共查询到18条相似文献，搜索用时 171 毫秒
1.
不同斥水剂作用下土壤斥水度测定及其变化规律 总被引：3，自引：2，他引：1
为获得不同斥水剂作用下土壤斥水度的变化规律,分别采用十二烷基硫酸钠、硅烷偶联剂KH-550与二氯二甲基硅烷改性砂土和十八烷基伯胺改性黏土,获得了不同斥水程度的改性土壤,并采用滴水穿透时间法、酒精溶液入渗法和接触角测定法获得了改性后土壤的斥水度及其随时间变化规律。结果表明:1)二氯二甲基硅烷改性砂土表现为极度斥水等级,且斥水性长期稳定,可作为制备斥水砂土的优选;硅烷偶联剂改性砂土的斥水性初期不明显,随着时间增长明显增强,最终可达极度斥水等级;但此类改性砂土易结块,均匀性及分散性较差,不推荐作为制备斥水砂土的优选;十二烷基硫酸钠改性砂土的斥水性不明显,且改性方法复杂耗时,不宜用来制备斥水砂土。2)当十八胺含量分别为0.2%、0.3%和0.6%时,改性黏土分别可达中等、严重和极度斥水等级,斥水性长期稳定,可作为制备斥水黏土的优选。3)将十八胺含量为0.5%的改性黏土掺入天然砂土混合制得的改性混合土,亦有不同程度的斥水性。当改性黏土含量为1%~3%时,改性混合土尚无明显斥水性;当改性黏土含量为3%~10%时,改性混合土斥水等级为中度;当改性黏土含量为10%~50%时,改性混合土斥水等级可达到严重。该成果可为深入研究土壤斥水性及其工程应用提供参考。 相似文献
2.
土壤初始含水率对优先流的影响简 总被引：1，自引：0，他引：1
土壤中优先流的存在会造成肥料利用率降低以及土壤深层甚至地下水污染.为确定土壤初始含水率对优先流的影响,通过室内含大孔隙土柱定水头入渗实验,以长武黑垆土及渭河砂土为研究对象,分析不同土壤初始含水率对优先流的影响.结果表明：1）相同质地,当土壤初始含水率大于其斥水性的峰值含水率时,湿润锋运移深度随着土壤初始含水率的增大而增大,反之湿润锋运移深度随着初始含水率的增加而减少,不同质地土壤湿润锋运移速度随土壤粉粒质量分数升高而减慢;2）累积入渗量受到土壤储水性及斥水性的双重影响,导致与湿润锋的运移趋势并不一致,黑垆土对照CK组及优先流O-C-30组（除7.04％含水率外）累积入渗量随着土壤初始含水率的增大而减小,渭河砂土CK组及O-C-30组均呈现2阶段特征,累积入渗量先随着土壤初始含水率的增加而减少,之后随土壤初始含水率的增加而增加;3）Kostiakov入渗模型能很好地拟合累积入渗量随时间的变化过程,适用于存在优先流的土壤入渗模拟.该研究结果对土壤优先流水分模拟具有一定的指导意义. 相似文献
3.
[目的] 分析改性黑垆土出现斥水性的条件及其影响因素,为研究气候暖干化背景下当地降雨入渗行为对斥水性的响应问题提供参考。[方法] 试验在黄土旱塬陕西省长武县农田试验场进行。选取玉米地和苜蓿地0—20 cm土壤作为试验对象,对2种作物下的土样设计4水平土壤含水量、3种容重和3水平十八烷基伯胺（OCT）添加量进行组合配制土样,用滴水穿透时间法进行斥水性测试。[结果] 土壤斥水性（SWR）随着土壤含水量（0%～6%范围）和容重的增加及OCT添加量的增加而增大,其中土壤含水量、OCT添加量和土壤容重对SWR的影响存在多因素交互效应。在逐步回归分析中,OCT和含水量共同参与下的拟合模型更优。1.3 g/cm3土壤容重下,在0%含水量和0.15% OCT添加量及2%含水量和0.10% OCT添加量条件时,非斥水的黑垆土土壤会转变为轻微斥水性土壤。[结论] 在黑垆土低水条件下的降水入渗过程中,应更多关注不同土地利用土壤含水量和极性物质的积累变化对斥水风险的影响。 相似文献
4.
