Two soils from the Fernow Experimental Forest near Parsons, West Virginia were characterized and evaluated in terms of their susceptibility to enhanced soil acidification via acidic atmospheric inputs. After initial physical, chemical, and mineralogical characterization, the soils were analyzed for their ability to adsorb and retain sulfate (SO₄²⁻) through a series of batch adsorption and desorption experiments. Reconstructed soil profiles were then subjected to water leaching as the preliminary step to a base release study in which each soil will be placed under simulated acid rain and evaluated for base cation release and subsequent changes in soil chemistry. Experiments with SO₄²⁻ adsorption and desorption divide the soils into two categories: (i) shallow surface horizons with high organic matter and little Fe oxide content which had little ability to adsorb additional SO₄²⁻ and low capacity to retain SO₄²⁻; and (ii) deeper subsurface soils with low organic matter and high Fe oxide content which could adsorb SO₄²⁻ at solution concentrations above 0.5 mmol/L. All soil horizons desorbed SO₄²⁻ and had no ability for additional adsorption at solution concentrations below 0.5 mmol/L, which implies that the site may be saturated with respect to natural conditions. Initial mass (IM) and Langmiur modeling were used to illustrate SO₄²⁻ dynamics and make correlations with soil physical, chemical, and mineralogical properties. Fe oxides and Al-saturated organic matter were shown to be the preferential sites for SO₄²⁻ adsorption but may be already saturated or very near saturation. Preliminary results from the base release study indicate that the two soils are dominated by different chemical processes and hence release ions into soil solution at different rates. Ion release is shown to be a function of both reactions on the exchange complex and the dissolution of mineral components. / Master of Science

In Arctic tundra soils pH serves as an important parameter related to several biotic parameters such as, plant and microbial community composition, biodiversity, nutrient dynamics and productivity. Both abiotic and biotic factors, for instance, base saturation (BS) and plant nutrient uptake may exert a control on soil pH, while it is still unclear to what extent different factors can explain soil pH across different tundra vegetation types. The aim of this study was to investigate to what extent different abiotic and biotic factors influence soil pH in the humus layer across different tundra vegetation types. To do so, eight different tundra vegetation types of which four were underlaid by permafrost (Arctic Alaska) and four with no permafrost (Arctic Sweden) were studied in detail with regard to different properties affecting soil pH. I found that BS was the main factor controlling soil pH across the different vegetation types regardless if the soil was underlain by permafrost or not. Factors, such as, ionic strength or soil water content could not explain any overall pH variation and did only significantly affect the heath soils. Further, the uptake of the most abundant base cations (Ca2+, Mg2+ and K+) from meadow and heath vegetation revealed a high difference between plant functional groups within the same vegetation types. The higher dominance of slow growing woody species in heath vegetation which had a lower uptake corresponded with a lower BC content (especially (Ca2+), pH and BS in the humus soil relative the meadow meanwhile the content of K+ was more than three times higher in heath. Overall, this study suggests that the degree of neutralization (base saturation) regulates pH either via the influence of bedrock and hydrogeochemistry and/or via plant traits that affects the uptake and turnover of base cations.

