Biogeochemische Entschlüsselung der Quellen organischen Materials in einer mehrschichtigen komplexen Bodensequenz

Entgegen der ursprünglichen Annahme wird ein Grossteil des pflanzenbürtigen organischen Materials in Böden nicht durch die Blattstreu eingetragen, sondern gerade in tieferen Bodenhorizonten durch Wurzeln. Da der Eintrag auch in tiefere Bodenhorizonte und Paläoböden stattfindet, ist die qualitative und quantitative Abschätzung unterschiedlicher Quellen organischen Materials wichtig, wenn man das organische Material in Paläoböden mit dem Ziel der Umweltrekonstruktion oder hinsichtlich der C-Speicherkapazität charakterisieren möchte. In der Präsentation wird ein Ansatz vorgestellt, in dem mittels Biomarkern, Datierung und Modellierung verschiedene anthropogene und natürliche Quellen in einer 2 m mächtigen Bodensequenz, bestehend aus mehreren Podsolen, einem Plaggenboden und zwischengelagerten Sedimenten, rekonstruiert werden. Mittels Alkanen, Fettsäuren und Alkoholen in unterschiedlichen Bodentiefen und dem Vergleich mit Pflanzenproben inklusive einer inversen Modellierung mittels VERHIB liessen sich nicht nur die dominanten Vegetationen zur Zeiten der Podsolbildung differenzieren. Ausserdem konnte die Quellvegetation der Plaggen, sowie die bevorzugte landwirtschaftliche Nutzung inklusive der Kulturpflanzen rekonstruiert werden. Weiterhin trägt die heutige Waldvegetation signifikant zum Eintrag wurzelbürtigen organischen Materials in den Plaggenboden und darunterliegende Bereiche bei. Zusätzlich lassen unterschiedliche Quellen an Fäkalien und Brandrückständen, die mittels Sterolen und Stanolen bzw. PAKs untersucht wurden, auf eine sukzessive Veränderung in verschiedenen Phasen der Plaggenwirtschaft schliessen. Unterstützt werden die Laborbefunde durch Erkenntnisse, die während der Feldarbeiten erhoben wurden, wie z.B. dreidimensionale Verteilung der Wurzelhäufigkeiten, Verteilungsmuster von Nährelementen, die die Verteilung der Wurzeln beeinflussen und Pollendaten aus einem benachbarten Bodenprofil. Der gewählte Ansatz zeigt in bisher einmaliger Weise das Potential von Biomarkeranalysen zur Vegetations- und Umweltrekonstruktion und archäologischer Deutung auf

Pedogenesis and carbon sequestration in transformed agricultural soils of Sicily

The increasing atmospheric CO2 concentration is a consequence of human activities leading to severe environmental deteriorations. Techniques are thus needed to sequester and reduce atmospheric carbon. One of the proposed techniques is the transformation or construction of new soils into which more organic carbon can be sequestered and CO2 be consumed by increased weathering. By using a chronosequence of new and transformed soils on crushed limestone (0–48 years) in a Mediterranean area (Sicily), we tried to quantify the amount of organic carbon that could be additionally sequestered and to derive the corresponding rates. A further aim was to trace chemical weathering and related CO2 consumption and the evolution of macropores that are relevant for water infiltration and plant nutrition. Owing to the irrigation of the table grape cultivation, the transformed soils developed fast. After about 48 years, the organic C stocks were near 12 kg m−2. The average org. C sequestration rates varied between 68 and 288 g m−2 yr−1. The C accumulation rates in the transformed soils are very high at the beginning and tend to decrease over (modelled) longer time scales. Over these 48 years, a substantial amount of carbonate was leached and reprecipitated as secondary carbonates. The proportion of secondary carbonates on the total inorganic carbon was up to 50%. Main mineralogical changes included the formation of interstratified clay minerals, the decrease of mica and increase of chloritic components as well as goethite. The atmospheric CO2 consumption due to silicate weathering was in the range of about 44–72 g C m−2 yr−1. Due to the high variability, the contribution of chemical weathering to CO2 consumption represents only an estimate. When summing up organic C sequestration and CO2 consumption by silicate weathering, rates in the order of 110–360 g C m−2 yr−1 are obtained. These are very high values. We estimated that high sequestration and CO2 consumption rates are maintained for about 50–100 years after soil transformation. The macropore volume decreased over the observed time span to half (from roughly 10 to 5 %). The transformation of soils may even amend their characteristics and increase agricultural production. Due to the relatively sandy character, enough macropores were present and no substantial compaction of the soils occurred. However, great caution has to be taken as such measures can trigger deterioration of both soil ecosystem services and soil quality

Climate warming and elevated CO2 alter peatland soil carbon sources and stability