砾石覆盖厚度对斥水土壤入渗特性的影响及模型优选 总被引：1，自引：1，他引：1
基于室内一维垂直入渗土柱试验,研究砾石覆盖厚度(0,3,6,9,12 cm)对斥水土壤积水入渗及水分再分布的影响,并利用不同入渗模型进行拟合。结果表明:砾石覆盖显著增加斥水土壤湿润锋运移距离(p<0.05);同一时段内,各处理累积入渗量皆高于对照组(p<0.05),斥水性红壤累积入渗量与砾石覆盖厚度呈正相关关系;斥水性红壤初渗率与稳渗率随砾石覆盖厚度变化均可用指数函数来描述,决定系数分别为0.91和0.87,砾石覆盖使得斥水性潮土初渗率与稳渗率增大,其中稳渗率与砾石覆盖厚度呈二次函数关系,决定系数为0.78,覆盖6 cm时稳渗率达到最大;砾石覆盖明显提高斥水土壤剖面平均含水率,斥水性红壤和潮土最大分别增长180.8%和57.6%;隔绝蒸发条件下,再分布过程斥水土壤湿润体含水率表现为停渗时刻>再分布1天>再分布3天>再分布7天;Horton模型对砾石覆盖斥水土壤入渗过程的拟合效果最好,是分析和预测砾石覆盖斥水土壤水分入渗特征的适宜模型。 相似文献
5.
斥水程度对脱水土壤水分特征曲线的影响 总被引：2，自引：3，他引：2
为研究斥水程度对土壤水分特征曲线的影响,该文基于滴水穿透时间法,人工配置7种斥水程度的黏壤土(L0~L6)和6种斥水程度的砂土(S0~S5),用高速离心机测定其土壤水分特征曲线,应用van Genuchten-Mualem(VG)模型进行拟合,得出VG模型水力参数。结果表明:在同一吸力条件下,斥水黏壤土的含水率比斥水砂土的高;随着斥水程度增加,在相同吸力情况下,土壤含水率随斥水程度增大而减小;斥水黏壤土的残余含水率随着斥水程度增加而减小,斥水砂土S0~S3的残余含水率没有差异,S4、S5的残余含水率显著减小;斥水黏壤土和砂土进气值的对数与斥水剂添加量呈负线性相关;随着斥水程度增加,田间持水率减小,凋萎系数没有明显差异,重力水增加,有效水和易有效水减小,易利用水比例随着斥水程度增加而减小;对于斥水黏壤土,微孔隙(0.3~5μm)和小孔隙(5~30μm)含量随着斥水程度的增加明显减小,土壤空隙(≥100μm)随着斥水程度的增加急剧增加;对于斥水砂土,中等孔隙(30~75μm)的含量随斥水程度的增加明显增加。该研究成果可为斥水土壤的入渗、蒸发和数值模拟提供理论支持。 相似文献
6.
微咸水灌溉对斥水土壤水盐运移的影响 总被引：10，自引：4，他引：6
土壤斥水性影响着作物的产量,为了研究微咸水灌溉对斥水土壤水盐运移的影响,进行了室内土柱微咸水入渗试验。对比了不同矿化度和斥水程度对两种土质水盐运移的影响,探讨了微咸水入渗后土壤斥水性的变化特征。结果表明,不斥水土壤的入渗能力随矿化度的增加而增加。亲水和斥水土壤的入渗率均可采用Kostiakov公式简单模拟。斥水土壤入渗能力在矿化度为1?g/L时达到最大,超过1?g/L后则随矿化度的增大而减小。微咸水入渗的累积入渗量与湿润锋推进距离呈良好的线性关系,斥水性土壤中的相同剖面水盐的含量比不斥水的减小。微咸水入渗后土壤产生了一定的斥水性。该研究表明微咸水灌溉对盐渍化土壤的水盐分布和斥水性均有一定程度的影响。 相似文献
7.
