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Alternative TitleTransportation regularity of colloid particle with surface runoff and fracture flow from sloping farmland in thin purple soil
鲜青松1,2; 唐翔宇1
Corresponding Author唐翔宇
Source Publication农业工程学报
Other Abstract

为查明薄层紫色土坡耕地土-岩二元结构中胶体颗粒随地表径流和泥岩裂隙潜流迁移的规律,在2015年3场自然降雨事件中对1 500 m~2大型坡耕地径流场进行监测研究。结果表明:1)地表径流的产流方式主要受土壤前期水饱和度、降雨强度和历时影响;裂隙潜流则主要受降雨量控制,其峰值流量对降雨的响应滞后于地表径流30 min左右;坡中部和坡下部对地表径流、裂隙潜流的贡献明显高于坡上部。2)地表径流中胶体颗粒质量浓度数十倍于裂隙潜流,最高可达4 827 mg/L,单场降雨事件中地表径流胶体迁移总量可超过7 kg。3)地表径流和裂隙潜流中胶体迁移速度快于径流,胶体质量浓度峰值的出现早于径流量峰值;地表径流中的胶体颗粒质量浓度主要受土壤水饱和度和径流过程控制。该研究结果对于估算农田中胶体结合态污染物的迁移通量具有参考价值。 


Colloids are defined as suspended fine particles with <10 μm diameter, which are ubiquitously present in subsurface geologic media. Excessive transport of colloids from terrestrial to aquatic environments may lead to various adverse impacts. It is important to quantify the export of colloids from agricultural field via surface runoff and subsurface flows as they may act as carriers of various strongly sorbing contaminants (e.g., radionuclides, heavy metals, pesticides). A field study on the dynamics of flow processes and associated colloid transport was carried out in a 1500 m2sloping (6°) farmland plot with thin purple soil layer overlying fractured mudrock in the hilly area of central Sichuan Basin, Southwest China. The plot was hydrologically isolated from the surrounding geologic formations with cement walls inserted into the impermeable sandstone layer for 20 cm that underlies the mudrock layer. Rain-fed cultivation was practiced under corn-wheat rotation at the study site. There were 6 tensiometers installed at the 3 locations on the upslope (at depths of 15 and 25 cm), mid-slope (at depths of 15 and 45 cm) and downslope (at depths of 15 and 45 cm) to determine the dynamics of soil water potential. The discharge of surface runoff and fracture flow was recorded with tipping buckets connected an event data logger. Monitoring results for 3 representative rain events with distinctively different rain amounts, durations and intensities in the summer of 2015 showed that: 1) The generation mechanism of surface runoff varied over time as the rainfall proceeded, depending on antecedent soil wetness and the intensity and duration of rainfall; the highest depth (3.10 mm) of surface runoff was observed in the event on June 29 having the highest rainfall intensity (27.2 mm/h) and the greatest preceding rainfall of 64.6 mm. 2) Rain amount governed the dynamics of fracture flow. Moreover, due to the apparently better connectivity of transport pathways and hydrodynamic condition, surface runoff showed quicker response to rainfall and earlier discharge peak as compared to fracture flow. 3) Contributions of the mid-slope and downslope to surface runoff as well as fracture flow were obviously higher than that of the upslope. 4) The dynamics of colloid concentration responded faster to rainfall than both surface runoff and fracture flow despite the distinct differences in transport pathway, retaining mechanism and discharge; colloid concentration peak of fracture flow appeared later than that of surface runoff. 5) Colloid concentration in surface runoff was controlled by soil water saturation and hydrological conditions, and showed a more distinct trend of quick rising and falling as compared to fracture flow. During storm events, surface runoff was much stronger than fracture flow in transporting colloids, as indicated by markedly higher colloid concentration and cumulative colloid discharge observed in surface runoff. For example, during the rain event on June 29 in which surface runoff dominated, and the maximum concentration and cumulative discharge of colloids in surface runoff (4827 mg/L and 7177 g, respectively) were both more than 30 times of those in fracture flow (146 mg/L and 129 g, respectively). In the rain event on September 9, which was dominated by fracture flow (the flow depth of surface runoff and fracture flow was 1.08 and 9.81 mm, respectively), the cumulative colloid discharge in surface runoff (628.51 g) was still higher than that in fracture flow (546.12 g). Given the potential of facilitating the rapid transport of nutrients (e.g., phosphorus in particular) and pesticides over a long distance for colloid, our results can provide the reference for accurately predicting their export fluxes from farmland.

Keyword土壤 径流 胶体 紫色土 坡耕地 裂隙潜流
Subject AreaS157.1
Indexed ByEI ; CSCD ; 北大中文核心
Funding Organization国家重点研发计划课题(2017YFD0800101) ; 国家自然科学基金项目(41471268、41430750)
Accession numberAccession number: 20174104253192
Citation statistics
Cited Times:2[CSCD]   [CSCD Record]
Document Type期刊论文
First 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
鲜青松,唐翔宇. 薄层紫色土坡耕地胶体颗粒随地表径流及裂隙潜流迁移规律[J]. 农业工程学报,2017,33(13):143-150.
APA 鲜青松,&唐翔宇.(2017).薄层紫色土坡耕地胶体颗粒随地表径流及裂隙潜流迁移规律.农业工程学报,33(13),143-150.
MLA 鲜青松,et al."薄层紫色土坡耕地胶体颗粒随地表径流及裂隙潜流迁移规律".农业工程学报 33.13(2017):143-150.
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