752 research outputs found
Low resolution stable isotopes of ice core Taylor Dome
No full textThe delta 18O values were determined at the Quaternary Isotope Laboratory (M. Stuiver, Box 351360, University of Washington, Seattle WA 98195, USA). The time scale (st9507) was estimated from a correlation of delta 18O with the Vostok delta D record (Grootes et al. 1994; Steig, 1996). Between 0-340m the samples measured were of 1m cuts taken in the field. Each 1m core section was slabbed to provide a surface for ECM measurement; a thin slice was removed uniformly along the length for isotope analysis. From 340m to the bottom, sampling was done at the National Ice Core Lab at 0.5m lengths. Note that these core sections were shipped intact to NICL; they were not processed in the field
GISP2 Oxygen Isotope Data
No full textMeasured at University of Washingtons Quaternary Isotope Laboratory. Timescale (down to 2808 m) includes revisions by Meese as of Sept 1994. Depths below 167 m are D core; above 167 meters depths are B core+1.09 meters. Depth is top of interval
Transformation of organic matter in agricultural soils: radiocarbon concentration versus soil depth
No full textRadiocarbon measured by accelerator mass spectrometry (AMS) was used as a tracer to study the origin and fate of organic materials in soils. Fractionation methods used to separate the heterogeneous organic material into functionally defined pools of different stability included acid-alkali-acid extraction and density fractionation. C-14 values of the humin fraction, isolated from samples of different field trials at the agricultural station Rotthalmunster (Germany), yielded C-14 decreases of about 30% to 54% from the surface soil to ca. 65 cm depth. These results indicate a progressive enrichment of stable organic compounds with increasing soil depth. In contrast, a minor decline in 14C concentrations of the humic acid fraction, which mostly showed higher 14C values than the humin, reflect the translocation of modern organic carbon towards greater depth. Low radiocarbon levels of the light occluded particulate organic matter (14C results for density fractions from field trials located in a rural and an industrialized region reflect their susceptibility to contamination by fossil fuel-derived carbon and their heterogeneous composition. As a consequence individual short-chain phospholipid fatty acids (PLFA), as indicators for viable soil microbial biomass, were isolated by preparative capillary gas-chromatography. Compound-specific radiocarbon analysis of the isolated PLFAs revealed the assimilation of different substrates for their synthesis. C-14 concentrations of the monounsaturated PLFAs (n-C16:1, n-C17:1, and n-C18:1), which were close to the modern atmospheric C-14 level, suggest a high specificity to young carbon sources. The saturated PLFAs, isolated from the plough-horizon, were synthesized from sub-recent soil organic carbon (SOC) as shown by a higher contribution of bomb-C-14. A considerable 14C decrease from the surface to 30-45 cm soil depth of the saturated PLFAs indicates the incorporation of more stabilized SOC particularly in subsoil i/a-C15:0, n-C16:0, and 17C17:0 PLFAs. (c) 2004 Elsevier B.V. All rights reserved. [References: 48
Storage and stability of organic matter and fossil carbon in a Luvisol and Phaeozem with continuous maize cropping: A synthesis
No full textQuantitative information about the amount and stability of organic carbon (OC) in different soil organic-matter (OM) fractions and in specific organic compounds and compound-classes is needed to improve our understanding of organic-matter sequestration in soils. In the present paper, we summarize and integrate results performed on two different arable soils with continuous maize cropping (a) Stagnic Luvisol with maize cropping for 24 y, b) Luvic Phaeozem with maize cropping for 39 y) to identify (1) the storage of OC in different soil organic-matter fractions, (2) the function of these fractions with respect to soil-OC stabilization, (3) the importance and partitioning of fossil-C deposits, and (4) the rates of soil-OC stabilization as assessed by compound-specific isotope analyses. The fractionation procedures included particle-size fractionation, density fractionation, aggregate fractionation, acid hydrolysis, different oxidation procedures, isolation of extractable lipids and phospholipid fatty acids, pyrolysis, and the determination of black C. Stability of OC was determined by 13C and 14C analyses. The main inputs of OC were plant litter (both sites) and deposition of fossil C likely from coal combustion and lignite dust (only Phaeozem).
Total soil OC stocks down to a depth of 65 cm (7.83 kg m–2 in the Luvisol and 9.66 kg m–2 in the Phaeozem) consisted mainly of mineral-bound OC (87% of total SOC in the Luvisol and 69% in the Phaeozem). In the Luvisol, free light particulate OM, OM associated with sand and coarse silt, and particulate OM occluded in macro-aggregates represented SOM fractions with mean turnover times shorter than that of the bulk soil OC (54 y). Additionally, the turnover of all individual compounds or compound classes (except for black carbon) was faster than that of bulk soil OC. These OM fractions that were less stable than the bulk soil OM made up 13% to 20% of the total OC. Organic matter in fine and medium silt and clay fractions, particulate OM occluded in micro-aggregates (53–250 lm) and OM resistant to acid hydrolysis had intermediate turnover times of about 50–100 y. These fractions with intermediate turnover times contributed 70%–80% to total soil OC. Passive OM with turnover times >200 y was isolated from the mineral-bound OM by different oxidation procedures (H2O2, Na2S2O8) and made up ≤10% of the total OC. The isotopic signature of PLFAs suggests an efficient recycling of OC derived from C3 substrate.