斥水剂作用下非饱和土壤抗剪强度测定及其变化规律 总被引：1，自引：1，他引：0
为获得斥水性土壤抗剪强度的变化规律,采用二甲基二氯硅烷(dimethyldichlorosilane,DMDCS)作为斥水剂,获得了不同斥水程度的改性砂土。在此基础上配制了不同斥水剂体质比和不同含水率的改性砂土及不同亲水黏土质量分数的改性混合土,并采用非饱和土直剪仪开展了不固结不排水剪强度试验。结果表明:1)不同DMDCS体质比下的5种改性砂土斥水等级均为极度。改性混合土的斥水等级受DMDCS和黏土含量的共同影响。相同DMDCS体质比下,随着黏土含量的增加,改性混合土的斥水性能不断减弱;相同黏土含量下,随着DMDCS体质比的增加,改性混合土的斥水性能不断增大。2)不同DMDCS体质比、含水率及黏土含量下的改性土壤抗剪强度均可用摩尔-库仑强度准则描述。DMDCS体质比从0增至1%时,黏聚力从19.6陡降至10.4 kPa,随后缓慢降低,最终趋于稳定。内摩擦角则随着DMDCS体质比的增加缓慢减小,从0时的16.2o降至3%时的11.8o;随着含水率的增加,改性砂土黏聚力逐渐减小,而内摩擦角呈先升后降形态;随着黏土含量的增加,改性混合土黏聚力显著增大,内摩擦角表现为先升后降,变幅不大。纯改性砂土的黏聚力仅为9.3 kPa,而掺入5%的黏土时,其黏聚力骤升至27.2 kPa;当黏土质量分数为50%时,混合土黏聚力为55.1 kPa;内摩擦角最大值为16.2°(黏土质量分数15%),最小值为9.7°(黏土质量分数50%)。该成果可为深入研究斥水性土壤力学性能及工程应用提供参考。 相似文献
8.
9.
初始含水率对土壤中原油入渗的影响 总被引：3，自引：0，他引：3
为确定土壤初始含水率对原油在土壤中入渗的影响,该文利用3种土壤,根据设定不同初始含水率进行配置,开展土柱模拟试验,研究了不同初始含水率条件下原油在土壤中的入渗。试验结果表明：对于同一质地土壤,随着初始含水率的增加,原油在土壤中入渗的湿润距离和湿润推进速率均增加。原油在土壤中的入渗与土壤粉粒含量密切相关,当土壤初始含水率较低时,不同质地土壤,粉粒含量越高,原油在土壤中入渗越慢;随土壤深度增加,土壤中原油残留物的含量呈波动递减趋势;原油在土壤中入渗的湿润距离随时间的变化可用对数函数拟合,湿润推进速率与时间的关系可用Kostiakov公式拟合。 相似文献
10.
黄土丘陵区长芒草群落对土壤水分入渗的影响 总被引：8，自引：2，他引：8
以黄土丘陵区长芒草群落为研究对象,采用圆盘人渗仪对不同盖度长芒草群落下的土壤入渗过程进行了对比研究.结果表明,在0-80 cm土壤剖面上.不同盖度的长芒草群落下土壤初始入渗速率和稳定入渗速率都随着土壤深度增加而下降.在同一深度的土壤剖面上,群落盖度越大土壤初始人渗速率和稳定入渗速率也分别越高.影响土壤初始入渗速率的主要因素是土壤有效孔隙度、初始含水量和水稳性团聚体含量.影响土壤稳定入渗速率的主要因素是土壤有效孔隙度、根长密度和水稳性团体含量.但水稳性团聚体对表层土壤初始人渗速率和稳定入渗速率的影响不显著.长芒草群落不仅通过根系对土壤的物理机械作用以及根系周转过程中形成的生物性大孔提高了土壤入渗速率.还通过提高土壤有机质和水稳性团聚体含量提高了土壤入渗速率. 相似文献
11.
