| 1. |
- Daniau, A. -L, et al.
(author)
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predictability of biomass burning in response to climate changes
- 2012
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In: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 26, s. GB4007-
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Journal article (peer-reviewed)abstract
- Climate is an important control on biomass burning, but the sensitivity of fire to changes in temperature and moisture balance has not been quantified. We analyze sedimentary charcoal records to show that the changes in fire regime over the past 21,000 yrs are predictable from changes in regional climates. Analyses of paleo-fire data show that fire increases monotonically with changes in temperature and peaks at intermediate moisture levels, and that temperature is quantitatively the most important driver of changes in biomass burning over the past 21,000 yrs. Given that a similar relationship between climate drivers and fire emerges from analyses of the interannual variability in biomass burning shown by remote-sensing observations of month-by-month burnt area between 1996 and 2008, our results signal a serious cause for concern in the face of continuing global warming.
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| 2. |
- Johanson, G., et al.
(author)
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Quantitative relationships of perfluoroalkyl acids in drinking water associated with serum concentrations above background in adults living near contamination hotspots in Sweden
- 2023
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In: Environmental Research. - : Elsevier BV. - 0013-9351 .- 1096-0953. ; 219
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Journal article (peer-reviewed)abstract
- Contaminated drinking water (DW) is a major source of exposure to per- and polyfluoroalkyl substances (PFAS) at locations around PFAS production/use facilities and military airports. This study aimed to investigate quantitative relationships between concentrations in DW and serum of nine perfluoroalkyl acids (PFAAs) in Swedish adult populations living near contamination hotspots. Short-chained (PFPeA, PFHxA, PFHpA, and PFBS) and long-chained PFAAs (PFOA, PFNA, PFDA, PFHxS and PFOS) were measured in DW and serum. We matched DW and serum concentrations for a total of 398 subjects living or working in areas receiving contaminated DW and in one non-contaminated area. Thereafter, linear regression analysis with and without adjustments for co-variates was conducted. This enabled to derive (i) serum concentrations at background exposure (CB) from sources other than local DW exposure (i.e. food, dust and textiles) at 0 ng/L DW concentration, (ii) population-mean PFAA serum:water ratios (SWR) and (iii) PFAA concentrations in DW causing observable elevated serum PFAA concentrations above background variability. Median concentrations of the sum of nine PFAAs ranged between 2.8 and 1790 ng/L in DW and between 7.6 and 96.9 ng/mL in serum. DW concentration was the strongest predictor, resulting in similar unadjusted and adjusted regression coefficients. Mean CB ranged from <0.1 (PFPeA, PFHpA, PFBS) to 5.1 ng/mL (PFOS). Serum concentrations increased significantly with increasing DW concentrations for all PFAAs except for PFPeA with SWRs ranging from <10 (PFHxA, PFHpA and PFBS) to 111 (PFHxS). Observed elevated serum concentrations above background variability were reached at DW concentrations between 24 (PFOA) and 357 ng/L (PFHxA). The unadjusted linear regression predictions agreed well with serum concentrations previously reported in various populations exposed to low and high DW levels of PFOA, PFHxS and PFOS. The quantitative relationships derived herein should be helpful to translate PFAA concentrations in DW to concentrations in serum at the population level.
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| 3. |
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| 4. |
- Bloomfield, K., et al.
(author)
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Changes in Alcohol-Related Harm after Alcohol Policy Changes in Denmark
- 2009
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In: European Addiction Research. - : S. Karger AG. - 1022-6877 .- 1421-9891. ; 15:4, s. 224-231
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Journal article (peer-reviewed)abstract
- Objectives: This paper examines changes in alcohol-related harm in Denmark between 2003 and 2005 after changes in alcohol policies were introduced between 2003 and 2005. Methods: Interrupted time series analysis was performed with data on violent assaults and hospitalisations for acute alcohol intoxication from 2003 through 2005. Results: A 26% increase in the number of acute alcohol intoxication hospitalisations among people aged 15 years and younger was detected after the tax reduction on spirits. No significant increase in violent assaults and acute intoxication among adults was found. Conclusions: Even modest alcohol price policies can affect more vulnerable population sub-groups such as under-age youth. Policy makers should consider such consequences when forming economic policies that also have public health implications.
