水土保持研究2024，Vol.31Issue(6)：119-129,11.DOI:10.13869/j.cnki.rswc.2024.06.038
侵蚀黄土不同粒级抑制CO2排放的有效沉积厚度
Experimental Study on the Effective Depth for Different Erodible Loess Particles to Inhibit CO2 Emissions
摘要
Abstract
[Objective]The aims of this study are to examine the effects of sediment grain size and thickness on the CO2 transport process in the profile,to clarify the effective deposition thickness of different grain sizes of eroded loess to inhibit CO2 emission under different water content conditions,and to provide a theoretical basis for improving the process of organic carbon mineralization and emission in the sedimentary area.[Methods]By settling fractionation,the loess particles of four different size classes(≥250 μm,250～125 pm,125～63 pm,and≤63 pm)were settled freely through a static water column to form thin soil columns with different thicknesses(0.4 cm,0.7 cm,1.4 cm,and 2 cm).Each sediment column was maintained at field water holding capacity,subjected to constant moisture mineralization,and subsequently amended with 13C-labeled glucose to serve as an independent CO2 source.The released 13C-labeled CO2was traced,and the relative abundance of 13C was analyzed during three stages:constant moisture mineralization,13C-labeled CO2 tracing,and natural desiccation.[Results](1)The average CO2emission rate during constant moisture mineralization(without 13C-labeled CO2)was 0.21 pg/(cm2·h),slightly lower than the 0.35 pg/(cm2·h)during 13C-labeled CO2 tracing,both significantly lower than the 0.9 pg/(cm2·h)during natural desiccation.This indicated that loess sediment layers exhibited varying degrees of inhibitory effects on CO2 emissions under moist conditions.However,upon soil desiccation,CO2 previously sequestered within the soil layer was concentrated and released,weakening the sediment carbon sink effect.(2)The average CO2emission rates for coarse particles(D≥250 pm)were 77.9％,39.6％,and 30.8％higher than for fine particles(D＜63 pm)in the three cultivation stages,respectively.Coarse particles exhibited more pronounced differences in CO2 emission rates and 13C relative abundance compared to fine particles,and this effect was observed one day earlier.(3)Under moist conditions,a sediment thickness of at least 2 cm was required to effectively inhibit CO2transport for particles with diameters≥125 pm.In contrast,sediment thicknesses of only 1.4 cm or even thinner were effective for particles with diameters 63≤D＜125 pm and D＜63 pm in suppressing CO2 diffusion to the surface soil.[Conclusion]This study elucidates the effective sediment depths for inhibiting CO2 transport and emissions in different particle size fractions of loess,and provides the quantitative data for understanding sediment carbon sink effects and mechanisms.关键词
黄土/沉积/碳汇/粒径/CO2/气体传输/13C示踪Key words
loess/sediment/carbon sink/particle size/CO2/gas transport/13C tracing分类
农业科技引用本文复制引用
王文倩,宋媛,张辉,郭胜利,栗现文,胡亚鲜..侵蚀黄土不同粒级抑制CO2排放的有效沉积厚度[J].水土保持研究,2024,31(6):119-129,11.基金项目
中国科学院"西部之光"人才培养计划"西部青年学者"项目(XAB2020YN03) （XAB2020YN03）
陕西省引进高层次人才专(F2020221001) （F2020221001）
