| 1. |
- Balzer, Laura, et al.
(författare)
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Role of formation and decay of seston organic matter in the fate of methylmercury within the water column of a eutrophic lake
- 2023
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Ingår i: Biogeosciences. - 1726-4170 .- 1726-4189. ; 20:7, s. 1459-1472
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Tidskriftsartikel (refereegranskat)abstract
- Anoxic microniches in sinking particles in lakes have been identified as important water phase production zones of monomethylmercury (MeHg). However, the production and decay of MeHg during organic matter (OM) decomposition in the water column and its relation to the total Hg concentration in seston are poorly understood. We investigated total Hg and MeHg in relation to chemical changes in sinking seston and hydrochemical settings in a small and shallow (12 m deep) eutrophic lake during phytoplankton blooms from April to November 2019. The results show that MeHg proportions reach up to 22 % in seston in oxygen super saturation at the water surface and highest values (up to 26 %) at the oxic–suboxic redox boundary. MeHg concentrations were highest in May and November when algal biomass production was low and seston were dominated by zooplankton. Biodilution of MeHg concentrations could not be observed in the months of the highest algal biomass production; instead, MeHg and THg concentrations in seston were comparatively high. During suboxic OM decomposition and with decreasing redox potential (Mn and nitrate reduction), the concentration and proportion of MeHg in seston strongly decreased (<0.5 %), whereas total Hg concentrations show a 3.8- to 26-fold increase with water depth. Here, it remains unclear to which extent biodilution on the one hand and OM decomposition on the other alter the MeHg and THg concentration in seston. Changes in OM quality were most intense within or slightly below the redox transition zone (RTZ). The concentrations of MeHg and THg in seston from the RTZ were comparable to those found in the sediment trap material which integrated the changes in seston composition during the entire sampling period, suggesting that changes in the MeHg and THg content in the hypolimnion below the RTZ are comparatively small. Our study suggests that, in shallow eutrophic lakes, the water phase formation and decomposition of MeHg is intense and controlled by the decomposition of algal biomass and is, assumedly, largely disconnected from Hg methylation in sediments, similar to what has been observed in deep oligotrophic lakes.
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| 2. |
- Baptista-Salazar, Carluvy, et al.
(författare)
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Experiments revealing the formation of refractory methylmercury pools in natural sediments and soils
- 2022
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 328, s. 76-84
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Tidskriftsartikel (refereegranskat)abstract
- Methylation and demethylation of mercury (Hg) are well recognized as processes controlling the concentrations of monomethylmercury (MeHg) in natural environments, and thus the pool of Hg available for biological uptake. In addition, studies have indicated the potential role of refractory MeHg pools (not readily available for demethylation) on the pool of MeHg in, for example, sediments and soils. These studies, however, remain scarce and often the role of refractory MeHg pools is overlooked. Here, we have conducted incubation experiments aiming to quantify refractory MeHg pools in contrasting environments. In our study, sediments (from lakes and brackish seawater sites) and soils (from forests and marshes) were incubated with isotopically enriched Hg tracers (Me201Hg and 198Hg) for up to 6 weeks. To follow the potential formation of refractory MeHg pools, %MeHg (fraction of Hg occurring as MeHg) after the first week of incubation for the added 198Hg and Me201Hg tracers, and ambient Hg was compared. The high %MeHg for the 198Hg tracer compared to the %MeHg of ambient Hg suggests a higher initial availability of added 198Hg in comparison to the ambient Hg in the sediments. For the soils, low %MeHg for the 198Hg tracer suggests low Hg methylation rates. The discrepancy observed between the sediments and soils can be explained by a higher availability of inorganic Hg in the sediments, as suggested by the Hg thermal fractional analysis conducted. The %MeHg steady state for the added Me201Hg tracer remained high (>17%) throughout the experiment, suggesting refractory pools of MeHg to be built-up in all tested sediments and soils. Together, the %MeHg for the added Hg tracers demonstrate that a significant fraction of the MeHg produced in sediments and soils is sequestered into refractory pools not readily available for demethylation. Furthermore, these results show that conditions favoring net methylation in sediments and soil could result in elevated concentrations of MeHg for a significant amount of time (months) even if the conditions favoring Hg net methylation are only temporary.
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| 3. |
- Baptista-Salazar, Carluvy, et al.