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| 5. |
- Donovan, Mary K., et al.
(author)
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Combining fish and benthic communities into multiple regimes reveals complex reef dynamics
- 2018
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
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Journal article (peer-reviewed)abstract
- Coral reefs worldwide face an uncertain future with many reefs reported to transition from being dominated by corals to macroalgae. However, given the complexity and diversity of the ecosystem, research on how regimes vary spatially and temporally is needed. Reef regimes are most often characterised by their benthic components; however, complex dynamics are associated with losses and gains in both fish and benthic assemblages. To capture this complexity, we synthesised 3,345 surveys from Hawai'i to define reef regimes in terms of both fish and benthic assemblages. Model-based clustering revealed five distinct regimes that varied ecologically, and were spatially heterogeneous by island, depth and exposure. We identified a regime characteristic of a degraded state with low coral cover and fish biomass, one that had low coral but high fish biomass, as well as three other regimes that varied significantly in their ecology but were previously considered a single coral dominated regime. Analyses of time series data reflected complex system dynamics, with multiple transitions among regimes that were a function of both local and global stressors. Coupling fish and benthic communities into reef regimes to capture complex dynamics holds promise for monitoring reef change and guiding ecosystem-based management of coral reefs.
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| 6. |
- Engelhardt, A. Josefin, 1992-, et al.
(author)
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Anthropogenic Organic Contaminants Analysed in Human Blood and Combined Risk
- 2023
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In: Exposure and Health. - : Springer Science and Business Media LLC. - 2451-9766 .- 2451-9685. ; 15:3, s. 551-565
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Research review (peer-reviewed)abstract
- The number of chemicals in the anthroposphere is increasing and some of them end up in humans. A literature search was made to assess which anthropogenic organic contaminants (OCs) that have been analysed in blood from the general population. The reviewed articles were used to create a database of studies [human blood database (HBDB), containing 559 OCs] reporting blood analyses made worldwide. All studies analysing blood from the Swedish population were compiled into a second database [Swedish exposure database (SEDB), containing 166 OCs] listing blood concentrations of OCs. Data from the SEDB showed decreasing levels of regulated chemicals in blood over time, indicating that regulation had made an impact. The Hazard Index (HI) approach was used as a qualitative mixture risk assessment of the OCs with established human biomonitoring guidance values (HBM-GVs) and blood levels in the SEDB. Nine HBM-GVs were found and the HI of the corresponding OCs/groups of OCs showed that a risk of adverse effects in the general population could not be excluded, which is a cause for concern considering that only a fraction of the analysed OCs in the SEDB were included. This study presents the OCs identified in human blood and concentration time trends. The study highlights the lack of HBM-GVs needed for mixture risk assessments to assess the combined risk of chemical exposure to the general population.
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| 7. |
- Ford, Amanda K., et al.
(author)
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Local Human Impacts Disrupt Relationships Between Benthic Reef Assemblages and Environmental Predictors
- 2020
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In: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 7
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Journal article (peer-reviewed)abstract
- Human activities are changing ecosystems at an unprecedented rate, yet large-scale studies into how local human impacts alter natural systems and interact with other aspects of global change are still lacking. Here we provide empirical evidence that local human impacts fundamentally alter relationships between ecological communities and environmental drivers. Using tropical coral reefs as a study system, we investigated the influence of contrasting levels of local human impact using a spatially extensive dataset spanning 62 outer reefs around inhabited Pacific islands. We tested how local human impacts (low versus high determined using a threshold of 25 people km(-2) reef) affected benthic community (i) structure, and (ii) relationships with environmental predictors using pre-defined models and model selection tools. Data on reef depth, benthic assemblages, and herbivorous fish communities were collected from field surveys. Additional data on thermal stress, storm exposure, and market gravity (a function of human population size and reef accessibility) were extracted from public repositories. Findings revealed that reefs subject to high local human impact were characterised by relatively more turf algae (>10% higher mean absolute coverage) and lower live coral cover (9% less mean absolute coverage) than reefs subject to low local human impact, but had similar macroalgal cover and coral morphological composition. Models based on spatio-physical predictors were significantly more accurate in explaining the variation of benthic assemblages at sites with low (mean adjusted-R-2 = 0.35) rather than high local human impact, where relationships became much weaker (mean adjusted-R-2 = 0.10). Model selection procedures also identified a distinct shift in the relative importance of different herbivorous fish functional groups in explaining benthic communities depending on the local human impact level. These results demonstrate that local human impacts alter natural systems and indicate that projecting climate change impacts may be particularly challenging at reefs close to higher human populations, where dependency and pressure on ecosystem services are highest.