Peatlands are an important carbon (C) reservoir storing one-third of global soil organic carbon (SOC), but little is known about the fate of these C stocks under climate change. Here, we examine the impact of warming and elevated atmospheric CO$_{2}$ concentration (eCO$_{2}$) on the molecular composition of SOC to infer SOC sources (microbe-, plant- and fire-derived) and stability in a boreal peatland. We show that while warming alone decreased plant- and microbe-derived SOC due to enhanced decomposition, warming combined with eCO$_{2}$ increased plant-derived SOC compounds. We further observed increasing root-derived inputs (suberin) and declining leaf/needle-derived inputs (cutin) into SOC under warming and eCO$_{2}$. The decline in SOC compounds with warming and gains from new root-derived C under eCO$_{2}$, suggest that warming and eCO$_{2}$ may shift peatland C budget towards pools with faster turnover. Together, our results indicate that climate change may increase inputs and enhance decomposition of SOC potentially destabilising C storage in peatlands

Plants or bacteria? 130 years of mixed imprints in Lake Baldegg sediments (Switzerland), as revealed by compound-specific isotope analysis (CSIA) and biomarker analysis

Soil erosion and associated sediment transfer are among the major causes of aquatic ecosystem and surface water quality impairment. Through land use and agricultural practices, human activities modify the soil erosive risk and the catchment connectivity, becoming a key factor of sediment dynamics. Hence, restoration and management plans of water bodies can only be efficient if the sediment sources and the proportion attributable to different land uses are identified. According to this aim, we applied two approaches, namely compound-specific isotope analysis (CSIA) of long-chain fatty acids (FAs) and triterpenoid biomarker analysis, to a eutrophic lake, Lake Baldegg, and its agriculturally used catchment (Switzerland). Soils reflecting the five main land uses of the catchment (arable lands, temporary and permanent grasslands, mixed forests, orchards) were subjected to CSIA. The compound-specific stable isotope δ13C signatures clearly discriminate between potential grasslands (permanent and temporary) and forest sources. Signatures of agricultural land and orchards fall in between. The soil signal was compared to the isotopic signature of a lake sediment sequence covering ca. 130 years (before 1885 to 2009). The recent lake samples (1940 to 2009, with the exception of 1964 to 1972) fall into the soil isotopic signature polygon and indicate an important contribution of the forests, which might be explained by (1) the location of the forests on steep slopes, resulting in a higher connectivity of the forests to the lake, and/or (2) potential direct inputs of trees and shrubs growing along the rivers feeding the lake and around the lake. However, the lake sediment samples older than 1940 lie outside the source soils' polygon, as a result of FA contribution from a not yet identified source, most likely produced by an in situ aquatic source, either algae, bacteria or other microorganisms or an ex-site historic source from wetland soils and plants (e.g. Sphagnum species). Despite the overprint of the yet unknown source on the historic isotopic signal of the lake sediments, land use and catchment history are clearly reflected in the CSIA results, with isotopic shifts being synchronous with changes in the catchment, land use and eutrophication history. The investigated highly specific biomarkers were not detected in the lake sediment, even though they were present in the soils. However, two trimethyltetrahydrochrysenes (TTHCs), natural diagenetic products of pentacyclic triterpenoids, were found in the lake sediments. Their origin is attributed to the in situ microbial degradation of some of the triterpenoids. While the need to apportion sediment sources is especially crucial in eutrophic systems, our study stresses the importance of exercising caution with CSIA and triterpenoid biomarkers in such environments, where the active metabolism of bacteria might mask the original terrestrial isotopic signals.</p

Timing and Potential Causes of 19th-Century Glacier Advances in Coastal Alaska Based on Tree-Ring Dating and Historical Accounts

The Little Ice Age (LIA), ca. CE 1250–1850, was a cold period of global extent, with the nature and timing of reduced temperatures varying by region. The Gulf of Alaska (GOA) is a key location to study the climatic drivers of glacier fluctuations during the LIA because dendrochronological techniques can provide precise ages of ice advances and retreats. Here, we use dendrochronology to date the most recent advance of La Perouse Glacier in the Fairweather Range of Southeast Alaska. After maintaining a relatively contracted state since at least CE 1200, La Perouse advanced to its maximum LIA position between CE 1850 and 1895. Like many other glaciers bordering the GOA, the La Perouse Glacier reached this maximum position relatively late in the LIA compared with glaciers in other regions. This is curious because reconstructions of paleoclimate in the GOA region indicate the 19th century was not the coldest period of the LIA. Using newly available paleoclimate data, we hypothesize that a combination of moderately cool summers accompanying the Dalton Solar Minimum and exceptionally snowy winters associated with a strengthened Aleutian Low could have caused these relatively late LIA advances. Such a scenario implies that winter climate processes, which are heavily influenced by ocean-atmospheric variability in the North Pacific region, have modulated these coastal glaciers’ sensitivity to shifts in summer temperatures

Downregulation of peroxisome proliferator-activated receptors (PPARs) in nasal polyposis

