摘要
深入探究农田排水沟水体与底泥界面微环境对界面间物质交换和迁移转化具有重要意义,为了明确不同水力联系的排水沟界面微环境特征,该研究利用微电极测量系统对陕西卤泊滩盐碱化改良区和盐荒地2种水力条件差异较大的排水沟水体与底泥界面微环境进行了研究。结果表明:改良区与盐荒地排水沟水体水质指标和底泥含水率、有机质、硫酸盐含量等方面均存在不同程度的差异,底泥含水率自表层向下逐渐减小;改良区与盐荒地底泥氧气最大渗透深度分别为10.2和2.6 mm,扩散边界层厚度分别为0.4~0.8 mm和0.2~0.4 mm;改良区排水沟底泥硫化氢浓度小于10μmol/L,而盐荒地高至178μmol/L。研究结果可为研究区及类似地区利用排水沟渠湿地控制和治理农业面源污染、改善农田生态环境提供参考。
Substance exchange and transfer depend mainly on the micro-environment of the interface between the water body and the underlying sediment in drainage ditches in Reclamation areas.In this study,the sediments were taken separately from two ditches that drain reclaimed and non-reclaimed fields in a salt impacted agricultural area in Shaanxi,China.A laboratory experiment was conducted to monitor physical and chemical properties at the sediment and water body interface using the Unisense micro-electrode system.The system consisted of microelectrode,four-channel host,motor controller,microelectrode thruster,the sensor trace PRO software,and lab support LS18.The tip diameter of Unisense DO microelectrode was 25μm,and the polarization voltage of DO microelectrode was-0.8 V,where the pre-polarization signal value was stable.Five parallel samples were set to separately measure DO values,and the average value was calculated.Each group in experiments was repeated three times.The measurement interval was 100μm,each DO concentration profile was measured for 30 min,and 120 DO profiles were observed.The Uniense H_(2)S microelectrode was a miniaturized picoamperometric microelectrode with a tip diameter of 25μm and a pre-polarization voltage of+0.08 V,including three electrodes for the measurement,protection,and reference.The pre-polarized signal was corrected after stabilizing.The temperature of the calibration solution was consistent with the test sample,and the calibration test was conducted in the same environment as the measurement.The measurement depth of H_(2)S profile was limited by the electrode length,where the maximum measurement depth was about 40 mm at 50μm measurement step.The measurement time was about 60 min for each setup of H_(2)S concentration profiles,and a total of 24 H_(2)S profiles were observed.The monitoring results showed that the maximum depth of oxygen penetration was 10.2 and 2.6 mm for sediment samples taken from the reclaimed and the non-reclaimed fields,whereas,the diffusion boundary-layer thicknesses were 0.4-0.8 mm and 0.2-0.4 mm,respectively.The observation results showed that the water content in the sediment decreased with the depth of sampling,due mainly to the compaction at the ditch bottom.Specifically,the measured water content ranged from 54%to 78%in the ditches of reclaimed field,and from 73%to 87%in ditch sediment of non-reclaimed field.The Electrical Conductivity(EC)was between 3.64 and 4.12 mS/cm in the ditch of the reclaimed field,while it ranged from 10.74 to 13.22 mS/cm in the ditch sediment of non-reclaimed field.There was a large difference(of 4 times)in EC between the two different sampling sites,indicating the salt accumulation in the drainage ditch from the non-reclaimed fields.The measured DO value remained stable at 8 mg/L for sediments from the ditch of the reclaimed field,while it varied from 3.21 mg/L to 5.44 mg/L in the ditch sediment of the non-reclaimed field.The concentration of hydrogen sulfide in the ditch sediment of reclaimed field less than 10μmol/L,while it was as high as 178μmol/L in the ditch sediment of non-reclaimed field.The findings can provide a sound reference for the design and application of ditches,and thereby to improving the ecological environment of farmland in similar areas.
作者
潘延鑫
冯绍元
井思媛
罗纨
贾忠华
Pan Yanxin;Feng Shaoyuan;Jing Siyuan;Luo Wan;Jia Zhonghua(College of Hydraulic Science and Engineering,Yangzhou University,Yangzhou 225009,China;National and Local Joint Engineering Laboratory of Hydraulic Engineering Safety and Efficent Utilization of Water Resources in Poyang Lake Basin,Nanchang Institute of Technology,Nanchang 330099,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2021年第2期258-267,共10页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金资助项目(51709144)
江西省教育厅科研项目(GJJ170981)
江西省自然科学基金项目(20202BABL204068)。
关键词
微电极
溶解氧
硫化氢
排水沟
水体与底泥界面
微环境
microelectrodes
dissolved oxygen
hydrogen sulfide
drainage ditch
sediment-water interface
micro-environment
