背景:硫同位素在生物学中越来越多地用作人类和动物的迁移率指标,考古学,和法医。然而,缺乏使用现代植物和动物的现代硫同位素基线“isoscape”研究,主要是由于现代污染对S同位素值的污染的可能性。
方法:我们从加拿大不列颠哥伦比亚省900公里的东西样带收集植物,并测量其硫同位素值。然后,我们使用随机森林模型来确定哪些变量最能解释同位素数据模式,并为不列颠哥伦比亚省南部地区生成了硫等值线。
结果:我们在植物硫同位素值中看到了与地理位置和降雨有关的清晰模式。我们的模型还表明,对于这个研究区域,人为污染对植物δ34S值的影响不大。我们还讨论了使用植物作为硫同位素的底物,以及对同一地区动植物δ34S值之间经常观察到的差异的可能解释。与人类和动物组织中的氨基酸相比,植物中硫的来源不同。
结论:我们发现,对于世界上硫污染可能不太普遍的地区,有可能产生现代植物S等容,这应该是移动性研究的准确基线。使用随机森林建模,我们制作了不列颠哥伦比亚省南部的基线硫磺等值线图,可用于生态学,法医和考古研究。
BACKGROUND: Sulfur isotopes are increasingly used as mobility indicators in humans and animals in biology, archaeology, and forensics. However, there has been a lack of modern sulfur isotope baseline \"isoscape\" studies using modern plants and animals, largely due to the possibility of contamination of the S isotope values by modern pollution.
METHODS: We collected plants from across a 900-km east-west transect of British Columbia Canada and measured their sulfur isotope values. We then used a random forest model to determine which variables best explained the isotope data patterning and produced a sulfur isoscape for the southern region of British Columbia.
RESULTS: We see clear patterning in the plant sulfur isotope values that relate to geographical location and rainfall. Our model also shows that for this study area, it is unlikely that there is a significant influence of anthropogenic pollution on plant δ34S values. We also discuss the use of plants as a substrate for sulfur isoscapes and possible explanations for the often-observed difference between plant and animal δ34S values from the same region, related to differing sources of sulfur in plants compared to amino acids in human and animal tissues.
CONCLUSIONS: We found that for areas of the world where sulfur pollution is likely less widespread, it is possible to produce a modern plant S isoscape that should be an accurate baseline for mobility studies. Using random forest modelling, we have produced a baseline sulfur isoscape map of southern British Columbia that can be used for ecology, forensic and archaeological studies.