Geochemical baselines based on stream waters: applications to environmental studies, Central Chile as a case study A thesis submitted to Imperial College London for the degree of Doctor of Philosophy in the Faculty of Natural Sciences By Carmina Olivia Jorquera Zuniga July 2013 Centre for Environmental Policy Imperial College London GEOCHEMICAL BASELINES BASED ON STREAM WATERS CARMINA JORQUERA DECLARATION OF OWN WORK I declare that this thesis ‘Geochemical baselines based on stream waters: applications to environmental studies, Central Chile as a case study’ is entirely my own work and has not been submitted previously for any other degree. Any material that could be understood as the work of others, it is fully cited and referenced. Name of student (Please print): Carmina Jorquera Name of supervisor: Nikolaos Voulvoulis Name of co-supervisor: Jane Plant Name of external Anglo American Advisor: Christopher Oates COPYRIGHT DECLARATION The copyright of this thesis rests with the author and is made available under a Creative Commons Attribution-Non Commercial-No Derivatives licence. Researchers are free to copy, distribute or transmit the thesis on the condition that they attribute it, that they do not use it for commercial purposes and that they do not alter, transform or build upon it. For any reuse or redistribution, researchers must make clear to others the licence terms of this work. i | P a g e GEOCHEMICAL BASELINES BASED ON STREAM WATERS CARMINA JORQUERA This thesis is dedicated to my beloved family. ii | P a g e GEOCHEMICAL BASELINES BASED ON STREAM WATERS CARMINA JORQUERA ABSTRACT Increasing environmental regulation has resulted in mining companies monitoring levels of toxic trace elements in the environment. However, little research has been done to identify the sources of such elements as natural or manmade. Whilst the mining industry has traditionally used hydrogeochemical baselines for exploration, this study has evaluated the use of such baselines for environmental assessments of drainage systems, particularly the identification and quantification of natural and anthropogenic sources. The results are discussed in the context of water quality regulation and guideline values. The research generated the first systematic regional geochemical baseline of Central Chile including the classic Andean copper mineral province and the Andina – Los Bronces mining district. The study area included three major catchments flowing from the Andean Cordillera into inhabited valleys, with the potential for contamination from agriculture and the urban environment. Waters were sampled at a density of 1 per 100 sq. km. over 20000 sq. km. in five seasons over three years. Multi-element chemistry and stable isotopes were determined. The geochemical baseline was prepared using high quality geochemical data. The distribution patterns of the anomalously high geochemistry showed strong relationships with bedrock geology, including the presence of evaporites, sulphide mineralisation and hydrothermally altered rocks (differentiated using isotopes in sulphate). High concentrations of nitrate and phosphate were identified in agricultural areas reflecting pollution from fertilisers and sewage (distinguished using isotopes in nitrate). Areas affected by fertilisers and sewage were significantly greater than those affected by mining. Waters draining unmined Cu-mineralisation had much higher Cu and Ni levels and lower pH than Cu-mine area waters. Most regional geochemistry was below international guidelines and Chilean regulatory levels and where elevated it reflected natural sources and seasonal variations. The study demonstrates that geochemical baselines have considerable potential for distinguishing between natural and anthropogenic pollutant sources in environmental assessments. iii | P a g e GEOCHEMICAL BASELINES BASED ON STREAM WATERS CARMINA JORQUERA ACKNOWLEDGEMENT My heartfelt thanks to all of the following for their support and encouragement throughout my PhD. •Anglo American Chile for funding this amazing project and supporting my career. •Chris Oates for believing in me and being a huge support all these years. •My supervisors, Professor Jane Plant for helping when I most needed it and Nick Voulvoulis for his valuable recommendations. •My parents Cecilia Zuniga and Jaime Jorquera, my siblings Carmen Gloria, Juan Pablo and Carola, and my nephews Benjamin, Ian and Javier for giving me with all their unconditional love. •All my Chilean friends that saw me leaving and have been in contact and sending me good vibrations all the time, Carolina Munoz, Miguel Trejo, Cristina Ortega, Valentina Flores, Macarena Silva, Carlos Castro, Maria Pia Rodriguez, Angelo Castruccio, Michelle Munoz, Marion Fuentes, Carolina Alvarez, Carla Lohr, Romina Guzman, Cesar Silva, Gladys Navarro, Salvador Flores, Mauricio Carranza and so many more. •All my friends in the UK and the ones that have returned home, every one of you has been important in this journey, thanks for every laugh, shoulder, dance and love, Aisha, Alex, Khareen, James T., James B., Charlotte, Olwenn, Sally, Ho-Sik, Jilang, Rebecca, Atun, Aida, Young. A special thanks to Danelle Dhaniram, Amit and Jhasan, thanks for considering me part of your family and gave me home, I still miss you. •All the small but good Latin American community in the UK for the spontaneous friendship, excellent times and good laughs, Rocio, Elisa, Carito, Pato, Lety, Omar, Pablo, Leo, Pizzas, Vivi and specially to Pedro Galindo for his love, support, encouragement, sharing his lovely culture and remind me all the time how precious I am with a funny sense of humour. iv | P a g e GEOCHEMICAL BASELINES BASED ON STREAM WATERS CARMINA JORQUERA TABLE OF CONTENTS CHAPTER 1: INTRODUCTION ..................................................................................................... 1 1.1 Introduction ............................................................................................................................ 1 1.2 Aim and objectives ................................................................................................................. 3 1.3 Thesis Outline ......................................................................................................................... 4 1.4 Significance of the research .................................................................................................... 5 1.5 Publications ............................................................................................................................ 6 CHAPTER 2: BACKGROUND LITERATURE REVIEW............................................................. 7 2.1 Geochemical baselines of drainage systems ........................................................................... 7 2.1.1 Introduction ..................................................................................................................... 7 2.1.2 The concept behind the geochemical background and baselines .................................... 8 2.1.3 Historical development of geochemical baselines ......................................................... 11 2.2 Applications of geochemical baselines to environmental research ...................................... 13 2.3 Sampling procedures to develop geochemical baselines ...................................................... 16 2.3.1 Sample density ............................................................................................................... 16 2.3.2 Sample media ................................................................................................................ 17 2.3.3 Sampling procedures ..................................................................................................... 20 2.4 Quality assurance and quality control of geochemical data ................................................. 21 2.4.1 Evaluating reliability of data ......................................................................................... 21 2.5 Current water guidelines and regulation values of environmental chemicals ...................... 23 2.6 Potentially toxic chemicals in the environment .................................................................... 25 2.6.1 Arsenic ........................................................................................................................... 25 2.6.2 Cadmium ....................................................................................................................... 28 2.6.3 Copper ........................................................................................................................... 30 2.6.4 Mercury ......................................................................................................................... 32 2.6.5 Lead ............................................................................................................................... 34 2.6.6 Nickel ............................................................................................................................ 37 2.6.7 Nitrate ............................................................................................................................ 39 2.6.8 Phosphorus .................................................................................................................... 41 2.6.9 Sulphur .......................................................................................................................... 44 CHAPTER 3: METHODOLOGY .................................................................................................