广州市饮用水中挥发性有机物的研究

Research of VOCs in drinking water of Guangzhou

饮用水中的挥发性有机化合物(VOCs)来源于水源水受到的环境污染或是在净化消毒工艺处理工程中反应产生的副产物,可对人体健康造成极大的危害。改革开放以来,广州人口和经济得到突飞猛进的发展,也带来了包括饮用水安全在内的诸多严重的社会和环境问题。虽然饮用水中VOCs的研究已经得到越来越多的重视,但是目前对广州市饮用水中挥发性有机物的研究还鲜有报道。本文在广州市中心城区选取15个不同位置的采样点进行了自来水水样采集,并利用吹扫-捕集-气相色谱-质谱(GC-MS)联用系统分析技术测定水中VOCs的种类和三卤甲烷的质量浓度。结果表明,广州市中心城区的自来水中VOCs有20种,以三卤甲烷(THMs)和芳香烃类为主,占了所检出的物质总量的78%以上。THMs中四种化合物(氯仿、一溴二氯甲烷、二溴一氯甲烷、溴仿)的检出率达100%,总三卤甲烷的平均质量浓度为46.46μg·L-1,最大值为53.31μg·L-1,最小值39.91μg·L-1。根据2006版国家饮用水标准,四种三卤甲烷质量浓度均低于标准限值,符合标准要求。对市面上一般的瓶装水的研究发现,瓶装水中三卤甲烷的质量浓度非常低,总三卤甲烷平均质量浓度仅为1.47μg·L-1,约是自来水中质量浓度的1/30。为了解温度及煮沸对自来水中THMs质量浓度的影响,本研究设计了实验进行探究。结果发现加热至沸腾过程中,THMs质量浓度随温度升高而升高,而沸腾后THMs骤降,煮沸5 min可降低水中约95%的THMs,接近瓶装水中THMs质量浓度。

The existence of volatile organic compounds （VOCs） in drinking water, which may create adverse health effects on human beings, is due to the organic pollution of the water sources and/or the formation of disinfection by-products （DBPs） during the drinking water treatment and supply processes. Since the reform and opening up, Guangzhou has been undergoing a rapid increase and development of population and economy, which is accompanied by many serious social and environmental problems, such as the safety of drinking water. Although the VOCs in drinking water has received increased attention in the world, the research on this issue in Guangzhou is still scarce. 〈br〉 In this study, 15 tap water samples were collected at different sampling sites in center city district of Guangzhou. The VOCs species and trihalomethanes （THMs） mass concentrations in the samples were analyzed with purge＆amp;trap preconcentrator coupled with a gas chromatography-mass selective detector （GC-MSD）.20 VOCs species were detected in the tap water in Guangzhou, and above 78%of these species were aromatic hydrocarbons and trihalomethanes. THMs, which include four species：chloroform （CF）, bromodichloromethane （BDCM）, dibromochloromethane （DBCM） and bromoform （BF）, were found in all samples. The mass concentration of Total THMs was 46.46μg＆#183;L-1, ranged from 39.91μg＆#183;L-1 to 53.31μg＆#183;L-1. Compared to the national standards for drinking water in 2006, THMs mass concentrations in Guangzhou tap water is under the corresponding standard limits. As for bottled water which is widely sold in the market, the THMs mass concentration was fairly low, and the total THMs in bottled water was 1.47μg＆#183;L-1 in average, which is about 30 times lower than the tap water’s mass concentration. In this research, we also designed experiments to study the influence of temperature and boiling on the THMs mass concentration in drinking water. It was found that before boiling, the concentration of THMs increased with the increasing temperature, and after boiling, the THMs mass concentrations plummeted. After 5 minutes boiling, more than 95%THMs in drinking water has been removed and the THMs mass concentrations were close to the levels in bottled water.