Adverse effects of metal mining on boreal lakes : metal bioavailability and ecological risk assessment

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uef.fi

PUBLICATIONS OF

THE UNIVERSITY OF EASTERN FINLAND Dissertations in Forestry and Natural Sciences

Dissertations in Forestry and Natural Sciences

DISSERTATIONS | KRISTIINA VÄÄNÄNEN | ADVERSE EFFECTS OF METAL MINING ON BOREAL LAKES | No 2

KRISTIINA VÄÄNÄNEN

ADVERSE EFFECTS OF METAL MINING ON BOREAL LAKES

PUBLICATIONS OF

THE UNIVERSITY OF EASTERN FINLAND

Metal mining is a large, global industry and the adverse effects of metal emissions to the environment are long-lasting. This study focuses

on the behavior of metals in mining-affected boreal lakes. Metal concentrations in these lakes

were elevated and the risks to the ecosystems were higher in spring than in autumn. The

results from this study can be used for improving ecological risk assessment methods

and for incorporating metal bioavailability evaluation to the existing protocols.

KRISTIINA VÄÄNÄNEN

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ADVERSE EFFECTS OF METAL MINING ON BOREAL LAKES

METAL BIOAVAILABILITY AND ECOLOGICAL RISK ASSESSMENT

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Kristiina Väänänen

ADVERSE EFFECTS OF METAL MINING ON BOREAL LAKES

METAL BIOAVAILABILITY AND ECOLOGIAL RISK ASSESSMENT

Publications of the University of Eastern Finland Dissertations in Forestry and Natural Sciences

No 284

University of Eastern Finland Joensuu

2017

Academic dissertation

To be presented by permission of the Faculty of Science and Forestry for public examination in the Auditorium AG100 in the Agora Building at the University of Eastern Finland, Joensuu, on November 17, 2017

at 12 o’clock noon

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Kristiina Väänänen

ADVERSE EFFECTS OF METAL MINING ON BOREAL LAKES

METAL BIOAVAILABILITY AND ECOLOGIAL RISK ASSESSMENT

Publications of the University of Eastern Finland Dissertations in Forestry and Natural Sciences

No 284

University of Eastern Finland Joensuu

2017

Academic dissertation

To be presented by permission of the Faculty of Science and Forestry for public examination in the Auditorium AG100 in the Agora Building at the University of Eastern Finland, Joensuu, on November 17, 2017

at 12 o’clock noon

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Grano Oy Jyväskylä, 2017 Editor: Matti Vornanen

Distribution: University of Eastern Finland / Sales of publications www.uef.fi/kirjasto

ISBN: 978-952-61-2614-2 (print) ISBN: 978-952-61-2615-9 (PDF)

ISSNL: 1798-5668 ISSN: 1798-5668 ISSN: 1798-5676 (PDF)

Author’s address: Kristiina Väänänen

University of Eastern Finland

Dept. of Environmental and Biological Sciences P.O. Box 111

80101 JOENSUU, FINLAND email: kristiina.vaananen@uef.fi Supervisors: Docent Jarkko Akkanen, Ph.D.

80101 JOENSUU, FINLAND email: jarkko.akkanen@uef.fi

University lecturer Merja Lyytikäinen, Ph.D.

University of Eastern Finland University services, Doctoral school P.O. Box 111

80101 JOENSUU, FINLAND email: merja.lyytikainen@uef.fi Kimmo Mäenpää, Ph.D. University of Eastern Finland

80101 JOENSUU, FINLAND

email: kimmomaenpaa3@gmail.com Professor Matti Vornanen, Ph.D. University of Eastern Finland

80101 JOENSUU, FINLAND email: matti.vornanen@uef.fi

Reviewers: Professor Kenneth Mey Yee Leung, Ph.D.

