长期自由大气CO2富集下稻田土壤有机碳分布结构与红外光谱特征研究OA北大核心CSTPCD

To explore the impact of long-term field free-air CO2 enrichment(FACE)on soil carbon and nitrogen con-tents and distribution across soil profile,soil samples were collected from China's FACE platform after 15 years of treat-ment,analyzed total soil carbon and nitrogen contents,and their distribution in particulate organic matter(POM)and mineral bound organic matter(MAOM)using wet sieving.Fourier transform infrared spectroscopy was used to determine soil organic carbon functional groups at different depths.The results showed that FACE tended to increase soil total car-bon and nitrogen contents in 0-15 and 15-30 cm depths.Specifically,the increases were 12.52％(C)and 14.32％(N),respectively,in 0-15 cm depth and 21.74％(C)and 33.33％(N),respectively,in 15-30 cm depth.The carbon and nitrogen contents of POM and MAOM were higher in the 0-15 and 15-30 cm depths than those in the 30-45 and 45-60 cm depths,with soil carbon and nitrogen being more stored in MAOM.FACE significantly increased POM carbon content by 25.92％and nitrogen content by 24.45％in the 0-15 cm depth only;FACE increased MAOM carbon and nitrogen con-tents in both 0-15 and 15-30 cm depths and the increases were 32.62％(C)and 59.52％(N)in 0-15 cm depth and 42.34％(C)and 31.06％(N)in 15-30 cm depth,respectively.Similar characteristic peaks of soil infrared spectra were observed for FACE and control treatments across soil profile,but the relative intensities of the main absorption peaks were different.FACE significantly decreased the peak area of aromatic functional groups(1 630 cm-1)in 45-60 cm depth.FACE in-creased the ratio of the absorption peak area in 0-15 and 15-30 cm depths,but decreased 1 630 cm 1/2 920 cm-1 in 30-45 and 45-60 cm depths.The results showed that long-term FACE tended to increase surface soil total carbon and nitrogen contents and the carbon and nitrogen increments were more stored in MOAM.Long-term FACE improved surface soil or-ganic carbon stability and was conducive to carbon sequestration based on soil infrared spectra analyses.