黑土层不同粒级结构下有机碳矿化的模拟研究  

Simulation of Organic Carbon Mineralization in Black Soil Layers with Different Particle Size Structures

作　　者：张小真 宋媛 胡亚鲜 ZHANG Xiaozhen;SONG Yuan;HU Yaxian(Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources,Yangling,Shaanxi 712100,China;University of Chinese Academy of Sciences,Beijing 100049,China;Institute of Soil and Water Conservation,Northwest A&F University,Yangling,Shaanxi 712100,China)

机构地区：[1]中国科学院水利部水土保持研究所,陕西杨凌7121002 [2]中国科学院大学,北京100049 [3]西北农林科技大学水土保持研究所,陕西杨凌712100

出　　处：《水土保持研究》2023年第2期74-80,共7页Research of Soil and Water Conservation

基　　金：中国科学院2020年度“西部青年学者项目”(XAB2020YN03);科技部“十三五”国家重点研发计划(2018YFC0507000)。

摘　　要：东北黑土坡耕地侵蚀沉积分异明显,且冻融交替频繁,但各坡位土层结构以及通气孔隙度随含水率和温度的季节性变化对有机碳矿化和CO_(2)扩散效率的影响机理尚不清楚。以典型黑土坡耕地为研究对象,采集未侵蚀区表土风干、筛分后,选取粗(0.5~1 mm)、细(<0.125 mm)两种粒级,分层回填,全粗、全细、上粗下细、上细下粗4种土柱模拟典型坡位土层结构,对比分析冻融与非冻融不同温度梯度下,各土层结构CO_(2)释放速率变化特征。结果表明:非冻融变温(5~30℃)条件下,各土层结构CO_(2)释放速率存在显著差异,其中上粗下细土层CO_(2)释放速率均值为14.45μg/(kg·h),显著高于其他土层,增幅达20%~59%,说明不同土层间土壤颗粒大小和上下堆叠关系对CO_(2)传输效率有重要调控作用。经两次冻融作用后,0~15℃变温培养中,各土层间无显著差异,上粗下细土层CO_(2)释放速率均值为4.17μg/(kg·h),略高于其他土层,说明冻涨融缩效应削弱了不同土层结构之间孔隙结构和联通性差异,减弱了因土层结构不同而导致的CO_(2)释放速率的差异。研究结果明确了黑土层不同粒级上下堆叠结构及孔隙连通性对有机碳矿化的影响,可为深化侵蚀环境下碳源强度的定量评价提供理论依据。On the rolling slopes in northeast China, erosion and deposition often result in distinct soil layer structures at different soil slope positions where frequent freeze-thaw cycles can further alter soil water and porosity distribution. However, how different soil layer structures with distinct porosity and connectivity respond to varying water and temperature changes, and how they affect soil organic carbon mineralization and CO_(2)emissions are far from being fully understood. The Mollisol samles were collected from the farmlands with gentle and extended slopes in the northeastern China, air-dried and then sieved. Soil particles of two sizes, coarse(0.5~1 mm) and fine(<0.125 mm), were refilled into different soil columns to simulate four typical slope soil structures: all coarse structure all fine structure, upper coarse + lower fine structure, and upper fine + lower coarse structure. The soil columns were incubated and their CO_(2)emission rates were measured at different temperature gradients to compare the different responses of the four soil structures to non-freeze-thaw and freeze-thaw conditions. The results show that under non-freeze-thaw conditions(over 5~30℃), CO_(2)emission rates among the four soil structures differed significantly, the average CO_(2)emission rate of the upper coarse + lower fine soil layers was 14.45 μg/(kg·h) which was 20%~59% higher than those of the other three soil structures, illustrating that the CO_(2)transfer efficiency was profoundly influenced by soil particle size and their overlaying patterns;after two freezing-thawing cycles, the differences of CO_(2)emission rates among the four soil structures became insignificant over 0~15℃, the average CO_(2)emission rate of upper coarse + lower fine soil column was 4.17 μg/(kg·h) which was merely slightly higher than those of the other three soil structures implying that freeze-thaw could change the structure and connectivity of soil pores, thereby weakening the differences of soil layer structure on CO_(2)emissions. These f

关 键 词：黑土 土层结构 孔隙度 有机碳矿化 冻融 

分 类 号：S152.4[农业科学—土壤学]