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Assessing Faecal Contamination Using Sterol Tracers in Environmental Studies

Explore the use of sterol molecular markers to evaluate faecal contamination levels in the environment, specifically focusing on Attenborough Ponds. Identify sewage markers and their pathways to assess environmental and human health impacts over time.

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Assessing Faecal Contamination Using Sterol Tracers in Environmental Studies

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  1. Organic Sewage Tracers • Sterols are components of cells & are synthesized by most organisms • In humans cholesterol is biohydrogenated by intestinal microflora to 5b-cholestrol • Other animals also produce 5b-cholestrol but at much lower concentrations • Herbiverous animals produce 24-ethyl coprostanol in greater concentrations Sterol structure

  2. Assessment of Faecal Contamination Using Sterol Molecular Markers Attenborough Ponds Nature: Long Term Effects of River Diversion

  3. Conneries dating 1986 ? 1963 ?

  4. TOC vs Sterol Concentration

  5. Resolving co-elution Sediment Sample TIC coprostanol m/z = 333 Cholesterol-d6 m/z = 231 Coprostan-3-one m/z = 329 Cholesterol m/z 333 m/z 231 m/z 329 Identification of Sewage Markers Target mix 5b-epicoprostanol coprostanol fucosterol + b-sitosterol 17b-estradiol 5a-cholestane 5a-cholestanol stigmasterol estrone campesterol 5b-stigmastanol Environment & Human Health Theme

  6. Ten of eleven sewage marker • compounds were identified • in the Attenborough cores • 5-cholestane not detected

  7. Sterol & Stanol Marker Pathways Environmental (5) Intestinal (5)

  8. 2 1 3 • Sitosterol: Clifton and Church = Input from plants & or avian FM • Stigmastanol: Conneries = Input from ruminants / manure, slurry ? • Coprostanol: Concs. >0.5ug/g = received appreciable amounts of sewage

  9. Coprostanol/Cholesterol: human sewage >0.2 criteria= Only Conneries • Coprostanol/(Coprostanol+Cholestanol) human sewage >0.7= Conneries • Epicoprostanol/coprostanol:treatment or age in environ. =Church & • Clifton little sewage or high degree of treatment

  10. 1.5 1.0 0.5 0.0 0.0 0.5 1.0 1.5 2.0 2.5 Bi-plot of sewage marker compounds Low sewage, old or treated High sewage, untreated

  11. Ratio 5Cholestanol/Cholesterol:anaerobic process marker • Conneries possible more reducing environ at 20 to 50 cm ?

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