【作者】 李顺姬；

【导师】 张兴昌；

【作者基本信息】 西北农林科技大学 ， 环境工程， 2009， 硕士

【摘要】 本研究以黄土高原几种典型土壤为研究对象,通过对0¹5cm和15³0cm土层总有机碳、活性有机碳库及其各组分和土壤理化性质的测定,研究了不同土壤类型和土层深度对总有机碳（TOC）、潜在可矿化碳（Cp）、微生物量碳（SMBC）、易氧化有机碳（ROC）和活性有机碳（LOC）的影响,揭示了土壤理化性质与活性有机碳库的关系,为进一步研究该区域土壤有机碳分布特征,丰富土壤有机碳研究内容,为黄土高原生态环境建设顺利进行提供理论依据。取得的主要结果和结论如下:1.黄土高原土壤TOC介于0.20¹6.44 g·kg^-1,处于较低水平。6类土壤TOC含量大小顺序为:褐土>黑垆土>黄绵土>湘黄土>风沙土>潮土,差异达极显著水平。2.土壤有机碳累计矿化量集中在0.064⁰.596 gCO₂-C·kg^-1范围内,有机碳潜在矿化量分布在0.06⁰.74 gC·kg^-1之间。在培养初期土壤有机碳日均矿化量较高,之后逐渐降低。土壤类型对黄土高原土壤有机碳矿化影响较大,不同土壤有机碳的日均矿化量、累积矿化量和矿化率具有显著差异。一级动力学方程能很好模拟黄土高原土壤有机碳矿化特征。供试土壤Cp和有机碳矿化速率常数（k）均较低,分别在0.116⁰.329 gC·kg^-1和4.55⁸.57×10-5d^-1范围之内。不同土壤的Cp值变异较大,而k和Cp/TOC无明显的变异。3.供试土壤SMBC、ROC和LOC分别介于15.59²03.90 mg·kg^-1、0.174¹4.565 g·kg^-1和0.031⁴.269 mg·g^-1范围内,变异系数较大,区域分布不均匀。土壤类型对土壤微生物学特性和有机碳的氧化稳定性影响较大,不同土壤的SMBC、微生物熵、微生物代谢熵（qCO₂）、ROC、Kos和LOC具有极显著差异性。4.土层深度对土壤TOC、活性有机碳库各组分及其在TOC中所占比例均无显著影响,除qCO₂和Kos外,其余各活性有机碳库含量及其占TOC比例均随土层加深而呈减少趋势。5.黄土高原6种典型土壤中褐土和黄绵土的活性有机碳库含量较高,生物有效性强,有机碳氧化稳定性高,土壤固碳能力较好;潮土和风沙土的活性有机碳库水平较低,有机碳固存能力较弱,碳损失较大。6.土壤Cp、SMBC、ROC、LOC与土壤总有机碳、全氮、全磷、速效钾、含水量、粘粉粒含量和经度之间存在显著正相关关系,土壤活性有机碳库各组分随土壤肥力、粘粉粒的增加而增加。土壤活性有机碳库含量从南至北,从东到西均有不同程度的下降。Cp、SMBC、ROC、LOC两两之间均存在着极显著相关性。qCO₂和Kos与活性有机碳库各组分都呈负相关关系,但这两者之间具有极显著正相关关系。ROC对土壤TOC含量的变化最敏感,能够作为指示土壤总有机碳变化的灵敏指标。更多还原

【Abstract】 In this paper, several types of typical soils in Loess Plateau were collected as research objects. Total organic carbon, different fractions of active organic carbon pool and physicochemical properties of soil in 0¹5cm and 15³0cm layers were measured. In this study, the objective was to research the effects of soil types and depth on total organic carbon （TOC）, potential mineralizable carbon （Cp）, soil microbial biomass carbon （SMBC）, readily oxidizable organic （ROC） and labile organic carbon （LOC）, and reveal the correlation between soil physicochemical properties and active organic carbon pool. This research had provided theoretical basis for further studying about the distribution characteristic of soil organic carbon, enriching the research contents of soil organic carbon, and ensuring ecological environment construction in Loess Plateau carried out smoothly. The main results and conclusions are as follows:1. The TOC of soil in Loess Plateau ranged from 0.20 to 16.44 g·kg^-1, it was a low level. The size order of TOC was cinnamon soil> dark loessial soil> loessial soil> xiang yellow soil> aeolian sandy soil> alluvial soil, and the difference between 6 types of soil was extremely significant level.2. Content of accumulative amount of CO₂-C and Cp of soil organic carbon ranged from 0.064⁰.596 gCO₂-C·kg^-1 and 0.06⁰.74 gC·kg^-1, respectively. The data had a wider dispersion, and variability of data was stronger. The daily amount of SOC mineralization in early time of incubation was greater than the values in late time, i.e., mineralization rate decreased gradually. The soil types had great influence on SOC mineralization, difference of daily average amount, accumulative amount and rate of SOC mineralization between different soil types reached to significant level（P <0.05）. The dynamics of SOC mineralization preferably followed the first-order kinetics. Both Cp and k values of all soils were low, Cp ranged from 0.116 to 0.329 gC·kg^-1 and k ranged from 4.55 to 8.57×10-5 d^-1. The soil types had great influence on Cp values, but had no obvious effect on k values and Cp/TOC ratio. 3. The content of SMBC, ROC, LOC of experimental soil ranged from 15.59²03.90 mg·kg^-1, 0.174¹4.565 g·kg^-1 and 0.031⁴.269 mg·g^-1, respectively. The coefficients of variation were high, and regional distribution of arctive organic carbon pool was uniform. The soil types had great influence on soil microbial characteristics and oxidative stability of soil organic carbon, difference of SMBC concentration, SMBC/TOC, qCO₂ , ROC Kos and LOC concentration between different soil types reached to extremely remarkable level.4. Soil depth had no obvious effect on content of TOC, fractions of active organic carbon pool and ration of active organic carbon to TOC. Most of indexes slightly decreased with the increase of soil depth, but the content of qCO₂ and Kos in subsoil were higher than that of upper layer of soil.5. The concentrations of active organic carbon pool in cinnamon soil and loessial soil were higher than these of other soils, the bioavailability, oxidative stability and ability of carbon fixation of these two soils were better. The concentrations of active organic carbon pool in alluvial soil and aeolian sandy soil were lower; these two soils had weak ability to fix carbon, the organic carbon loss much.6. There was a significant positive correlation between TOC, total nitrogen, total phosphorus, water content, longitude, clay content, silt content and concentrations of active organic carbon pool. It means that fractions of active organic carbon pool significantly increased with increasing soil nutrients, clay content and silt content. Contents of all fractions of active organic carbon pool from south to north, from east to west gradually decreased. Fractions of active organic carbon pool were not only significantly correlated to TOC but also interrelated themselves. qCO₂ and Kos were negatively correlated with all fractions of active organic carbon pool, but there was an obvious positive correlation between themself. ROC was more sensitive to variation of soil TOC, and it was able to be sensitive index to reflex TOC changes.更多还原