紫色土坡耕地裂隙潜流的产流机理与胶体颗粒迁移
|
摘要
土壤胶体是坡耕地农化物质迁移的主要载体.借助18O(氧同位素)示踪技术,探索了2014年8月29日和9月10日两场降雨下大型紫色土坡耕地(1 500 m~2)裂隙潜流产流的水源来源及过程特征,并耦合了胶体颗粒释放与迁移机理的研究.结果表明,裂隙潜流及胶体迁移的水文过程线均总体呈快速上升和长拖尾的特征.随裂隙潜流产流开始,雨水对潜流的贡献逐渐增大,并在流量快速上升段支配裂隙潜流产流,而潜流流量峰值前及退水阶段,土壤前期可动水是潜流的主要产流来源.两场降雨下裂隙潜流中胶体颗粒浓度介于0.60~6.85 mg/L之间,平均值分别为1.58和2.31 mg/L,水浴超声后胶体颗粒浓度平均值分别为原样的2.15和1.81倍.胶体颗粒迁移速率比产流速率快(>30 min),表明胶体辅助坡地农化物质迁移的潜力较大.对于长历时小降雨事件,潜流中胶体的迁移动态受潜流水化学因素[如ρ(DOC)、ρ(Mg2+)和EC(电导率)]支配,而强降雨事件下,潜流中胶体颗粒浓度还与潜流流量呈极显著负相关(R~2>0.5).此外,坡地内部产流方式(横向及垂向)对裂隙潜流中胶体颗粒的迁移通量有重要影响.研究显示,裂隙潜流产流过程线结合土水势、18O及水化学指标的动态变化,能够全面揭示裂隙潜流产流的阶段特征以及胶体颗粒释放与迁移的机理,对于进一步研究胶体对磷、有机农药等憎水性农化物的辅助运移特征有重要意义.
Soil colloids mobilized from a sloping farmland during the flow process can act as a carrier of agricultural chemicals. On a purple soil sloping farmland( 1500 m2) in Sichuan Basin,fracture flow water sources were identified using the18 O tracing technique,and the dynamics of colloid transport were explored for two rain events on August 29 thand September 10 th,2014. The results showed that,in response to the rain events,both hydrograph and colloid concentrations of fracture flow showed a pattern of early rapid rising to a peak followed by slow decrease with a long tail. Rainwater's contribution to flow increased at the early stage of fracture flow,while pre-event mobile soil water appeared to be the main water source of fracture flow at peak flow discharge and the receding stage. Colloid concentration in the fracture flow varied from 0. 60 to 6. 85 mg/L,with average concentrations of 1. 58 and 2. 31 mg/L,respectively,during the two events. Ultrasonic dispersion treatment of the water samples resulted in an average increase of colloid concentration of 1. 15 and 0. 81 times for the two rain events, indicating a high degree of the aggregation of mobilized colloids. For small rain events of long duration,fracture flow chemistry( e. g. ρ( DOC),ρ( Mg~(2+))and EC) dominated colloid transport dynamics; however,for the heavy storms,fracture flow rate also had a strong influence on colloid transport( R2> 0. 5). In addition, soil watermovement pattern( laterally or downward) affected the discharge of colloid from the sloping farmland. The combined use of fracture flow hydrograph's response to soil water potential dynamics,18 O and conservative flow tracers is an effective way to reveal the in-depth mechanisms of fracture flow generation and colloid transport,and to support the quantification of colloid-facilitated transport of agricultural chemicals( e.g.,phosphorus and pesticides).