(författare)
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Insights into the factors influencing mercury concentrations in tropical reservoir sediments
- 2021
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Ingår i: Environmental Science. - : Royal Society of Chemistry (RSC). - 2050-7887 .- 2050-7895. ; 23:10, s. 1542-1553
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Tidskriftsartikel (refereegranskat)abstract
- Thousands of dams are currently under construction or planned worldwide to meet the growing need for electricity. The creation of reservoirs could, however, lead to conditions that promote the accumulation of mercury (Hg) in surface sediments and the subsequent production of methylmercury (MeHg). Once produced, MeHg can bioaccumulate to harmful levels in organisms. It is unclear to what extent variations in physical features and biogeochemical factors of the reservoir impact Hg accumulation. The objective of this study was to identify key drivers of the accumulation of total Hg (THg) in tropical reservoir sediments. The concentration of THg in all analyzed depth intervals of 22 sediment cores from the five contrasting reservoirs investigated ranged from 16 to 310 ng g(-1) (n = 212, in the different sediment cores, the maximum depth varied from 18 to 96 cm). Our study suggests reservoir size to be an important parameter determining the concentration of THg accumulating in tropical reservoir sediments, with THg ranging up to 50 ng g(-1) in reservoirs with an area exceeding 400 km(2) and from 100 to 200 ng g(-1) in reservoirs with an area less than 80 km(2). In addition to the reservoir size, the role of land use, nutrient loading, biome and sediment properties (e.g., organic carbon content) was tested as potential drivers of THg levels. The principal component analysis conducted suggested THg to be related to the properties of the watershed (high degree of forest cover and low degree of agricultural land use), size and age of the reservoir, water residence time and the levels of nutrients in the reservoir. A direct correlation between THg and tested variables was, however, only observed with the area of the reservoir.
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| 4. |
- Carlsson, Gunilla, et al.
(författare)
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A hundred days in confinement : Doing, being, becoming, and belonging among older people in Sweden during the COVID-19 pandemic
- 2022
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Ingår i: Journal of Occupational Science. - : Informa UK Limited. - 1442-7591 .- 2158-1576. ; 29:3, s. 402-416
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Tidskriftsartikel (refereegranskat)abstract
- Background: When and how people were able to engage in everyday occupations changed suddenly with the coronavirus pandemic. Defined as a risk group due to their age, people 70 years and older in Sweden experienced confinement, as did older adults globally. Aim: To explore how doing, being, becoming, and belonging as dimensions of occupation were manifested in the lives of Swedish people 70 years or older, 100 days into the coronavirus pandemic. Method: Data were elicited through semi-structured interviews with 17 participants (11 women, 6 six men, mean age 76 years), living in ordinary housing in Sweden. Interviews were conducted in June 2020 as part of a larger longitudinal research project. A directed content analysis approach was used to analyse the data based on the occupational dimensions of doing, being, becoming, and belonging. Results: After 100 days of confinement, daily occupations had been changed, and habits and routines disrupted. However, the need to engage in occupations was strong. Participants expressed how they adapted their occupations to the restrictions, but also how their doing affected their well-being, further development, and opportunities for social interactions. Conclusion: The participants, who were older people without any specific diagnosis, reflected upon their daily occupations during an unrehearsed natural experiment when, more than anything else, the social environmental circumstances changed. The analysis elucidates how doing, being, becoming, and belonging is embedded in people’s lives. The study can serve as a foundation to further research on understanding people’s individual needs as occupational beings.
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| 5. |
- Carrasco, Nathalie, et al.
(författare)
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Seasonal riverine inputs may affect diet and mercury bioaccumulation in Arctic coastal zooplankton
- 2024
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 906
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Tidskriftsartikel (refereegranskat)abstract
- Climate change driven increases in permafrost thaw and terrestrial runoff are expected to facilitate the mobilization and transport of mercury (Hg) from catchment soils to coastal areas in the Arctic, potentially increasing Hg exposure of marine food webs. The main aim of this study was to determine the impacts of seasonal riverine inputs on land -ocean Hg transport, zooplankton diet and Hg bioaccumulation in an Arctic estuary (Adventfjorden, Svalbard). The Adventelva River was a source of dissolved and particulate Hg to Adventfjorden, especially in June and July during the river's main discharge period. Stable isotope and fatty acid analyses suggest that zooplankton diet varied seasonally with diatoms dominating during the spring phytoplankton bloom in May and with increasing contributions of dinoflagellates in the summer months. In addition, there was evidence of increased terrestrial carbon utilization by zooplankton in June and July, when terrestrial particles contributed substantially to the particulate organic matter pool. Total (TotHg) and methyl Hg (MeHg) concentrations in zooplankton increased from April to August related to increased exposure to riverine inputs, and to shifts in zooplankton diet and community structure. Longer and warmer summer seasons will probably increase riverine runoff and thus Hg exposure to Arctic zooplankton.
