from controlling which type of soil and age of the wetlands.Item ADVANCING IN VITRO TECHNIQUES FOR ECOTOXCIOLOGICAL APPLICATION: Evaluation of a novel fish cell line co-culture system through PFAS-induced transcriptional responses(2025-06-23) Karlsson, Nora; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapEcotoxicology is increasingly challenged by the demand for toxicological data on a growing range of environmental contaminants. At the same time, continued reliance on laboratory animals is limited by ethical considerations and regulatory principles. The development of novel cell-based methodologies, replacing and reducing the need for animal-based assays are therefore of vital importance for the continued progress and efficacy of ecotoxicological research and regulatory work. In this study a co-culture model combining the two rainbow trout cell lines RTgutGC and RTL-W1 has been established in a dual compartment system. The aim was to evaluate this novel co-culture model’s utility for future ecotoxicological applications. Following the establishment the model was exposed to perfluoroalkyl acids, most notably perfluorooctanoic acid (PFOA), and the transcriptional responses were recorded by real time quantitative PCR (qPCR). Additionally, a feeding regime in which rainbow trout was feed PFOA-spiked food was developed to enable comparisons to in vivo data. The study revealed both promising features as well as limitations for the in vitro model PFOA exposure induced significant transcriptional responses related to lipid metabolism and xenobiotic detoxification processes, both in the co-culture model and in monocultures of RTL-W1. However, more pronounced treatment related effects were found for the monoculture, suggesting a lower sensitivity in the co-cultured cells. The absence of transcriptional responses for RTL-W1 in the basolateral compartment indicated low toxicant exposure, likely explained by low permeability of the gut cell barrier above. Comparisons to the dietary exposure data was proven challenging, highlighting the complexity of in vitro to in vivo extrapolations. Interestingly, an elevated basal expression of CYP1A1 in the co-cultured RTL-W1 cells imply enhanced xenobiotic metabolic competence potentially triggered by the dual cell culturing environment. This finding shows potential for the model’s applicability as an improved in vitro model for mechanistic studies of toxicological processes related to biotransformation reactions.Item A COMPARATIVE STUDY OF AN ANIMAL PRODUCT FREE AND AN ANIMAL PRODUCT CONTAINING CELL CULTURE PROTOCOL AND ITS EFFECTS ON PLHC-1’S GROWTH, VITALITY AND EROD ACTIVITY(2025-06-23) Wiström, Linda; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskapAnimal-derived products, such as fetal bovine serum and porcine derived trypsin, has been utilized within cell cultivations for decades. However, these animal-derived products come with an increased environmental impact, technical difficulties and animal welfare issues, where the scientific community has expressed a need for an animal-product-free cell culture protocol. The aim of this study was therefore to evaluate the applicability of a recently established animal product-free protocol for mammalian cell cultures on the Poeciliopsis Lucida Hepatocellular Carcinoma (PLHC-1) fish cell line, in the context of the environmental toxicity assay ethoxyresorufin-O-deethylase (EROD) activity. The aim was answered by cultivating PLHC-1 according to the animal-product-free cell culture protocol and compare growth, vitality and EROD activity to cells cultured with the standard animal-derived protocol. This study found that animal free CTS™ TrypLE™ Select Enzyme did not have a negative effect on cell vitality or estimated EROD activity, making it a comparable option to porcine derived trypsin-EDTA (0.05 %). However, the results also displayed that PLHC-1 could not be cultured long-term or display measurable levels of EROD activity when cultured fully according to the animal-product-free protocol. These findings conclude that trypsin-EDTA has the possibility to be replaced by CTS™ TrypLE™ Select Enzyme, but further optimization of the animal-free-protocol is needed to replace fetal bovine serum. The substitution to animal-free CTS™ TrypLE™ Select Enzyme could lower the environmental impact of the animal-derived protocol typically used for PLHC-1 and the environmental toxicity assay EROD activity as well as aligning the protocol closer to animal welfare principles.