Soil colloids mobilized from a sloping farmland during the flow process can act as a carrier of agricultural chemicals. On a purple soil sloping farmland( 1500 m2) in Sichuan Basin,fracture flow water sources were identified using the18 O tracing technique,and the dynamics of colloid transport were explored for two rain events on August 29 thand September 10 th,2014. The results showed that,in response to the rain events,both hydrograph and colloid concentrations of fracture flow showed a pattern of early rapid rising to a peak followed by slow decrease with a long tail. Rainwater's contribution to flow increased at the early stage of fracture flow,while pre-event mobile soil water appeared to be the main water source of fracture flow at peak flow discharge and the receding stage. Colloid concentration in the fracture flow varied from 0. 60 to 6. 85 mg/L,with average concentrations of 1. 58 and 2. 31 mg/L,respectively,during the two events. Ultrasonic dispersion treatment of the water samples resulted in an average increase of colloid concentration of 1. 15 and 0. 81 times for the two rain events, indicating a high degree of the aggregation of mobilized colloids. For small rain events of long duration,fracture flow chemistry( e. g. ρ( DOC),ρ( Mg~(2+))and EC) dominated colloid transport dynamics; however,for the heavy storms,fracture flow rate also had a strong influence on colloid transport( R2> 0. 5). In addition, soil watermovement pattern( laterally or downward) affected the discharge of colloid from the sloping farmland. The combined use of fracture flow hydrograph's response to soil water potential dynamics,18 O and conservative flow tracers is an effective way to reveal the in-depth mechanisms of fracture flow generation and colloid transport,and to support the quantification of colloid-facilitated transport of agricultural chemicals( e.g.,phosphorus and pesticides).
引文
[1]ZHANG Wei,TANG Xiangyu,WEISBROD N,et al.A coupled field study of subsurface fracture flow and colloid transport[J].Journal of Hydrology,2015,524:476-488.
[2]GAO Yang,ZHU Bo,WANG Tao,et al.Seasonal change of nonpoint source pollution-induced bioavailable phosphorus loss:a case study of southwestern China[J].Journal of Hydrology,2012,420/421:373-379.
[3]SHEN Zhenyao,CHEN Lei,DING Xiaowen,et al.Long-term variation(1960-2003)and causal factors of non-point-source nitrogen and phosphorus in the upper reach of the Yangtze River[J].Journal of Hazardous Materials,2013,252:45-56.
[4]TANG Jialiang,WANG Tao,ZHU Bo,et al.Tempo-spatial analysis of water quality in tributary bays of the Three Gorges Reservoir Region(China)[J].Environmental Science and Pollution Research,2015,22(21):16709-16720.
[5]TANG Jialiang,WANG Tao,ZHU Bo,et al.Subsurface flow processes in sloping cropland of purple soil[J].Journal of Mountain Science,2012,9(1):1-9.
[6]郑子成,秦凤,李廷轩.不同坡度下紫色土地表微地形变化及其对土壤侵蚀的影响[J].农业工程学报,2015,31(8):168-175.ZHENG Zicheng,QIN Feng,LI Tingxuan.Changes in soil surface microrelief of purple soil under different slope gradients and its effects on soil erosion[J].Transactions of Chinese Society of Agricultural Engineering,2015,31(8):168-175.
[7]TANG Jialiang,CHEN Xunqiang,ZHU Bo,et al.Rainfall and tillage impacts on soil erosion of sloping cropland with subtropical monsoon climate:a case study in hilly purple soil area,China[J].Journal of Mountain Science,2015,12(1):134-144.
[8]BIRKEL C,SOULSBY C.Linking tracers,water age and conceptual models to identify dominant runoff processes in a sparsely monitored humid tropical catchment[J].Hydrological Processes,2016,30(24):4477-4493.
[9]王超.紫色土坡耕地径流水源的同位素示踪研究[D].北京:中国科学院大学,2013.
[10]ZHU Bo,WANG Tao,KUANG Fuhong,et al.Measurements of nitrate leaching from a hillslope cropland in the central Sichuan Basin,China[J].Soil Science Society of America Journal,2009,73(4):1419-1426.
[11]GAO Yang,ZHU Bo,HE Nianping,et al.Phosphorus and carbon competitive sorption-desorption and associated non-point loss respond to natural rainfall events[J].Journal of Hydrology,2014,517:447-457.
[12]LI Zhanbin,LI Peng,HAN Jiangang,et al.Sediment flow behavior in agro-watersheds of the purple soil region in China under different storm types and spatial scales[J].Soil&Tillage Research,2009,105(2):285-291.
[13]GAO Changjuan,YANG Shengke,WANG Wenke,et al.Influence of humic acid colloid on adsorption of DDT in the riverbed sediments[J].Asian Journal of Chemistry,2014,26(9):2637-2642.