Svensk Kärnbränslehantering AB beslutade 2009 att bygga ett slutförvar av använt kärnbränsle i anslutning till kärnkraftverket i Forsmark. Tekniken för slutförvaret går ut på att omge kapslarna med bentonitlera som skydd mot vatten och bergsrörelser. Studier har dock påpekat att bentonitleran riskerar att kemiskt erodera om jonstyrkan (baskatjonerna) i grundvattnet som omsluter förvaringen blir för låg. Baskatjoner består av natrium, kalium, kalcium och magnesium. Dessa joner är viktiga för bland annat att neutralisera syror i mark och vatten. Förekomsten av dessa har sedan 90-talet minskat men kan påverkas av både ökad nederbördsmängd och ökad temperatur i vissa regioner. Baskatjoner kan lakas ur marken när pH minskar eller komma via deposition från nederbörden. Studien syftar till att utreda vilka faktorer som påverkar dels förekomsten av baskatjoner, dels dess trender i tre olika vattentyper i Forsmark: grunt grundvatten, sjövatten och vattendrag. Dataunderlaget för baskatjonerna kom från Svensk Kärnbränslehantering AB och nederbördsmängd och temperatur från Sveriges Meteorologiska och Hydrologiska Institut. De statistiska testerna som utfördes var främst Wilcoxon rank-sum test, Spearmans rangkorrelation, Mann-Kendalls trend- test och Sen’s slope-metoden. Analyserna har utförts med statistikprogramvaran R och de geografiska med QGIS. Resultatet visade att flera provtagningspunkter låg på en låg altitud och inom samma delavrinningsområde. Det fanns små skillnader i baskatjonskoncentrationen i de tre vattentyperna oberoende av berggrund, jordart eller terräng. Dock återfanns högst koncentration i de flesta fall i grunt grundvatten vilket kunde bero på höga halter natrium från havsvattnet samt kalksten i jordlagren. Korrelationerna var få varav sulfat var den som tydligast visade på ett förhållande med baskatjonerna i alla tre vattentyperna. Inte heller kunde en samvariation med temperatur och nederbörd statistiskt säkerställas. Trenderna visade på minskande koncentration av baskatjoner i grunt grundvatten och i sjövatten. Om dessa trender fortsätter utifrån studiens resultat kan det på sikt finnas en risk för erodering av bentonitleran runt kapslarna till följd av landhöjning och utbyte av det nuvarande bräckta grundvattnet. / The Swedish Nuclear Fuel and Waste Management Company decided in 2009 to build a final repository for spent nuclear fuel in connection with the nuclear power plant in Forsmark. The technology for the final repository involves surrounding the capsules with bentonite clay as protection against water and rock movements. However, studies have pointed out that the bentonite clay is at risk of chemically eroding if the ionic strength of the groundwater surrounding the repository becomes too low. Base cations consist of sodium, potassium, calcium, and magnesium. These ions are important for neutralizing acids in soil and water. The occurrence of these has decreased since the 90s but can be affected by both increased rainfall and increased temperature in certain regions. Base cations can further be leached from the soil when the pH decreases or come via deposition from precipitation. This study aims to investigate which factors affect the presence of base cations and their trends in three different types of water in Forsmark: shallow groundwater, lake water and stream water. The data set for the base cations came from the Swedish Nuclear Fuel and Waste Management Company and rainfall and temperature from the Swedish Meteorological and Hydrological Institute. The statistical tests performed were mainly the Wilcoxon rank-sum test, Spearman's rank correlation, Mann-Kendall's trend test and Sen's slope method. The analyzes have been performed with the statistical software R and the geographic ones with QGIS. The result showed that several sampling points were at a low altitude and within the same sub-catchment. There were small differences in base cation concentration in the three water types regardless of bedrock, soil type or terrain. However, the highest concentration was found in most cases in shallow groundwater, which could be due to high levels of sodium from seawater and limestone in the soil layers. The correlations were few, of which sulfate was the one that most clearly showed a relationship with the base cations in all three water types. Nor could a co-variation with temperature and precipitation be statistically ensured. The trends showed a decreasing concentration of base cations in shallow groundwater and in lake water. If the trends continue based on the results, in the long term there may be a risk of erosion of the bentonite clay that surrounds the capsules because of land uplift and replacement of the current brackish ground water.

