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NMR Investigations of Natural Organic Matter in Forest Ecosystems Chris E. Johnson Dept. of Civil & Environmental Engineering Syracuse University
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Forest Ecosystem Analysis
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NMR Applications in Forest Ecosystem Studies 1.Plant tissues: −Wood quality −Response to environmental stress −Litter quality
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1.Plant tissues: −Wood quality −Response to environmental stress −Litter quality 2.Soil organic matter: −Decomposition −Accumulation and role as microbial substrate NMR Applications in Forest Ecosystem Studies
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1.Plant tissues: −Wood quality −Response to environmental stress −Litter quality 2.Soil organic matter: −Decomposition −Accumulation and role as microbial substrate 3.Aquatic organic matter: −Similarity to soil organic matter −Substrate for aquatic organisms NMR Applications in Forest Ecosystem Studies
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Northern Hardwood Forest
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Plant Tissues – Wood and Bark
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Spectral Integration Alkyl-CO-Alkyl-CAryl C COOH/ Amide O Aryl
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Plant Tissues – In situ Decomposition
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Sampling with replication Replication is crucial for: Avoiding spurious conclusions Statistical hypothesis testing (CPMAS method may be the only viable option)
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Plant Tissues – (Fresh) Beech Bark
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Plant Tissues – Wood & Bark
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NMR analysis of soils
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Soils – Humification of Organic Matter
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Soil vs. Soil Solution SoilsSoil Solutions
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Contrasting Soil and Solution Composition: % Aromatic C
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Approaches to Quantification 1. Bloch Decay (i.e. Direct Polarization)
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Oa Horizon Soil
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Approaches to Quantification 2. Spin (Ac)counting
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Approaches to Quantification 3. Correction Factors (from VCT Experiments) Oa Horizon Soil
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Approaches to Quantification 4. Spectral Editing Approaches a.Proton Spin Relaxation Editing (PSRE) b.RE storation of S pectra via T CH and T O ne R ho (T1 H ) E diting (RESTORE)
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Conclusions 1.NMR analyses provide useful information for ecological studies. An ideal application for low-field instruments. 2.Replication is essential for most ecological applications. Replication means high sample numbers. High sample numbers mean CPMAS may be the only viable option. 3.Limited quantitative reliability of the CPMAS method is a problem. Without reliable approaches to quantification, NMR will remain a supportive technology in ecosystem science
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