Suction cups are widely used in agricultural and environmental research and monitoring under the hypothesis that the sample chemistry represents the soil pore water solute composition around the cup location. The objective of this study was to analyze the sampling procedures that lead to the most representative sample for soil aqueous phase composition when using a falling head suction cup. This was achieved by simulating simultaneously the hydraulic and geochemical response of the suction cup sampled soil solution and its immediate surroundings when evacuated by a system‐dependent variable boundary condition. Different soils, water contents, vacuum applications, and suction cup internal volumes, as well as variable hydraulic conductivities of the ceramic cup, were evaluated, and their effects on the sampling rate and sample chemical composition were reported. Model results showed that potential extracted soil solution volume depends on a combination of internal suction cup volume and vacuum applied, independently from soil type or water content. A linear relationship was defined between the ratio of the extracted sample to suction cup volume and the initial applied vacuum, for all simulations. The pH values and general chemistry of the sampled solution were found to be more similar to those in the soil when a porous cup system is filled until hydraulic equilibrium is reached. Following this, a small volume suction cup system with a high initial applied vacuum, which allows for faster sample collection, could be optimal.

中文翻译：

---

取决于吸盘系统的可变边界条件：瞬态水流和多组分溶质运移

假设样品化学成分代表杯子周围土壤孔隙水的溶质组成，则吸盘被广泛用于农业和环境研究和监测。本研究的目的是分析使用落头式吸盘时导致土壤水相成分最具代表性的采样程序。这是通过同时模拟由系统决定的可变边界条件抽空的吸盘采样土壤溶液及其附近环境的水力和地球化学响应来实现的。评估了不同的土壤，水含量，真空应用和吸盘内部容积以及陶瓷杯的可变水力传导率，报告了它们对采样率和样品化学成分的影响。模型结果表明，潜在的提取土壤溶液体积取决于内部吸盘体积和施加的真空的组合，而与土壤类型或含水量无关。对于所有模拟，在提取的样品与吸盘体积之比与初始施加的真空之间定义了线性关系。当填充多孔杯系统直至达到水力平衡之前，发现样品溶液的pH值和一般化学性质与土壤中的pH值和化学性质更相似。此后，具有较高初始施加真空度的小容量吸盘系统可能是最佳选择，该系统可实现更快的样品收集。模型结果表明，潜在的提取土壤溶液体积取决于内部吸盘体积和施加的真空的组合，而与土壤类型或含水量无关。对于所有模拟，在提取的样品与吸盘体积之比与初始施加的真空之间定义了线性关系。当填充多孔杯系统直至达到水力平衡之前，发现样品溶液的pH值和一般化学性质与土壤中的pH值和化学性质更相似。此后，具有较高初始施加真空度的小容量吸盘系统可能是最佳选择，该系统可实现更快的样品收集。模型结果表明，潜在的提取土壤溶液体积取决于内部吸盘体积和施加的真空的组合，而与土壤类型或含水量无关。对于所有模拟，在提取的样品与吸盘体积之比与初始施加的真空之间定义了线性关系。当填充多孔杯系统直至达到水力平衡之前，发现样品溶液的pH值和一般化学性质与土壤中的pH值和化学性质更相似。此后，具有较高初始施加真空度的小容量吸盘系统可能是最佳选择，该系统可实现更快的样品收集。对于所有模拟，在提取的样品与吸盘体积之比与初始施加的真空之间定义了线性关系。当填充多孔杯系统直至达到水力平衡之前，发现样品溶液的pH值和一般化学性质与土壤中的pH值和化学性质更相似。此后，具有较高初始施加真空度的小容量吸盘系统可能是最佳选择，该系统可实现更快的样品收集。对于所有模拟，在提取的样品与吸盘体积之比与初始施加的真空之间定义了线性关系。当填充多孔杯系统直至达到水力平衡之前，发现样品溶液的pH值和一般化学性质与土壤中的pH值和化学性质更相似。此后，具有较高初始施加真空度的小容量吸盘系统可能是最佳选择，该系统可实现更快的样品收集。