BIOGEOCHEMISTRY OF GEOGENIC AND ANTHROPOGENIC TRACE ELEMENTS IN THE ECUADORIAN ANDES: A SCOPING REVIEW OF SOIL–PLANT TRANSFER AND EXPOSURE PATHWAYS

The Ecuadorian Andes constitute a dynamic socio-environmental system where geogenic processes, including active volcanism, mineralized lithologies, and accelerated weathering, interact with anthropogenic pressures such as mining and agricultural intensification, shaping the occurrence, mobility, and soil–plant transfer of trace elements of environmental and food relevance. To consolidate fragmented evidence, a systematic scoping review was conducted following PRISMA-ScR guidelines and structured under the PCC framework. Searches were performed in Scopus, SciELO, and Google Scholar for studies published between January 2016 and December 2025. Of 37 identified records, seven met the eligibility criteria. The evidence was concen-trated in volcanic settings, particularly Tungurahua and Cotopaxi, and primarily ad-dressed soil and crop matrices. Arsenic, cadmium, and lead were the most recurrently reported elements, followed by chromium, nickel, copper, and zinc, while mercury appeared marginally. Most studies relied on total concentrations measured by AAS or ICP-OES, with limited incorporation of mobility indicators, extractable fractions, iso-topic approaches, or standardized soil–plant transfer metrics. In volcanic agroecosys-tems, reported concentrations generally remained below national soil quality stand-ards and international food safety thresholds, suggesting that geogenic forcing alone does not necessarily imply immediate risk under conventional management. In con-trast, mining-influenced systems showed regulatory exceedances and elevated probabilistic health risk metrics. Overall, the review highlights the need for integrated mon-itoring approaches incorporating transfer indicators, hydrological pathways, and temporal designs to strengthen sustainable management of Andean agricultural land-scapes.