The effect of composition on stability ((14)C activity) of soil organic matter fractions from the albic and black soils

Jie Jin; Ke Sun; Ziying Wang; Lanfang Han; Fengchang Wu; Baoshan Xing

doi:10.1016/j.scitotenv.2015.09.041

The effect of composition on stability ((14)C activity) of soil organic matter fractions from the albic and black soils

Sci Total Environ. 2016 Jan 15:541:92-100. doi: 10.1016/j.scitotenv.2015.09.041. Epub 2015 Sep 21.

Authors

Jie Jin¹, Ke Sun², Ziying Wang³, Lanfang Han³, Fengchang Wu⁴, Baoshan Xing⁵

Affiliations

¹ State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China; Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA.
² State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China. Electronic address: sunke@bnu.edu.cn.
³ State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
⁴ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
⁵ Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA.

PMID: 26402480
DOI: 10.1016/j.scitotenv.2015.09.041

Abstract

The importance of the composition of soil organic matter (SOM) for carbon (C) cycling is still under debate. Here a single soil source was used to examine the specific influence of its composition on stability ((14)C activity) of SOM fractions while constraining other influential C turnover factors such as mineral, climate and plant input. The following SOM fractions were isolated from two soil samples: four humic acids, two humins, non-hydrolyzable carbon, and the demineralized fraction. We examined the isotope ratios of SOM fractions in relation to composition (such as aliphatic and aromatic C content) using solid state (13)C nuclear magnetic resonance (NMR) and thermal analysis. The Δ(14)C values of the fractions isolated from both an albic soil (SOMs-A) and a black soil (SOMs-B) correlated negatively with their peak temperature of decomposition and the temperature where half of the total heat of reaction was evolved, implying a potential link between thermal and biogeochemical stability of SOM fractions. Aryl C contents of SOMs-A determined using (13)C NMR varied inversely with δ(15)N values and directly with δ(13)C values, suggesting that part of aryl C of SOMs-A might be fire-derived. The Δ(14)C values of SOMs-A correlated positively with aliphatic C content and negatively with aromatic C content. We therefore concluded that fire-derived aromatic C in SOMs-A appeared to be more stable than microbially-derived aliphatic C. The greater decomposition of SOMs-B fractions weakened the relationship of their Δ(14)C values with alkyl and aryl C contents. Hence, the role of the composition of SOM fractions in regulating stability might be dependent on the source of specific C forms and their stage of decomposition.

Keywords: (14)C age; Chemical composition; Isotopic analysis; Soil organic matter; Thermal stability.

Publication types

Research Support, Non-U.S. Gov't