The University of Hong Kong

The Swire Institute of Marine Science and School of Biological Sciences

Pokfulam, HONG KONG email: kmyleung@hku.hk

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Grano Oy Jyväskylä, 2017 Editor: Matti Vornanen

Distribution: University of Eastern Finland / Sales of publications www.uef.fi/kirjasto

ISBN: 978-952-61-2614-2 (print) ISBN: 978-952-61-2615-9 (PDF)

ISSNL: 1798-5668 ISSN: 1798-5668 ISSN: 1798-5676 (PDF)

Author’s address: Kristiina Väänänen

80101 JOENSUU, FINLAND email: kristiina.vaananen@uef.fi Supervisors: Docent Jarkko Akkanen, Ph.D.

80101 JOENSUU, FINLAND email: jarkko.akkanen@uef.fi

University lecturer Merja Lyytikäinen, Ph.D.

University of Eastern Finland University services, Doctoral school P.O. Box 111

80101 JOENSUU, FINLAND email: merja.lyytikainen@uef.fi Kimmo Mäenpää, Ph.D.

80101 JOENSUU, FINLAND

email: kimmomaenpaa3@gmail.com Professor Matti Vornanen, Ph.D.

80101 JOENSUU, FINLAND email: matti.vornanen@uef.fi

Reviewers: Professor Kenneth Mey Yee Leung, Ph.D.

The University of Hong Kong

The Swire Institute of Marine Science and School of Biological Sciences

Pokfulam, HONG KONG email: kmyleung@hku.hk

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Väänänen, Kristiina

Adverse effects of metal mining on boreal lakes. Metal bioavailability and ecological risk assessment.

Joensuu: University of Eastern Finland, 2017 Publications of the University of Eastern Finland Dissertations in Forestry and Natural Sciences 2017; 284 ISBN: 978-952-61-2614-2 (print)

ISSNL: 1798-5668 ISSN: 1798-5668

ISBN: 978-952-61-2615-9 (PDF) ISSN: 1798-5676 (PDF)

ABSTRACT

Metal mining is a large, worldwide industry and a common source of metal emissions to the environment. The possible adverse effects of mining are long-lasting and, therefore, the evaluation of ecological effects is essential. In water ecosystems, part of the metals will end up in bottom sediment and may be released back to the water, if environmental conditions change. The ecological risk assessment (ERA) of metals is a complicated process. Traditional measurement of metal total concentrations is not enough, since not all the metals in the environment are toxic.

Moreover, metals are natural elements that are present in varying concentrations everywhere in nature. Only a fraction of the metals is toxic, and the evaluation of this bioavailable part is challenging. Many of the methods for evaluating metal bioavailability are either too complicated for routine environmental monitoring, or not suitable for boreal freshwater ecosystems.

The aims of this study were to evaluate the risks of metal mining in boreal lake ecosystems, to assess the importance of metal bioavailability in these local conditions and to evaluate the usability of different, existing ERA methods. An additional goal was to search for solutions for the remediation of contaminated sediments. Since there are no sediment quality guidelines in Finland, special attention was given to the applicability of the current risk assessment methods from other geographic regions and to the usability of novel scientific methods for regulatory use.

Methods used in this study include field experiments from four lakes, taken in spring and in autumn (analysis of metal concentrations in water, sediment and biota, measurements of water quality, plus benthic organism community structure analyses), laboratory experiments (toxicity tests, bioaccumulation tests, metal bioavailability studies with passive samplers) and several models for evaluating metal bioavailability and the ecological risks of metals (e.g., biotic ligand models).

Thereafter, the results achieved were compared to national and international legislations and environmental quality guidelines.

Docent Olli-Pekka Penttinen, Ph.D.

University of Helsinki

Dept. of Environmental Sciences P.O. Box 65

00014 LAHTI, FINLAND

email: olli-pekka.penttinen@helsinki.fi Opponent: Docent Kari-Matti Vuori, Ph.D.

Finnish Environment Institute Ecotoxicology and Risk Assessment Survontie 9 A

40500 JYVÄSKYLÄ, FINLAND email: kari-matti.vuori@ymparisto.fi

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Väänänen, Kristiina

Adverse effects of metal mining on boreal lakes. Metal bioavailability and ecological risk assessment.

