Catchment controls on mire properties in the post-glacial landscape

Mires are key ecosystems in the boreal biome which provide services related to carbon uptake, biodiversity, and regulation of hydrological and biogeochemical cycles. Minerogenic mires are supported by their upslope catchment area and underlying mineral soil, but a more detailed understanding and quantification of landscape drivers behind mire properties is needed. My thesis is focused on catchment controls on mire vegetation, and peat accumulation and expansion rates. The study was conducted in the Sävar Rising Coastline Mire Chronosequence in northern Sweden, where strong isostatic rebound has formed a natural age gradient that can be used for landscape level studies covering the Holocene. Given the similar climate, bedrock, and mineral soil properties across the area, the role of catchment eco-hydrological settings can be distinguished from that of mire ageing. Our results show that mire vegetation and recent nitrogen accumulation rates responded to catchment nutrient support, but older mires with deeper peat were also associated with lower plant productivity. In contrast, recent peat and carbon accumulation rates increased with mire age and a lower catchment supply of nutrients. The increase in peat and carbon accumulation rates with mire age was faster in hummocks than lawns, and after four thousand years hummock accumulation rates exceeded those in lawns. Mires in the area expanded non-linearly across the landscape depending on the availability of suitably wet areas. Mires occupied the wettest locations within one to two thousand years after land exposure and the slightly drier areas within three to four thousand years. Except for mires younger than a thousand years old, mire abundance was controlled by topography, while total mire area increase was a function of time and the formation of larger mire complexes. The results of this thesis contribute to the understanding of mire development at high latitudes and to scaling up our understanding of mire properties to the wider landscape level

Organic matter properties and their relation to phosphorus and nitrogen concentrations in Swedish agricultural streams

Many agricultural streams in Sweden exhibit high concentrations of nitrogen, phosphorus, suspended sediments and dissolved organic matter (DOM). Together these substances cause eutrophication in streams, rivers and eventually the Baltic Sea. The interactions between different fractions of DOM and nutrients are not very well understood. The aims of this study were to investigate spatial and temporal patterns in DOM in Swedish agricultural streams and to understand how DOM and nutrients interact. Ten catchments in south – central Sweden that are dominated by arable land were compared. Most of the catchments have intensive crop production with high nutrient turnover and in some the livestock density is also high. All these factors can affect the qualitative and quantitative properties of DOM. Water samples from the catchments and fields were analyzed for week 2, 4, 6 and 8 2017, covering a time period of one and a half month. DOM was analyzed optically using excitation-emission fluorescence spectroscopy (EEM) and absorbance spectroscopy (UV/Vis). A number of spectroscopic indices were used to describe the DOM properties. Turbidity, total organic carbon, dissolved organic carbon, pH and orthophosphate concentration were also analyzed. In addition, information about nitrogen and phosphorus concentrations was available. Only weak temporal trends could be found in the dataset but clear spatial differences in DOM properties were observed between the catchments. Catchment F26 differed from most other catchments by having heavier, more labile and to a greater extent plant derived DOM. Catchments O18 and E21 had opposite characteristics to F26 in nearly all studied indices. The DOM was fresher and the molecular weight lower. Correlations between phosphorus and several particulate properties could be found, which describe the absorbing nature of dissolved phosphorus. Nitrogen correlated with the molecular weight of DOM and with the ratio of humic-like to fuvic-like fluorophores. Neither nitrogen nor phosphorus correlated with the protein-like fluorophore. The results demonstrate the importance of reducing leaching of particles and large dissolved organic molecules to streams, since these fractions are related to nitrogen and phosphorus concentrations. This can be done by installing ponds and wetlands and by preventing erosion along stream banks. However, catchment specific actions need to be taken, since the study clearly demonstrated differences between catchments when it comes to DOM and nutrient properties.Många svenska vattendrag på jordbruksdominerade avrinningsområden bär höga koncentrationer av kväve, fosfor, suspenderade sediment och löst organiskt material (DOM). Tillsammans bidrar dessa substanser till övergödning av vattendragen. De biogeokemiska mekanismer som ligger bakom substansernas samverkan och sättet på vilket samverkar är inte välkända. Syftet med den här studien var att beskriva temporära och spatiala mönster i DOM egenskaper och koncentrationer, samt att undersöka hur DOM och näringsämnen samverkar. Tio jordbruksdominerade avrinningsområden i södra och centrala Sverige ingick i studien. På de flesta områdena bidrar en intensiv grödproduktion till hög näringsomsättning, vilket kan påverka egenskaperna hos DOM i omkringliggande vattendrag. Flödesproportionella vattenprov togs varannan vecka tillsammans med stickprov. I studien analyserades prover från vecka 2, 4, 6 och 8 år 2017, vilka täcker en tidsperiod av en och en halv månad. DOM analyserades optiskt med excitations-emissions fluorescensspektroskopi (EEM) och absorbansspektroskopi (UV/Vis). Olika spektroskopiska index användes för att beskriva DOM. Turbiditet, totalt organiskt kol, löst organiskt kol, pH och ortofosfat mättes även. Därtill användes tillgänglig information om olika kväve- och fosforkoncentrationer i vattendragen. Statistiska samband mellan de olika indexen och kväve, fosfor och kol analyserades, liksom temporära och spatiala mönster. Enbart svaga temporära trender kunde hittas. Däremot skiljde sig vattendragen tydligt från varandra. I avrinningsområde F26 var DOM av större molekylär storlek, mer labilt och till högre grad av växtursprung jämfört med övriga avrinningsområden. Område O18 och E21 hade motsatta egenskaper till F26 i så gott som alla undersökta index. Det organiska materialet var färskare och molekylerna av mindre storlek än i F26. Samband mellan fosfor och olika partikulära egenskaper kunde hittas, vilket beskriver absorberingen av fosfor till partiklar. Kväve korrelerade med molekylvikten av DOM och även med C:A, vilket beskriver förhållandet mellan humussyror och fulvosyror. Resultaten av studien demonstrerar vikten av att reducera avrinning av suspenderade partiklar och stora lösta organiska molekyler från jordbruksmark. Det kan göras genom att installera sedimentationsdammar eller våtmarker på odlingsområden, samt genom att minimera erosionsrisken längs vattendrag. Platsspecifika åtgärder bör dock planeras eftersom studien tydligt visade att avrinningsområden skiljer sig från varandra då det gäller DOM- och näringsegenskaper

