甾醇对南山老龙洞地下河粪便污染的指示

Fecal Contamination in Laolongdong Underground River as Measured by the Sterol Biomarkers

分别于2014年10月，2015年1、3、5月采集重庆南山老龙洞地下河出口的水样，过滤取水悬浮物质，采用气相色谱-质谱联用仪（CC·MS）定量分析悬浮物中甾类物质的成分与质量浓度；利用多指标综合分析对南山老龙洞地下河粪便污染进行判断并追溯粪便污染物的主要来源．结果表明，样品中共测出10种甾类物质，其中包括9种醇类和1种酮类．总甾类物质的质量浓度为1573～5007ng·L-1，且3、5月均大于10、1月．虽然各月间地下河的组成存在差异，但以胆固醇、β-谷甾醇和粪醇为主要成分，三者的质量浓度之和占总甾类的50．8％-80．4％．另外，（差向异构粪醇＋粪醇）／（粪醇＋差向异构粪醇＋二氢胆固醇）的值均大于0．7，指示各月均受到粪便污染；10月差向异构粪醇／粪醇的值小于0．2，指示污水主要来自上游污水处理厂；1、3、5月的粪醇／∑Steroids、粪醇／24-乙基粪醇的值分别为0．109—0．254、6．3～10．3，指示地下河主要受到人类粪便的影响；3月的24-乙基粪醇／24-乙基胆甾烷醇为0．86，小于1月的5．4和5月的2．3，说明该月地下河受家禽类动物粪便的影响较1月和5月严重．

To investigate whether the underground river was polluted or not,and trace the source of fecal sterols,the particulate water samples were collected from typical karst underground river named Laolongdong in Nan＇an District,Chongqing Municipality in October,2014,January, March and May,2015. Ten prior steroids in the underground river were quantitatively analyzed by the gas chromatography-mass spectrometer（ GC-MS）. The results showed ten steroids including 9 sterols and 1 ketone were detected. During the sampling period,the mass concentrations of particulate steroids（ ranging between 1 573 and 5 007 ng·L- 1） in March and May were higher than those in October and January. The 3 principal steroids—cholesterol,β-sitosterol and coprosterol—in the river accounted for50. 8%-80. 4% of the total steroids. The ratios of（ epicoprostanol ＋ coprostanol） to（ coprostanol ＋ epicoprostanol ＋ cholestanol） of three samples were greater than 0. 7,which indicated the river was contaminated in sampling months. The ratio of epicoprostanol to coprostanol was less than 0. 2 in October,which indicated the wastewater came from the upstream sewage treatment plant. The ratios of coprostanol to Σ Steroids and coprostanol to 24-ethylcoprostanol in January,March and May were respectively 0. 109-0. 254 and 6. 3-10. 3,which indicated that Laolongdong underground river was mainly polluted by human feces. The ratio of 24-ethylcoprostanol to 24-ethylcholestanol in March（ 0. 86） was less than those in January（ 5. 4） and May（ 2. 3）,which showed the river was polluted more severely in March than in January and May by poultry dung.