典型盐碱地改良区农田排水沟水体与底泥界面氧通量研究
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摘要
农田排水沟水体与底泥中的氧含量决定了底泥中各种生源要素的最终归趋,对维持农田排水沟的水环境至关重要。本论文以陕西富平县卤泊滩盐碱地改良区农田排水沟水体与底泥为研究对象,从环境微界面角度出发,根据多年监测数据构建室内试验,采用高分辨率微环境固液剖面传感系统(丹麦Unisense微电极系统),探究了研究区农田排水沟水体与底泥界面氧通量变化规律。研究结果表明:底泥中的溶解氧随深度的增加逐渐减小,直至溶解氧浓度为零,到达厌氧层;溶解氧剖面浓度的实测值与Profile模型模拟值的相关系数均在0.995以上,表明该模型能客观地描述溶解氧在农田排水沟水体与底泥扩散边界层和底泥中的分布;农田排水沟上游不同监测点位的底泥含氧层厚度在3.5～6 mm之间,而下游监测点位的底泥含氧层厚度约为1.5 mm,差异显著;通过氧浓度线性分布、剖面拐点法得到氧气扩散边界厚度,上游监测点位的氧气扩散边界层厚度基本在1 mm,而下游监测点位的氧气扩散边界层厚度减少至0.2 mm。农田排水沟水体与底泥界面氧通量的测定,对于认识农田排水沟底泥的地球化学过程及水环境作用机理具有重要意义,可为农田排水沟水环境治理提供参考依据。
The micro-interface between the sediment of farmland drainage ditch and the water environment is an important place for oxygen transfer between the water phase and the sediment phase, which determines the fate of various solutes in the bottom sediment of drainage ditches. Accurate representation of the flux and diffusion boundary layer of the reactive components at the interface is very important for studying their environmental micro-interface behavior. In this paper, the water body and bottom sediment of farmland drainage ditches in a saline-alkali land improvement area of Fuping County, Shaanxi province is taken as the research object. Targeting the environmental micro-interface, an indoor experiment based on field monitoring data was conducted by using a high resolution microenvironment solid-liquid profile sensing system(unisense microelectrode system in Denmark). The variation of oxygen flux at the bottom of the drainage ditch was investigated. The results show that the dissolved oxygen in the bottom mud decreased gradually with the increase of depth until the dissolved oxygen concentration became zero and reached the anaerobic layer. The correlation coefficient between the measured concentration of dissolved oxygen profile and the simulated value of the Profile model was above 0.995, indicating that the model can reasonably well describe the distribution of dissolved oxygen in the boundary layer and bottom mud of the interface diffusion.The thickness of oxygen layer in different monitoring points in the upper reaches of the drainage ditch was between 3.5 and 6 mm, while the thickness of oxygen layer in the downstream monitoring point was about1.5 mm, significant differences were observed. The diffusion boundary thickness was obtained by the linear distribution of oxygen concentration and the profile inflection point method. The diffusion boundary layer of the upstream monitoring point position was about 1 mm, while the diffusion boundary layer of the downstream monitoring point position was 0.5 mm and 0.2 mm, respectively. The determination of oxygen flux at the micro-interface between water body and sediment in farmland drainage ditch is of great significance to know the geochemical processes and water environment mechanism of sediment in drainage ditch, which may provide reference for water environment management in farmland drainage ditch.
