CAJ | 학술논문

从过程考虑,腐殖质的形成和转化主要是微生物主导的生物化学过程,但就其始态和终态的能量水平变化而言,是热力学稳定性问题.在土壤中,影响腐殖质的形成转化的因素很多,如黏粒含量和类型,植被和微生物状况,土壤湿度、温度和空气组成,土壤溶液的化学组成、浓度、酸度和氧化还原状况等.但从热力学角度,为了计算反应平衡常数(logK_R)和吉普斯生成自由能(ΔG_f~θ),如果将温度设为25℃,我们可以将土壤条件诸多因素简化为水活度([H_2O])、氧分压(P_(O_2))和二氧化碳分压(P_(CO_2))这3个参数.之所以简化为这3个参数,因为任何有机成分均是由含有这3种元素的物质形成的,最终又均可以分解为含有这3种元素的H_2O和CO_2.本文按照上述新思路,以黑土为例探讨了胡敏酸(HA)、富里酸(FA)形成转化的驱动因素和热力学稳定性的研究方法,用元素组成-土壤条件参数法计算HA、FA的logK_R和ΔG_f~θ及热力学稳定性范围.同时通过土壤添加有机物料的模拟培养实验研究了氧气和二氧化碳等单因素对HA和FA数量积累的影响.结果表明,黑土HA和FA的元素组成分子式分别为nC_(21)H_(21)O_9N和nC_(24)H_(33)O_(17)N.FA在缺氧、多水和高浓度二氧化碳条件下较稳定;HA则相反.培养实验中,高二氧化碳和低氧气浓度处理使FA与HA的相对比例增加.这一研究方法和结果将有助于解释和推测土壤腐殖质组成的空间变异规律,指导土壤肥力、土壤固碳的调控实践.
종과정고필,부식질적형성화전화주요시미생물주도적생물화학과정,단취기시태화종태적능량수평변화이언,시열역학은정성문제.재토양중,영향부식질적형성전화적인소흔다,여점립함량화류형,식피화미생물상황,토양습도、온도화공기조성,토양용액적화학조성、농도、산도화양화환원상황등.단종열역학각도,위료계산반응평형상수(logK_R)화길보사생성자유능(ΔG_f~θ),여과장온도설위25℃,아문가이장토양조건제다인소간화위수활도([H_2O])、양분압(P_(O_2))화이양화탄분압(P_(CO_2))저3개삼수.지소이간화위저3개삼수,인위임하유궤성분균시유함유저3충원소적물질형성적,최종우균가이분해위함유저3충원소적H_2O화CO_2.본문안조상술신사로,이흑토위례탐토료호민산(HA)、부리산(FA)형성전화적구동인소화열역학은정성적연구방법,용원소조성-토양조건삼수법계산HA、FA적logK_R화ΔG_f~θ급열역학은정성범위.동시통과토양첨가유궤물료적모의배양실험연구료양기화이양화탄등단인소대HA화FA수량적루적영향.결과표명,흑토HA화FA적원소조성분자식분별위nC_(21)H_(21)O_9N화nC_(24)H_(33)O_(17)N.FA재결양、다수화고농도이양화탄조건하교은정;HA칙상반.배양실험중,고이양화탄화저양기농도처리사FA여HA적상대비례증가.저일연구방법화결과장유조우해석화추측토양부식질조성적공간변이규률,지도토양비력、토양고탄적조공실천.
From the aspect of process, formation and transformation of humus are essentially microbe-based biochemical processes, while from that of difference in energy level between the initial and final stages, these processes could also be considered as an issue of the thermodynamic stability. In the soil there are quite a number of factors affecting these processes, such as type and content of clays, vegetation, microorganisms, soil moisture, temperature, air composition, chemical composition and concentration of soil solution, acidity, status of redox, etc. But from the angle of thermodynamics, in order to calculate reaction equilibrium constant (logK_R) and Gibbs energies (ΔG_f~θ) at a given temperature of 25℃, those soil conditions could be simplified into 3 parameters: water activity ([H_2O]), oxygen partial pressure (P_(O_2)) and carbon dioxide partial pressure (P_(CO_2)), since all organic substances are composed of these three elements and would eventually be decomposed into H_2O and CO_2 that contain these three elements. According to this new idea and principle mentioned above, this paper cited black soil as an example to explore approaches to the study on factors driving formation and transformation and thermodynamic stability of HA and FA, and to the calculation of ΔG_f~θ, logK_R and range of thermodynamic stability of HA and FA with "the elemental composition-soil condition parameter method". Meanwhile, a simulated incubation in the lab of soil with organic matter was conducted to study effect of mono-environmental factors like O_2 and CO_2 on accumulation of HA and FA. Results show that the molecular formula of HA and FA is nC_(21)H_(21)O_9N and nC_(24)H_(33)O_(17)N, respectively. In soils low in O_2, high in moisture and high in CO_2 concentration, FA was relatively stable whereas HA was on the contrary. In the incubation experiment, high CO_2 concentration and low O_2 concentration would result in higher FA/HA ratio. This method and the findings in this study could help explain and speculate the rule of spatial variability of the composition of soil humus, and provide guidance to regulation of soil fertility and soil carbon sequestration.