Water repellency can reduce the infiltration capacity of soils over timescales similar to those of precipitation events. Compaction can also reduce infiltration capacity by decreasing soil hydraulic conductivity, but the effect of compaction on soil water repellency is unknown. This study explores the effect of compaction on the wettability of water repellent soil. Three air‐dry (water content ～4 g 100 g?1) silt loam samples of contrasting wettability (non‐repellent, strongly and severely water repellent) were homogenized and subjected to various pressures in the range 0–1570 kPa in an odeometer for 24 h. Following removal, sample surface water repellency was reassessed using the water drop penetration time method and surface roughness using white light interferometry. An increase in compaction pressure caused a significant reduction in soil surface water repellency, which in turn increases the soil's initial infiltration capacity. The difference in surface roughness of soils compacted at the lowest and highest pressures was significant (at P > 0.2) suggesting an increase in the contact area between sessile water drops and soil surfaces was providing increased opportunities for surface wetting mechanisms to proceed. This suggests that compaction of a water repellent soil may lead to an increased rate of surface wetting, which is a precursor to successful infiltration of water into bulk soil. Although there may be a reduction in soil conductivity upon compaction, the more rapid initiation of infiltration may, in some circumstances, lead to an overall increase in the proportion of rain or irrigation water infiltrating water repellent soil, rather than contributing to surface run‐off or evaporation. 相似文献
12.
Occurrence, prediction and hydrological effects of water repellency amongst major soil and land-use types in a humid temperate climate 总被引：1，自引：1，他引：1
S. H. Doerr R. A. Shakesby L. W. Dekker & C. J. Ritsema 《European Journal of Soil Science》2006,57(5):741-754
Knowledge of soil water repellency distribution, of factors affecting its occurrence and of its hydrological effects stems primarily from regions with a distinct dry season, whereas comparatively little is known about its occurrence in humid temperate regions such as typified by the UK. To address this research gap, we have examined: (i) water repellency persistence (determined by the water drop penetration time method, WDPT) and degree (determined by the critical surface tension method, CST) for soil samples (0–5, 10–15 and 20–25 cm depth) taken from 41 common soil and land‐use types in the humid temperate climate of the UK; (ii) the supposed relationship of soil moisture, textural composition and organic matter content with sample repellency; and (iii) the bulk wetting behaviour of undisturbed surface core samples (0–5 cm depth) over a period of up to 1 week. Repellency was found in surface samples of all major soil textural types amongst most permanently vegetated sites, whereas tilled sites were virtually unaffected. Repellency levels reached those of the most severely affected areas elsewhere in the world, decreased in persistence and degree with depth and showed no consistent relationship with soil textural characteristics, organic matter or soil moisture contents, except that above a water content of c. 28% by volume, repellency was absent. Wetting rate assessments of 100 cm3 intact soil cores using continuous water contact (–20 mm pressure head) over a period of up to 7 days showed that across the whole sample range and irrespective of texture, severe to extreme repellency persistence consistently reduced the maximum water content at any given time to well below that of wettable soils. For slightly to moderately repellent soils the results were more variable and thus hydrological effects of such repellency levels are more difficult to predict. The results imply that: (i) repellency is common for many land‐use types with permanent vegetation cover in humid temperate climates irrespective of soil texture; (ii) supposedly influential parameters (texture, organic matter, specific water content) are poor general predictors of water repellency, whereas land use and the moisture content below which repellency can occur seem more reliable; and (iii) infiltration and water storage capacity of very repellent soils are considerably less than for comparable wettable soils. 相似文献
13.