Nitrogen stocks and flows in an acid sulfate soil

Besides causing acidification, acid sulfate (AS) soils contain large nitrogen (N) stocks and are a potential source of N loading to waters and nitrous oxide (N2O) emissions. We quantified the stocks and flows of N, including crop yields, N leaching, and N2O emissions, in a cultivated AS soil in western Finland. We also investigated whether controlled drainage (CD) and sub-irrigation (CDI) to keep the sulfidic horizons inundated can alleviate N losses. Total N stock at 0-100 cm (19.5 Mg ha(-1)) was smaller than at 100-200 cm (26.6 Mg ha(-1)), and the mineral N stock was largest below 170 cm. Annual N leaching (31-91 kg N ha(-1)) plus N in harvested grain (74-122 kg N ha(-1)) was 148% (range 118-189%) of N applied in fertilizers (90-125 kg N ha(-1)) in 2011-2017, suggesting substantial N supply from soil reserves. Annual emissions of N2O measured during 2 years were 8-28 kg N ha(-1). The most probable reasons for high N2O emission rates in AS soils are concomitant large mineral N pools with fluctuating redox conditions and low pH in the oxidized subsoil, all favoring formation of N2O in nitrification and denitrification. Although the groundwater level was higher in CD and CDI than in conventional drainage, N load and crop offtake did not differ between the drainage methods, but there were differences in emissions. Nitrogen flows to the atmosphere and drainage water were clearly larger than those in non-AS mineral soils indicating that AS soils are potential hotspots of environmental impacts.Peer reviewe

Landscape constraints on mire lateral expansion

Little is known about the long-term expansion of mire ecosystems, despite their importance in the globalcarbon and hydrogeochemical cycles. It has been firmly established that mires do not expand linearlyover time. Despite this, mires are often assumed to have expanded at a constant rate after initiationsimply for lack of a better understanding. There has not yet been a serious attempt to determine the rateand drivers of mire expansion at the regional, or larger spatial scales. Here we make use of a naturalchronosequence, spanning the Holocene, which is provided by the retreating coastline of NorthernSweden. By studying an isostatic rebound area we can infer mire expansion dynamics by looking at theportion of the landscape where mires become progressively scarce as the land becomes younger. Ourresults confirms that mires expanded non-linearly across the landscape and that their expansion isrelated to the availability of suitably wet areas, which, in our case, depends primarily on the hydro-edaphic properties of the landscape. Importantly, we found that mires occupied the wettest locationsin the landscape within only one to two thousand years, while it took mires three to four thousand yearsto expand into slightly drier areas. Our results imply that the lateral expansion of mires, and thus peataccumulation is a non-linear process, occurring at different rates depending, above all else, on thewetness of the landscape

