Increased amounts of available biomass residues from agricultural food production are present widely around the globe. These biomass residues can find essential applications as bioenergy feedstock and precursors to produce value-added materials. This study assessed the production of biogenic silica (SiO2) from different biomass residues in Africa, including cornhusk, corncob, yam peelings, cassava peelings and coconut husks. Two processes were performed to synthesize the biogenic silica. First, the biomass fuels were chemically pre-treated with 1 and 5% w/v citric acid solutions. In the second stage, combustion at 600 °C for 2 h in a muffle oven was applied. The characterization of the untreated biomasses was conducted using Inductively coupled plasma—optical emission spectrometry (ICP-OES), thermal analysis (TG-DTA) and Fourier-transform infrared spectroscopy (FTIR). The resulting ashes from the combustion step were subjected to ICP, nitrogen physisorption, Energy dispersive X-ray spectroscopy (EDX) as well as X-ray diffraction (XRD). ICP results revealed that the SiO2 content in the ashes varies between 42.2 to 81.5 wt.% db and 53.4 to 90.8 wt.% db after acidic pre-treatment with 1 and 5 w/v% acid, respectively. The relative reductions of K2O by the citric acid in yam peel was the lowest (79 wt.% db) in comparison to 92, 97, 98 and 97 wt.% db calculated for corncob, cassava peel, coconut husk and cornhusk, respectively. XRD analysis revealed dominant crystalline phases of arcanite (K2SO4), sylvite (KCl) and calcite (CaCO3) in ashes of the biomass fuels pre-treated with 1 w/v% citric acid due to potassium and calcium ions present. In comparison, the 5 w/v% citric acid pre-treatment produced amorphous, biogenic silica with specific surface areas of up to 91 m2/g and pore volumes up to 0.21 cm3/g. The examined biomass residues are common wastes from food production in Africa without competition in usage with focus application. Our studies have highlighted a significant end-value to these wastes by the extraction of high quality, amorphous silica, which can be considered in applications such as catalyst support, construction material, concrete and backing material.

This work introduces a cost and time efficient procedure to specifically increase mesopore volume and specific surface area of biogenic silica (specific surface area: 147 m2 g−1 and mesopore volume: 0.23 cm3 g−1) to make it suitable for applications in adsorption or as catalyst support. The target values were a specific surface area of ∼500 m2 g−1 and a mesopore volume of ∼0.40–0.50 cm3 g−1 as these values are industrially relevant and are reached by potential concurring products such as precipitated silica, silica gel, and fumed silica. The applied process of partial pseudomorphic transformation was carried out as a single reaction step in a microwave reactor instead of commonly used convective heating. In addition, the conventionally used surfactant cetyltrimethylammonium bromide (CTABr) was substituted by the low-cost surfactant (Arquad® 16-29, cetyltrimethylammonium chloride (CTACl) aqueous solution). The influence of microwave heating, type of surfactant as well as the concentration of NaOH and CTACl on the textural and structural properties of the modified biogenic silica was investigated using nitrogen adsorption as well as scanning and transmission electron microscopy. The results show that the textural parameters of the modified biogenic silica can be exactly controlled by the amount of NaOH in the reaction solution. By variation of the NaOH concentration, specific surface areas in the range of 215–1,001m2 g−1 andmesopore volumes of 0.25–0.56 cm3 g−1 were achieved after reaction at 393 K for 10min. The presented microwave route using the low-cost surfactant solution decreases the reaction time by 99% and as shown in an example for German prices, lowers the costs for the surfactant by 76–99%.

Coastal areas currently face a lot of anthropogenic pressures (Erlandsson et al, 2011; Wilcox et al, 2020) which might further increase through climate change (Maltby et al, 2022). This can lead to the disappearance of crucial, habitat engineering species like blue mussels (Tummon Flynn et al, 2020). The lack of those increases the risk of eutrophication and pollution, on the long run having negative consequences not only for biodiversity and ecological factors but also social and economic factors like income through fishing and risking coastal flood protection (Tummon Flynn et al, 2020; Schotanus et al, 2020; Cooley & Doney, 2009). Blue mussels can form biogenic reefs, which are protected as important habitats under the EU Habitats Directive (Council of the European Communities, 1992) as well as the EU Water Framework Directive (European Parliament & council, 2000). Nevertheless, actual implementation of protection and conservation of those reefs is lacking (Rees et al, 2018), which is why many of them are declining drastically (EEA, 2013). One reason for that lack of protection might be the diverse definitions applied to mussel reefs all over Europe (Stounberg, 2021), while another one could be that many of them are not mapped. In the present study, an attempt was made to map a potential blue mussel reef in the Roskilde Fjord in Denmark, which was first discovered by a previous study (Dahl et al, 2019:39) but not investigated to its extend as that study focused on other goals. A ROV was employed to collect video data of the seafloor of the respective fjord area over a period of three months. The recorded video and GPS data was then processed and analysed to produce a map in QGIS, showing if and where an area of, according to the Danish definition for blue mussel reefs, more than 2500m2 with more than 30% mussel cover and 3 year classes of mussels (Miljøstyrelsen, 2018), is present. Three areas in the chosen search area of this study were confirmed to fulfil those requirements, consistent with the previous findings of Dahl et al (2019). The actual blue mussel reef might be even bigger as other areas which have not been analysed in detail contain blue mussels as well. Therefore, protection measures based on best available scientific knowledge, interdisciplinary work and the knowledge of as many stakeholders possible, including social, economic and ecological aspects, should be developed for the blue mussel reef in Roskilde Fjord. One of them could be to make the reef part of the Natura 2000 protection area already existing in the same area.