[14]PANG Liping,LAFOGLER M,KNORR B,et al.Influence of colloids on the attenuation and transport of phosphorus in alluvial gravel aquifer and vadose zone media[J].Science of the Total Environment,2016,550:60-68.
[15]ZHANG Wei,TANG Xiangyu,WEISBROD N,et al.A review of colloid transport in fractured rocks[J].Journal of Mountain Science,2012,9(6):770-787.
[16]ZHAO Pei,TANG Xiangyu,ZHAO Peng,et al.Tracing water flow from sloping farmland to streams using oxygen-18 isotope to study a small agricultural catchment in southwest China[J].Soil&Tillage Research,2013,134:180-194.
[17]RANI R D,SASIDHAR P.Stability assessment and characterization of colloids in coastal groundwater aquifer system at Kalpakkam[J].Environmental Earth Sciences,2011,62(2):233-243.
[18]ZHAO Pei,TANG Xiangyu,ZHAO Peng,et al.Identifying the water source for subsurface flow with deuterium and oxygen-18 isotopes of soil water collected from tension lysimeters and cores[J].Journal of Hydrology,2013,503:1-10.
[19]DEGUELDRE C,BAEYENS B,GOERLICH W,et al.Colloids in water from a subsurface fracture in granitic rock,Grimsel Test Site,Switzerland[J].Geochimicaet Cosmochimica Acta,1989,53(3):603-610.
[20]TANG Xiangyu,WEISBROD N.Colloid-facilitated transport of lead in natural discrete fractures[J].Environmental Pollution,2009,157:2266-2274.
[21]ZVIKELSKY O,WEISBROD N,DODY A.A comparison of clay colloid and artificial microsphere transport in natural discrete fractures[J].Journal of Colloid and Interface Science,2008,323(2):286-292.
[22]李海明,李云,翟菁,等.咸水中胶体迁移-沉积对砂介质渗透性损失的数学模型[J].环境科学研究,2010,23(3):346-349.LI Haiming,LI Yun,ZHAI Jing,et al.Mathematical model of colloid transport-deposition on permeability loss of sand medium in salt water[J].Research of Environmental Sciences,2010,23(3):346-349.
[23]WEISBROD N,DAHAN O,ADAR E M.Particle transport in unsaturated fractured chalk under arid conditions[J].Journal of Contaminant Hydrology,2002,56:117-136.
[24]LI Haiming,WEI Jinbu,GE Yaochao,et al.The influence of Na+and Ca2+on the migration of colloids or/and ammonia nitrogen in an unsaturated zone medium[J].Journal of Contaminant Hydrology,2016,194:24-29.
[25]TORKZABAN S,KIM H N,SIMUNEK J,et al.Hysteresis of colloid retention and release in saturated porous media during transients in solution chemistry[J].Environmental Science&Technology,2010,44(5):1662-1669.
[26]张维,唐翔宇,鲜青松.紫色土小流域浅层井水中胶体颗粒的季节变化[J].环境科学,2017,37(1):87-94.ZHANG Wei,TANG Xiangyu,XIAN Qingsong.Seasonal variation of colloid particles in the shallow well water of a small watershed of purple soil[J].Environmental Science,2017,37(1):87-94.
[27]BRADFORD S A,KIM H.Implications of cation exchange on clay release and colloid-facilitated transport in porous media[J].Journal of Environmental Quality,2010,39(6):2040-2046.
[28]吕俊佳,许端平,李发生.不同环境因子对黑土胶体在饱和多孔介质中运移特性的影响[J].环境科学研究,2012,25(8):875-881.LJunjia,XU Duanping,LI Fasheng.Effects of different environmental factors on the transportation of black soil colloid in saturated porous media[J].Research of Environmental Sciences,2012,25(8):875-881.
[29]TARASEVICH Y I,DOLENKO S A,TRIFONOVA M Y,et al.Association and colloid-chemical properties of humic acids in aqueous solutions[J].Colloid Journal,2013,75(2):207-213.
[30]MAJDALANI S,MICHEL E,DI-PIETRO L,et al.Effects of wetting and drying cycles on in situ soil particle mobilization[J].European Journal of Soil Science,2008,59(2):147-155.