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| 8. |
- Hillberg, Emil, et al.
(author)
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Flexibility to support the future power systems
- 2019
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Conference paper (other academic/artistic)abstract
- Power system flexibility relates to the ability of the power system to manage changes. Solutions providing advances in flexibility are of utmost importance for the future power system. Development and deployment of innovative technologies, communication and monitoring possibilities, as well as increased interaction and information exchange, are enablers to provide holistic flexibility solutions. Furthermore, development of new methods for market design and analysis, as well as methods and procedures related to system planning and operation, will be required to utilise available flexibility to provide most value to society. However, flexibility is not a unified term and is lacking a commonly accepted definition. The flexibility term is used as an umbrella covering various needs and aspects in the power system. This situation makes it highly complex to discuss flexibility in the power system and craves for differentiation to enhance clarity. In this report, the solution has been to differentiate the flexibility term on needs, and to categorise flexibility needs in four categories: Flexibility for Power, Flexibility for Energy, Flexibility for Transfer Capacity, and Flexibility for Voltage. Here, flexibility needs are considered from over-all system perspectives (stability, frequency and energy supply) and from more local perspectives (transfer capacities, voltage and power quality). With flexibility support considered for both operation and planning of the power system, it is required in a timescale from fractions of a second (e.g. stability and frequency support) to minutes and hours (e.g. thermal loadings and generation dispatch) to months and years (e.g. planning for seasonal adequacy and planning of new investments). The categorisation presented in this report supports an increased understanding of the flexibility needs, to be able to identify and select the most suitable flexibility solutions.
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| 9. |
- Hu, Xiao-Lei, et al.
(author)
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Study protocol for a randomized, controlled, multicentre, pragmatic trial with Rehabkompassen®-a digital structured follow-up tool for facilitating patient-tailored rehabilitation in persons after stroke
- 2023
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In: Trials. - : BioMed Central (BMC). - 1745-6215. ; 24:1
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Journal article (peer-reviewed)abstract
- BackgroundStroke is a leading cause of disability among adults worldwide. A timely structured follow-up tool to identify patients' rehabilitation needs and develop patient-tailored rehabilitation regimens to decrease disability is largely lacking in current stroke care. The overall purpose of this study is to evaluate the effectiveness of a novel digital follow-up tool, Rehabkompassen (R), among persons discharged from acute care settings after a stroke.MethodsThis multicentre, parallel, open-label, two-arm pragmatic randomized controlled trial with an allocation ratio of 1:1 will be conducted in Sweden. A total of 1106 adult stroke patients will have follow-up visits in usual care settings at 3 and 12 months after stroke onset. At the 3-month follow-up, participants will have a usual outpatient visit without (control group, n = 553) or with (intervention group, n = 553) the Rehabkompassen (R) tool. All participants will receive the intervention at the 12-month follow-up visit. Feedback from the end-users (patient and health care practitioners) will be collected after the visits. The primary outcomes will be the patients' independence and social participation at the 12-month visits. Secondary outcomes will include end-users' satisfaction, barriers and facilitators for adopting the instrument, other stroke impacts, health-related quality of life and the cost-effectiveness of the instrument, calculated by incremental cost per quality-adjusted life year (QALY).DiscussionThe outcomes of this trial will inform clinical practice and health care policy on the role of the Rehabkompassen (R) digital follow-up tool in the post-acute continuum of care after stroke.Trial registrationClinicalTrials.gov NCT04915027. Registered on 4 June 2021. ISRCTN registry ISRCTN63166587. Registered on 21 August 2023.
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| 10. |
- Jouffray, Jean-Baptiste, et al.
