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紫色土坡耕地土壤大孔隙流的定量评价
Alternative TitleQuantitative evaluation of macropore flow in purple soil of sloping cropland
王红兰1,2; 蒋舜媛2; 崔俊芳1; 唐翔宇1
Corresponding Author崔俊芳
2017-11
Source Publication农业工程学报
ISSN1002-6819
Volume33Issue:22Pages:167-174
Contribution Rank1
Abstract

为阐明大孔隙丰富且孔径呈两极分化的紫色土坡耕地土壤大孔隙流的运移规律,通过室内土柱试验获取耕作层0~20 cm、非耕作层20~40 cm原状土柱和填装土柱的穿透曲线,分析饱和条件下土壤大孔隙流发生规律,并采用解析法CXTFIT软件拟合了水分优先运移参数,PFSP指标(大孔隙流引起的穿透曲线延展量与水动力弥散作用及两区作用引起的延展量的比值)定量评价土壤大孔隙流的贡献率。研究结果表明:1)以填装土柱水流为平衡基质流计算,耕作层0~20 cm原状土柱中大孔隙流的导水贡献率为66.2%~68.5%,而Br-累积淋出量占总淋出量的62.3%~66.1%。对于非耕作层20~40 cm,土壤大孔隙流导水贡献率为0.2%~1.7%,而Br-随大孔隙流运移的比例却达14.5%~20.5%。说明耕作层土壤中大孔隙流现象远比在非耕作层土壤中更为显著;2)PFSP值结果表明大孔隙流作用对穿透曲线延展量的贡献率最大,两区交换运移作用次之,水动力弥散作用的最小。即PFSP值越大,大孔隙流对总水流通量的贡献率越大。

Other Abstract

The importance of macropore flow as a preferential flow mechanism for infiltrating water and transport of solutes has been generally recognized during a couple of decades. Macropore flow plays significant roles in the structured soil, such as leading to more infiltration and thus reducing overland flow and rapidly transferring pesticides and other pollutants through the soil macropores into the groundwater. Due to its critical effect on field-scale soil water flow and transport of contaminants in soils, macropore flow is gaining more interest. In this study, soil samples were collected at depths of 0-20 cm and 20-40 cm from sloping cropland of purple soil, which are located at Yanting Agro-ecological Experimental Station of Purple Soil (10527E, 3116N), hilly central Sichuan, Southwest China. Using Br- tracer and simulated rainfall methods, lab-scaled
disturbed and undisturbed soil column experiments were conducted to characterize the preferential transport behavior and evaluate the contribution of preferential flow based on simulations with the CXTFIT model. The breakthrough curves (BTCs)
for each soil column were also obtained by analyzing the dynamics of Br- in the outflow. The integrated parameter, PFSP, defined as the ratio of extended quantity of BTCs due to preferential flow to extended quantity of BTCs caused by hydrodynamic dispersion and two-region effect, was calculated based on BTCs and CXTFIT datasets of the undisturbed soil columns. The BTCs of undistributed soil column showed an early breakthrough of Br- and also an upturned tail, indicating the presence of both preferential flow and matrix flow in studied soil. The preferential flow contributed 66.2%-68.5% of water
discharge and 62.3%-66.1% of cumulative Br- discharge from undisturbed soil columns collected at the 0-20 cm depth, and at the 20-40 cm depth, their contributions was 0.2%-1.7% and 14.5%-20.5%, respectively. These implied that preferential flow made a much greater contribution to cumulative Br- discharge for the soils at the 0-20 cm depth compared to the soils at the 20-40 cm depth. Transport parameters of Br- were obtained by fitting its BTCs in the soil column with two-region model and CXTFIT software. It was found that the values of pore velocity and hydrodynamic diffusion coefficient for the soil at the depth of 0-20 cm were higher than those at 20-40 cm depth, while the retardation factor, with higher value indicating more preferential flow developed in the soil, showed contrast trend for the 2 depths. This was due to the fact that Br- quickly migrates with preferential flow through soil macropores, which may weaken the retardation effect. As for the dynamic watershed scale factor, the value was higher at the depth of 0-20 cm than that of 20-40 cm, indicating the higher percentage of flowing water in the soil column collected at 0-20 cm depth that has better developed preferential flow. The mass transfer
coefficient value of the undisturbed soil column taken at 0-20 cm after plowing activity was the lowest, while the values were close among other soil columns. The PFSP value, which can ascertain the contribution of preferential flow out of other mechanisms, revealed that macropore flow made the biggest contribution to the extended quantity of BTCs, two-region effect made the second and hydrodynamic dispersion made the third, indicating PFSP can be a useful index to quantify the contribution extent of macropore flow.

Keyword土壤 径流 坡地 大孔隙流 土柱实验 Br-示踪
Subject AreaS152.7
DOI10.11975/j.issn.1002-6819.2017.22.021
Indexed ByEI ; CSCD
Language中文
CSCD IDCSCD:6129232
EI Accession NumberAccession number: 20181104889854
Citation statistics
Cited Times:4[CSCD]   [CSCD Record]
Document Type期刊论文
Identifierhttp://ir.imde.ac.cn/handle/131551/20698
Collection山地表生过程与生态调控重点实验室
Corresponding Author崔俊芳
Affiliation1.中国科学院、水利部成都山地灾害与环境研究所
2.四川省中医药科学院
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Corresponding Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
王红兰,蒋舜媛,崔俊芳,等. 紫色土坡耕地土壤大孔隙流的定量评价[J]. 农业工程学报,2017,33(22):167-174.
APA 王红兰,蒋舜媛,崔俊芳,&唐翔宇.(2017).紫色土坡耕地土壤大孔隙流的定量评价.农业工程学报,33(22),167-174.
MLA 王红兰,et al."紫色土坡耕地土壤大孔隙流的定量评价".农业工程学报 33.22(2017):167-174.
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