IMHE OpenIR  > 山地表生过程与生态调控重点实验室
紫色土丘陵区小流域胶体迁移规律及溯源分析
Alternative TitleColloid transport and source identification in a small catchment of the purple soil hilly area
鲜青松
Subtype博士
Thesis Advisor唐翔宇
2018
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline土壤学
Keyword胶体颗粒 紫色土 低山丘陵区小流域 产胶模数
Abstract长江上游紫色土丘陵区小流域土地利用方式复杂,水土流失与面源污染问题突出,胶体颗粒(直径在10 μm以下的悬浮细颗粒)携带农药、抗生素、磷等农化物质进行长距离、快速迁移的能力不容小视。目前,对于流域尺度自然胶体颗粒迁移规律及来源分析还缺乏系统的研究。因此,本研究以川中丘陵区典型小流域为对象,分别选取了林地(1.60 ha)、坡耕地(0.15 ha)、居民点(1.68 ha)三种典型单一土地利用集水区和苏荣(3.00 ha)、截流(35.00 ha)两级复合土地利用集水区,对径流和胶体颗粒迁移过程对降雨的响应规律进行同步监测研究,分析小流域溪沟系统中胶体颗粒的来源。主要研究结论如下: (1)紫色土丘陵区小流域径流三维荧光光谱特征及其水源指示意义采用三维荧光光谱平行因子分析方法,得出小流域径流DOM以陆源输入为主,主要包含五类荧光组分(三种腐殖质组分和两种类蛋白质组分),相应的荧光峰位置(Ex/Em,nm)依次为245(320)/410(C1)、265(375)/480(C2)、300/375(C3)、280/340(C4)和270/310(C5)。径流DOM中腐殖质组分含量高于类蛋白,均对降雨响应强烈,其中荧光组分C3和C4分别在林地和居民点集水区降雨事件性地表径流中表现出显著较高的含量,可用作径流的水源示踪指标。(2)单一土地利用集水区胶体迁移规律林地、坡耕地和居民点集水区降雨事件性地表径流胶体颗粒质量浓度均主要受前期土壤水饱和度和降雨强度控制;胶体颗粒迁移对降雨响应规律的差异主要受地表植被覆盖度和土壤结构影响。其中,坡耕地集水区在单场降雨事件中随地表径流和裂隙潜流的产胶模数最高分别可达4.78 g/m2(地表径流为主导水文过程)和1.09 g/m2(裂隙潜流为主导水文过程)。值得注意的是,居民点集水区降雨事件性地表径流胶体颗粒质量浓度远高于林地和坡耕地集水区,其携带污染物迁移对小流域水环境的影响不容忽视。(3)复合土地利用集水区径流与胶体迁移规律及尺度效应在以农田和林地为主的复合土地利用集水区,基于降雨事件的地表径流系数呈现高度的尺度依赖性,原因在于面积较大的集水区的河道径流不仅来源于地块尺度的地表径流汇聚,雨水入渗后还会通过地下径流在溪沟两侧侧渗出流,成为河道径流的一部分,导致集水区河道径流系数明显高于地块的地表径流系数;地表径流对降雨的响应时间由前期土壤水饱和度和降雨强度主导,径流量峰值主要受降雨量控制。不同土地利用对小流域地表径流的贡献及其动态主要受其面积占比和空间分布特征影响,面积占比越大,距离溪沟系统越近,对径流的贡献越大,响应越迅速、强烈。复合土地利用集水区地表径流胶体颗粒质量浓度对降雨的响应主要受地表植被覆盖度和降雨强度的影响,地表植被覆盖度越低、降雨强度越大,地表径流量越高,冲刷剪切等水动力条件越强,胶体级细颗粒比例上升,质量浓度越高。在单场降雨事件中,随小流域尺度扩大,地表径流系数呈倍数增加,径流冲刷输胶能力大幅增强,以农田和林地为主的复合土地利用集水区(截流集水区)随地表径流产胶模数最大为6.70 g/m2,高于以不透水下垫面为主的苏荣集水区(2.11 g/m2),主要受降雨强度(居主导地位)和降雨量控制。受地下多孔介质对胶体颗粒的吸附、滤除等作用的影响,浅层地下水中胶体颗粒质量浓度远小于地表径流。在非雨季或干旱期,人类生产、生活行为(包括耕作、取水、灌溉、污水排放等)是小流域地表水及浅层地下水(井水)胶体颗粒质量浓度及颗粒粒径分布最主要的影响因素。(4)紫色土丘陵区小流域胶体来源分析小流域(以坡耕地为主)地表径流输移的悬浮胶体颗粒主要来源于坡耕地,在溪沟系统中沉积的表层细颗粒物则主要由水田贡献(55.26%)、林地次之(29.73%)、坡耕地最小(15.00%)。
Other AbstractSerious soil erosion and non-point source environmental pollution have been well recognized at small catchments with complicated land uses and ongoing changes in the hilly area of purple soils in the upper reaches of the Yangtze River. Excessive transport of colloids (defined as suspended fine particles with<10 μm diameter) can act as carriers of various strongly sorbing contaminants such as pesticides, antibiotics and phosphorus, which result in their rapid transport over long distance. However, systematic research on the catchment-scale transport dynamics and source analysis of natural colloids are still lacking. In this light, field runoff and colloid transport process were monitored synchronously in three typical single-land-use catchments (lysimeters of 1.6 ha woodland, 0.15 ha sloping farmland and 1.68 ha Linshan residential area, respectively) and two representative complex-land-use catchments (3 ha Surong weir and 35 ha Jieliu weir) in the hilly area of central Sichuan Basin, Southwest China. The objectives of this study were: to systematically understand the dynamics of flow processes and the corresponding colloid transport during typical rain events at catchment scale, and to analyze the source of the colloids by using tracer technologies. The major results and conclusions of this dissertation are as follows:(1)Spectroscopic characteristics of DOM in runoff and its potential use as water source tracer for small catchments of the purple soil hilly areaFluorescence excitation emission matrix (EEM)- parallel factor analysis (PARAFAC) had indicated that DOM was primarily from terrestrial inputs in catchment, and consisted of five major components with peaks located at Ex/Em (nm) 245(320)/410 (C1), 265(375)/480 (C2), 300/375 (C3), 280/340 (C4)and 270/310 (C5), respectively. Among these, humic-like species C1, C2 and C3 had relatively higher concentrations than protein-like species C4 and C5. Concentrations of these five components all responded strongly to rain events in both surface runoff and fracture flow for the observed lysimeters and weirs. Particularly, the significantly higher concentrations of C3 and C4 in surface runoff of woodland lysimeter and Linshan residential area during rain events, respectively, may indicate their potential use as tracers for these two surface runoff sources.