(author)
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Parsing human and biophysical drivers of coral reef regimes
- 2019
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In: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 286:1896
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Journal article (peer-reviewed)abstract
- Coral reefs worldwide face unprecedented cumulative anthropogenic effects of interacting local human pressures, global climate change and distal social processes. Reefs are also bound by the natural biophysical environment within which they exist. In this context, a key challenge for effective management is understanding how anthropogenic and biophysical conditions interact to drive distinct coral reef configurations. Here, we use machine learning to conduct explanatory predictions on reef ecosystems defined by both fish and benthic communities. Drawing on the most spatially extensive dataset available across the Hawaiian archipelago-20 anthropogenic and biophysical predictors over 620 survey sites-we model the occurrence of four distinct reef regimes and provide a novel approach to quantify the relative influence of human and environmental variables in shaping reef ecosystems. Our findings highlight the nuances of what underpins different coral reef regimes, the overwhelming importance of biophysical predictors and how a reef's natural setting may either expand or narrow the opportunity space for management interventions. The methods developed through this study can help inform reef practitioners and hold promises for replication across a broad range of ecosystems.
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| 11. |
- Katrantsiotis, Christos, et al.
(author)
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Eastern Mediterranean hydroclimate reconstruction over the last 3600 years based on sedimentary n-alkanes, their carbon and hydrogen isotope composition and XRF data from the Gialova Lagoon, SW Greece
- 2018
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In: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 194, s. 77-93
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Journal article (peer-reviewed)abstract
- Understanding past hydroclimate variability and related drivers is essential to improve climate forecasting capabilities especially in areas with high climatic sensitivity, such as the Mediterranean. This can be achieved by using a broad spectrum of high resolution, multiple proxy records which can also allow us to assess linkages between regional hydroclimate variability and shifts in the large-scale atmospheric patterns. Here, we present a multiproxy reconstruction of the central-eastern Mediterranean hydro climate changes over the last 3600 years based on a sediment core from the Gialova Lagoon, a shallow coastal ecosystem in SW Peloponnese, Greece. Our combined dataset consists of the distribution and compound-specific carbon and hydrogen isotope (delta C-13 and 8D) composition of n-alkanes, bulk organic matter properties and X-ray fluorescence (XRF) core scanning data. This approach was complemented with a semi-quantitative analysis of plant remains in the core. The results indicate a high contribution of local aquatic vegetation to organic matter. Large delta C-13 variations in predominantly aquatic plant-derived mid-chain alkanes (C23-23) mainly reflect changes in the aquatic plant abundance and their carbon source. Our data suggest that higher delta C-13(23-25) values (up to 19 parts per thousand) largely correspond to expansion of aquatic vegetation during wet and/or cold periods causing carbon-limiting conditions in the water and assimilation of isotopically-enriched bicarbonate by the plants. The 8D records of the individual n-alkanes (C-17 to C-31) exhibit a nearly identical pattern to each other, which implies that they all reflect changes in the source water isotope composition, driven by hydroclimate variability. In addition, the 8D profiles are consistent with the XRF data with both proxies being driven by a common hydroclimate signal. We observe two major shifts from dry and/or warm periods at ca 3600-3000 cal BP and ca 17001300 cal BP to wet and/or cold episodes at ca 3000-2700 cal BP and ca 1300-900 cal BP. The period ca 700-200 cal BP is the wettest and/or coldest in our record and coeval with the Little Ice Age. The climatic fluctuation reported in this study can be explained by the relative dominance of high-latitude (e.g. North Atlantic Oscillation during winters) and the low-latitude atmospheric patterns (Intertropical convergence zone, Subtropical High and the effects of Asian monsoons during summers) which suggests an Atlantic-Mediterranean-Monsoon climate link in this area for the late Holocene.
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| 12. |
- Kugelberg, Elisabeth, et al.
