Data for: Field observations to establish the impact of fluvial flooding on potentially toxic element (PTE) mobility in floodplain soils

These datasets support the publication Ponting, J., Verhoef, A., Watts, M.J. and Sizmur, T., 2021. Field observations to establish the impact of fluvial flooding on potentially toxic element (PTE) mobility in floodplain soils. Science of The Total Environment, p.151378. The site used in this study is a floodplain downstream of a lowland urban catchment in England and is located adjacent to the River Loddon, a tributary of the River Thames, to the south of Reading, in southeast England, United Kingdom (51º24’47.6” N, 0º55’10.6” W). The data used in this paper was collected through the period of December 2018 to March 2019; pre-flood, during the flood, and post-flood. The flood event occurred due to high groundwater levels and overbanking of the River Loddon. There were 5 sampling visits before the flood (pre-flood), one visit during the flood (towards the end of approximately a one-week flood) and 5 sampling visits after the flood (post-flood). The 12 soil sampling locations used throughout the sampling regime were selected by creating a Fishnet grid (5m x 5m) in ArcGIS and taking the centre of the grid as the sampling point. At each sampling location, 5 soil samples were collected from an approximately 1m2 area using a stainless-steel auger to consistently sample the top 30cm of floodplain soil. These 5 samples were combined into 1 composite sample and stored in a cool box before return to the laboratory. Homogenised (~100 g) samples were centrifuged at 5,000 rpm (RCF 3830 x g) for 1 hour to extract pore water samples. Analyses conducted on the pore water samples included elements using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), anions using Ion Chromatography (IC), and dissolved organic carbon using the Non-Purgeable Dissolved Organic Carbon (NPOC) method. River water samples were collected with a Nalgene bottle on a pole from a bridge located upstream of the floodplain at two time points (8 am and noon) on each sampling day during the period between November 2018 and March 2019. Groundwater samples were collected from two boreholes located on the Loddon Meadow Floodplain on each sampling day during the period between December 2018 and March 2019. An acid-washed 1 m plastic tube with 60 ml syringe was used to create a vacuum to draw water up from the borehole. The first sample drawn up was used to wash the 500 ml Nalgene sample bottle and then discarded. The river water and groundwater samples collected were transported in a cool box back to the laboratory and then were filtered using a 0.45 µm cellulose nitrate syringe filter and acidified prior to storage in the fridge and further analyses for elements (ICP-MS), anions (IC) and dissolved organic carbon (NPOC).本数据集支撑以下发表论文：Ponting, J.、Verhoef, A.、Watts, M.J. 及 Sizmur, T. 于2021年发表的《野外观测确定河流洪水对泛滥平原土壤中潜在有毒元素（Potentially Toxic Element, PTE）迁移性的影响》，刊载于《总体环境科学》（Science of The Total Environment），论文编号p.151378。 本研究选取的研究位点位于英格兰境内一处低地城市集水区下游的泛滥平原，毗邻泰晤士河支流洛登河（River Loddon），地处英国英格兰东南部雷丁市以南，地理坐标为51°24′47.6″N，0°55′10.6″W。 本文所用数据采集于2018年12月至2019年3月期间，覆盖洪水前、洪水发生时及洪水后三个阶段。本次洪水事件由洛登河水位过高引发漫滩，叠加地下水位抬升所导致。本次采样计划为：洪水前开展5次采样，洪水期间（约一周洪水过程的末期）开展1次采样，洪水后开展5次采样。 本次采样共设置12个土壤采样点位，通过ArcGIS创建5m×5m的渔网网格（Fishnet grid），以网格中心点作为采样点位。在每个采样点位，使用不锈钢取土钻在约1平方米的区域内采集5份土壤样品，统一采集泛滥平原土壤表层30cm深度的样本。将同点位的5份土壤样品混合为1份复合样品，置于冷藏箱中运输返回实验室。将均质后的约100g样品以5000转/分钟（相对离心力RCF 3830×g）离心1小时，提取孔隙水样品。孔隙水样品的分析项目包括：采用电感耦合等离子体质谱法（Inductively Coupled Plasma Mass Spectrometry, ICP-MS）检测元素含量、采用离子色谱法（Ion Chromatography, IC）检测阴离子含量，以及采用非吹扫性溶解有机碳（Non-Purgeable Dissolved Organic Carbon, NPOC）法测定溶解有机碳含量。 河水样品采集于2018年11月至2019年3月的每个采样日，通过安装在长杆上的Nalgene采样瓶，在泛滥平原上游的桥梁处分两个时间点（上午8时及正午）采集。地下水样品采集于2018年12月至2019年3月的每个采样日，采样点位为洛登草甸泛滥平原上的两口钻井。采集时使用经酸洗处理的1米长塑料管搭配60ml注射器形成真空，将地下水从钻井中抽出。首次抽出的样品用于润洗500ml Nalgene采样瓶后弃去。采集的河水及地下水样品均置于冷藏箱运回实验室，随后使用0.45μm硝酸纤维素注射器过滤器进行过滤并酸化，之后冷藏保存，以待开展元素（ICP-MS）、阴离子（IC）及溶解有机碳（NPOC）相关分析。