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1.
T. A. Arkhangel’skaya 《Eurasian Soil Science》2009,42(2):162-172
Functional dependences of the thermal diffusivity of soil horizons on their water contents obtained via parameterization of experimental curves are used for the mathematical modeling of the soil temperature regime. If there are no experimental data on thermal diffusivity, parameters of the functional dependence may be calculated from data on the major soil properties. A lognormal function describes experimental dependences of the thermal diffusivity of soil horizons on their water content more accurately than power and polynomial functions. Regression equations making it possible to calculate the thermal diffusivity of gray forest soils on the basis of data on their bulk density, water content, organic matter content, and particle-size distribution are suggested. 相似文献
2.
土壤热参数确定方法比较与修正 总被引：4，自引：4，他引：0
土壤热参数是分析研究土壤热传递的基本参数,寻求确定热参数简单方法是研究的热点问题.该文利用自行研制的土壤热特性试验系统,测定了4种质地土壤热特性,计算了不同质地土壤在不同含水率、不同容重情况下的热扩散率,进一步推导出不同情况下的导热率,并与Campbell经验公式计算的导热率进行比较,发现计算值与实测值相差较大,并对Campbell经验公式进行修正,同时对修正经验公式进行分析、检验,并讨论此经验公式的适用范围.结果显示在体积含水率小于20%的时候,修正经验公式可以用于计算导热率. 相似文献
3.
Eurasian Soil Science - This work provides parameters of the soil thermal diffusivity vs. water content function for eight textural classes. The experimental thermal diffusivity vs. water content... 相似文献
4.
Two empirical models have been developed describing the relationship between the thermal diffusivity in soils and their properties in the solonetzic complex. The first model represents a regressive relationship between the thermal diffusivity and the most dynamic parameters (moisture, density, and their derivatives) of the soil physical status. The second (more comprehensive) model is based on the first one and takes into account the properties that appear to be the most informative about the variation of the heat transfer velocity along the solonetz profile, i.e., the indices of the particle-size distribution (the content of physical clay and fine and medium silt); the content of humus, easily soluble salts, and carbonate CO2; and the total alkalinity index. 相似文献
5.
原状土与装填土热特性的比较 总被引：2，自引：2，他引：0
土壤热特性是研究土壤—植物—大气系统中能量传输的必要参数。目前的研究集中在室内装填土柱上热特性与含水率、质地、温度和体积质量(容重)等因素的关系,田间条件下土壤结构对热特性影响的报道很少。该研究通过比较2种质地土壤田间原状土和室内装填土热特性的差异,初步探讨了不同含水率范围内结构形成对土壤热特性的影响。采集田间原状土,在室内利用热脉冲技术测定其热容量、热导率和热扩散率;然后将样品磨碎、过2mm土筛,填装后得到相同体积质量和含水率的装填土壤样品,并测定其热特性。结果表明,装填土和原状土的热容量基本一致;在中等含水率区域(砂壤土:0.07～0.24m3/m3;壤土:0.15～0.31m3/m3),重新装填后砂壤土和壤土的热导率分别降低了9.7%和9.8%。另外,结构形成增加了土壤热扩散率,在中等含水率区域尤其明显;在接近饱和区域,原状土与装填土的热扩散率趋于一致。因此,土壤结构形成对土壤热容量没有显著影响,但提高了中等含水率区域土壤的热导率和热扩散率。 相似文献
6.
地表覆盖对土壤热参数变化的影响 总被引：2，自引：0，他引：2
覆盖条件下土壤热性质的研究对于包气带水热运移及覆盖技术的应用均有重要意义。使用11针热脉冲探头对沙黄土不同深度(6 mm、18 mm、30 mm)的土壤热扩散率、热容量和热导率三个热参数进行测定,并进行地表覆盖(石子覆盖、秸秆覆盖)处理,旨在探究覆盖条件下表层土壤热性质动态变化过程及土壤热参数与水分的内在联系。结果表明:(1)相对于裸土,石子和秸秆覆盖条件下土壤热参数增大,且覆盖对于靠近表层土壤热参数的影响更加明显;(2)随降雨的发生,土壤热参数均增大,在两次降雨期间,土壤热参数逐渐减小,覆盖与裸土热参数差异逐渐增大;(3)三个热参数随降雨的发生,其动态变化过程表现不同,热容量对降雨的响应最为敏感,热导率次之,热扩散率开始减小的时间较热导率和热容量滞后,三个深度滞后时间均在48 h以上,而且覆盖以后热扩散开始减小的时间较裸土推迟(48 h以上)。土壤容重不变的情况下,在频繁干湿交替的过程中土壤水分为土壤热参数变化的最主要影响因素。覆盖条件下土壤热参数与土壤含水量关系研究表明:石子和秸秆覆盖条件下土壤热参数与土壤含水量的变化关系与裸土条件下一致,热导率与含水量呈幂函数增加的趋势,热容量随含水量线性增加,热扩散率随含水量增加先增后减,本研究所用沙黄土热扩散率峰值对应的含水量在0.20 cm3cm-3左右。由以上结果可以发现覆盖对近表层土壤热参数的动态变化有显著的影响,覆盖的保水效应直接影响土壤热参数的变化。 相似文献
7.