(author)
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Establishment of a superficial skin infection model in mice by using Staphylococcus aureus and Streptococcus pyogenes
- 2005
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In: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 49:8, s. 3435-3441
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Journal article (other academic/artistic)abstract
- A new animal model for the purpose of studying superficial infections is presented. In this model, an infection is established by disruption of the skin barrier by partial removal of the epidermal layer by tape stripping and subsequent application of the pathogens Staphylococcus aureus and Streptococcus pyogenes. The infection and the infection route are purely topical, in contrast to those used in previously described animal models in mice, such as the skin suture-wound model, where the infection is introduced into the deeper layers of the skin. Thus, the present model is considered more biologically relevant for the study of superficial skin infections in mice and humans. Established topical antibiotic treatments are shown to be effective. The procedures involved in the model are simple, a feature that increases throughput and reproducibility. This new model should be applicable to the evaluation of novel antimicrobial treatments of superficial infections caused by S. aureus and S. pyogenes.
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| 13. |
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| 14. |
- Lindkvist, Annica, et al.
(author)
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Reduction of the HIV-1 reservoir in resting CD4+ T-lymphocytes by high dosage intravenous immunoglobulin treatment: a proof-of-concept study
- 2009
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In: AIDS research and therapy. - : Springer Science and Business Media LLC. - 1742-6405. ; 6:1
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Journal article (peer-reviewed)abstract
- BACKGROUND: The latency of HIV-1 in resting CD4+ T-lymphocytes constitutes a major obstacle for the eradication of virus in patients on antiretroviral therapy (ART). As yet, no approach to reduce this viral reservoir has proven effective. METHODS: Nine subjects on effective ART were included in the study and treated with high dosage intravenous immunoglobulin (IVIG) for five consecutive days. Seven of those had detectable levels of replication-competent virus in the latent reservoir and were thus possible to evaluate. Highly purified resting memory CD4+ T-cells were activated and cells containing replication-competent HIV-1 were quantified. HIV-1 from plasma and activated memory CD4+ T-cells were compared with single genome sequencing (SGS) of the gag region. T-lymphocyte activation markers and serum interleukins were measured. RESULTS: The latent HIV-1 pool decreased with in median 68% after IVIG was added to effective ART. The reservoir decreased in five, whereas no decrease was found in two subjects with detectable virus. Plasma HIV-1 RNA >or= 2 copies/mL was detected in five of seven subjects at baseline, but in only one at follow-up after 8-12 weeks. The decrease of the latent HIV-1 pool and the residual plasma viremia was preceded by a transitory low-level increase in plasma HIV-1 RNA and serum interleukin 7 (IL-7) levels, and followed by an expansion of T regulatory cells. The magnitude of the viral increase in plasma correlated to the size of the latent HIV-1 pool and SGS of the gag region showed that viral clones from plasma clustered together with virus from activated memory T-cells, pointing to the latent reservoir as the source of HIV-1 RNA in plasma. CONCLUSION: The findings from this uncontrolled proof-of-concept study suggest that the reservoir became accessible by IVIG treatment through activation of HIV-1 gene expression in latently-infected resting CD4+ T-cells. We propose that IVIG should be further evaluated as an adjuvant to effective ART.
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| 15. |
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| 16. |
- Mumford, AD, et al.
(author)
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Factor VI359T: a novel mutation associated with thrombosis and resistance to activated protein C
- 2003
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In: British Journal of Haematology. - : Wiley. - 0007-1048. ; 123:3, s. 496-501
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Journal article (peer-reviewed)abstract
- We report a kindred in which two siblings suffered spontaneous venous thromboses in the second decade of life. Further investigation showed reduced coagulation factor V (FV) activity and activated protein C resistance (APCR) ratio but no other thrombophilic abnormalities. The reduction in APCR ratio persisted in a modified APCR assay in which FV activity was normalized between test and control plasmas. Analysis of the FV gene showed that the thrombotic individuals had a complex genotype that included two novel point mutations c.529G>T and c.1250T>C resulting in FV E119X and FV I359T substitutions inherited on different alleles. Individuals in the kindred with FV E119X or FV I359T substitutions alone were asymptomatic. We suggest that the FV I359T substitution confers pro-thrombotic risk and APCR, but that this is only clinically manifest when co-inherited with the FV E119X allele. The FV I359T substitution creates a new consensus sequence for N-linked glycosylation within the FV heavy chain and we speculate that this abnormal glycosylation may disrupt activated protein C-mediated proteolysis of the variant FV and FVa.
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| 17. |
- Nilsson, T., et al.
