Determination of forest soil organic nitrogen determination using technique of X-ray absorption near-edge structure

Abstract

The forest soil organic N was investigated using N K-edge X-ray absorption near-edge structure (XANES) to gain an insight into the relationship between N speciation and its transformation in quantity. Soil samples were collected from spruce, hemlock and pine forests in central Taiwan. Results showed that various organic N types could be revealed by XANES spectra. Amide and pyrrolic N are the major parts of the composition in the humic substance, soluble organic nitrogen and original soils. The relative distribution of N speciation differed in treatments and vegetations samples. The spruce had a significant difference from the hemlock in soluble organic nitrogen (SON) spectra at 402.3 eV energy peak. In the A-horizon soils, the relative amount of pyridinic N was much higher than that in the O-horizon soils, indicating N transformation in quantity in the mineral horizon was different from that in the organic horizon, which might play an important role in N cycling of forest ecosystems.

Keywords

Forest soils / N K-edge XANES spectra / Nitrogen speciation Organic nitrogen / Nitrogen transformation

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