Thermal diffusivity of the upper horizons of leached meadow-chernozemic soils varies in dependence on the soil water content
within the following limits: 1.20–4.11 × 10−7 m2/s for the Ap horizon, 1.21–3.85 ×10−7 m2/s for the A1 horizon, and 1.35–3.73 × 10−7 m2/s for the A1B horizon. The relationships between the thermal diffusivity and the soil water content are described by S-shape
curves with a long gently inclined segment within the range of water contents of <0.20 cm3/cm3, a distinct rise in thermal diffusivity within the water contents from 0.20 to 0.30–0.35 cm3/cm3, and a flattened or somewhat declining segment in the area with the high (>0.30–0.35 cm3/cm3) water contents. The thermal diffusivity of air-dried soil samples correlates with the physical clay (<0.01 mm) content.
The Pearson correlation coefficient for these two variables equals −0.67 and is statistically significant at the significance
level of 0.05. Regression equations allowing one to calculate the thermal diffusivity of the investigated soil horizons on
the basis of data on the soil water content have been obtained. 相似文献
8.
农田土壤热特性受地表能量平衡、土壤特性和作物生长的影响,存在显著的时空变异性,而目前缺乏关于作物行尺度土壤热特性变异特征的研究。本研究采用定位试验,利用热脉冲技术监测了玉米农田行尺度四个位置处（1/2行间、1/4行间、棵下和棵间）两个深度（2 cm和4.5 cm）土壤热特性的时空变异规律,并分析了土壤温度和含水量对土壤热特性的影响。结果表明,在试验期间,热导率、热容量和热扩散率的变化范围分别为0.66—2.22 W/(m?K),1.46—4.49 MJ/(m3?K)和4.07×10-7—6.88×10-7 m2/s。降雨之后,热导率和热容量增加,且随着时间推移逐渐降低。2 cm深度的土壤热特性的波动较大,棵下位置土壤热导率和热容量值最大,波动最为明显;土壤热扩散率在1/2行间位置最大。在4.5 cm深度,各位置土壤热特性变化趋势基本一致,土壤热导率和热容量值在1/2行间位置最大,土壤热扩散率在棵间位置最大。综合两个土层数据得出1/4行间位置的热导率和热容量更具代表性。本研究中土壤热特性对土壤含水量的响应规律较为明显,随着土壤含水量增加,热导率和热容量线性增加,热扩散率则表现出先增加后降低的规律。在测定的土壤温度范围内,热扩散率随土壤温度增加呈上升趋势。该研究可以为农田水热管理提供理论依据。 相似文献
9.
Alteration of soil thermal properties by structure formation 总被引：2，自引：0，他引：2
Temperatures were measured in a disturbed and a structured loess soil to study the influence of aggregation on thermal properties. The disturbance was done by mechanically destroying soil aggregates, and the structured soil was obtained by subjecting the disturbed soil to several irrigation and drying cycles. In all soils, five harmonics of a Fourier-series representation accounted for ≥99% of the variance of daily soil surface temperatures, and two to three harmonics did so below the soil surface. For soil water contents between 0.04 and 0.23 m3 m-3, the apparent thermal diffusivity, computed by the harmonic method, was higher in the structured soil than in the disturbed soil. The same was true for the apparent thermal conductivity, since the volumetric heat capacities of both the disturbed and structured soil were similar. The differences in the apparent thermal diffusivity and conductivity were attributed to increased heat conduction and water vapour transport in the structured soil. 相似文献
10.
11.
Shein E. V. Pozdnyakova A. D. Sorokina N. V. Dembovetsky A. V. Shvarov A. P. Il’in L. I. 《Eurasian Soil Science》2019,52(11):1363-1368
Eurasian Soil Science - The temperature regime and the dependence of thermal diffusivity on the volumetric water content in high-ash drained peat soils (Sapric Drainic Histosols (Lignic)) on woody... 相似文献
12.
