海水中溶解氧碘量法测定结果的有效位数推算

当前海洋监测系统和环保监测系统面临着监测数据公开需求，溶解氧是环境监测的常规测项，其监测结果需要进行科学的规范性表达。有效数字能够体现测量值的可信程度，有效数字位数是测试结果规范表达的重要指标。本文详细分析"GB17378.4-2007海洋监测规范第4部分海水分析中第31章溶解氧"中的测定步骤中影响因素，对溶解氧测定结果的有效位数进行科学推断。分析表明，硫代硫酸钠浓度、硫代硫酸钠消耗体积、水样体积是关键影响因素。结果表明，硫代硫酸钠浓度有效位数3位，硫代硫酸钠使用体积有效位数3位或4位，水样体积有效位数5位；溶解氧碘量法测定结果的有效位数，通常为3位。

Calculation of significant digits of dissolved oxygen in seawater by iodimetry

At present, the open of monitoring data is the important working of monitoring system.Significant digits indicate the reliability of date.Dissolved oxygen (DO) is a routine environmental monitoring item.In this paper, we discuss and calculate the significant digits of dissolved oxygen in seawater by iodimetry.The results show that the concentration of Na₂S₂O₃ and the volume of Na₂S₂O₃ and water sample are the three key influence factors.And in general, the concentration of Na₂S₂O₃ is three digits; and the volume of Na₂S₂O₃ is three or four digits; the volume water sample is five digits; the DO measure results are three digits.