Antecedent soil moisture prior to freezing can affect quantity, composition and stability of soil dissolved organic matter during thaw

作者：Wu, Haohao; Xu, Xingkai^*; Cheng, Weiguo; Fu, Pingqing; Li, Fayun

来源：Scientific Reports, 2017, 7(1): 6380.

DOI：10.1038/s41598-017-06563-8

• FLUORESCENCE SPECTROSCOPY
• MICROBIAL ACTIVITY
• FOREST SOILS
• GAS FLUXES
• WATER
• CARBON
• NITROGEN
• DYNAMICS
• TEMPERATURE
• QUALITY

There are large amounts of dissolved organic matter (DOM) released into the soil during spring thaw, but its bioavailability and components are still unknown. The quantity, composition and stability of DOM in water extracts of forest soils during thaw were studied after two-month freezing with 9 levels of soil moisture ranging from 10% to 90% water-filled pore space (WFPS), by measuring soil carbon dioxide (CO2) flux, biodegradable dissolved organic carbon (BDOC) and nitrogen (BDON), ultraviolet absorbance and parallel factor analysis of fluorescence excitation-emission matrices. Concentrations of BDOC, BDON, DOC and DON were lowest around 30% WFPS and relatively higher and lower soil moisture both increased DOM and BDOM concentrations in thawing soil. With increasing WFPS, the dominant component of soil DOM changed from humic acid-like substances to fulvic acid-like substances and the biological origin of DOM increased gradually. The protein-like component accounted for 8-20% of soil DOM and was affected by vegetation type and WFPS singly and interactively. The results implied that forest soils with more than 50% WFPS before winter freezing could release large amounts of fulvic acid-like DOM, which would be easily biodegraded and emitted as CO2 or run off with ground water during spring snow thaw.

• 出版日期2017-7-25
• 单位中国科学院大学; 中国科学院大气物理研究所; 辽宁石油化工大学; 大气边界层物理与大气化学国家重点实验室