Topography and Time Shape Mire Morphometry and Large-Scale Mire Distribution Patterns in the Northern Boreal Landscape

Peatlands are major terrestrial soil carbon stores, and open mires in boreal landscapes hold a considerable fraction of the global peat carbon. Despite decades of study, large-scale spatiotemporal analyses of mire arrangement have been scarce, which has limited our ability to scale-up mire properties, such as carbon accumulation to the landscape level. Here, we use a land-uplift mire chronosequence in northern Sweden spanning 9,000 years to quantify controls on mire distribution patterns. Our objectives include assessing changes in the spatial arrangement of mires with land surface age, and understanding modifications by upland hydrotopography. Characterizing over 3,000 mires along a 30 km transect, we found that the time since land emergence from the sea was the dominant control over mire coverage, especially for the establishment of large mire complexes. Mires at the youngest end of the chronosequence were small with heterogenous morphometry (shape, slope, and catchment-to-mire areal ratios), while mires on the oldest surfaces were variable in size, but included larger mires with more complex shapes and smaller catchment-to-mire ratios. In general, complex topography fragmented mires by constraining the lateral expansion, resulting in a greater number of mires, but reduced total mire area regardless of landscape age. Mires in this study area occurred on slopes up to 4%, indicating a hydrological boundary to peatland expansion under local climatic conditions. The consistency in mire responses to spatiotemporal controls illustrates how temporal limitation in peat initiation and accumulation, and topographic constraints to mire expansion together have shaped present day mire distribution patterns

Malaria with neurological involvement in Ugandan children: effect on cognitive ability, academic achievement and behaviour

<p>Abstract</p> <p>Background</p> <p>Malaria is a leading cause of ill health and neuro-disability in children in sub-Saharan Africa. Impaired cognition is a common outcome of malaria with neurological involvement. There is also a possibility that academic achievement may be affected by malaria with neurological involvement given the association between cognitive ability and academic achievement. This study investigated the effect of malaria with neurological involvement on cognitive ability, behaviour and academic achievement.</p> <p>Methods</p> <p>This prospective case-control study was carried out in Kampala City, Uganda between February 2008 and October 2010. Sixty-two children with a history of malaria with neurological involvement were followed up and given assessments for cognitive ability (working memory, reasoning, learning, visual spatial skills and attention), behaviour (internalizing and externalizing problems) and academic achievement (arithmetic, spelling and reading) three months after the illness. Sixty-one community controls recruited from the homes or neighbouring families of the cases were also given the same assessments. Tests scores of the two groups were compared using analysis of covariance with age, sex, level of education, nutritional status and quality of the home environment as covariates. This study was approved by the relevant ethical bodies and informed consent sought from the caregivers.</p> <p>Results</p> <p>Children in the malaria group had more behavioural problems than the community controls for internalizing problems (estimated mean difference = -3.71, 95% confidence interval (CI), = -6.34 to -1.08, p = 0.007). There was marginal evidence of lower attention scores (0.40, CI = -0.05 to 0.86, p = 0.09). However, excluding one child from the analyses who was unable to perform the tests affected the attention scores to borderline significance (0.32, CI, = 0.01 to 0.62, p = 0.05). No significant differences were observed in other cognitive abilities or in academic achievement scores.</p> <p>Conclusion</p> <p>Malaria with neurological involvement affects behaviour, with a minimal effect on attention but no detectable effect on academic achievement at three months post discharge. This study provides evidence that development of cognitive deficits after malaria with neurological involvement could be gradual with less effect observed in the short term compared to the long term.</p

Catchment characteristics control boreal mire nutrient regime and vegetation patterns over ~5000 years of landscape development

Vegetation holds the key to many properties that make natural mires unique, such as surface microtopography, high biodiversity values, effective carbon sequestration and regulation of water and nutrient fluxes across the landscape. Despite this, landscape controls behind mire vegetation patterns have previously been poorly described at large spatial scales, which limits the understanding of basic drivers underpinning mire ecosystem services. We studied catchment controls on mire nutrient regimes and vegetation patterns using a geographically constrained natural mire chronosequence along the isostatically rising coastline in Northern Sweden. By comparing mires of different ages, we can partition vegetation patterns caused by long-term mire succession

