High-frequency field nutrient analyzers offer a promising technology to solve time-consuming and laborious sampling problems in dynamic and complex river–estuarine–coastal ecosystems. However, few studies on the simultaneous underway analysis of five key nutrients (ammonium, nitrite, nitrate, phosphate, and silicate) in seawaters are available because of the limitations of the technique. In this study, a state-of-the-art autonomous portable analyzer for the shipboard analysis of nutrients in the environment of varied salinities and concentration ranges was reported. The analyzer consisted of compact hardware that was well suited for shipboard deployment with minimal maintenance. Moreover, a novel LabVIEW-based software program was developed, containing additional functions such as automated calibration curve generation, autodilution of high-concentration samples, and a user-friendly interface for multiparameter analysis using a single instrument. After the optimization of chemical reactions and work flow chart, the analyzer exhibited low limits of detection, a large linear range with automated dilution, and relative standard deviations of less than 2% (n = 11). Compared to other flow-based techniques, this analyzer is more portable and consumes less reagent with an autonomous data processing function and applicability within a broad salinity range (0–35). The analyzer was successfully applied for real-time analysis in the Jiulong River Estuary–Xiamen Bay with excellent on-site accuracy and applicability. The relationship between high spatial resolution nutrient concentrations and salinities showed very different patterns in estuarine and coastal areas, indicating the benefit of using an underway automated analyzer for chemical mapping in a dynamic environment.

中文翻译：

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使用自主流量分析仪对地表海水营养浓度进行实时制图

高频现场养分分析仪提供了一种很有前途的技术，可以解决动态和复杂的河流-河口-沿海生态系统中耗时且费力的采样问题。然而，由于技术的局限性，很少有关于同时进行海水中五种关键营养素（铵、亚硝酸盐、硝酸盐、磷酸盐和硅酸盐）分析的研究。在这项研究中，报告了一种最先进的自主便携式分析仪，用于对不同盐度和浓度范围环境中的营养物质进行船上分析。该分析仪由紧凑的硬件组成，非常适合船上部署，维护量极少。此外，还开发了一种基于 LabVIEW 的新型软件程序，其中包含自动校准曲线生成等附加功能，高浓度样品的自动稀释，以及使用单一仪器进行多参数分析的用户友好界面。经过化学反应和工作流程图的优化，分析仪检测限低，线性范围大，自动稀释，相对标准偏差小于2%（n = 11)。与其他基于流量的技术相比，该分析仪更便携，试剂消耗更少，具有自主数据处理功能，适用于广泛的盐度范围（0-35）。该分析仪成功应用于九龙江口-厦门湾的实时分析，具有出色的现场准确度和适用性。高空间分辨率养分浓度和盐度之间的关系在河口和沿海地区表现出非常不同的模式，表明使用正在进行的自动分析仪在动态环境中进行化学绘图的好处。