Hydrochemistry of pit lakes in the Portuguese sector of the Iberian Pyrite Belt

Patrícia Gomes,Teresa Valente,Mayara Cordeiro,Filipa Moreno

doi:10.1051/e3sconf/20199809007

Abstract

The Iberian Pyrite Belt (IPB) is a world-class metallogenic province with volcanogenic massive sulphide ore deposits. Most ore exploitation occurred since pre-Roman time, creating extensive galleries, wells, waste-dumps and pit lakes. These last structures are a concern for their potential environmental impact because they accumulate large volumes of mine water affected acid mine drainage. The present work classifies the pit lakes based on the surface water hydrochemistry. Using the Ficklin diagram for classification, pit lake waters vary from acid, high-metal to high-acid, extreme-metal and exhibit similarities with other pit lakes from the Spanish sector of the IPB.

Highlights

Mining activities generates environmental impact, especially by the presence of reactive minerals such as sulphides
The present study focused on acidic lagoons from two major sulphide mines in the Iberian Pyrite Belt (IPB), namely São Domingos and Lousal
Results were compared with data from similar pit lakes in the Spanish sector of the IPB [2]

Summary

Introduction

Mining activities generates environmental impact, especially by the presence of reactive minerals such as sulphides. Water can become acidic, with high concentrations of metals and sulfates. Ore exploitation in the IPB dates back to preRoman times and was intensified with the beginning of the Industrial Era. After mine operation closure, surface and rain water transforms open cut mines into pit lakes [1]. The present study focused on acidic lagoons from two major sulphide mines in the IPB, namely São Domingos and Lousal. Their water properties were analysed in order to interpret hydrochemical relationships, classified in terms of acid and metallic contamination, and potential risks to aquatic ecosystems examined. Results were compared with data from similar pit lakes in the Spanish sector of the IPB [2]

Methods

Results

Conclusion