不同坡向亚高山草甸土壤有机碳光降解特征及其对铁添加的响应  

Effects of iron addition on photodegradation of soil organic carbon under different slope aspects in a subalpine meadow

作　　者：郭晓宇 程曼 徐茂宏 何新华 文永莉 GUO Xiaoyu;CHENG Man;XU Maohong;HE Xinhua;WEN Yongli(Institute of Loess Plateau,Shanxi University,Taiyuan 030006,China;Shanxi Lishan National Nature Reserve Administration,Jincheng 048211,Shanxi,China;College of Resources and Environment,Southwest University,Chongqing 400716,China)

机构地区：[1]山西大学黄土高原研究所,太原030006 [2]山西历山国家级自然保护区管理局,山西晋城048211 [3]西南大学资源环境学院,重庆400716

出　　处：《生态学杂志》2024年第1期33-40,共8页Chinese Journal of Ecology

基　　金：国家自然科学基金项目(41807025和41807072);山西省应用基础研究计划面上青年基金项目(201901D211131)资助。

摘　　要：在全球中波紫外辐射(UVB)增加的背景下,土壤有机碳(SOC)矿化速率增强是多数陆地生态系统正在经历的重要生态学过程。铁氧化物可以通过吸附或共沉淀作用,影响土壤有机碳的稳定性,在调节碳循环过程起到重要作用。以历山舜王坪亚高山草甸东南坡与西北坡表层土壤为对象,通过为期50 d的室内培养实验,研究铁添加对土壤有机碳光降解的影响机制。结果表明:不同坡向亚高山草甸表层SOC矿化特征不相同,西北坡的SOC累积矿化量和矿化速率均显著高于东南坡,主要是因为西北坡土壤中非晶形铁(Feo-p)含量显著低于东南坡,对SOC保护力较弱;在UVB辐射下,表层土壤有机碳发生了光降解作用,促进了土壤有机碳的矿化。UVB辐射下西北坡的矿化量以及矿化速率增加幅度(即光引发作用)显著高于东南坡;外源添加铁抑制了土壤有机碳矿化,显著降低了土壤碳的累积矿化量和矿化效率,也显著了降低土壤碳的光降解;在未来UVB辐射持续增强下,西北坡向土壤有机碳有较强的光降解潜力,外源添加铁可以在一定程度上缓解表层土壤有机碳光降解作用。本文可为气候变化背景下深入理解亚高山草甸表层土壤有机碳固持机制提供理论依据。Increasing soil organic carbon(SOC)mineralization rate is an important ecological process that most terrestrial ecosystems are undergoing under the context of global UVB enhancement.Iron(Fe)oxides could affect the stability of SOC through adsorption or coprecipitation with carbon,and play an important role in regulating the process of soil carbon cycling.With an incubation experiment,we examined the effects of Fe addition on the photodegradation of SOC in surface soils(0-5 cm depth)from the southeast and northwest slopes of Shunwangping subalpine meadow in Lishan National Nature Reserve,Shanxi,northwest China.There were four treatments:(1)ambient light intensity under natural room light exposure(AM),(2)AM+0.1 g Fe(II)as FeCl2/0.02 kg soil(AM+Fe),(3)minus 280-320 nm ultraviolet-B radiation with Mylar tape under no-Fe addition(-UVB),and(4)-UVB+Fe addition(-UVB+Fe).The UVB radiation was 60μW·cm^(-2) at noon of 12:00 pm and no UVB radiation was detected under the-UVB treatment.Fresh soil was incubated at 25±1 oC under 50%field water-holding capacity for 1,3,5,10,15,20,30,and 50 days.CO_(2) released from incubated soil was absorbed with 0.1 mol·L-1 NaOH and then analyzed firstly with 1 mol·L-1 BaCl2 and then 0.05 mol·L-1 HCl.Results showed that the cumulative mineralization and mineralization rate of SOC were significantly greater in the northwest slope than that in the southeast slope,mainly because the lower concentration of amorphous iron(Feo-p)in soil from the northwest slope led to a weaker SOC protection.Moreover,photodegradation of SOC occurred under UVB radiation,which promoted the mineralization of soil organic carbon.The increasing extent of mineralization amount and mineralization rate under UVB radiation,namely photo-priming,was significantly higher in the northwest slope than that in the southeast slope.The addition of exogenous Fe resulted in a significant decrease of both cumulative mineralization and mineralization efficiency of SOC,as well as a significant decrease of SOC photodegradation in bot

关 键 词：UVB辐射 土壤有机碳矿化 铁氧化物 光化学降解 

分 类 号：S812.2[农业科学—草业科学]