In the Phaeozem, partitioning of maize-derived C exhibited a pattern similar to the Luvisol, but turnover rates of vegetation-derived soil OC were lower, probably because of the considerably smaller input of plant residues. Fossil C contributed approx. 50% to the total OC and accumulated preferentially in the particulate OM occluded in aggregates and in the fine-sand and coarse-silt fractions. It formed a large stock of passive soil OM but a minor part also entered the microbial C cycle. The results show that the partitioning of OC derived from vegetation and deposition of fossil compounds among soil fractions differed mainly because of their different bioavailability and recalcitrance. There was no evidence for a high recalcitrance of individual plant compounds. Mineral-bound OM resistant to oxidation by H2O2 and Na2S2O8 represented highly stable OC pools in both soils
Pollen profile from exposure Fluderbach II, Samerberg
No full textZero at the base of the profile. A Picea trunk found at 2.26 m gave a radiometrical age of 72300 +4100/-2700 yrs BP, GrN-7225; Grootes, P.M. (1977). If autochthonous the wood dates the younger part of the spreading phase of Picea. A layer of sand and gravel between 4.465 m and 4.62 m divides the gyttja of the third interstadial into two parts
World Ocean 14C plateau tuning
No full textOn the basis of minor time scale adjustments including the synchronization on IntCal20 the Suigetsu-based atmospheric 14C plateau structures are shown to be authentic. Their global significance is demonstrated by the coherence with the tree ring record 10 to 15 cal. ka. The suite of atmospheric structures can be recognized in high-resolution ocean sediment records independent of various processes leading to partial distortion of a sediment record. This provides a unique tool for global stratigraphic correlation and paleoceanographic studies as shown by supplementary figures and tables from 19 cores obtained from key locations in the world ocean
Mood Regulation as a Design Topic: Interview with Pieter Desmet
Get PDFPieter Desmet is the founding co-director of the Delft Institute of Positive Design, chair of the TU Delft Department of Human Centered Design, and Director of the Delft Design Labs. After introducing cognitive emotion theory to the field of design research, he established the Design and Emotion Society. Full professor of Design for Experience at TU Delft, Desmet is also co-editor of Design and Emotion Moves (Cambridge Scholars, 2008) and co-author of Positive Design: An Introduction to Design for Subjective Well-Being (IJDesign, 2013). Pieter Desmet, who holds a PhD in the domain of Emotion Psychology, has been recently awarded a five-year personal grant to research about the nuances of human mood in human-product interactions. Besides his academic activities, he also contributes to local community projects, such as a recently developed sensory wellness neighborhood park, and a cultural ‘House of Happiness’ located in Rotterdam. In this interview, Desmet discusses the background to positive design, as well as the practical and ethical challenges that arise from using such an approach. He also refers to his latest research initiative: Design for Mood Regulation. Finally, Desmet explains how he transfers the knowledge he develops to companies
GISP2 Oxygen Isotope Data (1 year averages)
No full textThe timescale includes revisions by D. A. Meese as of Sept 1994. Depths below 167 meters are those of the D core; above 167 meters the depths are those of the B core + 1.09 meters. Layer count ages at top depths where 0 BP represents AD 1950 SUMMER to AD 1949 SUMMER. d18O measured at the Quaternary Isotope Laboratory, Univ of Washington
Mood Regulation as a Design Topic: Interview with Pieter Desmet
Get PDFPieter Desmet is the founding co-director of the Delft Institute of Positive Design, chair of the TU Delft Department of Human Centered Design, and Director of the Delft Design Labs. After introducing cognitive emotion theory to the field of design research, he established the Design and Emotion Society. Full professor of Design for Experience at TU Delft, Desmet is also co-editor of Design and Emotion Moves (Cambridge Scholars, 2008) and co-author of Positive Design: An Introduction to Design for Subjective Well-Being (IJDesign, 2013). Pieter Desmet, who holds a PhD in the domain of Emotion Psychology, has been recently awarded a five-year personal grant to research about the nuances of human mood in human-product interactions. Besides his academic activities, he also contributes to local community projects, such as a recently developed sensory wellness neighborhood park, and a cultural ‘House of Happiness’ located in Rotterdam. In this interview, Desmet discusses the background to positive design, as well as the practical and ethical challenges that arise from using such an approach. He also refers to his latest research initiative: Design for Mood Regulation. Finally, Desmet explains how he transfers the knowledge he develops to companies
Mood Regulation as a Design Topic: Interview with Pieter Desmet
No full textPieter Desmet is the founding co-director of the Delft Institute of Positive Design, chair of the TU Delft Department of Human Centered Design, and Director of the Delft Design Labs. After introducing cognitive emotion theory to the field of design research, he established the Design and Emotion Society. Full professor of Design for Experience at TU Delft, Desmet is also co-editor of Design and Emotion Moves (Cambridge Scholars, 2008) and co-author of Positive Design: An Introduction to Design for Subjective Well-Being (IJDesign, 2013). Pieter Desmet, who holds a PhD in the domain of Emotion Psychology, has been recently awarded a five-year personal grant to research about the nuances of human mood in human-product interactions. Besides his academic activities, he also contributes to local community projects, such as a recently developed sensory wellness neighborhood park, and a cultural ‘House of Happiness’ located in Rotterdam. In this interview, Desmet discusses the background to positive design, as well as the practical and ethical challenges that arise from using such an approach. He also refers to his latest research initiative: Design for Mood Regulation. Finally, Desmet explains how he transfers the knowledge he develops to companies
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