(author)
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Effects of local alcohol prevention initiatives in Swedish municipalities, 2006–2014
- 2020
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In: Substance Use & Misuse. - : Informa UK Limited. - 1082-6084 .- 1532-2491. ; 55:6, s. 1008-1020
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Journal article (peer-reviewed)abstract
- Background: Several components of the Swedish alcohol policy, e.g., pricing and availability, weakened when Sweden joined the EU in 1995. To counteract the possible negative effects of this, emphasis was placed on the local level as an important arena of alcohol prevention. Thus, considerable efforts were made to strengthen alcohol prevention in Swedish municipalities. Objectives: The aim of this study was to examine whether local alcohol prevention reduced consumption and alcohol-related harm in Swedish municipalities. Methods: Alcohol prevention was monitored using a composite measure called the Alcohol Prevention Magnitude Measure (APMM), with subcategories of staff and budget, inspections and licenses, policy, activities, and cooperation. APMM and its categories were analysed in relation to alcohol consumption and harm over time, 2006–2014. A fixed effects model was used with 63% (N¼182, consumption) and 71% (N¼207, harm) of 290 Swedish municipalities, respectively, included in the analyses. Results: The main results suggest that when APMM increases with 1 percent, the alcohol-related mortality decreases with 0.26 percent, controlled for changes in population size, median income, unemployment, and post-secondary education. In light of this result, the estimated effect of APMM on alcohol consumption (sales) is small (0.02 percent decrease); possible explanations for this are discussed in the article. Conclusion:The overall results indicate that local alcohol prevention initiatives in Sweden have reduced some forms of alcohol-related harm, not least alcohol-related mortality, during the period 2006–2014. Further studies are needed to assess the generalizability of the present study.
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| 18. |
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| 19. |
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| 20. |
- Norström, Sara H, et al.
(author)
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Initial effects of wood ash application to soil and soil solution chemistry in a small, boreal watershed
- 2012
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In: Geoderma. - : Elsevier. - 0016-7061 .- 1872-6259. ; 187, s. 85-93
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Journal article (peer-reviewed)abstract
- With the conception that whole tree harvesting leads to an impoverishment of forest soils wood ash application is recommended, with the foremost benefits being increased pH in soil and subsequent surface waters, and recycling of nutrients from the wood ash.In this investigation a small boreal catchment in central Sweden was studied for two years before and two years after treatment with the maximum recommended dose, 3 tonnes/ha, of crushed, self-hardened wood ash. The sampling area was situated in a slope towards a stream, to include the effect on both recharge- and discharge areas with different soil constitutions. The soil solution chemistry, exchangeable pool of cations and potential heavy metal accumulation in berries were studied. Temporary increases in soil solution concentration were found for K in the recharge area and Ca and SO4 in the discharge area when comparing ashed and control areas. No change in exchangeable cations was observed during the study period, and no increase of heavy metals in bilberries did occur. These small changes in the constitution of the soil solution do not suggest wood ash application as a method to improve soil quality in an initial phase.
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| 21. |
- Norström, Sara, et al.
(author)
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Initial effects of wood ash application on the stream water chemistry in a boreal catchment in central Sweden
- 2011
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In: Water, Air and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 221:1-4, s. 123-136
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Journal article (peer-reviewed)abstract
- Due to increased whole-tree harvesting in Swedish forestry, concern has been raised that a depletion of nutrients in forest soil will arise. The Swedish Forest Agency recommends compensation fertilization with wood ash to ensure that unwanted effects are avoided in the nutrient balance of the forest soil and in the quality of surface water. In this investigation, the chemistry of two first-order streams, of which one was subjected to a catchment scale treatment with 3 tonnes of self-hardened wood ash/ha in the fall of 2004, was monitored during 2003-2006. Large seasonal variations in stream water chemistry made changes due to ash application difficult to detect, but evaluating the ash treatment effects through comparison of the stream water of the treated catchment with the reference was possible via statistical tools such as randomized intervention analysis in combination with cumulative sum charts. The wood ash application did not yield any significant effect on the pH in the stream water and hence did not affect the bicarbonate system. However, dissolved organic carbon increased, a previously unreported effect of WAA, bringing about an increase of organic anions in the stream water. The wood ash application also induced significant increases for Ca, Mg, K, Si, Cl and malonate, of which K was most prominent. Although significant, the changes induced by the wood ash application were all small compared to the seasonal variations. As a tool to counteract acidification of surface waters, WAA seems to have limited initial effects
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Sjöström, Jenny K., 1978-, et al.