The acidification has been a known problem in Sweden for several decades. Sulphurous compounds, spread from the British Isles and the European continent led to a decrease in the pH-value of the rain that fell over Sweden. Since the acidification was discovered in the 1960s, active measures against the sulphurous deposition have been undertaken. The sulphurous deposition has decreased by 90 %, and the problem was for some time considered under control, until recently when a new era of the acidification may have started. Due to the increased demand of renewable energy, and Sweden’s potential to use biomass instead of fossil fuels, whole tree harvesting has been more utilized. Studies indicate that the forest soils are depleted in base cations in a faster rate when whole tree harvesting is performed compared to regular stem harvesting. Mass balance calculations and simulations indicate that an increased bio uptake of base cations due to whole tree harvesting leads to an increased biological acidification. However, although many studies agree that the impact of the whole tree harvest on the base cation supply of the soils is significant, long running Swedish experiments indicate that the difference between whole tree harvesting and regular stem harvesting diminishes over time. After a 40 year period, the difference in base cation supply between whole tree harvested soils and stem harvested soils are small. The reason for this could be different processes that reallocate base cations from different pools, which are not usually studied. The aim has been to investigate and evaluate different chemical extraction methods (Aqua Regia, HCl, EDTA, BaCl2, NH4OAc and water) capability to extract the base cations calcium, potassium, magnesium and sodium from four different Swedish forest soils and what this means for our understanding of how much base cations a soil contains. The extractions indicated that there is a statistical significant difference between the methods ability to extract base cations. Generally Aqua Regia was the most potent method, followed by HCl, EDTA, BaCl2, NH4OAc and water in decreasing order of effectiveness to extract the base cations. Linear correlations were found between EDTA, BaCl2 and NH4OAc. The internationally widely used method NH4OAc was considered to be at risk of underestimating the amount of base cations in the soil. / Försurningsproblematiken har länge varit ett känt problem i Sverige. Svavelhaltiga föroreningar som spreds från de brittiska öarna och den europeiska kontinenten ledde till att pH-värdet i regnet som föll över Sverige sjönk. Sedan upptäckten på 60-talet har aktiva åtgärder vidtagits mot utsläppen vilket har lett till en minskning av de försurande föroreningarna med 90 %. På grund av den stora utsläppsreduktionen som skett ansågs försurningsproblematiken vara under kontroll, tills nyligen då en ny etapp av för- surningen kan ha påbörjats. På grund av den ökande efterfrågan av förnyelsebar energi, i kombination med Sveriges stora skogstillgångar, har helträdsskörd av träd blivit alltmer nyttjad. Studier visar att markens baskatjonförråd utarmas i större utsträckning av helträdsskörd, då även grenar, rötter och toppar tas om hand jämfört med vanlig stamskörd då endast stammen tas med från skogen. Massbalanssimuleringar antyder att ett ökat bioupptag av baskatjoner på grund av helträdsskörd leder till en ökad biologisk försurning. Trots att många studier är överens om helträdsskördens inverkan på markens innehåll av baskatjoner visar lång- liggande försök i Sverige att skillnaderna mellan uttag av hela träd och stamved minskar med tiden. Efter en period på 40 år återstår endast små skillnader mellan avverknings- metoderna. Orsakerna till varför mätningarna och massbalansberäkningarna och simuleringarna inte stämmer överens kan vara många, t.ex. att det finns processer som kan omfördela baskatjoner från de som vanligtvis studeras. Syftet har varit att undersöka och utvärdera olika kemiska extraktionsmetoders (Aqua Regia, HCl, EDTA, BaCl2, NH4OAc och vatten) förmåga att extrahera baskatjonerna kalcium, kalium, magnesium och natrium från fyra olika skogsjordar i Sverige och vad resultaten betyder för vår uppfattning av mängden baskatjoner i marken. Extraktionerna visade att en statistiskt signifikant skillnad fanns mellan metodernas förmåga att extrahera de olika baskatjonerna. Generellt var Aqua Regia den metod som extraherade den största mängden baskatjoner, HCl, EDTA, BaCl2, NH4OAc och vatten följde i fallande ordning efter förmåga att extrahera baskatjonerna. Linjära korrelationer mellan EDTA, BaCl2 och NH4OAc upptäcktes. Den internationellt ofta använda metodiken för att extrahera baskatjoner, NH4OAc, ansågs riskera att underskatta mängden baskatjoner i marken.

År 2012 publicerades en sammanfattande syntesrapport från Energimyndigheten (2012). Rapporten fann bevis på att grotuttaget låg på ca 14 TWh/år. Rapporten visar också att Sveriges skogar kan hantera upp till 24 TWh/ år utan att orsaka allvarliga konsekvenser på omgivningen eller nästkommande generationer av träd. Studien beräknade grotens potentiella uttag utifrån insamlade analyser av markkemi, tekniska verktyg och uppskattningar. Dagens rapporter angående ämnet estimerar potentialen till ungefär densamma med en liten höjning till ca 27-30 TWh/år. Detta har satts i relation till hur olika hyggeslagrings tekniker påverkar det möjliga uttaget av grot tillsammans med hur kemin i marken påverkar trädens tillväxt och omgivningen. Grotuttaget gick ner till ca 8-9 TWh/år från år 2012 till 2019, från 14 TWh/år. Eftersom skogsägarna i Sydsverige är privatbrukare och behöver gå runt ekonomiskt för att kunna fortsätta sina verksamheter leder detta till att grotuttaget följer kostnadseffektiviteten av grot i sverige. I framtiden uppskattas det att grotuttaget kan öka drastiskt. Beroende på hur utvecklingen sker kan det verkliga uttaget skilja stort med många påverkande faktorer som t.ex. kostnadseffektivitet och utveckling av andra energikällor. / In 2012 a synthesis report was published by ”Energimyndigheten (2012)”. The report states that forest residues used as bioenergy represents around 14 TWh/year. The report also shows that Swedish forests can manage an outtake of up to 24 TWh/year without suffering from serious consequences, -on the plantation grounds or for, the next coming generation of trees. The study calculated the potential residue of forest outtake from collected analysis of soil chemistry, technical tools and estimations. Recent reports on forest residue outlet estimates a potential of about the same as 2012 with a slight rise to approximately 27-30 TWh/year. This has been put into relation of how different logging storage techniques affect the trees growth, the plantation grounds and the surroundings. The forest residue outlet went down to between 8-9 TWh/year from 2012-2019. This is because the main part of the forests in southern Sweden belongs to private owners and who experienced a decreasing economy to sell their residue. That leads to a problem, where the actual forest residue outlet is heavily dependent on the cost efficiency of forest residues. In the future it is estimated that the forest residue outlet can increase drastically. Depending on how the development proceed, the future outlet of forest residues may differ greatly depending on the future cost efficiency and how other energy sources develop and progress.

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