Joensuu: University of Eastern Finland, 2017 Publications of the University of Eastern Finland Dissertations in Forestry and Natural Sciences 2017; 284 ISBN: 978-952-61-2614-2 (print)

ISSNL: 1798-5668 ISSN: 1798-5668

ISBN: 978-952-61-2615-9 (PDF) ISSN: 1798-5676 (PDF)

ABSTRACT

Metal mining is a large, worldwide industry and a common source of metal emissions to the environment. The possible adverse effects of mining are long-lasting and, therefore, the evaluation of ecological effects is essential. In water ecosystems, part of the metals will end up in bottom sediment and may be released back to the water, if environmental conditions change. The ecological risk assessment (ERA) of metals is a complicated process. Traditional measurement of metal total concentrations is not enough, since not all the metals in the environment are toxic.

Moreover, metals are natural elements that are present in varying concentrations everywhere in nature. Only a fraction of the metals is toxic, and the evaluation of this bioavailable part is challenging. Many of the methods for evaluating metal bioavailability are either too complicated for routine environmental monitoring, or not suitable for boreal freshwater ecosystems.

The aims of this study were to evaluate the risks of metal mining in boreal lake ecosystems, to assess the importance of metal bioavailability in these local conditions and to evaluate the usability of different, existing ERA methods. An additional goal was to search for solutions for the remediation of contaminated sediments. Since there are no sediment quality guidelines in Finland, special attention was given to the applicability of the current risk assessment methods from other geographic regions and to the usability of novel scientific methods for regulatory use.

Methods used in this study include field experiments from four lakes, taken in spring and in autumn (analysis of metal concentrations in water, sediment and biota, measurements of water quality, plus benthic organism community structure analyses), laboratory experiments (toxicity tests, bioaccumulation tests, metal bioavailability studies with passive samplers) and several models for evaluating metal bioavailability and the ecological risks of metals (e.g., biotic ligand models).

Thereafter, the results achieved were compared to national and international legislations and environmental quality guidelines.

Docent Olli-Pekka Penttinen, Ph.D.

University of Helsinki

Dept. of Environmental Sciences P.O. Box 65

00014 LAHTI, FINLAND

email: olli-pekka.penttinen@helsinki.fi Opponent: Docent Kari-Matti Vuori, Ph.D.

Finnish Environment Institute Ecotoxicology and Risk Assessment Survontie 9 A

40500 JYVÄSKYLÄ, FINLAND email: kari-matti.vuori@ymparisto.fi

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Metal concentrations in the studied lakes were elevated and total concentrations were high enough to give reason for further studies. The seasonal variation in water quality was distinct, and metal bioavailability was higher in spring than in autumn.

In the studied lakes, water quality parameters (pH, cations) in lakes were in many cases outside the validation ranges of the metal bioavailability assessment methods (biotic ligand models). When bioavailability was assessed, the highest risks were seen for Zn and Ni. The results from the toxicity tests varied, and there were major challenges when conducting the tests, since these sediments were not suitable for most of the organisms. In many cases, too low pH combined with elevated metal concentrations induced adverse effects, and hence it was difficult to determine the cause of observed toxicity. Even though some adverse effects were observed in the toxicity tests, contamination in these lakes is not an acute threat to the studied organisms. Generally, based on the results of this study, parallel use of several ERA methods is advised in order to increase the reliability of the results. None of the methods can take into account all the aspects that are needed in ERA and hence, use of a single method could lead to either over- or under-estimating the risks. For these boreal lakes, an optimal combination or ERA included the analysis of total concentrations of metals and metal bioavailability (in water and in sediment), plus the evaluation of the ecological status of the lakes (benthic community structure analysis).

In Finland, the guidance for ecological risk assessment of metals is based on legislation from the European Union (EU). It is limited to only four metals in surface waters, without guidance for the sediment phase. While some of the EU member countries have additional guidance for metal ERA, Finland has not yet applied any of these guidelines. More detailed methods that are used in the USA or in the Netherlands, could at least partly be adopted in our practices. These methods include evaluation of metal bioavailability, evaluation of sediment compartment and metal mixture toxicity assessment. In future, more work should be conducted especially to widen the validation ranges of biotic ligand models to make them suitable for boreal lakes, creating models for evaluating metal mixture toxicity and building biologic metrics that are suitable for regulatory use, for example by relating metal body residues in organisms to adverse effects.

