PM15 Biomarkers
Exhibit Hall
8:00 AM - Monday
(PM226) Fecal steriod ratios as chemical markers for fecal indicator bacteria.
Noblet, J1, Young, D2, Zeng, E2, Ensari, S3, 1 Department of Chemistry, California State University, San Bernardino, CA, USA2 Southern California Coastal Water Research Project, Westminster, CA, USA3 Henry Samueli School of Engineering, University of California, Irvine, CA, USA
ABSTRACT- The Santa Ana River (SAR), CA and adjacent wetlands have been identified as potential sources of fecal indicator bacteria (FIB) to the surf zone at Huntington Beach, CA. A suite of fecal steroids, including coprostanol (COP), epicoprostanol (eCOP), cholesterol (CHOE), cholestanol (CHOA), a-cholestanone (aONE), b-cholestanone (bONE), b-sitosterol (bSIT), stigmasterol (STIG), stigmastanol (STAN), and campesterol (CAM), and caffeine (CAF) were used as chemical markers to examine whether sewage was a significant source of FIB within the lower Santa Ana River watershed. A total of 54 water samples were collected from three locations in the intertidal zone near the mouth of the Santa Ana River, with sampling times so chosen to assess the influence of daily and fortnightly tidal cycles. Steroid ratios in SAR samples were different from those found in raw and treated sewage from a local wastewater treatment plant or in nearby effluent plume, and were more influenced by the spring/neap tidal cycle than by the daily tides or by station location. The characteristics of steroid ratios, coupled with the strong correlation between COP and turbidity, suggested a diagenetic rather than a biogenic source for the COP content of the samples. In addition, multivariate statistical analysis showed that the concentrations of FIB were better correlated with bird fecal steroids than with the typical sewage sterols. The results implied that sewage was not a significant source of fecal steroids, and therefore perhaps FIB to the study area. Instead, birds may be one possible source of the intermittently high levels of FIB observed in the Santa Ana River and the nearby surf zone.
Key words: chemical-markers, steriods