„A novel single-run dual temperature combustion (SRDTC) method for the determination of organic, inorganic and total carbon“ • Isabella Bisutti, • Ines Hilke, • Jens Schumacher and • Michael Raessler • Max-Planck-Institut für Biogeochemie, Hans- Knoell-Strasse 10, D-07745 Jena, Germany
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Isabella Bisutti, Ines Hilke, Jens Schumacher and Michael Raessler
„A novel single-run dual temperature combustion (SRDTC) method for the determination of organic, inorganic and total carbon“. Isabella Bisutti, Ines Hilke, Jens Schumacher and Michael Raessler Max-Planck-Institut für Biogeochemie, Hans-Knoell-Strasse 10, D-07745 Jena, Germany. Target:. - PowerPoint PPT Presentation
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„A novel single-run dual temperature combustion (SRDTC) method for the determination of
organic, inorganic and total carbon“
• Isabella Bisutti,• Ines Hilke,• Jens Schumacher and• Michael Raessler
• Max-Planck-Institut für Biogeochemie, Hans-Knoell-Strasse 10, D-07745 Jena, Germany
Target:• exact determination of inorganic and organic
carbon in soil samples for evaluation of the carbon cycles on regional and global scales
• soils contain 2200 Pg (10 15 g) carbon in the first 100 cm
2/3 OC and 1/3 IC
• soils contain three times more carbon than above-ground biomass
„Classical“ methods for determination of OC and IC:
• combustion of sample to determine total carbon (TC)
• either acid or ashing pretreatment removes IC or OC
• remaining form of carbon is determined by combustion
• complementary part of carbon is calculated by difference
• ACID PRETREATMENT (ISO 10694)
• 1st combustion: TC 2nd combustion: OC
IC = TC - OC
Disadvantages (1)
• acid pretreatment:
• non-quantitative removal of carbonate carbon
• great variability of results
• possible loss of soluble OC
• possible loss of volatile organic carbon (VOC)
Disadvantages (2)
• ashing pretreatment:
• thermal instability of carbonates
• uncertainty of complete OC removal
• neither acid nor ashing pretreatment provide information on TC, OC and IC in ONE single analitycal run
Carbonate minerals in soil samples
Mineral TDecomp(̊C) Impact of temperature
Impact of acid
Calcite (CaCO3)
675$ 500°C / 7h no loss of carbonate; 600°C / 4h loss of about 90 %(13); 780°C / 15 min. completely converted (18)
5 – 25 s HCI 20 % (25); 1 h at 50°C H3PO4 (26)
Aragonite (CaCO3)
645
Dolomite (CaMg(CO3)2)
450§ 500°C / 16h loss up to 20% (1); 800 °C / 5 min. completely
Up to 24 h for total reaction (25, 26)
Magnesite (MgCO3)
425¥ 500°C / 4h loss up to 80 % (13)
Not dissolved with normal acid treatment (25); 52 days at 50°C H3PO4 (26)
Siderite (FeCO3)
425 550°C / 15 min. 93 % is decomposed (18)
See dolomite (25); 14 days at 50°C H3PO4 (26)
• Possible solution
• dry combustion at TWO DIFFERENT temperatures
• OC is combusted at lower T while higher T are needed for complete decomposition of IC
• Disadvantage
• samples have to be analyzed twice
• equilibration of furnace
• longer analyses times
• possible loss of VOC not detected
Suggested Solution: SRDTC• instrumental device: „Liqui TOC“, Elementar GmbH
• dynamic heater with catalytic post-combustion
• TC,OC and IC from ONE sample with ONE analysis
• no loss of VOC; all carbon is oxidized
• indication of thermally instable carbonates
OVERVIEW OF SOIL SAMPLES
IC material Provider Origin Calcite Mineralogical Collection, Jena
• Magnesite-Cellulose in sand• Magnesite-Wood in sand• Calcite-Cellulose in sand• Calcite-Wood in sand• Calcite-Cellulose in sand-bentonite• Calcite-Wood in sand-bentonite