(2)Colloid transport mechanism of single-land-use lysimetersThe colloid concentrations in surface runoff of the three monitored lysimeters were all controlled by the antecedent soil wetness and rainfall intensity, while the differences in the response to rainfalls among varying land uses were determined by surface vegetation coverage and soil structure. For the sloping farmland, the maximum specific colloid yield during a single rain event was 4.78 and 1.09 g/m2 for surface-runoff- and fracture-flow-dominated hydrological processes, respectively.It is noteworthy that, colloid concentrations of the surface runoff in Linshan residential area during rains were much higher than in woodland and sloping farmland, suggesting its high potential of facilitating the pollutant transport to the downstream water environment.(3)Colloid transport mechanism of complex-land-use catchments and scaling effectFor a catchment with land uses dominated by farmland and woodland, surface runoff coefficient during rainfall events is highly scale-dependent. This is because, in a relatively large area of catchment, the river runoff at the catchment outlet is not only contributions of surface runoff from different land uses, but also from subsurface lateral flow flowing through the sides of the stream bank after rainwater infiltration, which resulted in a significantly increased runoff coefficient as compared to the values of single land uses. During rain events, the dynamics of surface runoff responding to rainfall are governed by the antecedent soil wetness and rainfall intensity, with the peak discharge determined by the rain amount. The contribution of surface runoff from different land uses to the catchment was decided by the area ratio of each land use and its spatial distribution characteristics; a higher area ratio and a nearer distance to the stream system of one land use would lead to a bigger contribution and faster response to the catchment surface runoff.Colloid concentration in complex land use catchments was significantly controlled by land cover and rainfall intensity, with lower land cover and higher rainfall intensity leading to higher runoff discharge and stronger hydraulic shearing and scouring forces which resulted in both increased concentration and proportion of colloid particles. In a single rain event, a multiplier increase in the surface runoff coefficient was observed with the expansion of surface area at catchment scale, leading to significantly increased colloid transport capacity. The maximum specific colloid yield in surface runoff in farmland-dominated catchment was 6.70 g/m2, being higher than impervious surface dominated catchment (2.11 g/m2), which both were governed by the rainfall intensity and rain amount.Due to adsorption and filtration effect in the subsurface porous soil layer, colloid concentration of shallow groundwater was much lower than the surface runoff in the catchment. In non-rainy and dry seasons, colloid concentration and particle size distributions in surface base flow and shallow groundwater were determined by human activities (e.g., tillage, water taken, irrigation and sewage discharge).(4)Source analysis of colloid in small catchment of the purple soil hilly area In farmland-dominated catchment, the suspended fine sediment export at catchment outlet was mainly from the sloping farmland plot during rain events, while the deposited fine sediment on stream bed was from paddy field (55.26%), woodland (29.73%), and sloping farmland (15.00%). 
Pages148
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24778
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
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. 紫色土丘陵区小流域胶体迁移规律及溯源分析[D]. 北京. 中国科学院大学,2018.
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