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The bile acid content of raw sewage, treated effluent, and estuarine sediment was determined as the first step in the development of bile acids as a new class of sewage pollution indicator. Sediments and particulates from raw sewage and effluent, were solvent extracted, saponified, fractionated by solid phase extraction (SPE) and "flash" column chromatography, derivatized, and analyzed by gas chromatography (GC) and GC/mass spectrometry (GC/ MS). Mass spectral comparisons confirmed unambiguously the presence of bile acids in all the samples studied. The major compounds detected were deoxycholic and lithocholic acids, together with minor components, in a characteristic distribution that reflected the predominantly human origin of the effluent. Bile acids were found to exist in a "bound" form and were released upon saponification. They were found to be quantitatively relatively more resistant to degradation during sewage treatment as compared to coprostanol. Some changes were observed in the abundances of certain minor bile acids, for example, the 3βepimers were much reduced in relative abundance in the treated effluent and sediment as compared to their 3R counterparts. Bile acids offer considerable promise as indicators of specific sources of sewage pollution, particularly if used in conjunction with the widely employed 5β-stanols, e.g., coprostanol.

This investigation tests the extent to which free soil lipids reflect known manuring practices associated with a relict twelfth-to nineteenth-century anthropogenic deep top soil in West Mainland Orkney. The results demonstrate that total lipid extracts reflect the expected spatial variability in manuring intensity across the deep top soil area, declining with distance from the farmstead. Specific organic manure inputs are also identified; the presence of campesterol, sitosterol and 5β-stigmastanol confirm expected composted turf and ruminant animal manure application to the deep top soil area. A departure from the expected results is the presence of coprostanol, reflecting omnivorous animal manure deposition and confirmed as pig manure through the identification of hyodeoxycholic acid. These analyses establish that lipid biomarkers of past land-management activity are retained in medieval to early modern relict landscapes, and that they allow more precise identification of manure sources and patterns of deposition than conventional pedological techniques. Further, they suggest that historic documentation forms only a partial record of manuring practices

This investigation aimed to demonstrate the combined use of bile acids, stanols, and sterols to assess fecal matter inputs into aquatic environments. Bile acids, stanols, and sterols were determined in suspended particulates in water samples collected from sites in the vicinity of discharges from sewage treatment works along the course of the Avon River, Bristol, U.K. The concentrations of the major fecal bile acids [lithocholic (LCA) and deoxycholic (DOCA)] were determined using GC and GC/MS and found to increase along the course of the river. These results agreed with those obtained for coprostanol, the traditional indicator of fecal pollution and other related sterols and stanols. In contrast, sterols and stanols not originating from feces, i.e., 24-ethylcholesterol and 24-ethylcholestanol, tended to decrease in concentration as compared to coprostanol and other fecal markers in the lower reaches of the river. The increasing concentration of bile acids downstream of sewage discharges correlates with the coprostanol/ (coprostanol + 5R-cholestanol) ratio of >0.7, thus supporting the use of bile acids as sewage pollution markers. Overall, it is demonstrated that a combined multimolecular approach involving bile acids, stanols, and sterols provides an enhanced means of assessing fecal matter inputs into aquatic environments.

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