Yes / The Mg/Ca ratios of biogenic calcite is commonly seen as a valuable palaeo-proxy for reconstructing past ocean temperatures. The temperature dependence of Mg/Ca ratios in bivalve calcite has been the subject of contradictory observations. The palaeoceanographic use of a geochemical proxy is dependent on initial, rigorous calibration and validation of relationships between the proxy and the ambient environmental variable to be reconstructed. Shell Mg/Ca ratio data are reported for the calcite of two bivalve species, Mytilus edulis (common mussel) and Pecten maximus (king scallop), which were grown in laboratory culturing experiments at controlled and constant aquarium seawater temperatures over a range from 10 to 20 C. Furthermore, Mg/Ca ratio data of laboratory- and fieldgrown M. edulis specimens were compared. Only a weak, albeit significant, shell Mg/Ca ratio¿temperature relationship was observed in the two bivalve species: M. edulis (r2=0.37, p<0.001 for laboratory-cultured specimens and r2=0.50, p<0.001 for field-cultured specimens) and P. maximus (r2=0.21, p<0.001 for laboratory-cultured specimens only). In the two species, shell Mg/Ca ratios were not found to be controlled by shell growth rate or salinity. The Mg/Ca ratios in the shells exhibited a large degree of variability among and within species and individuals. The results suggest that the use of bivalve calcite Mg/Ca ratios as a temperature proxy is limited, at least in the species studied to date. Such limitations are most likely due to the presence of physiological effects on Mg incorporation in bivalve calcite. The utilization is further limited by the great variability both within and among shells of the same species that were precipitated under the same ambient conditions

Recent research using stable isotope analysis has shown a dependence on migrating or breeding populations of vertebrates as vectors for the transfer of marine-derived nutrients within coastal ecosystems. Sable Island, Nova Scotia, Canada supports numerous species of plants, a variety of seabird colonies (including common [Sterna hirundo] and Arctic [Sterna paradisaea] terns), the world’s largest grey seal (Halichoerus grypus) breeding colony, and a self-sustaining population of wild (feral) horses (Equus ferus caballus). I hypothesize that nitrogen cycling within this island ecosystem is highly influenced by the input of nutrients from seals and seabirds (‘biogenic vectors’), affecting primary production and potentially stabilizing higher trophic levels (i.e., horses). To examine this relation I developed a spatially-explicit isoscape for Sable Island through stable isotope analysis of nitrogen (δ15N) in samples (n = 282) of marram grass (Ammophila breviligulata). I incorporated significant variables (i.e., distance to vector colony and distance to shoreline, r2 = 0.41) into the final parsimonious interpolation model using universal co-kriging techniques. The greatest 15N enrichment occurred within the tips and along the perimeter of the island, coinciding with greater densities of grey seals, while the lowest values occurred within the centre of the island. I then identified individual contributions of seal-, tern- and horse-mediated transfer of marine-derived nutrients inland. Marram grass exhibited higher δ15N within seal (μ = 7.5‰) and tern (μ = 5‰) colonies, while horses and biogeochemical processes (i.e., volatilization, ammonification, etc.) most likely contributed to the homogeneity within the centre of the island (μ = 3.6‰). Due to the higher densities, wider distribution, and greater 15N enrichment of marram tissues, grey seals appear to be the most important vector species while seabirds have a more localized effect. The greater availability of N within vector colonies supplemented the local vegetation community, contributing to greater vegetation cover within colony boundaries. This relation had secondary effects on the horse population, which showed correspondingly higher horse δ15N values within the tips of the island (δ15N + 1.6‰) due to consumption of 15N enriched forage. I conclude that biogenic vector species promote nutrient transfer by establishing nutrient gateways which indirectly cause cascading effects throughout the food web.

