室内饮用水管滞留水的铅污染

Lead Contamination of Drinking Water Stagnated in Household Pipe

目的探讨室内饮用水管滞留水的铅污染及其特点。方法随机选择30个室内水龙头,根据滞留时间的不同将水样分成A组(12～13h)、B组(7～8h)和C组(3～4h)3组。在拧开龙头后第0、1、2分钟采集水样。采用石墨炉原子吸收光谱法测定水中铅含量,共分析了320件水样。结果A组中,第0、1、2分钟水样的铅含量的几何均数分别为61.33、12.27、5.47μg/L,B组则分别为33.90、9.13、4.59μg/L,C组水样的铅含量仅略有增加。A、B、C3组水样超过10μg/L(WHO推荐限量)的比例分别为55.6%,47.8%和21.1%。而未滞留水样和出厂水样的铅含量仅分别为2.80μg/L和2.03μg/L,且均在此限量内。结论水管中滞留时间超过7h水样的铅含量显著增加,滞留时间越长,铅含量越高;饮用及烹调用水前让水管水流一定时间是卫生和安全的用水方法。

Objective To investigate lead pollution of drinking water stagnated in household pipe and its characteristic, and provide the scientific basis for safe and health consumption of drinking water. Methods 30 taps in households were randomly chosen as objects. According to the stagnated time the water samples were divided into group A (12-13 hours), group B (7-8 hours) and group C (3-4 hours). The samples were collected in 0 min, 1 min and 2 min after opening taps. Lead levels in the samples were determined by atomic absorption spectrometry (AAS), whose comparative analysis was performed by SPSS software. In total, 320 samples were analyzed. Results In group A, lead concentrations (geometric mean, the same for latter) of water samples in 0 min, 1 min and 2 min were 61.33, 12.27and 5.47 μg/L respectively, but they were 33.90, 9.13 and 4.59 μg/L in group B,and 11.37, 6.29 and 4.27 μg/L in group C. There were significant differences among three groups (P<0.001), and among 0 min, 1 min and 2 min (P<0.001). Of the 90 samples of group A, 55.6%(50/90) had a concentration of excessed 10 μg/L(recommended limit of the WHO), but 47.8%(43/90) in group B and 21.1%(19/90) in group C. The top concentration (205.2 μg/L) was 19 times of the limit. However,the lead levels in the samples without stagnation and from water disposal plant were only 2.80 μg/L and 2.03 μg/L respectively. All of them were under the limit. Conclusion Lead levels may increase dramatically in water samples stagnated in household pipe more than seven hours. The longer stagnated time is, the higher the lead levels will be. It will be safe to make the water running out for a certain time before used for drinking and cooking.