拉萨城市饮用水安全：管网末梢水化学稳定性评价

饮用水安全问题关系人体健康和国计民生。自上世纪80年代以来,我国供水管网和二次供水导致的饮用水污染问题呈上升趋势。管网老化、水化学稳定性差引起管道腐蚀和结垢是影响供水末梢水质下降的主要原因之一。文章以拉萨城区用户末梢水为研究对象,展开管网对末梢水质的潜在影响调查,并采用饱和指数（IL）和稳定指数（IR）来评价管网水化学稳定性。结果显示,2008到2011年期间拉萨城区集中式供水管网水化学稳定性较差,管网被腐蚀和结垢倾向明显,并有逐年加剧趋势。

Safety of Drinking Water in Lhasa： Evaluation of Chemical Stability of the Tap Water

The issues of drinking water safety is essential for human health and the people’s livelihood. The prob-lems of drinking water polluted by water supply network and secondary water supply have shown an increasingtrend in China since the 1980s of last century. The corrosion and fouling of pipeline caused by aging pipe net-work and low chemical stability of water are the major factors influencing the water quality of the tap water. Incomparison with other cities in China, centralized water supply source-water quality in Tibet was safe. However,report regarding to impact of water distribution systems, especially pipes, on the quality of tap water in the regionwas not seen yet. This paper, based on Langelier saturation index（IL）and Ryznar stability index（IR）, was the firststudy that evaluated the potential impact of water supply pipes on the quality of tap water in households in LhasaCity. The results showed that chemical stability of tap water in Lhasa City was low. IL and IR values confirm cor-rosion condition and scale formation of the drinking water in the city and, there was an increasing tendency from2008 to 2011. Corrosion and scale formation may led to a high turbidity in the city water. Nevertheless, low chem-ical stability of the tap water may result in dissolution of some pipe material metals, such as Cu, Pb, Zn and Fe in-to the water and, finally cause harm.