Natural archives such as lake sediments allow us to assess contemporary ecosystem responses to climate and environmental changes in a long-term context beyond the few decades to at most few centuries covered by monitoring or historical data. To achieve a comprehensive view of the changes preserved in sediment records, multi-proxy studies – ideally in high resolution – are necessary. However, this combination of including a range of analyses and high resolution constrains the amount of material available for analyses and increases the analytical costs. Infrared spectroscopic methods are a cost-efficient alternative to conventional methods because they offer a) a simple sample pre-treatment, b) a rapid measurement time, c) the non- or minimal consumption of sample material, and d) the potential to extract quantitative and qualitative information about organic and inorganic sediment components from a single measurement. The main objective of this doctoral thesis was twofold. The first part was to further explore the potential of Fourier transform infrared (FTIR) and visible-near infrared (VNIR) spectroscopy in paleolimnological studies as a) an alternative tool to conventional methods for quantifying biogenic silica (bSi) – a common proxy of paleoproductivity in lakes – in sediments and b) as a tool to infer past lake-water total organic carbon (TOC) levels from sediments. In a methodological study, I developed an independent application of FTIR spectroscopy and PLS modeling for determining bSi in sediments by using synthetic sediment mixtures with known bSi content. In contrast to previous models, this model is independent from conventional wet-chemical techniques, which had thus far been used as the calibration reference, and their inherent measurement uncertainties. The second part of the research was to apply these techniques as part of three multi-proxy studies aiming to a) improve our understanding of long-term element cycling in boreal and arctic landscapes in response to climatic and environmental changes, and b) to assess ongoing changes, particularly in lake-water TOC, on a centennial to millennial time scale. In the first applied study, high-resolution FTIR measurements of the 318-m long sediment record of Lake El’gygytgyn provided a detailed insight into long-term climate variability in the Siberian Arctic over the past 3.6 million years. Highest bSi accumulation occurred during the warm middle Pliocene (3.6-3.3 Ma), followed by a gradual but variable decline, which reflects the first onset of glacial periods and then the finally full establishment of glacial–interglacial cycles during the Quaternary. The second applied study investigated the sediment record of Torneträsk in subarctic northern Sweden also in relation to climate change, but only over the recent post-glacial period (~10 ka). By comparing responses to past climatic and environmental forcings that were recorded in this large-lake system with those recorded in small lakes from its catchment, I determined the significance and magnitude of larger-scale changes across the study region. Three different types of response were identified over the Holocene: i) a gradual response to the early landscape development following deglaciation (~10000-5300 cal yr BP); ii) an abrupt but delayed response following climate cooling during the late Holocene, which occurred c. 1300 cal yr BP – about 1000-2000 years later than in smaller lakes from the area; and iii) an immediate response to the ongoing climate change during the past century. The rapid, recent response in a previously rather insensitive lake-ecosystem emphasizes the unprecedented scale of ongoing climate change in northern Fennoscandia. In the third applied study, VNIR-inferred lake-water TOC concentrations from lakes across central Sweden showed that the ongoing, observed increase in surface water TOC in this region was in fact preceded by a long-term decline beginning already AD 1450-1600. These dynamics coincided with early human land use activities in the form of widespread summer forest grazing and farming that ceased over the past century. The results of this study show the strong impact of past human activities on past as well as ongoing TOC levels in surface waters, which has thus far been underestimated. The research in this thesis demonstrates that infrared spectroscopic methods can be an essential component in high-resolution, multi-proxy studies of past environmental and climate changes.

<p>Proizvodnja fermentisanih mliječnih napitaka unapreijeđenih funkcionalnih karakteristika postala je jedan od glavnih fokusa u industriji prerade mlijeka. Cilj doktorske disertacije je ispitivanje biolo&scaron;ke aktivnosti fermentisanih mliječnih napitaka dobijenih primjenom nekonvencionalne starter kulture, kombuhe (kultivisane na crnom čaju zaslađenim saharozom u koncentraciji od 10%) i poređenje sa karakteristikma proizvoda dobijenih primenom konvencionalnih starter kultura, jogurtne odnosno probiotske, tokom skladi&scaron;tenja. Za fermentaciju je kori&scaron;ćeno mlijeko sa 2,8% mliječne masti na temperatura 42&deg;C.<br />Promjene tokom fermentacije mlijeka primjenom kombuhe i konvencionalnih starter kultura praćene su određivanjem stepena proteolize, sadržaja laktoze, D&ndash; galaktoze, D&ndash;glukoze i D&ndash;fruktoze i masnih kiselina pri sledećim pH vrijednostima: 6,4; 6,0; 5,5; 5,0 i 4,6. Promjene antihipertenzivne aktivnosti (AKE inhibitorna aktivnost), antioksidativne aktivnosti (ABTS i DPPH metod) kao i promjene stepena proteolize, reolo&scaron;kih i senzornih karakteristika sve tri vrste fermentisanih mliječnih napitaka praćene su tokom 21-og dana skladi&scaron;tenja. Osim toga praćene su i promjene sadržaja &scaron;ećera, masnih kiselina, minerala (kalcijuma, natrijuma i kalijuma), vitamina C i biogenih amina.