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STEROLS AND BILE ACIDS IN URBAN AND RURAL SOILS AS FAECAL MARKERS OF
LAND-USE SINCE THE BRONZE AGE
Renata Zocatelli, Jean-Robert Disnar, Jérémy Jacob, Claude Le Milbeau
To cite this version:
Renata Zocatelli, Jean-Robert Disnar, Jérémy Jacob, Claude Le Milbeau. STEROLS AND BILE ACIDS IN URBAN AND RURAL SOILS AS FAECAL MARKERS OF LAND-USE SINCE THE BRONZE AGE. IMOG2013 : the 26th International Meeting on Organic Geochemistry, Sep 2013, Tenerife, Spain. �insu-00866040�
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LAKE AYDAT V V V V V Narse d'Espinasse Veyre Narse Labadeau N 500 m Rhône River 5 km N NeolithicLate Bronze Age Mediaeval Period Antiquity
Iron Age
Coring (settlement layers)
0 2000 4000 6000 8000 10000 12000 Pig Human 0 200 400 600 800 1000 1200 µg/g µg/g µg/g µg/g Sterols Bile Acids 0 100 200 300 400 500
LC DOC CDOC C HDOC UDOC
Horse Cow Sheep
0 1000 2000 3000 4000 5000
LC DOC CDOC C HDOC UDOC
Pig Human pastured soil forest soil samples urbanized surface Legend
Horse Cow Sheep
3
1 2
LC DOC CDOC C HDOC UDOC
µg/g 0 5 10 15 20 70 66 St14 St16 St15 St19 Human faecal material 0 10 20 30 40 50 60 70 Septic tanks 20 µg/g
The goal of this study is to test the potentialities of fecal biomarkers in soils and sedi-ments to resolve, at the field-scale, the strategies of land use. For this purpose, we designed our study in three steps:
i) characterization of faecal biomarkers imprints of source animals,
ii) evaluation of the faecal biomarkers stability through the analysis of samples of dif-ferent age,
iii) examination of the distribution of faecal biomarkers in a wide diversity of contexts under different type of soils, different land-uses and degrees of anthropization.
Dried and crushed samples (~5 g) were extracted using accelerated solvent extraction with CH2Cl2:MeOH (1:1 v/v; ASE 200 Dionex®). Total extract was fractionated into neutral and acidic compounds using solid phase extraction on Aminopro-pyl Bond Elute© phase according to Jacob et al. (2005). Acid fractions were methylated (anhydrous MeOH and acetyl chlo-ride). Then, sterols and acidic fractions were further derivatized by BSTFA. Standards (5α-cholestane and nor-deoxycholic acid) were added prior to GC-MS analysis.
Methodology
STEROLS AND BILE ACIDS IN URBAN AND RURAL SOILS
AS FAECAL MARKERS OF LAND-USE SINCE THE BRONZE AGE
Renata Zocatelli, Jean-Robert Disnar, Jérémy Jacob, Claude Le Milbeau
Université d’Orléans, Institut des Sciences de la Terre d’Orléans (ISTO), CNRS/INSU, BRGM - UMR 7327, F45071 Orléans Cedex 2, France.
compound MM major m/z
Introduction and aims
Land-use Soils
Reference Samples
Sheep Cow Horse
Aydat Lake, Central Massif France
Collection Samples
19th century
10 soils under pasture 6 soils under forests
Archaeological excavations Archaelogical site
septic tanks
(14th, 15th and 16th century)
3 middens
25 settlement layers Bourget Lake, France
Faecal biomarkers (C27, C28 and C29 coprostanols and bile acids) found in soils and sediments have been proposed as direct indicators of human presence or of breeding since these compounds are formed in the intestinal tracts of higher mammals (Elhmmali et al, 2000, Bull et al., 2002).
Significant differences in sterol imprints between herbivores and omnivores
Omnivores Herbivores
Sheeps show different bile acids imprint than cows and horses
Omnivores Herbivores
Section A18
Poster 508
Sterols index
C28+C29/C27sterols Coprostanols/sterols Stanols/sterolsSterol ratios were used to identify the likely source and degradation state of faecal biomarkers in samples.
Recent samples such as the fresh faecal material (Reference samples), pastured and florest soils (Aydat catchment) are spread along coprostanol/sterol and C28+C29/C27 sterols axis.
Archeological samples from septic tanks and middens have low stanols/sterols index whereas settlement layers have high values, indicating the sterols trans-formation into stanols (reduction) through time.
Diagenesis could entail coprostanols reduction thus masking the source imprints (Mermoud et al., 1984; Rushdi et al., 2006).
GC-MS details for bile acids
compound MM major m/z
LC lithocholic acid 462 215,257,357,372
DOC deoxycholic acid 550 208,255,345,370
C cholic acid 638 253,343,368,458
CDOC chenodeoxycholic acid 550 255,355,370,460
HDOC hyodeoxycholic acid 550 255,355,370,460
UDOC ursodeoxycholic acid 550 255,355,370,460
Pig Human
Septic tank 4
Animal imprints
Faecal biomarkers preservation in septic tanks
- In septic tanks, sterols and bile acids
decrease with time. For bile acids, diagene-sis undistinctively affects compounds whe-reas sterols are inequally affected.
