Environmental geochemical characteristics of Xuanwei Formation coal and their controlling geological factors, with comments on the relationship with lung cancer incidence and distribution

Abstract

This paper attempts to review the environmental geochemical characteristics (re.: enriched elements) in coals of the Late Permian Xuanwei Formation of NW Yunnan, China, and gauge the possible existence of significant relationships with the incidence and distribution of lung cancer in the region. To achieve this goal, 27 samples were collected in this region; the mineralogical characteristics and major and trace elements were analysed; the Pb isotopic composition was traced; the contribution of the source rock was calculated; and principal component analysis (PCA) was carried out. Our current findings are summarized as follows: (1) the minerals are mainly quartz (silica), chamosite, calcite and kaolinite; (2) MnO, SiO 2 , V, Cr, Co, Ni, Cu, Cd and W are enriched; (3) the LREYs (La, Ce, Pr, Nd, Pm, Sm and Eu) and HREYs (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) have similar enrichment degrees, and the fractionation degree of HREYs is higher than that of LREYs; (4) the source distance restricts the Pb isotope composition; (5) MnO, V, Cr, Co, Ni, Cu and Cd are controlled by the Emeishan basalt; the origin of SiO 2 (authigenic quartz) is unclear; (6) the lung cancer tissue characteristics, PCA, and toxicological characteristics of elements suggest that the main components of enriched elements probably come from V, Cr, Co, Ni and Cd, not SiO 2 . In conclusion, the carcinogenic elements V, Cr, Co, Ni and Cd may be related to lung cancer. Since our study is highly explorative, this result leaves many interesting aspects to be further studied. Thematic collection: This article is part of the Geochemical processes related to mined, milled, or natural metal deposits collection available at: https://www.lyellcollection.org/topic/collections/geochemical-processes-related-to-mined-milled-or-natural-metal-deposits Supplementary material : The coal mine and coal sample description, major, trace elements, and XRD results of coal as well as regional geological map are available at https://doi.org/10.6084/m9.figshare.c.6444476