选取我国西北干旱区敦煌地区6种不同类型的典型土壤为研究对象，通过测定各土壤剖面Cl－和NO－3浓度，探究Cl－和NO－3的空间分布特征以及NO－3的富集程度。结果表明，NO－3与Cl－的分布特征基本一致，并与水分含量具有良好的相关性，随包气带埋深的增加呈现波动递减的变化趋势。强烈的蒸散发作用和微生物的硝化作用使土壤表层的NO－3含量较高，植物根系对NO－3和水分的吸收降低了NO－3浓度，并导致NO－3与Cl－的分布特征存在不同程度的差异性。不同类型土壤中的NO－3含量不同，盐碱地＞林地＞农田＞草地＞戈壁＞沙漠。沙土可促进NO－3的淋溶，无植被生长的戈壁沙漠中较高的NO－3／Cl－伴随较低的Cl－含量说明硝态氮的富集主要发生在干旱阶段，蓝藻菌的固氮作用活跃，而农田土壤中硝态氮的富集受人为源影响显著。
By measuring the concentrations of Cl- and NO-3 in six typical soils collected from Dunhuang in northwest China, this study explored the spatial distribution characteristics of Cl- and NO-3 and accumulation of NO-3 . The results indicated that the distribution characteristic of NO-3 was similar to that of Cl-, and both of them correlated well with the soil moisture. With the increase in the depth of the unsaturated zone, the concentration of NO-3 displayed a decreasing trend of volatility. The intense evaporation and microbial nitrification resulted in relatively high NO-3 content in the soil surface, while water and nutrition uptake by plant roots reduced the concentration of NO-3 in the root zone. This process caused some differences in the vertical distributions between NO-3 and Cl-. The concentration of NO-3 showed significant difference among different soils, with an order of saline >forest > farmland > grassland > gobi > desert. Because NO-3 can easily leach out in sand soil, the lower level of Cl- and high level of NO-3/Cl- in gobi and desert indicated that nitrate enrichment mainly occurs in the arid phase and nitrogen fixation of cyanobacteria is active. However, nitrate enrichment in farmland soil was significantly affected by anthropogenic activities.
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