<br />Tokom procesa fermentacije mlijeka primjenom različitih starter kultura može se zaključiti da postoji razlika u promjenama udijela pojedinačnih proteinskih frakcija analiziranih metodom kapilarne elektroforeze.<br />Različite starter kulture utiču na različitu AKE inhibitornu aktivnost tokom skladi&scaron;tenja, &scaron;to ukazuje na različitu proteolitičku aktivnost kori&scaron;ćenih starter kultura. Utvrđeno je da AKE inhibitorna aktivnost raste tokom skladi&scaron;tenja, pri čemu uzorci proizvedeni primjenom kombuhe imaju najveću AKE inhibitornu aktivnost na kraju 14 dana skladi&scaron;tenja i ona iznosi 79,4%, dok su u jogurtu i probiotskom jogurtu te vrijednsoti 63,4 i 64,6% redom. Takođe, tokom skladi&scaron;tenja stepen proteolize raste u svim uzorcima sa značajnim međusobnim varijacijama. Antiksidativna aktivnost svih uzoraka opada tokom skladi&scaron;tenja ali je u svim uzorcima zabilježena veća aktivnost na ABTS nego na DPPH slobodne radikale. Nakon 21-og dana skladi&scaron;tenja najveći antioksidativni potencijal određen metodom stabilizacije ABTS.+ katjona imali su uzorci sa jogurtnom starter kulturom (TEAC vrijednost 8,922 mmolmg-1). U pogledu sastava masnih kiselina, tokom 14 dana skladi&scaron;tenja u kombuha fermentisanim mliječnim napicima<br />kao i napicima dobijenim sa jogurtnom i probiotskom starter kulturom dolazi do porasta udjela zasićenih (SFA) i opadanje mononezasićenih (MUFA) i polinezasićenih masnih kiselina (PUFA). Nakon 21-og dana skladi&scaron;tenja sadržaj SFA; MUFA i PUFA u kombuha fermentisanom mliječnom napitku iznosio je 65,94; 30,73 i 3,33% redom, dok su te vrijednosti kod jogurta iznosile 66,02; 30,77 i 3,21% i probiotskog jogurta 66,04; 30,66 i 3,30 % redom. Najveći sadržaj vitamina C nakon proizvodnje i 14 dana skladi&scaron;tenja imali su uzorci sa kombuha starter kulturom (0,5457 &plusmn; 0,017 mg100g-1). Uzorci dobijeni upotrebom konvencionalnih startera pokazali su bolje reolo&scaron;ke osobine pri ispitivanim uslovima tokom 21 dana skladi&scaron;tenja. Kombuha fermentisani mlečni proizvod imao je karakterističan, blago kiseli, osvežavajući ukus i nagla&scaron;enu aromu.<br />Na osnovu dobijenih rezultata biolo&scaron;ke aktivnosti i promjena kvaliteta kombuha fermentisanog mliječnog napitka tokom skladi&scaron;tenja, u odnosu na karakteristike proizvoda dobijenih upotrebom konvencionalnih starter kultura može se objasniti opravdanost upotrebe kombuha starter kulture u fermentaciji mlijeka sa ciljem dobijanja novog funkcionalnog fermentisanog mliječnog proizvoda.</p> / <p><span style="font-size:11px;">Nowadays, production of fermented dairy products with elevated benefits on human health has become one of the major focuse in dairy industry. The aim of the PhD thesis is to examine the biological activity of fermented milk products obtained using non-conventional starter culture kombucha (cultivated on black tea with 10% of sucrose) and comparision with products obtained by conventional starter cultures, probiotic/yoghurt during storage. Milk with 2.8% of milk fat was used for the samples production at temperature of 42 &deg;C.<br />The changes of components content during the milk fermentation by kombucha and conventional starter cultures were monitored at the following pH values: 6.4; 6.0; 5.5; 5.0 and 4.6., by determining the degree of proteolysis, lactose, D-galactose, D-glucose and D-fructose, fatty acids. The antihypertensive activity (ACE inhibitory activity), antioxidant activity (ABTS and DPPH tests) and the degree of proteolysis, sensory and rheological characteristics of all three types of fermented milk products were observed during 21 days of storage. Moreover, the chemical qualities of samples were monitored analyzing the contents of sugars, fatty acids, minerals (calcium, sodium and potassium), vitamin C and biogenic amines.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; There were differences in protein fractions (analyzed by capillary electrophoresis) of products obtained by using different starter cultures during the milk fermentation. Different starter cultures affect different ACE inhibitory activity during the storage, which implies different proteolytic activity of used starter cultures. It has been found that the ACE inhibitory activity was increased during the storage; wherein the samples obtained using kombucha starter culture have the highest ACE inhibitory activity at the 14th day of storage, 79,4%, while in yogurt and probiotic yoghurt it was 63.4 and 64.6% respectively. Also, the degree of proteolysis during the storage was increased in all samples with significant mutual variations. In all products, higher ABTS than 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was determined, while both activities slightly decreased during the storage. The antioxidant activity of all samples decreases during storage. After 21 days of storage, the highest antioxidant potential, determined by the ABTS. + method had a yoghurt samples (TEAC value of 8.922 mmolmg-1). In terms of the fatty acids composition during 14 days of storage in all type of fermented dairy products relative content of SFA (saturated fatty acids - SFA) increased, while relative contents of MUFA (monounsaturated fatty acids) and PUFA (polyunsaturated fatty acids) decreased during that period of storage. After 21 days of storage the content of SFA; MUFA and PUFA in kombucha fermented milk product was 65.94; 30.73 and 3.33% respectively. In yogurt sample their content was 66.02, 30.77 and 3.21%, while in probiotic 66.04; 30.66 and 3.30% respectively. In all fermented milk products, long chain fatty acids were dominant with a total share of about 45% in all varieties of fermented dairy products. The highest content of vitamin C after production and 14 days of storage was in samples obtained by kombucha starter culture (0.5457 &plusmn; 0.017 mg100g-1). Samples obtained by conventional starter showed better overall rheological properties at the tested conditions for 21 days of storage. Kombucha fermented milk product had a characteristic, distinctive mild sour, refreshing taste and conspicuous aroma.