4 results on '"Voltz, B."'
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2. Scherben scheibenweise:Röntgen- und Neutronentomographie von experimenteller und archäologischer Keramik
- Author
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Philippsen, Bente, Weller, U., Lessig-Weller, T., Hanning, E., and Strugalla-Voltz, B.
- Abstract
Ceramic sherds contain valuable information about chronology, nutrition and cuisine of prehistoric cultures, and can be used to reconstruct life and economy of our ancestors. Scientific methods can obtain many of this information from the pottery. Radiocarbon dating can determine the time of production or use of the pottery.Often, archaeological sherds have to be crushed to obtain material for radiocarbon dating and other analyses. This is the case when dating organic temper, or analysing the lipids which the clay absorbed during food preparation. The desired sample material may often not be present in the sherd in sufficient amounts, though. In those cases, the sherd would be destroyed needlessly.The aim of our study is therefore to determine the presence of datable material, fat, etc., in a sherd without destroying it. X-rays can only show the mineral parts of the sherd. Neutrons, however, can show organic compounds, while the rest of the sherd is “invisible” for the neutrons. During a tomography, the object is being analysed “slice by slice”. Finally, 3D-illustrations can be rendered. In this paper, I will present a pilot study, which explores the potential of neutron tomography on ceramic sherds. Reference material was obtained from experiments on pottery production and use, which I have presented at earlier EXAR conferences.
- Published
- 2014
3. Global dataset of soil organic carbon in tidal marshes.
- Author
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Maxwell TL, Rovai AS, Adame MF, Adams JB, Álvarez-Rogel J, Austin WEN, Beasy K, Boscutti F, Böttcher ME, Bouma TJ, Bulmer RH, Burden A, Burke SA, Camacho S, Chaudhary DR, Chmura GL, Copertino M, Cott GM, Craft C, Day J, de Los Santos CB, Denis L, Ding W, Ellison JC, Ewers Lewis CJ, Giani L, Gispert M, Gontharet S, González-Pérez JA, González-Alcaraz MN, Gorham C, Graversen AEL, Grey A, Guerra R, He Q, Holmquist JR, Jones AR, Juanes JA, Kelleher BP, Kohfeld KE, Krause-Jensen D, Lafratta A, Lavery PS, Laws EA, Leiva-Dueñas C, Loh PS, Lovelock CE, Lundquist CJ, Macreadie PI, Mazarrasa I, Megonigal JP, Neto JM, Nogueira J, Osland MJ, Pagès JF, Perera N, Pfeiffer EM, Pollmann T, Raw JL, Recio M, Ruiz-Fernández AC, Russell SK, Rybczyk JM, Sammul M, Sanders C, Santos R, Serrano O, Siewert M, Smeaton C, Song Z, Trasar-Cepeda C, Twilley RR, Van de Broek M, Vitti S, Antisari LV, Voltz B, Wails CN, Ward RD, Ward M, Wolfe J, Yang R, Zubrzycki S, Landis E, Smart L, Spalding M, and Worthington TA
- Abstract
Tidal marshes store large amounts of organic carbon in their soils. Field data quantifying soil organic carbon (SOC) stocks provide an important resource for researchers, natural resource managers, and policy-makers working towards the protection, restoration, and valuation of these ecosystems. We collated a global dataset of tidal marsh soil organic carbon (MarSOC) from 99 studies that includes location, soil depth, site name, dry bulk density, SOC, and/or soil organic matter (SOM). The MarSOC dataset includes 17,454 data points from 2,329 unique locations, and 29 countries. We generated a general transfer function for the conversion of SOM to SOC. Using this data we estimated a median (± median absolute deviation) value of 79.2 ± 38.1 Mg SOC ha
-1 in the top 30 cm and 231 ± 134 Mg SOC ha-1 in the top 1 m of tidal marsh soils globally. This data can serve as a basis for future work, and may contribute to incorporation of tidal marsh ecosystems into climate change mitigation and adaptation strategies and policies., (© 2023. The Author(s).)- Published
- 2023
- Full Text
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4. Importance of the vegetation-groundwater-stream continuum to understand transformation of biogenic carbon in aquatic systems - A case study based on a pine-maize comparison in a lowland sandy watershed (Landes de Gascogne, SW France).
