Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
NMR Investigations of Natural Organic Matter in Forest Ecosystems Chris E. Johnson Dept. of Civil & Environmental Engineering Syracuse University Forest Ecosystem Analysis NMR Applications in Forest Ecosystem Studies 1. Plant tissues: − Wood quality − Response to environmental stress − Litter quality NMR Applications in Forest Ecosystem Studies 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 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 Maine White Mountain National White MountainForest Hubbard Brook Experimental Forest National Forest # # New Hampshire N Northern Hardwood Forest Plant Tissues – Wood and Bark Spectral Integration COOH/ O Amide Aryl Aryl C O-Alkyl-C Alkyl-C Plant Tissues – In situ Decomposition Sampling with replication Replication is crucial for: • Avoiding spurious conclusions • Statistical hypothesis testing (CPMAS method may be the only viable option) Plant Tissues – (Fresh) Beech Bark Plant Tissues – Wood & Bark NMR analysis of soils Oa Horizon Bh Horizon Bs1 Horizon 250 200 150 100 50 Chemical Shift (ppm) 0 -50 Soils – Humification of Organic Matter Soils – Humification of Organic Matter Soil vs. Soil Solution Soils Soil Solutions Oa Horizon Bh Horizon Bs1 Horizon 250 200 150 100 50 Chemical Shift (ppm) 0 -50 250 200 150 100 50 Chemical Shift (ppm) 0 -50 Contrasting Soil and Solution Composition: % Aromatic C W1 (uncut) W5 (clear-cut) Oa Oa 12.6 14.3 9.8 14.6 Bh Bh 16.8 10.8 Bs 14.9 15.5 Bs 20.2 14.7 20.7 13.7 Stream 15.1 19.4 Stream Approaches to Quantification 1. Bloch Decay (i.e. Direct Polarization) Approaches to Quantification 1. Bloch Decay (i.e. Direct Polarization) Oa Horizon Soil Approaches to Quantification 2. Spin (Ac)counting Approaches to Quantification 3. Correction Factors (from VCT Experiments) Oa Horizon Soil Approaches to Quantification 4. Spectral Editing Approaches a. Proton Spin Relaxation Editing (PSRE) b. REstoration of Spectra via TCH and T One Rho (T1rH) Editing (RESTORE) 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