<br />The obtained results of biological activity and the quality of kombucha fermented milk products during storage in comparison to the same characteristics of the products obtained using conventional starter culture, could explain that kombucha is convenient starter for milk fermentation with the aim of obtaining new functional fermented milk products with pronounced bioactive characteristics and distinctive sensory and rheology properties.</span></p>

A significant share of the global climate change impacts can be attributed to the construction sector. One mitigation strategy is increasing the use of biobased materials. Life cycle assessment (LCA) has been used to demonstrate the benefits of this, but forest complexities create uncertainty due to omission of key aspects. The aim of this thesis is to enhance understanding of the effects of increasing use of biobased materials in climate change mitigation of construction works with a life cycle perspective. Non-traditional LCA methodology aspects were identified and the climate impact effects of increasing the use of biobased materials while accounting for these was studied. The method applied was dynamic LCA combined with forest carbon data under multi-approach scenarios. Diverse case studies (a building, a small road bridge and the Swedish building stock) were used. Most scenarios result in impact reductions from increasing the use of biobased materials in construction. The inclusion of non-traditional aspects affected the results, but not this outcome. Results show that the climate mitigation potential is maximized by simultaneously implementing other strategies (such as increased use of low-impact concrete). Biobased building materials should not be generalised as climate neutral because it depends on case-sensitive factors. Some of these factors depend on the modelling of the forest system (timing of tree growth, spatial level approach, forest land use baseline) or LCA modelling parameters (choice of the time horizon, end-of-life assumptions, service life). To decrease uncertainty, it is recommended to use at least one metric that allows assessment of emissions based on their timing and to use long-term time horizons. Practitioners should clearly state if and how non-traditional aspects are handled, and study several methodological settings. Technological changes should be accounted for when studying long-term climate impacts of building stocks. / Irreversibel global påverkan på klimat och miljö måste undvikas och olika strategier som begränsar klimatförändringarna kan utnyttjas för att hantera denna utmaning. En betydande andel av de globala utsläppen av växthusgaser kan hänföras till byggsektorn i allmänhet och cementproduktion i synnerhet, och begränsningsstrategier söker alternativ till fossil- och mineralbaserade resurser, med mindre påverkan, som exempelvis en ökad användning av biobaserade material i byggandet. Livscykelanalys (LCA) har använts för att demonstrera klimatnyttan av denna ökning, men skogens komplexiteter i samband med biogent koldioxid skapar osäkerhet i resultaten då de som genomför LCA-studier traditionellt utelämnar viktiga nyckelaspekter. Denna avhandling syftar till att öka förståelsen för effekterna av en ökad användning av biobaserade material för begränsning av byggandets klimatpåverkan i ett livscykelperspektiv. Forskningsfrågorna formulerades med fokus på att identifiera icke-traditionell LCA-metodik, samt att bedöma miljöeffekterna av en ökad användning av biobaserade material med redovisning av dessa aspekter på olika nivåer, gällande enstaka konstruktioner och byggnadsbeståndet som helhet. Den metodik som används är dynamisk LCA i kombination med data om skogskolbalans, med analyser av flera scenarier med olika metodologiska antaganden. Fallstudier med olika kännetecken användes, nämligen en byggnad, en bilvägsbro och en uppskattning av det svenska byggnadsbeståndet på lång sikt. Resultaten bekräftar att en ökad användning av biobaserade material minskar klimatpåverkan av byggandet – en tydlig majoritet av de scenarier som analyserats för alla fallstudier resulterar i sänkt klimatpåverkan. Införandet av icke-traditionella LCA-aspekter påverkar resultatet, men förändrar inte att en ökad användning av biobaserade material resulterar i lägre långsiktig och kumulativ klimatpåverkan. Resultaten visar också att den maximala klimatbegränsningspotentialen endast nås genom att samtidigt införa andra tekniska lösningar med lägre klimatpåverkan. När det gäller LCA-metodik visar resultaten att antagandet att biobaserade byggnadsmaterial är klimatneutrala är en överförenkling eftersom deras klimatpåverkan beror på fallspecifika faktorer och därför bör inga generaliseringar göras. Några av dessa klimatpåverkande faktorer beror på modellering av skogssystemet i en dynamisk LCA; såsom när skogstillväxten antas börja i förhållande till avverkningen, den geografiska upplösningen för att analysera de biogena kolflödena dvs. som ett avverkningsbestånd eller på landskapsnivå och vad