我国14个城市饮用水中硒形态水平分布研究

Investigation of Selenium Speciation in Drinking Water in 14 Cities of China

目的了解我国重点流域和湖泊14个城市饮用水中5种常见硒形态水平和分布特征,为硒的污染防控和限值修订提供依据。方法在9个重点流域和1个重点湖泊(巢湖)选择14个城市的28个市政水厂作为监测点,于2020年11—12月分别采集水源水、出厂水和末梢水共84份水样。采用高效液相色谱—电感耦合等离子体质谱联用法(HPLC-ICP-MS)测定水样中5种不同硒形态[3种有机硒:硒代胱氨酸(SeCys2)、甲基硒代半胱氨酸(MeSeCys)、硒代蛋氨酸(SeMet);2种无机硒:亚硒酸根Se(Ⅳ)、硒酸根Se(Ⅵ)]浓度水平。采用Kruskal-Wallis H检验和Mann-Whitney U检验分析不同水样类型和不同水源类型中硒形态浓度水平的差异。结果我国14个城市饮用水中3种有机硒形态均未检出,Se(Ⅳ)、Se(Ⅵ)、总无机硒和5种形态硒总量的中位数(最小值,最大值)分别为0.03(0.03,0.39)、0.18(0.03,0.58)、0.23(0.06,0.79)和0.45(0.29,1.01)μg/L。水源水中Se(Ⅳ)浓度水平高于出厂水和末梢水(P<0.05),水源水、出厂水和末梢水中Se(Ⅵ)、总无机硒和5种形态硒总量浓度水平差异均无统计学意义(H为0.86~3.12,P>0.05)。地表水中Se(Ⅳ)、Se(Ⅵ)、总无机硒和5种形态硒总量浓度水平均高于地下水(Z分别为-2.72、-2.98、-3.50和-3.50,P<0.05)。结论本次研究饮用水中3种有机硒形态未检出、水中硒主要以无机硒Se(Ⅳ)和Se(Ⅵ)形态存在。不同水样类型和不同水源类型水样中Se(Ⅳ)和Se(Ⅵ)有不同程度检出,但浓度水平均未超标。总无机硒水平不会对人体产生健康风险,但仍需加强饮用水中硒形态水平监测,同时人群可从膳食角度补充有机硒的摄入。

Objective To inwestigate the level and distribution characteristics of 5 common selenium speciation in drinking water of 14 cities in key river basins and lakes of China,and to provide basis for selenium pollution control and limit revision.Methods A total of 84 water samples of source water,finished water and tap water were collected from 28 municipal water plants which were selected as monitoring points in 14 cities of nine key river basins and one key lake(Chaohu)from November to December 2020.The speciation and concentration of selenium were determined by high performance liquid chromatography inductively coupled plasma mass spectrometry(HPLC-ICP-MS).The selenium form content in different water sample types and different water source types were analyzed by Kruskal-Wallis H test and Mann-Whitney U test.Results Three organic selenium speciation were not detected in the drinking water of 14 cities in China.The Median(minimum,maximum)of Se(Ⅳ),Se(Ⅵ),total inorganic selenium,and the total amount of the five selenium forms were 0.03(0.03,0.39),0.18(0.03,0.58),0.23(0.06,0.79)and 0.45(0.34,1.01)μg/L,respectively.The concentration of Se(Ⅳ)in source water was higher than that of finished water and tap water(P<0.05),there was no statistically significant differ-ence of Se(Ⅵ),total inorganic selenium and the total amount of the five selenium forms in source water,finished water and tap water(H values were 3.12,0.86 and 0.86,respectively,P>0.05).Se(Ⅳ),Se(Ⅵ),the total inorganic selenium and the total amount of the five selenium forms in surface water were higher than those of groundwater(Z values were-2.72,-2.98,-3.50 and-3.50,respectively,P<0.05).Conclusion Three or-ganic selenium were not detected in the drinking water samples in this study,and the selenium in the water mainly exists in the form of inorganic selenium Se(Ⅳ)and Se(Ⅵ).Se(Ⅳ)and Se(Ⅵ)were detected to different de-grees in different water sample types and different water source types,but the detected concentration levels did not exceed the standard.The total inorganic selenium level will not pose a health risk to the human body,but it is still necessary to strengthen the monitoring of the selenium form level in drinking water,and people could supplement their dietary intake of organic selenium.