[31]MOHANTY S K,SAIERS J E,RYAN J N.Colloid mobilization in a fractured soil:effect of pore-water exchange between preferential flow paths and soil matrix[J].Environmental Science&Technology,2016,50(5):2310-2317.
[32]PORUBCAN A A,XU Shangbo.Colloid straining within saturated heterogeneous porous media[J].Water Research,2011,45(4):1796-1806.
[33]KNAPPENBERGER T,ARAMRAK S,FLURY M.Transport of barrel and spherical shaped colloids in unsaturated porous media[J].Journal of Contaminant Hydrology,2015,180:69-79.
[2]GAO Yang,ZHU Bo,WANG Tao,et al.Seasonal change of nonpoint source pollution-induced bioavailable phosphorus loss:a case study of southwestern China[J].Journal of Hydrology,2012,420/421:373-379.
[3]SHEN Zhenyao,CHEN Lei,DING Xiaowen,et al.Long-term variation(1960-2003)and causal factors of non-point-source nitrogen and phosphorus in the upper reach of the Yangtze River[J].Journal of Hazardous Materials,2013,252:45-56.
[4]TANG Jialiang,WANG Tao,ZHU Bo,et al.Tempo-spatial analysis of water quality in tributary bays of the Three Gorges Reservoir Region(China)[J].Environmental Science and Pollution Research,2015,22(21):16709-16720.
[5]TANG Jialiang,WANG Tao,ZHU Bo,et al.Subsurface flow processes in sloping cropland of purple soil[J].Journal of Mountain Science,2012,9(1):1-9.
[6]郑子成,秦凤,李廷轩.不同坡度下紫色土地表微地形变化及其对土壤侵蚀的影响[J].农业工程学报,2015,31(8):168-175.ZHENG Zicheng,QIN Feng,LI Tingxuan.Changes in soil surface microrelief of purple soil under different slope gradients and its effects on soil erosion[J].Transactions of Chinese Society of Agricultural Engineering,2015,31(8):168-175.
[7]TANG Jialiang,CHEN Xunqiang,ZHU Bo,et al.Rainfall and tillage impacts on soil erosion of sloping cropland with subtropical monsoon climate:a case study in hilly purple soil area,China[J].Journal of Mountain Science,2015,12(1):134-144.
[8]BIRKEL C,SOULSBY C.Linking tracers,water age and conceptual models to identify dominant runoff processes in a sparsely monitored humid tropical catchment[J].Hydrological Processes,2016,30(24):4477-4493.
[9]王超.紫色土坡耕地径流水源的同位素示踪研究[D].北京:中国科学院大学,2013.
[10]ZHU Bo,WANG Tao,KUANG Fuhong,et al.Measurements of nitrate leaching from a hillslope cropland in the central Sichuan Basin,China[J].Soil Science Society of America Journal,2009,73(4):1419-1426.
[11]GAO Yang,ZHU Bo,HE Nianping,et al.Phosphorus and carbon competitive sorption-desorption and associated non-point loss respond to natural rainfall events[J].Journal of Hydrology,2014,517:447-457.
[12]LI Zhanbin,LI Peng,HAN Jiangang,et al.Sediment flow behavior in agro-watersheds of the purple soil region in China under different storm types and spatial scales[J].Soil&Tillage Research,2009,105(2):285-291.
[13]GAO Changjuan,YANG Shengke,WANG Wenke,et al.Influence of humic acid colloid on adsorption of DDT in the riverbed sediments[J].Asian Journal of Chemistry,2014,26(9):2637-2642.
[14]PANG Liping,LAFOGLER M,KNORR B,et al.Influence of colloids on the attenuation and transport of phosphorus in alluvial gravel aquifer and vadose zone media[J].Science of the Total Environment,2016,550:60-68.
[15]ZHANG Wei,TANG Xiangyu,WEISBROD N,et al.A review of colloid transport in fractured rocks[J].Journal of Mountain Science,2012,9(6):770-787.
[16]ZHAO Pei,TANG Xiangyu,ZHAO Peng,et al.Tracing water flow from sloping farmland to streams using oxygen-18 isotope to study a small agricultural catchment in southwest China[J].Soil&Tillage Research,2013,134:180-194.