- This is futher evidenced by the
deoxycholic/cholic acid ratio that remains constant (~20) whereas the coprostanol/ epi-coprostanol ratio decreases with time.
Pig and Human can be distin-guished by bile acids imprints
~ ~ ~
~
Present St19 St16 St15 St14
Bile acids in soils under pastures and forests
Soils under pastures contain notable amounts of lithocholic and deoxycholic acids that testifies to their present/recent use for cattle breeding or to manuring practises. Bile acids were absents in soils
under forest. LC DOC CDOC C
µg/g
0 1 2 3
4 Soils under pastures
Cp coprostanol 388 215, 257, 355,370 epi-Cp epi-coprostanol 388 215, 257, 355,370 Chl cholesterol 386 368, 353, 329, 255 Cln cholestanol 388 215, 355, 455, 460 mCp methyl-coprostanol 402 215, 257, 369, 384 eCp ethyl-coprostanol 416 215, 257, 383, 398 epi-eCp epi-ethyl-coprostanol 416 215, 257, 383, 398 Sterl stigmasterol 412 255, 394, 379 Stanl stigmastanol 416 215, 257, 383, 398 Sit sitosterol 414 396, 357, 381, 255
Conclusions
- Significant differences in faecal biomarker imprints between allow distin-guishing between animal sources: sheeps, cows, horses, pigs and Humans. - Discrimination based on presence/absence of bile acids appear more effec-tive than that based on sterols relaeffec-tive abundances.
- Bile acids proportion remain constant with time, and more stable than sterols. - Combination of sterols and bile acids over a wide range contexts demonstrate their complementarity and efficiency in providing information on former land-uses. 0 10 20 30 40 50 60
deoxycholic acid / cholic acid coprostanol / epi-coprostanol 45 12
0
16 6 14 10 2 8 -2 18 4 20 120
16 6 14 10 2 8 -2 4 5 20 15 25 10 30 Human Cow Sheep Pig PsPs Ps Ps Ps Ps Ps St19 St 14 St16 St15 sFs FssFsF Ps F Ps Ps sF Horse MdMdMd Ps Fs Md St14 St15 St19 St16 Middens (Md) Settlement layersGC-MS details for sterols
UNIVERSITE D'ORLEANS µg/g 0.0 0.1 0.2 0.3 0.4 LC DOC CDOC C
Middens
Bile acids in Bronze Age settlement layers and middens
Samples from middens contain low amounts of bile acids (only LCA and DCA) indicative of cattle breeding. These data corroborate information obtained sterol data (in the same range as pastures, cows, sheeps and horses).
Coprostanols and bile acids vary across the profile in settlement layers. However, all settlement layers exhibit similar bile acids distribution with a deoxycholic/cholic acid ratio are greater than 20. This is indicative of a major contribution from Human feces but is contradictory to information retrieved from sterols that point to a significant contribution of cattle (cf. 3d graph). Nevertheless, sterols are more prone to degradation that can bias the original imprint. LC DOC C LC DOC C LC DOC C LC DOC C µg/g 0 4 8 12 16 0.0 0.4 0.8 1.2 1.6 2.0 0 10 20 30 0.0 0.5 1.0 1.5 2.0 2.5 0 5 10 15 20 25 30 35 0 10 20 30 40 coprostanols bile acids 15 25 35 5
Settlement layers
depht (cm)Cp epi-Cp Chl Cln mCp eCp Sit
Cp epi-Cp Chl Cln mCp eCp Sit
Once demonstrated that animals have different imprints, we are interested in eva-luating the preservation of faecal biomarkers in sedimentary profiles. Their distri-bution in septic tanks active during the 19th, 16th,15th and 14th centuries are com-pared (St19, St16, St15 and St14, respectively).
Cp epi-Cp Chl Cln mCp eCp Sit
Variability of faecal biomarker imprints
Bronze Age
References:
- Bull et al., 2002. Environment International 27, 647- 654 - Elhmmali et al, 2000. Environ. Sci. Technol. 34 (1), 39 - 46 - Bull et al., 2002. Environment International 27, 647- 654 - Jacob et al, 2005. Organic Geochemistry 36, 449 - 461 - Mermoud et al., 1984. Organic Geochemistry 6, 25 - 29 - Rushdi et al., 2006. Environmental Geology 50, 1171 - 1181
Acknowledgments:
The study was accomplished as part of Otarie project (Region Centre and FEDER), ERODE project (EC2CO/ CNRS/INSU) and PalHydroMil project (ANR). We thank Yves Billaud (DRASSM), Yohann Gerard (ISTO), Mar-lène Lavrieux (LSCE / Chrono-Environnement), Pascal Joyeux (INRAP) and Thomas Guillemard (INRAP) for their help during field works and for providing samples.