A series of models has been proposed for estimating thermal diffusivity of soils at different water contents. Models have been trained on 49 soil samples with the texture range from sands to silty clays. The bulk density of the studied soils varied from 0.86 to 1.82 g/cm3; the organic carbon was between 0.05 and 6.49%; the physical clay ranged from 1 to 76%. The thermal diffusivity of undisturbed soil cores measured by the unsteady-state method varied from 0.78×10–7 m2/s for silty clay at the water content of 0.142 cm3/cm3 to 10.09 × 10–7 m2/s for sand at the water content of 0.138 cm3/cm3. Each experimental curve was described by the four-parameter function proposed earlier. Pedotransfer functions were then developed to estimate the parameters of the thermal diffusivity vs. water content function from data on soil texture, bulk density, and organic carbon. Models were tested on 32 samples not included in the training set. The root mean square errors of the best-performing models were 17–38%. The models using texture data performed better than the model using only data on soil bulk density and organic carbon. 相似文献
13.
Drainage is often claimed to increase soil temperatures in early spring by decreasing the soil's heat capacity. Measurements of water table depth, soil water content and soil temperature were made during winter and spring on mole-pipe drained and undrained plots of a silt loam soil under pasture. Despite differences in water table depth and soil water content, drainage had no observable effect on soil temperature. Laboratory measurements of the thermal properties of soil cores at a matric potential of ?4kPa and then at saturation showed the volumetric heat capacity increased from 3.1 to 3.3 MJ m?3 K?1, with a proportional increase in the thermal conductivity from 1.1 to 1.2 W m?1 K?1. The thermal diffusivity remained unchanged. These values were used in a numerical simulation of the effects of drainage on the seasonal and diurnal oscillations in soil temperature. It is argued that the soil heat flux under pasture in spring is unaffected by drainage. The predicted temperature differences due to drainage are of the order of 0.2°C. As differences of this magnitude were observed between replicate thermometers in the field, it follows from the calculations above that any differences in soil temperature due to drainage would be too small to detect. 相似文献
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15.
土壤盐分对土壤水分扩散率的影响 总被引：3，自引：0，他引：3
土壤水分扩散率是土壤水盐运动的重要参数之一。利用水平土柱吸渗法对不同含盐量土壤的水分扩散率与含水量之间的关系进行了测定,并建立了土壤水分扩散率、土壤含水量与Boltzmann参数间的定量关系。结果表明,不同含盐量土壤之间的水分扩散率存在明显差异,表现在相同土壤含水量情况下,土壤水分扩散率随土壤含盐量的增大而增大;土壤水分扩散率随土壤含水量增大而单调增大,且当含水量接近饱和时,土壤水分扩散率接近无穷,通过建立含水量与土壤水分扩散率的经验函数关系能较好地反映了土壤含水率与土壤水分扩散率间的关系。 相似文献
16.
Effect of reduced air pressure on soil thermal conductivity over a wide range of water content and temperature 总被引：1，自引：1，他引：1
To clarify the role of air molecules in coupled heat and mass transfer in soil, we measured the thermal conductivity of three kinds of soil (Ando soil, Red Yellow soil, and Toyoura sand) under reduced air pressure over a wide range of water content and temperature (10–75°C). The thermal conductivity increased sharply under reduced air pressure above a critical water content of the soil, becoming several times larger than that under normal pressure (101 kPa). The maximum thermal conductivity for each soil was obtained below 75°C and was similar to the thermal conductivity of some metals such as Mn, Hg and stainless steel. When the soil was drier than its critical water content, the thermal conductivity did not increase under reduced air pressure. The hydraulic diffusivity at the critical water content for each soil was of the order of 10?8 m2 s?1. This suggests that the latent heat transfer is enhanced by the circulation of the condensed water. However, very little is known about the effect of circulating water on the latent heat transfer under reduced air pressure. To make this clear, the thermal conductivity would need to be measured in the steady state under reduced air pressure. 相似文献
17.
