2015—2019年湖南省洞庭湖区饮用水中氨氮水平及其影响因素分析

目的了解湖南省洞庭湖区饮用水中氨氮含量水平及其影响因素。方法利用2015—2019年湖南省洞庭湖区生活饮用水水质监测网络直报数据,通过比较不同时间、采样类型、水源类型、供水方式、水样类型的氨氮含量,分析洞庭湖区饮用水中氨氮含量及其影响因素。结果 2015—2019年湖南省洞庭湖区氨氮浓度中位数为0.040(0.010,0.100)mg/L,总合格率为98.54%,不同年份间氨氮合格率差异有统计学意义(χ^(2)=19.724,P=0.001),其中2015—2018年呈上升趋势(χ^(2)=16.477,P<0.001)。与农村饮用水比较,城市饮用水氨氮浓度较低(Z=-107.403,P<0.001),合格率较高(χ_(趋势)^(2)=16 136.000,P<0.001)。不同水源类型、供水方式和水样类型的饮用水中氨氮浓度和合格率比较,差异均有统计学意义(P<0.001);多因素logistic逐步回归分析结果表明,农村水(OR=7.569,95%CI:1.008~56.864)、地下水(OR=4.702,95%CI:2.397~9.224)及分散式供水(OR=6.28,95%CI:2.251~17.519)是湖南省洞庭湖区饮用水中氨氮超标的危险因素。结论 2015—2019年湖南省洞庭湖区饮用水中氨氮平均浓度符合生活饮用水中氨氮限值标准,有时间性差异,采样类型、水源类型和供水方式均是其影响因素。

Ammonia nitrogen concentration and its influencing factors in drinking water in Dongting Lake area in Hunan Province, 2015-2019

Objective To investigate the concentration of ammonia nitrogen and its influencing factors in drinking water in Dongting Lake area in Hunan Province. Methods Based on the data about drinking water in Dongting Lake area in Hunan Province during 2015-2019 and directly reported by Hunan Drinking Water Quality Monitoring Network, we analyzed the concentration of ammonia nitrogen and its influencing factors in drinking water in Dongting Lake area through comparing ammonia nitrogen concentration of water samples collected from different years, sampling types, water sources, water supply types and water types. Results The median of ammonia nitrogen concentration in drinking water in Dongting Lake area in Hunan Province during 2015-2019 was 0.040 (0.010, 0.100) mg/L, with a total qualified rate of 98.54%. The qualified rates in different years showed statistically significant differences (χ²=19.724, P=0.001), with an increased trend from 2015 to 2018 (χ²_trendency=16.477, P<0.001).Compared with the rural drinking water, the concentration of ammonia nitrogen was lower in the urban drinking water (Z=-107.403, P<0.001), but the qualified rate was higher in the urban drinking water (χ²=16,136.000, P<0.001). There were statistically significantly differences in the concentration of ammonia nitrogen and the qualified rate in drinking water from different water sources, water supply types and water types (all P<0.001). The results of multivariate logistic stepwise regression analysis revealed that rural water (OR=7.569, 95%CI:1.008-56.864), underground water (OR=4.702, 95%CI:2.397-9.224) and non-central water supply (OR=6.28, 95%CI:2.251-17.519) were risk factors for the exceeding standard of ammonia nitrogen in drinking water in Dongting Lake area in Hunan Province. Conclusion The average concentration of ammonia nitrogen in drinking water in Dongting Lake area in Hunan Province during 2015-2019 met the national standard, with annual differences. Sampling types, water sources and water supply types were all the factors influencing ammonia nitrogen concentration in drinking water.