utgångsläget sätts till vid analys av skogens markanvändning. Andra faktorer beror på LCA-modellering, nämligen valet av integrerad tidshorisont för beräkning av klimatpåverkan, det antagna scenariot för avfallshantering och lagringsperioden för det biogena kolet i tillverkade produkter. För att minska osäkerheten i bedömning av klimatpåverkan av biobaserade byggmaterial rekommenderas användning av minst en mätmetod som gör det möjligt att bedöma koldioxidutsläppen baserat på tidpunkten på dessa, samt att tillämpa mätvärden med långa tidsperspektiv. Redovisning av icke-traditionella aspekter har en betydande effekt på klimatpåverkan av biobaserade byggmaterial. Utförare av analyser rekommenderas därför även att redovisa hur dessa aspekter hanteras och att ställa upp flera olika scenarier och analysera dessa med flera olika metodologiska inställningar. Slutligen rekommenderas att ta hänsyn till den tekniska utvecklingen vid analyser av långsiktig klimatpåverkan av byggnadsbeståndet som genomförs med dynamiska värden för processer som äger rum i framtiden. / Para evitar impactos irreversibles a nivel global, es necesario mitigar el cambio climático. Una parte significativa de las emisiones globales de gases efecto invernadero puede atribuirse al sector de la construcción y la producción de cemento. Entretanto, se busca implementar estrategias de mitigación de bajo impacto, tal es el caso de incrementar el uso de materiales de origen forestal. El análisis de ciclo de vida (ACV) se aplica con frecuencia para demostrar los beneficios climáticos de este incremento, pero las complejidades relacionadas con el bosque y el carbono biogénico crean incertidumbre ya que los autores normalmente omiten ciertos aspectos clave. Esta tesis busca mejorar la comprensión de los efectos de un incremento en el uso de materiales de origen forestal en la mitigación del cambio climático en el sector de la construcción, bajo una perspectiva de ciclo de vida. Para ello se han formulado preguntas de investigación centradas en la identificación de los aspectos metodológicos no tradicionales del ACV que pueden afectar el resultado, así como en la evaluación de los efectos ambientales del aumento del uso de materiales biológicos en construcciones o en la construcción en existencia, mientras se toman en cuenta dichos aspectos. Los métodos aplicados incluyen el ACV dinámico en combinación con modelos del balance de carbón en el bosque, además del análisis de múltiples escenarios con diferentes configuraciones metodológicas y asunciones. Se utilizaron casos de estudio con diferentes características y sus respectivos productos equivalentes de referencia; un edificio, un puente para carretera pequeño y la construcción en existencia en Suecia a largo plazo. Los resultados confirman que el aumento del uso de materiales de origen forestal disminuye el impacto climático de la construcción, ya que la gran mayoría de los escenarios analizados para todos los casos de estudio resultan en reducciones del impacto climático. La inclusión de aspectos no tradicionales del ACV ha influido en los resultados, sin afectar el hecho de que incrementar el uso de material biológico se traduce en menores impactos climáticos acumulados a largo plazo. Los resultados también muestran que el potencial máximo de mitigación climática sólo se alcanza mediante la implementación simultánea de otras tecnologías de bajo impacto. En cuanto a la metodología del ACV, la tesis ilustra que la hipótesis de que los biomateriales de construcción son neutrales respecto a sus impactos climáticos es una simplificación excesiva, y demuestra también que los flujos de carbono biogénico deben ser tenidos en cuenta. El balance de carbono de los materiales de construcción de origen forestal depende de factores relacionados con el sistema forestal que son sensibles las circunstancias del caso de estudio; por lo que no deberían hacerse generalizaciones. De dichos factores, algunos dependen de los modelos usados para simular el sistema forestal; tales como la contabilización del punto temporal de ocurrencia de los flujos de carbono biogénico, la perspectiva espacial para medir estos flujos y la línea de base trazada para el sistema forestal. Otros factores dependen del modelo usado para el ACV, como la elección del horizonte temporal integrado para el cálculo del impacto, el escenario de disposición final y el período de almacenamiento del carbono biogénico en los productos. Para obtener conclusiones más robustas, se recomienda que los autores de estudios utilicen al menos un método adicional al GWP que les permita evaluar las emisiones de carbono basadas en el punto temporal de su ocurrencia, así como que se apliquen horizontes temporales a largo plazo en el uso de dichos métodos. Tener en cuenta los aspectos no tradicionales estudiados en esta tesis en estudios de ACV de materiales de construcción de origen forestal puede tener una influencia significativa en su impacto climático, por lo que se recomienda que los autores expongan claramente si estos aspectos se incluyen y cómo se incluyen. También se recomienda que se analicen múltiples escenarios con una variedad de configuraciones metodológicas alternativas. Por último, se recomienda tener en cuenta los cambios tecnológicos en los análisis a largo plazo de los impactos climáticos de la construcción en existencia, utilizando factores de impacto dinámico para los procesos que trascurran en el futuro. / <p>QC 20170517</p> / EnWoBio - Engineered Wood and Biobased Building Materials Laboratory