The micro-interface between the sediment of farmland drainage ditch and the water environment is an important place for oxygen transfer between the water phase and the sediment phase, which determines the fate of various solutes in the bottom sediment of drainage ditches. Accurate representation of the flux and diffusion boundary layer of the reactive components at the interface is very important for studying their environmental micro-interface behavior. In this paper, the water body and bottom sediment of farmland drainage ditches in a saline-alkali land improvement area of Fuping County, Shaanxi province is taken as the research object. Targeting the environmental micro-interface, an indoor experiment based on field monitoring data was conducted by using a high resolution microenvironment solid-liquid profile sensing system(unisense microelectrode system in Denmark). The variation of oxygen flux at the bottom of the drainage ditch was investigated. The results show that the dissolved oxygen in the bottom mud decreased gradually with the increase of depth until the dissolved oxygen concentration became zero and reached the anaerobic layer. The correlation coefficient between the measured concentration of dissolved oxygen profile and the simulated value of the Profile model was above 0.995, indicating that the model can reasonably well describe the distribution of dissolved oxygen in the boundary layer and bottom mud of the interface diffusion.The thickness of oxygen layer in different monitoring points in the upper reaches of the drainage ditch was between 3.5 and 6 mm, while the thickness of oxygen layer in the downstream monitoring point was about1.5 mm, significant differences were observed. The diffusion boundary thickness was obtained by the linear distribution of oxygen concentration and the profile inflection point method. The diffusion boundary layer of the upstream monitoring point position was about 1 mm, while the diffusion boundary layer of the downstream monitoring point position was 0.5 mm and 0.2 mm, respectively. The determination of oxygen flux at the micro-interface between water body and sediment in farmland drainage ditch is of great significance to know the geochemical processes and water environment mechanism of sediment in drainage ditch, which may provide reference for water environment management in farmland drainage ditch.
引文
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[15]郑阳华,邹浩东,何强,等.水动力条件对沉积物-水界面氧通量的影响[J].湖泊科学,2018,30(6):1552-1559.
[16]潘延鑫,罗纨,贾忠华,等.盐碱地排水沟蓄水后底泥与水体盐分交换试验[J].农业工程学报,2013,29(2):81-87.
[17]韩霁昌,解建仓,朱记伟,等.陕西卤泊滩盐碱地综合治理模式的研究[J].水利学报,2009,40(3):472-477.
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[21] FABRICIUS A L,DUESTER L,ECKER D,et al. Metalandmetalloid size-fractionation strategies in spatial high-resolution sediment pore water profiles[J]. Environmental Science&Technology, 2016, 50(17):9506-9514.
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[23] BRAVO A G,BOUCHET S,TOLU J,et al. Molecular composition of organic matter controls methylmercury formation in boreal lakes[J]. Nature Communications,2017,8:14255.
[24] WANG PF,YAO Y,WANG C,et al. Impact of macrozoobenthic bioturbation and wind fluctuation interactions on net methylmercury in freshwater lakes[J]. Water Research,2017,124:320-330.
[25]雷沛,张洪,王超,等.沉积物水界面污染物迁移扩散的研究进展[J].湖泊科学,2018,30(6):1489-1508.
[26] BERG P,RISGAARD-PETERSEN N,RYSGAARD S. Interpretation of measured concentration profiles in sediment pore water[J]. Limnology and Oceanography,1998,43(7):1500-1510.
[27]钱宝,刘凌,肖潇,等.湖泊沉积物-水微界面上磷的释放过程研究[J].水利学报,2014,45(4):482-489.
[28] LORENZEN J,LARSEN L H,KJAR T,et al. Biosensor determination of the microscale distribution of nitrate,nitrate assimilation,nitrification,and denitrification in adiatom-inhabited freshwater sediment[J]. Applied and Environmental Microbiology,1998,64(9):3264-3269.
[2]冯绍元,黄冠华.试论水环境中的氮污染行为[J].灌溉排水学报,1997,16(2):34-36.
[3]高占义.我国灌区建设及管理技术发展成就与展望[J].水利学报,2019,50(1):88-96.
[4]罗纨,朱金城,贾忠华,等.排水沟塘分布特性及与农田水力联系对水质净化能力的影响[J].农业工程学报,2017,33(10):161-167.
[5] LUTHER G W,REIMERS C E,NUZZIO D B,et al. In situ deployment of voltammetric,potentiometric and ampero-metric microelectrodes from a ROV to determine dissolved O2,Mn,Fe,S(-2)and pH in pore waters[J].Environmental Science&Technology,1999,33:4352-4356.
[6] HONEYMAN B D. Colloidal culprits in contamination[J]. Nature,1999,397(7):23-24.
[7]汤鸿霄.环境纳米污染物与微界面水质过程[J].环境科学学报,2003,23(2):146-155.
