建立了气相分子吸收光谱法测定土壤和沉积物中亚硝酸盐氮、氨氮和硝酸盐氮含量的方法。参考HJ 634-2012中的提取方法，在（20±2）℃条件下，用氯化钾溶液作为浸提液浸提土壤和沉积物样品中的3种氮形态，离心后，采用气相分子吸收光谱法测定上清液中亚硝酸盐氮、氨氮和硝酸盐氮的含量。结果显示，亚硝酸盐氮、氨氮和硝酸盐氮的质量浓度在0.05~2.00 mg·L^-1内与其对应的吸光度呈线性关系，检出限（3.143s）分别为0.02，0.08，0.02 mg·kg^-1，低于HJ 634-2012的。加标回收率分别为81.1%~96.2%，81.9%~88.1%和86.0%~105%，测定值的相对标准偏差（n=6）均在15%以内，准确度和精密度结果与HJ 634-2012的相当。方法和HJ 634-2012进行方法比对，2种方法的精密度和回收试验结果基本一致，且双侧F检验和t检验结果显示，这两种方法无显著性差异。

A method for the determination of nitrite-nitrogen, ammonia-nitrogen and nitrate-nitrogen in soil and sediment by gas-phase molecular absorption spectrometry was established. Based on the extraction method in HJ 634-2012, 3 nitrogent forms were extracted from soil and sediment samples with potassium chloride solution at (20±2)℃. After centrifugation, the contents of nitrite-nitrogen, ammonia-nitrogen and nitrate-nitrogen in the supernatant were determined by gas-phase molecular absorption spectrometry. The results showed that linear relationships between mass concentrations of nitrite-nitrogen, ammonia-nitrogen and nitrate-nitrogen and their absorbances were kept in the same range of 0.05-2.00 mg·L^-1, and detection limits (3.143s) were 0.02, 0.08, 0.02 mg·kg^-1, respectively, lower than those given by HJ 634-2012. Recoveries from the spiked recovery test were in the range of 81.1%-96.2%, 81.9%-88.1% and 86.0%-105%, respectively, with RSDs (n=6) of the determined values within 15%. Tests for method comparison between the proposed method and HJ 634-2012 were made, results of tests for recovery and precision of the 2 methods were basically the same, and there was no significant difference between the 2 methods by results of two-sideds F test and t test .