Les composés organiques volatils (COV) sont des composants clé en chimie atmosphérique. Ils participent à des réactions photochimiques dans la basse atmosphère et jouent ainsi un rôle majeur dans le cycle de l'ozone troposphérique et la formation d‘aérosols organiques secondaires. A l'échelle globale, ces COV sont à 10% d'origine anthropique et à 90% d'origine biotique. Les enjeux liés aux émissions de COVB sont d‘autant plus importants en région méditerranéenne en raison du potentiel d‘émission élevé ainsi que des évènements réguliers de pollution photochimique. Cette thèse propose, à travers deux campagnes de mesures intensives, la caractérisation expérimentale des COVB et de leurs produits d‘oxydation dans deux sites ruraux représentatifs de la végétation méditerranéenne.Dans le cadre du projet CANOPEE (ANR-JCJC 2011-2014) une campagne de mesure a eu lieu à l‘Observatoire du chêne pubescent de Haute Provence (O3HP). Des mesures de concentrations et de flux d‘émission ont été réalisées à l‘échelle de la canopée dans le but de quantifier l‘export des COVB hors canopée et d‘étudier la chimie intra-Canopée. Dans la forêt de l‘O3HP, des concentrations en isoprène très élevées ont été mesurées, en particulier au sein de la canopée où elles ont atteint 16 ppbv les journées les plus chaudes. Selon le facteur d‘émission de 7.2 mg m-2 h-1 déterminé, la forêt de chênes pubescents de l‘O3HP fait partie des écosystèmes les plus fortement émetteurs d‘isoprène à travers le monde. Parmi les COV oxygénés, seul le méthanol a des flux d‘émission significatifs, avec un taux d‘émission moyen égal à 0.3 mg m-2 h-1. Un des points forts de ce travail a consisté en l‘étude du transport et de la chimie intra-Canopée. D‘après nos estimations, les processus intra-Canopée sur le site de l‘OHP jouent un rôle mineur sur les flux nets d‘isoprène sortant de la canopée.La deuxième campagne de mesure s‘inscrit dans le cadre du programme ChArMEx (Chemistry-Aerosol Mediterranean Experiment). Elle a pris place sur le site du Cap Corse, situé à distance des sources anthropiques et qui abrite une diversité d'espèces végétales. Les résultats obtenus ont permis la quantification et spéciation de nombreux COVB. Un grand contraste dans la signature des émissions de COVB a été observé entre les deux sites d‘étude. Ainsi, tandis que l‘isoprène est responsable de plus de 90% des COVB en termes de concentrations à l‘OHP, il ne représente que 35% de leurs concentrations totales au Cap Corse. Les 65% restants sont composés de nombreux monoterpènes. Ces résultats ont également mis en évidence la chimie rapide des COVB et l‘importance de leur contribution à la formation de composés secondaires oxygénés dans les conditions de photochimie intense qui caractérisent le bassin méditerranéen en période estivale.Au Cap Corse, comme à l‘O3HP, les COVB représentent le puit dominant des radicaux hydroxyles. En présence de NOx et pour des concentrations équivalentes à celles de l‘OHP ou du Cap Corse, le potentiel des COVB à former de l‘ozone a été évalué à 10 ppbv en moyenne. / Volatile organic compounds (VOCs) are key components in atmospheric chemistry. They participate in photochemical reactions in the lower atmosphere and thus play a major role in the formation of tropospheric ozone and secondary organic aerosols. Biogenic VOCs (BVOCs) constitute approximately 90% of global VOC emissions. In the Mediterranean region, the emissions and reactivity of BVOCs are enhanced due to high temperatures and sunny conditions. In this context, this work proposes, through intensive field campaigns, the experimental characterization of BVOCs and their oxidation products in two rural sites where the vegetation is representative of the Mediterranean region. Within the framework of the CANOPEE program (ANR-JCJC 2011-2014) an intensive field campaign took place at the Oak Observatory of the Observatoire de Haute Provence (O3HP). Measurements of concentrations and emission fluxes were carried out in order to quantify the export of BVOC off the canopy and study in-Canopy processes. High concentrations of isoprene were measured with daily maximum ambient concentrations ranging between 2-16 ppbv inside the forest. According to the emission factor of 7.2 mg m-2 h-1 determined, downy oak forest of the O3HP is one of the strongest emitters of isoprene worldwide. Evidence of direct emission of methanol was also found exhibiting an average emission rate equal to 0.3 2 mg m-2 h-1. One of the strengths of this work consisted in the study of transport and intra-Canopy chemistry. In-Canopy chemical oxidation of isoprene was found to be weak and did not seem to have a significant impact on isoprene concentrations and fluxes above the canopy. The second field campaign is part of the ChArMEx (Chemistry-Aerosol Mediterranean Experiment) program. It took place on the remote site of Cap Corse, characterized by a strong diversity of plant species. The rich dataset obtained allowed the quantification and speciation of many BVOCs. A great contrast in the signature emissions was observed between the two study sites. Thus, while isoprene is responsible for over 90% of BVOCs in terms of concentrations at the O3HP, it represents only 35% of their total concentrations in Cap Corse. The remaining 65% are composed of many monoterpenes. These results have also highlighted the rapid chemistry of BVOCs and the importance of their contribution to the formation of secondary oxygenated compounds under intense photochemistry conditions, typical of the summertime in the Mediterranean basin. Biogenic BVOCs represented the dominant hydroxyl radicals sink at the O3HP as well as in Cap Corse. In the presence of NOx, the potential of the measured BVOCs to produce ozone has been estimated at about 10 ppbv on average.