The potential of biochar to ameliorate soil water repellency has not been widely studied. Previous studies have focused on the potential for biochar to induce or exacerbate existing water repellency rather than alleviate it. This study investigates the effect of adding wettable biochar to water‐repellent soil by comparing the water drop penetration times (WDPTs) of a control and biochar‐amended soil. The potential of wettable biochar to act as a physical amendment to water‐repellent soil was evaluated by mixing coarsely‐ground biochar (CGB, particle size range 250–2000 µm) or finely‐ground biochar (FGB, particle size range < 250 µm) with one strongly and one severely naturally water‐repellent soil in various quantities, and then measuring the WDPT for each mixture. When biochar particles did not fall within the size range of existing soil particles, an initial increase in both mean WDPT (WDPTM) and variation in WDPT was observed with small additions of biochar. These effects possibly result from increased surface roughness and inhibition of infiltration by the suspension of drops above the average soil–air interface at a few hydrophobic points. Both CGB and FGB reduced soil water repellency, FGB more effectively than CGB. The addition of 10% w/w FGB reduced soil WDPT by 50%, and 25% FGB eliminated repellency. Direct absorption of water by biochar and an increase in soil surface area in contact with water are the predominant physical mechanisms involved. This exploratory study suggests biochar has the potential to amend water‐repellent soil. 相似文献
14.
Elena Benito Rueda María Rodríguez‐Alleres Eufemia Varela Teijeiro 《Land Degradation \u0026amp; Development》2016,27(3):719-728
Soil water repellency (SWR) is a dynamic property that changes throughout the year. The objective of this work was to identify the environmental factors governing the temporal patterns in SWR in a pine plantation in northwest Spain with a view of predicting its occurrence and persistence. For this purpose, 24 samples were collected from the soil surface (0–5 cm) at 25 different times over a 1‐year period and analysed for SWR by using water drop penetration time test and soil moisture measurements. Temporal variations in SWR exhibited a well‐defined seasonal pattern. The soil surface was largely wettable from late autumn to early spring and extremely water repellent during summer and early autumn. Repellency persistence was rather variable during spring. There was highly significant correlation between SWR and soil moisture content. The moisture range defining the presence or absence of repellency under field conditions was 22–57%. There were also significant correlations with the target variables (maximum temperature, minimum temperature, precipitation and water balance during variably long antecedent periods), with coefficients that increased with increasing length of the antecedent period considered. The moisture content of soil at the time of sampling and the average maximum temperature for the 28 days before sampling are the best predictors of occurrence of SWR and its persistence in different seasons. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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为探求再生水灌溉对斥水和亲水土壤水力特性的影响,该文选用有代表性的斥水黏壤土和亲水黏壤土、斥水砂土和亲水砂土,测定其在自来水、再生水和其他4种生活污水条件下的土壤水分特征曲线,采用主成分分析法得到不同水质综合指标,分析水质综合指标对不同土壤水分特征曲线的影响,采用van Genuchten-Mualem模型对黏壤土土-水曲线的参数进行拟合,并分析水质综合指标对黏壤土累积当量孔径分布、比水容量和水分常数的影响。结果表明:在相同基质吸力情况下,黏壤土含水率随水质综合指标增加(水质变差)而减小,砂土的含水率随水质变化不大;在低吸力段,斥水和亲水黏壤土的比水容量随水质综合指标的增加而增加;土壤进气值与水质综合指标呈显著负线性相关关系(R~2分别为0.94和0.78);相同水质条件下,斥水土壤的进气值比亲水土壤小;随着水质综合指标的增加,斥水和亲水黏壤土的极微孔隙降低,而中等孔隙和大孔隙增加,小于某当量孔径的累积百分比增加;随着水质综合指标的增加,斥水和亲水黏壤土的田间持水率、凋萎系数、有效水和易利用水比例均减小,但再生水对田间持水率和易利用水比例降低作用不显著。研究结果可为大面积再生水灌溉及其管理提供一定的理论依据。 相似文献