[8]曲久辉,贺泓,刘会娟.典型环境微界面及其对污染物环境行为的影响[J].环境科学学报,2009,29(1):2-10.
[9] AHMERKAMP S,WINTER C,KRAEMER K,et al. Regulation of benthic oxygen fluxes in permeable sediments of the coastal ocean[J]. Limnology and Oceanography,2017,62(5):1935-1954.
[10] NAKAMURA Y. Sediment oxygen consumption and vertical flux of organic matter in the Seto Inland Sea,Japan[J]. Estuarine Coastal&Shelf Science,2003,56(2):213-220.
[11] DENISE B,LISA A L,ANDREAS O,et al. Declining oxygen in the global ocean and coastal waters[J]. Science,2018,359:1-11.
[12]范成新,相崎守弘,福岛武彦,等.霞浦湖沉积物需氧速率的研究[J].海洋与湖沼,1998,29(5):508-513.
[13] BIERLEIN KA,REZVANI M,SOCOLOFSKY SA,et al. Increased sediment oxygen flux in lakes and reservoirs:the impact of hypolimnetic oxygenation[J]. Water Resources Research,2017,53(6):4876-4890.
[14]王建军,沈吉,张路,等.湖泊沉积物-水界面氧气交换速率的测定及影响因素[J].湖泊科学,2009,21(4):474-482.
[15]郑阳华,邹浩东,何强,等.水动力条件对沉积物-水界面氧通量的影响[J].湖泊科学,2018,30(6):1552-1559.
[16]潘延鑫,罗纨,贾忠华,等.盐碱地排水沟蓄水后底泥与水体盐分交换试验[J].农业工程学报,2013,29(2):81-87.
[17]韩霁昌,解建仓,朱记伟,等.陕西卤泊滩盐碱地综合治理模式的研究[J].水利学报,2009,40(3):472-477.
[18] NIELSEN L P,RISGAARD-PETERSEN N,FOSSING H,et al. Electric currents couple spatially separated biogeochemical processes in marine sediment[J]. Nature,2010,463(7284):1071-1074.
[19] GUNDERSEN J K,JORGENSEN B B. Microstructure of diffusive boundary layers and the oxygen uptake of the sea floor[J]. Nature,1990,345:604-607.
[20] PFEFFER C,LARSEN S,SONG J. Filamentous bacteria transport electrons over centimeter distances[J]. Nature,2012,463:11586-11590.
[21] FABRICIUS A L,DUESTER L,ECKER D,et al. Metalandmetalloid size-fractionation strategies in spatial high-resolution sediment pore water profiles[J]. Environmental Science&Technology, 2016, 50(17):9506-9514.
[22] DAVLSON W,ZHANG H. In situ speciation measurements of trace components in natural waters using thin-film gels[J]. Nature,1994,367:546-548.
[23] BRAVO A G,BOUCHET S,TOLU J,et al. Molecular composition of organic matter controls methylmercury formation in boreal lakes[J]. Nature Communications,2017,8:14255.
[24] WANG PF,YAO Y,WANG C,et al. Impact of macrozoobenthic bioturbation and wind fluctuation interactions on net methylmercury in freshwater lakes[J]. Water Research,2017,124:320-330.
[25]雷沛,张洪,王超,等.沉积物水界面污染物迁移扩散的研究进展[J].湖泊科学,2018,30(6):1489-1508.
[26] BERG P,RISGAARD-PETERSEN N,RYSGAARD S. Interpretation of measured concentration profiles in sediment pore water[J]. Limnology and Oceanography,1998,43(7):1500-1510.
[27]钱宝,刘凌,肖潇,等.湖泊沉积物-水微界面上磷的释放过程研究[J].水利学报,2014,45(4):482-489.
[28] LORENZEN J,LARSEN L H,KJAR T,et al. Biosensor determination of the microscale distribution of nitrate,nitrate assimilation,nitrification,and denitrification in adiatom-inhabited freshwater sediment[J]. Applied and Environmental Microbiology,1998,64(9):3264-3269.