[17]RANI R D,SASIDHAR P.Stability assessment and characterization of colloids in coastal groundwater aquifer system at Kalpakkam[J].Environmental Earth Sciences,2011,62(2):233-243.
[18]ZHAO Pei,TANG Xiangyu,ZHAO Peng,et al.Identifying the water source for subsurface flow with deuterium and oxygen-18 isotopes of soil water collected from tension lysimeters and cores[J].Journal of Hydrology,2013,503:1-10.
[19]DEGUELDRE C,BAEYENS B,GOERLICH W,et al.Colloids in water from a subsurface fracture in granitic rock,Grimsel Test Site,Switzerland[J].Geochimicaet Cosmochimica Acta,1989,53(3):603-610.
[20]TANG Xiangyu,WEISBROD N.Colloid-facilitated transport of lead in natural discrete fractures[J].Environmental Pollution,2009,157:2266-2274.
[21]ZVIKELSKY O,WEISBROD N,DODY A.A comparison of clay colloid and artificial microsphere transport in natural discrete fractures[J].Journal of Colloid and Interface Science,2008,323(2):286-292.
[22]李海明,李云,翟菁,等.咸水中胶体迁移-沉积对砂介质渗透性损失的数学模型[J].环境科学研究,2010,23(3):346-349.LI Haiming,LI Yun,ZHAI Jing,et al.Mathematical model of colloid transport-deposition on permeability loss of sand medium in salt water[J].Research of Environmental Sciences,2010,23(3):346-349.
[23]WEISBROD N,DAHAN O,ADAR E M.Particle transport in unsaturated fractured chalk under arid conditions[J].Journal of Contaminant Hydrology,2002,56:117-136.
[24]LI Haiming,WEI Jinbu,GE Yaochao,et al.The influence of Na+and Ca2+on the migration of colloids or/and ammonia nitrogen in an unsaturated zone medium[J].Journal of Contaminant Hydrology,2016,194:24-29.
[25]TORKZABAN S,KIM H N,SIMUNEK J,et al.Hysteresis of colloid retention and release in saturated porous media during transients in solution chemistry[J].Environmental Science&Technology,2010,44(5):1662-1669.
[26]张维,唐翔宇,鲜青松.紫色土小流域浅层井水中胶体颗粒的季节变化[J].环境科学,2017,37(1):87-94.ZHANG Wei,TANG Xiangyu,XIAN Qingsong.Seasonal variation of colloid particles in the shallow well water of a small watershed of purple soil[J].Environmental Science,2017,37(1):87-94.
[27]BRADFORD S A,KIM H.Implications of cation exchange on clay release and colloid-facilitated transport in porous media[J].Journal of Environmental Quality,2010,39(6):2040-2046.
[28]吕俊佳,许端平,李发生.不同环境因子对黑土胶体在饱和多孔介质中运移特性的影响[J].环境科学研究,2012,25(8):875-881.LJunjia,XU Duanping,LI Fasheng.Effects of different environmental factors on the transportation of black soil colloid in saturated porous media[J].Research of Environmental Sciences,2012,25(8):875-881.
[29]TARASEVICH Y I,DOLENKO S A,TRIFONOVA M Y,et al.Association and colloid-chemical properties of humic acids in aqueous solutions[J].Colloid Journal,2013,75(2):207-213.
[30]MAJDALANI S,MICHEL E,DI-PIETRO L,et al.Effects of wetting and drying cycles on in situ soil particle mobilization[J].European Journal of Soil Science,2008,59(2):147-155.
[31]MOHANTY S K,SAIERS J E,RYAN J N.Colloid mobilization in a fractured soil:effect of pore-water exchange between preferential flow paths and soil matrix[J].Environmental Science&Technology,2016,50(5):2310-2317.
[32]PORUBCAN A A,XU Shangbo.Colloid straining within saturated heterogeneous porous media[J].Water Research,2011,45(4):1796-1806.
[33]KNAPPENBERGER T,ARAMRAK S,FLURY M.Transport of barrel and spherical shaped colloids in unsaturated porous media[J].Journal of Contaminant Hydrology,2015,180:69-79.