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The distribution and variation with soil depth of water repellency has been studied in fire-affected sand dunes under three different vegetation types (pine forest, shrubland and sparse herbaceous vegetation) in SW Spain. The persistence and intensity of water repellency at the exposed surface of soil was measured using the water drop penetration time test and the contact angle method, respectively, in surface samples (0–3 cm) collected at burned and unburned areas. The variation of water repellency with depth in burned areas was studied in soil profiles every 5 cm between 0 and 40 cm depth. None or slight soil water repellency was observed at unburned soil sites, whereas burned soil sites showed a high degree of repellency, especially under pines and shrubland. The spatial pattern of fire-induced soil water repellency was found to be associated to vegetation types, although it was modulated by soil acidity and the soil organic carbon content. Soil water repellency was generally higher at the soil surface, and decreased with depth. Dense pine forests and shrublands showed strong and/or severe water repellency in depth, but it was rare and limited to the first five centimeters under sparse herbaceous vegetation. The heterogeneity of moisture patterns under dense pine forests or shrublands showed the existence of wetting and water repellent three-dimensional soil patches. 相似文献
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Khaled Ibrahimi Jake Mowrer Roua Amami Abdelhamid Belaid 《Communications in Soil Science and Plant Analysis》2019,50(7):827-837
To date, evidence of the potential effects of burning practices on soil properties in Tunisia is limited. In order to address this issue, we carried out laboratory investigations of the effects of burning on soil aggregate stability (AS) and water repellency (WR) of a clayey and a sandy loam Fluvisol soils. The treatments included low (100°C, LT), medium (300°C, MT) and high (600°C, HT), heating temperatures. Unburned (0°C, UB) soil samples were used as a control. Two breakdown mechanisms, fast wetting (FW) and mechanical breakdown (MB), were used for the measurement of AS. The latter is expressed by calculating the mean weight diameter (MWD). The water drop penetration time (WDPT) was used to evaluate the soil WR. The results showed that the unburned clayey and sandy loam soils are poorly aggregated. The HT and MT treatments significantly (p < 0.05) increased MWD of both soils, compared to UB samples, following the FW stability test. A lesser increase of MWD was observed with the MB test. The LT treatment did not significantly (p < 0.05) affect the soils AS. For the unburned clayey soil, the FW and MB tests gave significantly (p < 0.05) different MWDs . In contrast, the unburned sandy loam soil had similar MWDs under both tests. As for water repellency, the sandy loam soil was initially wettable and the clayey soil slightly water repellent. Burning treatments did not affect the sandy loam soil behavior but caused a decrease of clayey soil WR. 相似文献
18.
再生水灌溉对土壤斥水性的影响 总被引：8，自引：4，他引：4
深入探求再生水灌溉条件下不同土壤中水分和溶质的分布及斥水性变化规律,能为再生水灌溉条件下土壤斥水性产生原因及其影响因素的研究提供一定的参考。选用砂土、砂姜黑土、塿土和盐碱土进行土柱再生水灌溉试验,取样测定不同灌水量条件下剖面土壤的潜在斥水性、含水率、Cl-、有机质(organicmatter,OM)含量及电导率(electrical conductivity,EC)等。结果表明:再生水灌溉后,塿土及盐碱土分别出现0～2,1～3级斥水性,砂土及砂姜黑土为0级斥水性,4种土表层表现出较强的斥水性。土壤斥水性随再生水灌水量和灌溉时间的增加而显著增强,并且灌水量越大,斥水性差异性越显著。4种土有机质含量OM与土壤斥水持续时间变化值TR呈正相关关系,Cl-含量、EC值与土壤斥水持续时间变化值TR呈负相关关系。相比较其他3种土而言,砂土更适合再生水灌溉。 相似文献