探针有限特性对热脉冲技术测定土壤热特性的影响 总被引：1，自引：1，他引：0
在利用热脉冲方法测定热特性时,通常对探针形状做理想化处理,即假设探针为线性热源,热导率无限大而热容量为零。在实际应用中,探针本身的有限特性(有限半径以及有限热容量)会导致热特性测定误差。为了研究探针有限特性对热脉冲技术测定土壤热特性的影响,该研究采用改进的热脉冲探针(直径2 mm、长度40 mm、间距8 mm)测定土壤热特性,并分别使用PILS(pulsed infinite line source,无限长线性脉冲热源)和ICPC(identical cylindrical perfect conductors,近似圆柱形完美导体)2种理论估计土壤热特性,比较分析了探针有限特性对热脉冲技术测定热特性结果的影响。结果表明:1)与PILS理论相比,利用ICPC理论拟合得到的温度升高曲线,可以有效减少探针有限半径和热容量对土壤热特性测定结果的影响。与ICPC理论相比,在0.03~0.25 m3/m3的含水率范围内,用PILS理论得到的砂土热扩散率和热导率分别偏低11.8%和5.2%;与模拟热容量相比,PILS和ICPC理论分别将热容量高估16.1%和7.9%;2)探针有限特性对土壤热特性的影响与含水率有关:在干土上最大;随着土壤含水率的增加,其影响逐渐降低。该研究对提高热脉冲技术测定土壤热特性的准确性具有指导意义。 相似文献
18.
亚热带土壤导水特征对钠盐溶液浓度的响应 总被引：1，自引：1，他引：0
再生水中高浓度钠盐溶液入渗对土壤水力特性的影响是长期低质水灌溉引起土壤生态环境退化的关键问题之一。该文采用定水头渗透法、一维水平土柱吸渗法测定不同浓度钠盐溶液条件下亚热带地区黏性潮土、沙性潮土、红壤、水稻土、紫色土共5种土壤的水动力学参数,分析了土壤理化性质和钠盐溶液浓度对土壤导水特征的影响及其作用机制。结果表明:土壤粉粒、交换性钙及交换性镁含量具有促进土壤水分运动的作用,而土壤黏粒、交换性铁及交换性铝含量则表现出抑制作用。与蒸馏水处理相比较,钠盐加快了土壤水分黏性潮土、沙性潮土及水稻土中的土壤水分运动速率,分别可最高提升其土壤水分扩散率为22.0%、37.3%、39.7%;钠盐减缓了红壤和紫色土的水分扩散速率,溶液钠盐浓度越高,其抑制作用越明显。土壤饱和导水率随溶液盐浓度升高呈先降后升的趋势,1~10 g/L钠盐浓度范围内土壤饱和导水率与钠盐浓度具有良好的抛物线关系(R^2>0.807),各土壤导水率最小极值点的钠盐浓度在5 g/L左右。因此,再生水灌溉利用时其盐浓度适度控制低于其极值点浓度。 相似文献
19.
土壤含水量、温度、热特性以及其它物理参数的动态监测是描述土壤中各种物理、化学和生物过程的基础。本文利用热脉冲 -时域反射技术 (Thermo -TDR)对不同质地土壤的含水量、电导率、温度、容积热容量、导热率和热扩散系数进行了测定 ,并利用土壤容积热容量与容重和含水量的关系 ,计算了土壤容重、通气孔度和饱和度。结果表明 ,Thermo -TDR技术能够提供可靠的土壤含水量、温度、容重、通气孔度和饱和度的信息。本文也分析了Thermo -TDR技术的测定误差并探讨了降低误差的对策 相似文献
20.
The primary objective of this study was to investigate the impact of observation scale on the estimation of soil thermal properties. Transients are usually filtered out and ignored when classical Fourier approaches are used to deconstruct and model temperature time series. It was hypothesized that examination of such transients may be more important in identifying and quantifying short-term perturbations in internal soil heat transfer induced by agronomic disturbances. Data-logged temperatures were collected at 10-minute intervals from thermistor probes installed at 10 and 25 cm depths in isolated areas of two grassed plots. One plot （6T） had been treated twice with 6 Mg ha^-1 composted turkey litter as received. The other plot （NPK） was fertilized at the same time with NPK fertilizer. Various methods were used to analyze the series to obtain apparent soil thermal diffusivity （D-value） at various time scales. Results supported the hypothesis that short-term differences in internal soil heat transfer between the 6T and NPK plots were more manifest and effectively captured by estimated D-values calculated from the monthly and daily partial series. The 6T plot had higher soil organic matter content than the NPK plot and had lower apparent soil thermal diffusivity. Diurnal soil temperature amplitudes, required to calculate the mean D-values from partial series, were more effectively obtained using a temperature change rate method. The more commonly used Fourier analysis tended to be effective for this purpose when the partial series reasonably presented well-defined diurnal patterns of increasing and decreasing temperatures. 相似文献