University of Geneva, Department of Inorganic and Analytical Chemistry, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland.
Environ Sci Process Impacts. 2015 May;17(5):906-14. doi: 10.1039/c5em00038f. Epub 2015 Apr 8.
Since aquatic environments are highly heterogeneous and dynamic, there is the need in aquatic ecosystem monitoring to replace traditional approaches based on periodical sampling followed by laboratory analysis with new automated techniques that allow one to obtain monitoring data with high spatial and temporal resolution. We report here on a potentiometric sensing array based on polymeric membrane materials for the continuous monitoring of nutrients and chemical species relevant for the carbon cycle in freshwater ecosystems. The proposed setup operates autonomously, with measurement, calibration, fluidic control and acquisition triggers all integrated into a self-contained instrument. Experimental validation was performed on an automated monitoring platform on lake Greifensee (Switzerland) using potentiometric sensors selective for hydrogen ions, carbonate, calcium, nitrate and ammonium. Results from the field tests were compared with those obtained by traditional laboratory analysis. A linear correlation between calcium and nitrate activities measured with ISEs and relevant concentrations measured in the laboratory was found, with the slopes corresponding to apparent single ion activity coefficients γ()(Ca(2+)) = 0.55(SD = 0.1mM) and γ()(NO(3)(-)) = 0.75(SD = 4.7μm). Good correlation between pH values measured with ISE and CTD probes (SD = 0.2 pH) suggests adequate reliability of the methodology.
由于水生环境高度不均匀且动态变化，因此在水生生态系统监测中需要用新的自动化技术取代传统的基于定期采样和实验室分析的方法，这些新技术可以获得具有高时空分辨率的监测数据。我们在此报告了一种基于聚合膜材料的电位传感阵列，用于连续监测淡水生态系统中与碳循环相关的营养物质和化学物质。所提出的设置可自主运行，测量、校准、流体控制和采集触发都集成到一个独立的仪器中。在瑞士 Greifensee 湖的自动化监测平台上，使用对氢离子、碳酸盐、钙、硝酸盐和铵具有选择性的电位传感器对其进行了实验验证。现场测试的结果与传统实验室分析得到的结果进行了比较。发现 ISE 测量的钙离子和硝酸盐活性与实验室测量的相关浓度之间存在线性相关性，斜率对应于表观单离子活度系数 γ()(Ca(2+)) = 0.55(SD = 0.1mM)和 γ()(NO(3)(-)) = 0.75(SD = 4.7μm)。ISE 测量的 pH 值与 CTD 探头之间具有良好的相关性(SD = 0.2 pH)，表明该方法具有足够的可靠性。
