Technosols after coal mining: The challenges to be overcome by soil science

Technosols are anthropogenic soils, and are mostly intentionally created and/or modified to serve a specific purpose, such as waste management and the restoration of ecosystems degraded by industrial activities. In this sense, open-cast coal mining areas can be classified as Technosols, which already use their own mining waste in their topographic restoration. The construction of Technosols for the purpose of mining waste disposing and recovering degraded areas has the potential to offset up to 60 % of the CO 2 emissions caused by this activity, contributing achieving Sustainable Development Goals (SDGs) 13, 15 and 2 (in some cases, depending on the type of residue to be used in the overburden layer), relating respectively to climate action, the preservation of terrestrial life, and hunger eradication. Therefore, this study aims to provide a literature review of Technosols constructed from coal mining waste, highlighting the challenges that still need to be addressed by soil science to restore these areas ecologically. The methodology consisted of a bibliometric analysis using the terms “Mined Soils” OR “Minesoils” OR “Technosols” AND “Coal” in the Web of Science Core Collection database. The search was restricted to article-type documents published in English between 2004 and 2023, resulting in a dataset of 199 articles. The analysis was performed using VOSviewer and HistCite software, which enable bibliographic coupling between bibliometric variables such as countries, keywords, and citations. The analysis of keyword co-occurrence highlighted a trend towards increased academic relevance of topics related to the environmental contamination potential of coal mining waste, carbon sequestration by Technosols, the morphological characteristics of these soils, and recovery indicators for mined areas. The integration of the properties that characterize soil health, especially the biological ones, is the main gap in this field of study. On a global scale, Technosols are a promising strategy for the recovery of areas degraded by anthropogenic activities, aligning with greater efficiency in waste management and the mitigation of impacts associated with the climate crisis, due to their high potential for CO 2 capture.