Universal Decimal Classification: 504.5, 574.64, 622

CAB: bioavailability, metal pollution, mining, models, risk assessment, sediment, toxicology, water quality

LCSH: Environmental toxicology.

YSA: biosaatavuus, ekotoksikologia, kaivostoiminta, mallintaminen, metallit, riskinarviointi, sedimentit, vedenlaatu

ACKNOWLEDGEMENTS

I am grateful to a countless number of people for helping me along the way, and for sharing this bumpy, but exciting, journey with me. First of all, this project would not come into existence without my main supervisor, Jarkko Akkanen. My sincere thanks for those many days we have spent together in meetings, sampling trips and conferences. Your door has always been open and you have always found time for my questions and concerns. I am also grateful to all of my supervisors; Merja Lyytikäinen, Kimmo Mäenpää and Matti Vornanen, and to my unofficial supervisor Matti T Leppänen from SYKE, for your support and guidance. I do not know where I would be without Matti’s tough questions and Merja’s attention to details.

I would like to thank all my co-authors for your contribution to this project:

Tommi Kauppinen and Jari Mäkinen from the Geological Survey of Finland and Sebastian Abel, Tähti Oksanen and Inna Nybom from UEF, Anna K Karjalainen, Harri Asikainen and Maj Rasilainen from the University of Jyväskylä and Chen XuePing from Shanghai University. I thank all the Master´s students, who have worked on this project: Sebastian, Tähti, Sanni and Tiina. This work has been funded by several organizations: the Kone Foundation, Maa- ja vesitekniikan tuki R.y., SETAC Europe, the European Commission (Erasmus Mundus Swap and Transfer project), the EnSTe doctoral school, The Finnish Concordia Fund, the Finnish Cultural Foundation (Längmanin yrittäjärahasto), the Olvi Foundation and the International Institute for Environmental Studies.

Acknowledgements are due to University of Eastern Finland for providing all the facilities for my work and to the graduate school EnSTe for the excellent courses, travel grants and unforgettable annual meetings. My most sincere thanks go to each and every member of our ecotox group – especially to Inna, Greta, Kaisa and Kukka, for introducing me to the world of research and for sharing the ever-happy coffee breaks with me. Furthermore, I wish to thank Kari Ratilainen and Lauri Solismaa for their expertise in field work and Marja Noponen for all help in the lab. Many thanks to Ritva Lahtinen and Rosemary Mackenzie for their proof-reading and editing work.

I would also like to thank Jussi Kukkonen for turning my interest towards ecotoxicology and sharing his knowledge about research, China and gastronomy, and Anneli Tuomainen, my mentor, for all the fruitful conversations we have had during this interesting process.

My Chinese supervisors and colleagues He Chiquan, Chen Xueping and Hao Ma, thank you for broadening my view and giving me an opportunity to join your research group in Shanghai. I am also grateful to Sergey Kuznetsov and his group at FIMM, especially to Gu Yuexi, for showing me the wonderful world of research back in my student days. I am grateful to my godmother, colleague, classmate and dear friend, Anu Hangas, for being there for me during the whole journey from our freshman year to this day.

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Metal concentrations in the studied lakes were elevated and total concentrations were high enough to give reason for further studies. The seasonal variation in water quality was distinct, and metal bioavailability was higher in spring than in autumn.

In the studied lakes, water quality parameters (pH, cations) in lakes were in many cases outside the validation ranges of the metal bioavailability assessment methods (biotic ligand models). When bioavailability was assessed, the highest risks were seen for Zn and Ni. The results from the toxicity tests varied, and there were major challenges when conducting the tests, since these sediments were not suitable for most of the organisms. In many cases, too low pH combined with elevated metal concentrations induced adverse effects, and hence it was difficult to determine the cause of observed toxicity. Even though some adverse effects were observed in the toxicity tests, contamination in these lakes is not an acute threat to the studied organisms. Generally, based on the results of this study, parallel use of several ERA methods is advised in order to increase the reliability of the results. None of the methods can take into account all the aspects that are needed in ERA and hence, use of a single method could lead to either over- or under-estimating the risks. For these boreal lakes, an optimal combination or ERA included the analysis of total concentrations of metals and metal bioavailability (in water and in sediment), plus the evaluation of the ecological status of the lakes (benthic community structure analysis).