(author)
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Complex evolution of Holocene hydroclimate, fire and vegetation revealed by molecular, minerogenic and biogenic proxies, Marais Geluk wetland, eastern Free State, South Africa
- 2023
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In: Quaternary Science Reviews. - 0277-3791 .- 1873-457X. ; 314
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Journal article (peer-reviewed)abstract
- The Holocene climate history of Southern Africa remains inconclusive despite the increasing number of proxy records from the region. This might be related to the diversity of proxy records, how the proxies are interpreted, or that proxies may respond to more than one forcing (e.g. hydroclimate, fire, temperature.). Here, a 175-cm peat sequence from Free State, South Africa (28°17′53″S, 29°25′10.9″E), was analyzed using a comprehensive set of novel and conventional proxies, including isotopic (δ13C), elemental (CS-XRF), mineral (pXRD), molecular (FTIR-ATR and pyrolysis-GC-MS), grain size (Malvern 3000) and GSSC phytolith composition. The chronology was constructed through AMS radiocarbon dating (n = 7). The early Holocene (10,380–7000 cal yr BP) was characterized by an initial wet phase, followed by relative dryness, at least seasonally, evidenced by slow accumulation rates, low organic content and dominance of terrestrial vegetation in the organic matter matrix. From 7000 cal yr BP, decreasing temperatures, as evidenced in regional climate reconstructions, were associated at Marias Geluk with higher biogenic silica and organic matter content and an increase of moisture-adapted grasses, indicating increasingly mesic conditions. This trend was amplified after 6000 cal yr BP, co-occurring with a southward displacement of the ITCZ. Complex proxy dynamics were observed between 4300 and 2180 cal yr BP, with bulk organic proxies indicating a drier environment (lower carbon content, slow accumulation rates, enriched δ13C values) but the phytolith record pointing towards relatively mesic conditions. The period was also associated with increased fire frequency, that also reached the local wetland. We suggest that the period was associated with seasonally mesic conditions together with increased fire incidence, which affected some of the organic proxies. Increased fire activity was also recorded in the region, while the hydroclimatic indications differed. The last 2000 years, during which human activity is known to have increased in the region, was characterized by lower fire incidence and variable, but relatively moist, conditions. The hydroclimatic inferences for the last 2000 years are in line with previous studies from the region, but additional studies are needed to decipher if the decline in fire incidence was associated to climate forcings, human activities, or a combination of both. The multiproxy approach applied here - in particular the inclusion of FTIR-ATR and pyrolysis GC-MS - revealed a complex interplay between vegetation dynamics, hydrology and paleofire variability. This study confirms that relatively small Holocene temperature variations (compared to northern higher latitudes) were associated with major hydrological variability at Marais Geluk, and reinforces concerns from earlier studies that the hydroclimate of the region is vulnerable to climate change. The result s also show that the southward displacement of the ITCZ, and associated tropical air masses, likely had significant effects on regional hydrology and fire incidence.
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| 26. |
- Vestin, Jenny L. K., et al.
(author)
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Soil solution and stream water chemistry in a forested catchment I: Dynamics
- 2008
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In: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 144:1/2, s. 256-270
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Journal article (peer-reviewed)abstract
- Soil solution and stream water chemistry were studied during two years in a catchment in Bispgården in central Sweden (63°07′N, 16°70′E). Soil samples and soil solution were collected in a slope at two distances (10 and 80 m) from a stream. The aims were to examine interactions between recharge (podzol) and discharge (arenosol) areas and to investigate the relations between soil solution and stream water chemistry. The parent material was similar within the catchment, but the content of C and N were higher in the discharge area most likely due to the difference in hydrological conditions compared to the recharge area. Exchangeable cations and base saturation were higher in the discharge area than in the recharge area, which may be due to the higher content of C. The concentrations in soil solution of H, DOC, NO3, SO4, Al, Si, Ca and K charge area compared to the recharge area which was probably caused by transportation of elements in soil and retention due to the increased content of C. During snow melt, the concentrations in soil solution of DOC, SO4, Al, Si, Ca and K were low due to dilution and low biological activity. The concentrations were then increasing during the seasons as an effect of biological activity and mineral weathering. NO3 concentration in soil solution was found in higher concentrations during snow melting and was then diminishing during summer likely as a result of biological uptake. After a dry period followed by an intensive rain in August 2003, the stream water chemistry was markedly altered for a few days. The concentrations of H, DOC SO4, Al and Ca were increased and the concentration of Si was decreased in the stream water. It therefore appeared that the stream water mirrored the upper soil horizons in the discharge area during high flows, while reflecting the lower soil horizons and ground water during low flows.