Metano (CH4) e dióxido de carbono (CO2) são gases de grande importância climática e energética, pois contribuem para o efeito de estufa, mas também para produção de energia, no caso do CH4. Do ponto de vista energético, reconhecer as diferentes fontes de geração de CH4 torna-se um fator crucial na avaliação das reservas mundiais de gás natural, uma vez que as estimativas atuais de reservas potenciais não levam em consideração as diferentes origens dos hidrocarbonetos presentes ou, na grande maioria, considera apenas a origem termogênica. A temperatura é um dos fatores mais importantes que afetam o crescimento microbiano e as reações biogeoquímicas ligadas à metanogênese. A Formação Irati (Permiano da Bacia do Paraná) ocorre na região sul da América do Sul e representa um dos folhelhos orgânicos mais importantes do mundo já que o conteúdo em carbono orgânico total (COT) atinge até 23% e cobre uma área de aproximadamente 700.000 km2. A história térmica deste importante reservatório de carbono é atípica por hospedar rochas ígneas do Cretáceo. Isto proporcionou a ocorrência de zonas termicamente imaturas até zonas com maturidade suficiente para a geração termogênica de CH4. Este estudo trata da influência da temperatura na geração de CH4 e CO2 biogênicos em folhelhos da Formação Irati. Para isto, amostras de folhelho foram utilizadas em experimentos de incubação realizados sob diferentes temperaturas (22°C, 50°C, 70°C e 80°C), com objetivo de avaliar a influência das condições térmicas sobre a geração biogênica de CH4 e CO2. Temperaturas mais elevadas promoveram maiores taxas de produção de CH4 e CO2. A produção biogênica de CH4 mostrou-se mais eficiente em condições de temperatura de 80°C, com um rendimento máximo de 2,45 ml/t.d em comparação com 0,49 ml/t.d a 22°C, 1,75 ml/t.d e 2,09 ml/t.d a 50°C e 70°C, respectivamente. A mesma tendência foi observada para o CO2. O potencial de produção máximo de CO2 foi observado sob condições térmicas de 80°C, atingindo 23467,37 ml/t.d. As diferenças de produção obtidas para as diferentes amostras analisadas parecem estar relacionadas com a composição química da matriz mineral, observando-se maior produção em amostras com maior quantidade de enxofre (S), quando submetidas a altas temperaturas (50°C, 70°C e 80°C). Além dos folhelhos da Formação Irati, níveis orgânicos das formações Água de Madeiros e Vale das Fontes, Jurássico da Bacia Lusitânica, foram também estudados, os quais são termicamente imaturos e apresentam querogênio tipicamente marinho, distinto do observado na Formação Irati. O aumento da geração biogênica de CH4 e CO2 com a elevação da temperatura também foi observado para amostras das formações Água de Madeiros e Vale das Fontes. Com o presente estudo, é quebrado o paradigma de que 80°C seria a temperatura máxima para a ocorrência de metanogênese em bacias sedimentares, ou reservatórios. Assim, a geração biogênica de CH4 é favorecida por temperaturas mais elevadas (até no mínimo 80°C), considerando-se que a microbiota dos experimentos decorridos durante o presente trabalho seria similar aquelas que ocorrem em bacias sedimentares, bem como o ecossistema. Este trabalho constitui o primeiro estudo que avaliou o efeito da temperatura na produção de gases de origem biogênica em folhelhos da Formação Irati (Bacia do Paraná) e das formações Água de Madeiros e Vale das Fontes (Bacia Lusitânica - Portugal). / Methane (CH4) and carbon dioxide (CO2) have great environmental and economic importance due to their contribution to the greenhouse effect and climate change, but also as energy resource, in the case of CH4. From the energy point of view, recognizing the different sources of CH4 in sedimentary basins has a crucial factor in assessing the world\'s natural gas reserves, since the current estimates of hydrocarbons accumulations in sedimentary basins are based on thermogenic generation of hydrocarbons. However, few studies evaluate the importance of CH4 and CO2 generation as a product of organic matter biodegradation in sedimentary basins. This issue has great relevance to improve the estimates about the geological accumulations of CH4 and CO2. Temperature is one of the most important factors affecting microbial growth and biogeochemical processes responsible for CH4 and CO2 generation in subsurface environments. In this context, the Irati Formation (Permian of the Paraná Basin) in southern of South America represents one of the most organicrich shale around the world, reaching up to 23% of total organic carbon (TOC) and covering an area of approximately 700.000 km2. The thermal history of this important geological carbon pool is atypical because of the emplacement of igneous bodies during the Early Cretaceous. In this study, shale samples of the Irati Formation were used in incubation experiments performed under different temperatures (22°C, 50°C, 70°C and 80°C) to evaluate the influence of thermal conditions on biogenic generation of CH4 and CO2. Higher temperatures promoted higher production rates of CH4 and CO2. Biogenic CH4 production was more efficient when shale samples were incubated at 80°C, with a maximum yield of 2.45 ml/t.d compared to 0.49 ml/t.d at 22°C, 1.75 ml/t.d at 50°C and 2.09 ml/t.d at 70°C. The same trend was observed for CO2 generated as by-product of methanogenesis. The maximum production for CO2 was observed at 80°C, reaching 23467.37 ml/t.d. The differences in CH4 and CO2 production observed for different analyzed samples seem to be related to the composition of the mineral matrix, being observed higher production in samples with higher amount of sulfur. Additionaly, organic layers of the Água de Madeiros and Vale das Fontes Formations (Lusitanian Basin), which are thermally immature and present typically marine kerogen, were also submitted to incubation experiments to evaluate CH4 and CO2 generation. Higher biogenic generation of CH4 with the elevation of temperature was also observed for the Água de Madeiros and Vale das Fontes Formations. This suggests that biogenic CH4 generation is favored by higher temperatures, at least until 80°C, independent of the thermal maturity of the substrate, pointing that the temperature window (and depth zone) for the generation of biogenic CH4 in sedimentary basins is larger than suggested in previous studies.