In Finland, the guidance for ecological risk assessment of metals is based on legislation from the European Union (EU). It is limited to only four metals in surface waters, without guidance for the sediment phase. While some of the EU member countries have additional guidance for metal ERA, Finland has not yet applied any of these guidelines. More detailed methods that are used in the USA or in the Netherlands, could at least partly be adopted in our practices. These methods include evaluation of metal bioavailability, evaluation of sediment compartment and metal mixture toxicity assessment. In future, more work should be conducted especially to widen the validation ranges of biotic ligand models to make them suitable for boreal lakes, creating models for evaluating metal mixture toxicity and building biologic metrics that are suitable for regulatory use, for example by relating metal body residues in organisms to adverse effects.

Universal Decimal Classification: 504.5, 574.64, 622

CAB: bioavailability, metal pollution, mining, models, risk assessment, sediment, toxicology, water quality

LCSH: Environmental toxicology.

YSA: biosaatavuus, ekotoksikologia, kaivostoiminta, mallintaminen, metallit, riskinarviointi, sedimentit, vedenlaatu

ACKNOWLEDGEMENTS

I am grateful to a countless number of people for helping me along the way, and for sharing this bumpy, but exciting, journey with me. First of all, this project would not come into existence without my main supervisor, Jarkko Akkanen. My sincere thanks for those many days we have spent together in meetings, sampling trips and conferences. Your door has always been open and you have always found time for my questions and concerns. I am also grateful to all of my supervisors; Merja Lyytikäinen, Kimmo Mäenpää and Matti Vornanen, and to my unofficial supervisor Matti T Leppänen from SYKE, for your support and guidance. I do not know where I would be without Matti’s tough questions and Merja’s attention to details.

I would like to thank all my co-authors for your contribution to this project:

Tommi Kauppinen and Jari Mäkinen from the Geological Survey of Finland and Sebastian Abel, Tähti Oksanen and Inna Nybom from UEF, Anna K Karjalainen, Harri Asikainen and Maj Rasilainen from the University of Jyväskylä and Chen XuePing from Shanghai University. I thank all the Master´s students, who have worked on this project: Sebastian, Tähti, Sanni and Tiina. This work has been funded by several organizations: the Kone Foundation, Maa- ja vesitekniikan tuki R.y., SETAC Europe, the European Commission (Erasmus Mundus Swap and Transfer project), the EnSTe doctoral school, The Finnish Concordia Fund, the Finnish Cultural Foundation (Längmanin yrittäjärahasto), the Olvi Foundation and the International Institute for Environmental Studies.

Acknowledgements are due to University of Eastern Finland for providing all the facilities for my work and to the graduate school EnSTe for the excellent courses, travel grants and unforgettable annual meetings. My most sincere thanks go to each and every member of our ecotox group – especially to Inna, Greta, Kaisa and Kukka, for introducing me to the world of research and for sharing the ever-happy coffee breaks with me. Furthermore, I wish to thank Kari Ratilainen and Lauri Solismaa for their expertise in field work and Marja Noponen for all help in the lab. Many thanks to Ritva Lahtinen and Rosemary Mackenzie for their proof-reading and editing work.

I would also like to thank Jussi Kukkonen for turning my interest towards ecotoxicology and sharing his knowledge about research, China and gastronomy, and Anneli Tuomainen, my mentor, for all the fruitful conversations we have had during this interesting process.

My Chinese supervisors and colleagues He Chiquan, Chen Xueping and Hao Ma, thank you for broadening my view and giving me an opportunity to join your research group in Shanghai. I am also grateful to Sergey Kuznetsov and his group at FIMM, especially to Gu Yuexi, for showing me the wonderful world of research back in my student days. I am grateful to my godmother, colleague, classmate and dear friend, Anu Hangas, for being there for me during the whole journey from our freshman year to this day.

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Dearest thanks are due to all of my friends – especially Annu and the Tivoli bunch.

