“三氮”是评价水体污染程度的重要指标。在水源卫生侦察(调查)时,常因无条件作卫生细菌学检验,而只凭“三氮”来判断水体的污染程度。这种评价的结果是否可靠,国内曾有不同的看法。结合东北地区220个市、县(旗)20,345个水源的调查分析,我们对此问题进行了初步探讨。 “Three nitrogen ” is an important indicator of water pollution assessment. In the water health surveillance (investigation), often because of unconditional health bacteriology test, but only by “three nitrogen ” to determine the degree of pollution of water bodies. Whether the result of such evaluation is reliable or not has been different in China. Based on the investigation and analysis of 20,345 water sources in 220 cities and counties in northeast China, we conducted a preliminary study on this issue.