Opposing spatial trends in methylmercury and total mercury along a peatland chronosequence trophic gradient

Peatlands are abundant elements of boreal landscapes where inorganic mercury (IHg) can be transformed into bioaccumulating and highly toxic methylmercury (MeHg). We studied fifteen peatlands divided into three age lasses (young, intermediate and old) along a geographically constrained chronosequence to determine the role of biogeochemical factors and nutrient availability in controlling the formation of MeHg. In the 10 cm soil layer just below the average annual growing season water table, concentrations of MeHg and %MeHg (of total Hg) were higher in younger, more mesotrophic peatlands than in older, more oligotrophic peatlands. In contrast, total mercury (THg) concentrations were higher in the older peatlands. Partial least squares (PLS) analysis indicates that the net MeHg production was positively correlated to trophic demands of vegetation and an increased availability of potential electron acceptors and donors for Hg methylating microorganisms. An important question for further studies will be to elucidate why there is less THg in the younger peatlands compared to the older peatlands, even though the age of the superficial peat itself is similar for all sites. We hypothesize that ecosystem features which enhance microbial processes involved in Hg methylation also promote Hg reduction that makes previously deposited Hg more available for evasion back to the atmosphere. (C) 2020 Elsevier B.V. All rights reserved

The prevalence of pain in bipolar disorder: a systematic review and large-scale meta-analysis

Objective: To conduct a meta-analysis investigating the prevalence of pain in people with bipolar disorder (BD). Method: A systematic review and random effects meta-analysis searching major electronic databases from inception till 01/2014 in accordance with the PRISMA statement. We included articles reporting quantitative data on the prevalence of pain in people with BD with or without a healthy control group. Two independent authors conducted searches, extracted data, and completed methodological quality assessment. Results: Twenty two cross-sectional studies were included, representing 12 375 644 individuals (BD n = 171 352, n controls = 12 204 292). The prevalence of pain in people with BD was 28.9% (95% CI = 16.4–43.4%, BD n = 171 352). The relative risk (RR) of pain in BD compared to controls was 2.14 (95% CI = 1.67–2.75%, n = 12 342 577). The prevalence of migraine was 14.2% (95% CI = 10.6–18.3%, BD n = 127 905), and the RR was 3.30 (95% CI = 2.27–4.80%, n = 6 732 220).About 23.7% (95% CI = 13.1–36.3%, n = 106 214) of people with BD experienced chronic pain. Age, percentage of males, methodological quality, and method of BD classification did not explain the observed heterogeneity. Conclusion: People with BD experience significantly increased levels of pain (particularly chronic pain and migraine). The assessment and treatment of pain should form an integral part of the management of BD

Cortisol levels and suicidal behavior: a meta-analysis

Suicide is a major cause of death worldwide, responsible for 1.5% of all mortality. The causes of suicidal behavior are not fully understood. Dysregulated hypothalamic-pituitary-adrenal (HPA) axis activity, as measured by cortisol levels, is one potential risk factor. This meta-analytic review aimed i) to estimate the strength and variability of the association between naturally fluctuating cortisol levels and suicidal behavior and ii) to identify moderators of this relationship. A systematic literature search identified 27 studies (N = 2226; 779 suicide attempters & 1447 non-attempters) that met the study eligibility criteria from a total of 417 unique records initially examined. Estimates of effect sizes (r) obtained from these studies were analysed using Comprehensive Meta-Analysis. In these analyses, we compared participants identified as having a past history of suicide attempt(s) to those with no such history. Study quality, mean age of sample and percentage of male participants were examined as potential moderators. Overall, there was no significant effect of suicide group on cortisol. However, significant associations between cortisol and suicide attempts were observed as a function of age. In studies where the mean age of the sample was below 40 years the association was positive (i.e., higher cortisol was associated with suicide attempts; r = .234, p < .001), and where the mean age was 40 or above the association was negative (i.e., lower cortisol was associated with suicide attempts; r = - .129, p < .001). These findings confirm that HPA axis activity, as indicated by age-dependent variations in cortisol levels, is associated with suicidal behavior. The challenge for theory and clinical practice is to explain the complete reversal of the association with age and to identify its clinical implications