Determination of low molecular weight dicarboxylic acids and organic functional groups in rhizosphere and bulk soils of Tsuga and Yushania in a temperate rain forest

Abstract

Low molecular weight organic acids (LMWOAs) derived from root exudates, decomposing organic matter, and other sources are important ligands. The species of these LMWOAs in the Tsuga rhizosphere soil (TRS), and Yushania rhizosphere soil (YRS), and bulk soil (BS) from an alpine forest region were identified. LMWOA and organic functional groups were used to those fresh twigs and leaves, litters, and roots as comparison. The objectives of this study were to (i) develop a method that could be used to determine LMWOAs in soil solution by gas chromatography (GC), (ii) assess methods for processing LMWOAs in soil samples, and (iii) determine the relative proportions of organic carbon functional groups in the TRS, YRS and BS, and fresh plant materials with13C nuclear magnetic resonance (13C NMR) analysis. The proportion of organic acid contents followed the order of YRS > TRS > BS, and also showed significant differences (P O-alkyl-C > N-alkyl-C > acetal-C > aromatic-C > carboxylic-C > phenolic-C.