- Author
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Deirmendjian L, Anschutz P, Morel C, Mollier A, Augusto L, Loustau D, Cotovicz LC Jr, Buquet D, Lajaunie K, Chaillou G, Voltz B, Charbonnier C, Poirier D, and Abril G
- Subjects
- Embryophyta physiology, France, Pinus growth & development, Zea mays growth & development, Carbon analysis, Environmental Monitoring, Farms, Forests, Groundwater analysis, Rivers
- Abstract
During land-aquatic transfer, carbon (C) and inorganic nutrients (IN) are transformed in soils, groundwater, and at the groundwater-surface water interface as well as in stream channels and stream sediments. However, processes and factors controlling these transfers and transformations are not well constrained, particularly with respect to land use effect. We compared C and IN concentrations in shallow groundwater and first-order streams of a sandy lowland catchment dominated by two types of land use: pine forest and maize cropland. Contrary to forest groundwater, crop groundwater exhibited oxic conditions all-year round as a result of higher evapotranspiration and better lateral drainage that decreased the water table below the organic-rich soil horizon, prevented the leaching of soil-generated dissolved organic carbon (DOC) in groundwater, and thus limited consumption of dissolved oxygen (O
2 ). In crop groundwater, oxic conditions inhibited denitrification and methanogenesis resulting in high nitrate (NO3 - ; on average 1140 ± 485 μmol L-1 ) and low methane (CH4 ; 40 ± 25 nmol L-1 ) concentrations. Conversely, anoxic conditions in forest groundwater led to lower NO3 - (25 ± 40 μmol L- 1) and higher CH4 (1770 ± 1830 nmol L-1 ) concentrations. The partial pressure of carbon dioxide (pCO2 ; 30,650 ± 11,590 ppmv) in crop groundwater was significantly lower than in forest groundwater (50,630 ± 26,070 ppmv), and was apparently caused by the deeper water table delaying downward diffusion of soil CO2 to the water table. In contrast, pCO2 was not significantly different in crop (4480 ± 2680 ppmv) and forest (4900 ± 4500 ppmv) streams, suggesting faster degassing in forest streams resulting from greater water turbulence. Although NO3 - concentrations indicated that denitrification occurred in riparian-forest groundwater, crop streams nevertheless exhibited important signs of spring and summer eutrophication such as the development of macrophytes. Stream eutrophication favored development of anaerobic conditions in crop stream sediments, as evidenced by increased ammonia (NH4 + ) and CH4 in stream waters and concomitant decreased in NO3 - concentrations as a result of sediment denitrification. In crop streams, dredging and erosion of streambed sediments during winter sustained high concentration of particulate organic C, NH4 + and CH4 . In forest streams, dissolved iron (Fe2+ ), NH4 + and CH4 were negatively correlated with O2 reflecting the gradual oxygenation of stream water and associated oxidations of Fe2+ , NH4 + and CH4 . The results overall showed that forest groundwater behaved as source of CO2 and CH4 to streams, the intensity depending on the hydrological connectivity among soils, groundwater, and streams. CH4 production was prevented in cropland in soils and groundwater, however crop groundwater acted as a source of CO2 to streams (but less so than forest groundwater). Conversely, in streams, pCO2 was not significantly affected by land use while CH4 production was enhanced by cropland. At the catchment scale, this study found substantial biogeochemical heterogeneity in C and IN concentrations between forest and crop waters, demonstrating the importance of including the full vegetation-groundwater-stream continuum when estimating land-water fluxes of C (and nitrogen) and attempting to understand their spatial and temporal dynamics., (Copyright © 2019 Elsevier B.V. All rights reserved.)- Published
- 2019
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