摘要：

海水具有盐度及硬度高、存在有机污染等特点，水质检测方法的精度和适用性会受到很大影响。氨氮是海水环境监测与海水养殖等领域的重要水质指标之一，其测定也存在检测精度较低和检测过程繁琐等问题。对此，在水杨酸分光光度法基础上改进了海水氨氮检测方法，优化了非离子氨的计算方法，并采用实际海水进行了验证。结果表明，在25 ℃、亚硝基铁氰化钠催化作用下，海水中的氨氮与水杨酸钠、二氯异氰尿酸钠反应可生成稳定的吲哚类化合物，在655 nm处氨氮与反应后溶液吸光度成正比，线性相关系数为0.999 1，量程为0.02~2.00 mg/L，显色时间为10 min。该方法检出限为0.006 mg/L，测定下限为0.024 mg/L。在实际海水中测定氨氮为0.20、1.00 mg/L的样品时相对标准偏差分别为3.70%、-0.50%，加标回收率分别为100.20%、102.10%。最后，通过引入盐度修正项，推导出海水氨氮中非离子氨质量分数与水温、pH及海水盐度的关系式。

关键词: 海水, 氨氮, 非离子氨, 水杨酸分光光度法

Abstract:

The precision and applicability of water quality assessment methods for seawater analysis is significantly impacted by its high salinity,hardness and organic pollutant content. Ammonia-nitrogen is a crucial indicator in marine environmental monitoring and aquaculture, and its measurement also has problems such as low detection accuracy and complex procedures. This study presented an enhanced ammonia-nitrogen determination method based on salicylic acid spectrophotometry and an optimized non-ionic ammonia calculation method was developed and validated using actual seawater samples. The results showed that ammonia-nitrogen in seawater could react with sodium salicylate and sodium dichloroisocyanurate to form stable indole compounds at 25 ℃ with sodium nitroprusside as catalyst, creating a proportional relationship between ammonia-nitrogen and absorbance at 655 nm. The linear correlation coefficient was 0.999 1, with a range of 0.02-2.00 mg/L, and a coloration time of 10 minutes. The detection limit was 0.006 mg/L, and the lower limit was 0.024 mg/L. In seawater samples with ammonia-nitrogen of 0.20 and 1.00 mg/L, relative standard deviations were 3.70% and -0.50%, respectively, with recovery rates of 100.20% and 102.10%. By introducing a salinity correction term, the relational formula linking mass fraction of non-ionic ammonia in seawater to temperature, pH, and salinity was derived.

Key words: seawater, ammonia-nitrogen, unionized ammonia, salicylic acid spectrophotometry

中图分类号: 

• X830.2