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| 27. |
- Vestin, Jenny L. K., et al.
(author)
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Soil solution and stream water chemistry in a forested catchment II: Influence of organic matter
- 2008
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In: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 144:2008, s. 271-278
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Journal article (peer-reviewed)abstract
- Differences between recharge and discharge areas in soil forming processes and nutrient conditions were observed in an earlier study of a catchment area in central Sweden (63°07′N, 16°70′E; Vestin, J.L.K., Norström, S.H., Bylund, D., Mellander, P-E., Lundström, U.S., submitted for publication to Geoderma. Soil solution and stream water chemistry in a forested catchment, I Dynamics.). To further examine the factors that determine the soil and stream water properties in the catchment area, the present study focused on the organic dynamics and the association of cations to different size fractions of organic matter. Six sampling plots were established in each of the recharge and discharge areas, respectively, with samples taken in June 2004. Dissolved organic carbon (DOC) and cation concentrations in the soil solution and stream water were determined. In the recharge area, low molecular mass (LMM) organics played an important role in transportation of several cations through the soil profile, inducing the podzolisation process by associating with Al and Fe. In the discharge area close to the stream, high molecular mass (HMM) organics appeared to play a crucial role in transportation of cations. Here the majority of recovered cations were associated with HMM organic matter, inhibiting the podzolisation process. The total concentration of C and DOC was higher than in the recharge area, and the concentration of cations increased with depth in the mineral soil. In the stream water, as in the discharge area soil solution, all carboxylic groups were associated to cations. Both Al and Fe were completely associated with the HMM DOC fraction, which indicated a rapid turnover of LMM DOC in stream water. Thus we conclude that DOC plays an important role in soil forming processes, and that its different size fractions have large effects on the transportation of elements in different soils and in stream water.
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| 28. |
- Wedding, Lisa M., et al.
(author)
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Advancing the integration of spatial data to map human and natural drivers on coral reefs
- 2018
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 13:3
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Journal article (peer-reviewed)abstract
- A major challenge for coral reef conservation and management is understanding how a wide range of interacting human and natural drivers cumulatively impact and shape these ecosystems. Despite the importance of understanding these interactions, a methodological framework to synthesize spatially explicit data of such drivers is lacking. To fill this gap, we established a transferable data synthesis methodology to integrate spatial data on environmental and anthropogenic drivers of coral reefs, and applied this methodology to a case study location-the Main Hawaiian Islands (MHI). Environmental drivers were derived from time series (2002-2013) of climatological ranges and anomalies of remotely sensed sea surface temperature, chlorophyll-a, irradiance, and wave power. Anthropogenic drivers were characterized using empirically derived and modeled datasets of spatial fisheries catch, sedimentation, nutrient input, new development, habitat modification, and invasive species. Within our case study system, resulting driver maps showed high spatial heterogeneity across the MHI, with anthropogenic drivers generally greatest and most widespread on O'ahu, where 70% of the state's population resides, while sedimentation and nutrients were dominant in less populated islands. Together, the spatial integration of environmental and anthropogenic driver data described here provides a first-ever synthetic approach to visualize how the drivers of coral reef state vary in space and demonstrates a methodological framework for implementation of this approach in other regions of the world. By quantifying and synthesizing spatial drivers of change on coral reefs, we provide an avenue for further research to understand how drivers determine reef diversity and resilience, which can ultimately inform policies to protect coral reefs.
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