BACKGROUND: Peroxisome proliferator-activated receptor (PPAR) α, βδ and γ are nuclear receptors activated by fatty acid metabolites. An anti-inflammatory role for these receptors in airway inflammation has been suggested. METHODS: Nasal biopsies were obtained from 10 healthy volunteers and 10 patients with symptomatic allergic rhinitis. Nasal polyps were obtained from 22 patients, before and after 4 weeks of local steroid treatment (fluticasone). Real-time RT-PCR was used for mRNA quantification and immunohistochemistry for protein localization and quantification. RESULTS: mRNA expression of PPARα, PPARβδ, PPARγ was found in all specimens. No differences in the expression of PPARs were obtained in nasal biopsies from patients with allergic rhinitis and healthy volunteers. Nasal polyps exhibited lower levels of PPARα and PPARγ than normal nasal mucosa and these levels were, for PPARγ, further reduced following steroid treatment. PPARγ immunoreactivity was detected in the epithelium, but also found in smooth muscle of blood vessels, glandular acini and inflammatory cells. Quantitative evaluation of the epithelial immunostaining revealed no differences between nasal biopsies from patients with allergic rhinitis and healthy volunteers. In polyps, the PPARγ immunoreactivity was lower than in nasal mucosa and further decreased after steroid treatment. CONCLUSION: The down-regulation of PPARγ, in nasal polyposis but not in turbinates during symptomatic seasonal rhinitis, suggests that PPARγ might be of importance in long standing inflammations

Control of Gene Expression by the Retinoic Acid-Related Orphan Receptor Alpha in HepG2 Human Hepatoma Cells

Retinoic acid-related Orphan Receptor alpha (RORα; NR1F1) is a widely distributed nuclear receptor involved in several (patho)physiological functions including lipid metabolism, inflammation, angiogenesis, and circadian rhythm. To better understand the role of this nuclear receptor in liver, we aimed at displaying genes controlled by RORα in liver cells by generating HepG2 human hepatoma cells stably over-expressing RORα. Genes whose expression was altered in these cells versus control cells were displayed using micro-arrays followed by qRT-PCR analysis. Expression of these genes was also altered in cells in which RORα was transiently over-expressed after adenoviral infection. A number of the genes found were involved in known pathways controlled by RORα, for instance LPA, NR1D2 and ADIPOQ in lipid metabolism, ADIPOQ and PLG in inflammation, PLG in fibrinolysis and NR1D2 and NR1D1 in circadian rhythm. This study also revealed that genes such as G6PC, involved in glucose homeostasis, and AGRP, involved in the control of body weight, are also controlled by RORα. Lastly, SPARC, involved in cell growth and adhesion, and associated with liver carcinogenesis, was up-regulated by RORα. SPARC was found to be a new putative RORα target gene since it possesses, in its promoter, a functional RORE as evidenced by EMSAs and transfection experiments. Most of the other genes that we found regulated by RORα also contained putative ROREs in their regulatory regions. Chromatin immunoprecipitation (ChIP) confirmed that the ROREs present in the SPARC, PLG, G6PC, NR1D2 and AGRP genes were occupied by RORα in HepG2 cells. Therefore these genes must now be considered as direct RORα targets. Our results open new routes on the roles of RORα in glucose metabolism and carcinogenesis within cells of hepatic origin

It's getting hot in here – Microcontextual study of a potential pit hearth at the Middle Paleolithic site of El Salt, Spain

By studying combustion structures, which conceal information about anthropogenic activity, we might learn about their makers. This is especially important for remote time periods like the Middle Paleolithic, whose archaeological record comprises numerous combustion structures. The majority of these are simple, flat, open hearths, although a small number of features situated in pit-like depressions have been recorded. Given that hearths built on a flat surface can result in pit-like color alteration of the underlying sediment, accurate identification of pit hearths is a crucial step prior to behavioral interpretation. Here we present a comprehensive study of a possible pit hearth from the Middle Paleolithic site of El Salt, Spain, using a microcontextual approach combining micromorphology, lipid biomarker analysis, archaeomagnetism and zooarchaeology. This pit hearth involves a true depression containing a thick plant ash deposit. It reached very high temperatures, possibly multiple burning events and long combustion times. Morphologically distinct combustion structures in a single archaeological context may indicate different functions and thus a diverse fire technology, pointing to Neanderthal behavioral variability.ERC Consolidator Grant project PALEOCHAR – 648871 https://erc.europa.eu/funding/consolidator-grants, I + D Project HAR2008-06117/HIST, HAR2015-68321-P (MINECO-FEDER/UE), and the Cultural Heritage Department of the Valencia Government and the Archaeological Museum Camil Visedo of Alcoy, under the direction of Professor Bertila Galván of Universidad de La Laguna, Junta de Castilla y León (project BU235P18), the European Fund for Economic and Regional Development (EFRD) and the project PID2019-105796 GB-I00 of the Agencia Estatal de Investigación (AEI/10.13039/501100011033