海洋水质在线监测系统中硝酸盐测量方法比较

Comparison of Nitrate Measurement Methods of Marine Water Quality On-line Monitoring System

硝酸盐是海洋水质监测的重要指标,目前在海洋水质在线监测系统中搭载的硝酸盐在线分析仪的种类较多,采用的测量原理也不尽相同。选取了3种采用不同测量方法的代表性硝酸盐分析仪[氯化钒还原比色法硝酸盐分析仪、二乙烯三胺五乙酸还原比色法(DTPA)硝酸盐分析仪、紫外分光光度法硝酸盐分析仪],结合各自的测量原理、化学试剂特性等,就水样盐度和不同测量方法对硝酸盐测定结果的影响进行比较研究,并对实际水样进行测定。实验结果可知,氯化钒法硝酸盐分析仪适用于硝酸盐背景值<0.5 mg/L的海洋水域,DTPA法硝酸盐分析仪适用于硝酸盐背景值<0.5 mg/L的入海河流水域,紫外法硝酸盐分析仪适用于硝酸盐背景值>0.5 mg/L的各类海洋水质。

Nitrate is an important indicator of marine water quality monitoring.At present,there are many kinds of on-line nitrate analyzers in marine water quality on-line monitoring system,and the measurement principles are also different.Taking the measurement principles and chemical characteristics into consideration,three representative nitrate analyzers with different measurement principles were selected,which includes vanadium chloride method,DTPA method and ultraviolet spectrophotometric method,to make a comparative study on the effect of salinity and method on results.The real samples were determined as well.According to the study,suitable nitrate measurement method can be selected for different water quality and it provides technical support for the accurate measurement of nitrate of marine water quality on-line monitoring system.The experimental results show that the nitrate analyzer using vanadium chloride is suitable for the marine water with the nitrate background value less than 0.5 mg/L.When DTPA is to be applied to the nitrate analyzer,it is suitable for the river estuary with the nitrate background value less than 0.5 mg/L,while the nitrate analyzer equipped with ultraviolet spectrophotometer is suitable for all kinds of marine water with the nitrate background value more than 0.5 mg/L.