Abstract Steroids are used as biomarkers for tracing faecal material in the environment, but their dissipation behaviour in the course of composting has remained unclear. To assess their stability, we tracked the fate of Δ5-sterols, 5α-stanols, 5β-stanols, epi-5β-stanols, stanones and bile acids after 0, 7, 14, 28, 56, 112 and 168 days and after 0 and 168 days of composting cattle and horse farmyard manure, respectively. After composting, extractable steroid content decreased by 93.8–99.9% for cattle manure and by 54.0–100% for horse manure relative to the initial amount. The loss was with 98.8–99.9%, particularly pronounced for bile acids in the cattle manure compost. Our findings challenge the assumption that bile acids are generally more resistant towards degradation than other steroids. Contrary to the bile acids, the Δ5-sterol content did not decrease constantly, but showed a temporary increase, pointing to a delayed release from straw (β-sitosterol, stigmasterol and cholesterol) or to temporary production by fungi (cholesterol). Similarly, there was no continued loss of cholesterol transformation products (5α-cholestanol, cholestanone and epicoprostanol); they either increased temporarily or showed delayed degradation. These changes in steroid patterns complicate the identification of compost as faecal matter by way of commonly used steroid ratios and stress the importance of additional bile acid analysis in geo-archaeological research. Nevertheless, slower dissipation and smaller relative loss of epi-5β-stanols vs. 5β-stanols increased the value of r = epi-5β-stigmastanol/5β-stigmastanol + epicoprostanol/coprostanol during composting and allowed differentiation between fresh farmyard manure, and immature and mature compost.

中文翻译：

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农家肥堆肥过程中类固醇​​的耗散与形成

摘要 类固醇被用作追踪环境中粪便物质的生物标志物，但其在堆肥过程中的耗散行为尚不清楚。为了评估它们的稳定性，我们在 0、7、14、28、56、112 和 168 天后以及 0 天后追踪了 Δ5-甾醇、5α-甾烷醇、5β-甾烷醇、epi-5β-甾烷醇、甾烷酮和胆汁酸的去向。和 168 天分别堆肥牛和马的农家肥。堆肥后，与初始量相比，牛粪的可提取类固醇含量降低了 93.8-99.9%，马粪的可提取类固醇含量降低了 54.0-100%。损失为 98.8-99.9%，尤其是牛粪堆肥中的胆汁酸。我们的发现挑战了胆汁酸通常比其他类固醇更能抵抗降解的假设。与胆汁酸相反，Δ5-甾醇含量没有持续下降，而是暂时增加，表明从秸秆中延迟释放（β-谷甾醇、豆甾醇和胆固醇）或由真菌暂时产生（胆固醇）。同样，胆固醇转化产物（5α-胆甾醇、胆甾酮和表前列醇）也没有持续损失；它们要么暂时增加，要么表现出延迟退化。类固醇模式的这些变化使通过常用类固醇比率将堆肥识别为粪便变得复杂，并强调了额外胆汁酸分析在地质考古研究中的重要性。尽管如此，epi-5β-stanols 的耗散较慢且相对损失较小。