The PUMA beamline, created for the heritage community and accessible by all fields of science, welcomed its first users in 2019. Its optical layout uses a horizontal focusing mirror to prefocus the light emitted from the wiggler source for the experimental endstation. It provides a 5 mu m x 7 mu m microbeam for XRF, XAS, XRD and XEOL analysis or a wide 20 x 5 mm full field when the beam is defocused, and the KB mirrors are retracted. An extremely stable fixed-exit Si(111) monochromator is used to select the wavelength. Many experiments have been performed at PUMA, particularly in archaeology, paleontology, conservation, art history and in identifying safer conditions of irradiation for precious heritage samples. XRF analysis has been used, for example, to show the effects of the interaction of Palaeolithic ivory with soil; to identify the elemental composition of mineralized textiles and to reveal hidden morphologies of fossils.

Recent warming in the Andes is affecting the region's water resources including glaciers and lakes, which supply water to tens of millions of people downstream. High-elevation wetlands, known locally as bofedales, are an understudied Andean ecosystem despite their key role in carbon sequestration, maintenance of biodiversity, and regulation of water flow. Here, we analyze subfossil diatom assemblages and other siliceous bioindicators preserved in a peat core collected from a bofedal in Peru's Cordillera Vilcanota. Basal radiocarbon ages show the bofedal likely formed during a wet period of the Little Ice Age (1520-1680 CE), as inferred from nearby ice core data. The subfossil diatom record is marked by several dynamic assemblage shifts documenting a hydrosere succession from an open-water system to mature peatland. The diatoms appear to be responding largely to changes in hydrology that occur within the natural development of the bofedal, but also to pH and possibly nutrient enrichment from grazing animals. The rapid peat accretion recorded post-1950 at this site is consistent with recent peat growth rates elsewhere in the Andes. Given the many threats to Peruvian bofedales including climate change, overgrazing, peat extraction, and mining, these baseline data will be critical to assessing future change in these important ecosystems.