ANOMALOUSLY HIGH ARSENIC IN LLUTA VALLEY SOILS, NORTHERN CHILE: A NATURAL PHENOMENON OR ANTHROPOGENIC POLLUTION?
- heavy metals,
- contamination,
- mining,
- risk assessment,
- acid drainage
Copyright (c) 2026 SCHQ
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Abstract
The Lluta river basin (northern Chile) is characterized by anomalously high arsenic contents in soils, typically attributed to natural volcanic processes. The primary objective of this research was to evaluate the impact of a historical tailings dam on the elemental content of the Lluta basin soil. The 95th percentiles of total soil contents of arsenic, copper, lead, and zinc upstream of the tailings were 197, 17, 438, and 33 mg kg-1, respectively, representing the background contents of elements in the basin’s soils. A Kruskal-Wallis analysis comparing arsenic contents in soils upstream and downstream of the tailings provided convincing evidence of anthropogenic pollution originating from the dam. This observation is further supported by elevated levels of other chalcophiles (lead and zinc) and increased electrical conductivity in the soil. In conclusion, although the Lluta basin soil has naturally occurring high arsenic content, acid drainage from the tailings is causing soil pollution, requiring an urgent intervention by the Chilean environmental authorities.
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