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| 6. |
- Fristedt, Sofi, 1969-, et al.
(författare)
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Changes in daily life and wellbeing in adults, 70 years and older, in the beginning of the COVID-19 pandemic
- 2021
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Ingår i: Scandinavian Journal of Occupational Therapy. - : Taylor & Francis. - 1103-8128 .- 1651-2014. ; 29:6, s. 511-521
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In the beginning of the COVID-19 pandemic, Swedish authorities enforced specific recommendations on social distancing for adults 70 years and older (70+). Day-to-day life changed for 15% of the Swedish population. The aim of the study was to explore how adults 70+ experienced and managed changes in everyday life due to the COVID-19 pandemic and how those changes affected wellbeing at the beginning of the virus outbreak.METHODS: Eleven women and six men, (mean age 76 years), living in ordinary housing, participated in remote semi-structured interviews in April 2020. The interviews were analysed with qualitative content analysis.FINDINGS: The theme Suddenly at risk - '…but it could have been worse' included four categories My world closed down; Negotiations, adaptations and prioritizations to manage staying at home; Barriers and facilitators to sustain occupational participation; and Considerations of my own and other's health and wellbeing emerged from the data analysis.CONCLUSION: Everyday life changes had implications for health and well-being. The participants questioned previous conceptions of meaning in relation to habitual activities, likely leading to consistent occupational changes. However, these long-term effects remain to be explored, and considered to enable older adult's health during the pandemic and beyond.
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| 7. |
- Fristedt, Sofi, et al.
(författare)
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Suddenly at risk: Older adults’ changes in everyday life early on during the COVID-19 pandemic
- 2022
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Konferensbidrag (refereegranskat)abstract
- ABSTRACT:Introduction / Rationale: From the onset of the COVID-19 pandemic, social distancing was recommended for adults 70 years and older (70+) in Sweden. From an outside view, they then became deprived of possibilities to engage in meaningful activities. However, as meaning is highly subjective, we need to listen to older adults’ voices to really know.Objectives: To explore how adults 70+ experienced and managed changes in everyday life due to the COVID-19 pandemic and how those changes affected wellbeing at the beginning of the virus outbreak.Method / Approach: Eleven women and six men, (mean age 76 years), living in ordinary housing, participated in remote semi-structured interviews in April and June 2020. The interviews were analysed with qualitative content analysis.Results: An overall theme Suddenly at risk – “…but it could have been worse” and four categories emerged from the data analysis. The participants had to accept some changes summarized in the first category; my world closed down. They described continuous negotiations, adaptations and prioritizations to manage staying at home in the second category, but they also experienced contextual barriers and facilitators to sustain occupational participation as the third category elucidate, where e.g. the shift of seasons facilitated social activities. Their experiences of health and wellbeing varied and are captured in the fourth category, considerations about my own and other’s health and wellbeing.Conclusion: The participants questioned previous conceptions of meaning in relation to habitual activities, likely leading to consistent occupational changes, potentially affecting health and well-bring also beyond the pandemic.
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| 8. |
- Granbom, Marianne, et al.
(författare)
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'Normality in all the abnormality' : Older adults' experiences of holidays and celebrations from the COVID-19 pandemic
- 2024
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Ingår i: Australian Occupational Therapy Journal. - : John Wiley & Sons. - 1440-1630 .- 0045-0766.
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: The importance of holidays, traditions, and family celebrations to human culture and occupational engagement has been neglected. The aim of this study was to explore how older adults experienced holidays and celebrations with social and physical distancing during the COVID-19 pandemic.METHODS: A secondary analysis was made on data from the At-Risk Study. Seventeen community-living adults (11 women and 6 men) aged 71-87 years, from Sweden participated. They were interviewed remotely four times during the first year of the pandemic. Data were analysed with qualitative content analysis. No consumer/community involvement occurred.FINDINGS: Three categories on how the participants hoped for, planned, decided, adapted, avoided, and experienced holidays and celebrations with social and physical distancing included expectations and preparations in unpredictable times; the constant need for re-evaluation; and almost everything turned out differently.CONCLUSIONS: The desire to celebrate despite pandemic restrictions shows the importance and meaning holidays hold for older adults. Celebrations can be disrupted for many reasons, not only as extreme as the ongoing pandemic. For wellbeing in later life health care, social care, and society need to understand the inherent components and acknowledge ways of supporting participation in occasional events such as holidays, traditions, and family celebrations.
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