Loving thanks to my family: my sister Minna, who has done her best in understanding the nature of ecotoxicological research and with whom I have shared many laughs about my research titles; my mom Iitu for being my private IT support and proof-reader since the early days, and for sharing the everyday university experiences through Skype on a weekly basis; my dad Markku for always supporting me and putting the family first, no matter what. Besides my own family, the family of Niklander-Vartiainen-Väänänen has been there for me all the way, thank you everyone!

Finally, I would like to express my gratitude to my beloved husband Lasse.

Without you, I would never have come to Joensuu nor began my studies at UEF.

Thank you for listening all my babble about the work, encouraging me when I have been insecure and joining me in all our adventures in Finland and beyond.

Thank you everyone, it would not have been the same without you! 谢谢大家!

Joensuu, 10^th October, 2017 Kristiina Väänänen

LIST OF ABBREVIATIONS

AA-EQS Annual Average Environmental Quality Standard AAS Atomic Absorption Spectrometry

ACR Acute Chronic Ratio AFW Artificial Fresh Water AVS Acid Volatile Sulfides BLM Biotic Ligand Model

DGT Diffusive Gradients in Thin Films DOC Dissolved Organic Carbon

dw dry weight

EC⁵⁰ half maximal Effective Concentration EL Effect Level

EPA Environmental Protection Agency EQG Environmental Quality Guideline EqP Equilibrium Partitioning theory ERA Ecological Risk Assessment

ESBwqc Equilibrium partitioning Sediment Benchmark (water quality criteria), used in USA.

EU European Union

fw fresh weight

HC⁵ Hazardous Concentration (protecting 95% of the species) IA Independent Action -model

IC Ion Chromatography

ICP-MS Inductively Coupled Plasma Mass Spectrometry

ICP-OES Inductively Coupled Plasma Optical Emission Spectrometry JS Lake Junttiselkä

KS Lake Kirkkoselkä LJ Lake Laakajärvi

LC50 half maximal Lethal Concentration LOEC Lowest Observed Effect Concentration

MAC-EQS Maximum Annual Concentration Environmental Quality Standard MFB Multispecies Freshwater Biomonitoring® -device

NOEC No Observed Effect Concentration OC Organic Carbon

PAF Potentially Affected Fraction PJ Lake Parkkimanjärvi

PEL Probable effect level

PNEC Predicted no effect concentration SEM Simultaneously Extracted Metals

SJ Lake Sysmäjärvi

SQG Sediment Quality Guideline

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Dearest thanks are due to all of my friends – especially Annu and the Tivoli bunch.

Loving thanks to my family: my sister Minna, who has done her best in understanding the nature of ecotoxicological research and with whom I have shared many laughs about my research titles; my mom Iitu for being my private IT support and proof-reader since the early days, and for sharing the everyday university experiences through Skype on a weekly basis; my dad Markku for always supporting me and putting the family first, no matter what. Besides my own family, the family of Niklander-Vartiainen-Väänänen has been there for me all the way, thank you everyone!

Finally, I would like to express my gratitude to my beloved husband Lasse.

Without you, I would never have come to Joensuu nor began my studies at UEF.

Thank you for listening all my babble about the work, encouraging me when I have been insecure and joining me in all our adventures in Finland and beyond.

Thank you everyone, it would not have been the same without you! 谢谢大家!

Joensuu, 10^th October, 2017 Kristiina Väänänen

LIST OF ABBREVIATIONS

AA-EQS Annual Average Environmental Quality Standard AAS Atomic Absorption Spectrometry

ACR Acute Chronic Ratio AFW Artificial Fresh Water AVS Acid Volatile Sulfides BLM Biotic Ligand Model

DGT Diffusive Gradients in Thin Films DOC Dissolved Organic Carbon

dw dry weight

EC⁵⁰ half maximal Effective Concentration EL Effect Level

EPA Environmental Protection Agency EQG Environmental Quality Guideline EqP Equilibrium Partitioning theory ERA Ecological Risk Assessment

ESBwqc Equilibrium partitioning Sediment Benchmark (water quality criteria), used in USA.

EU European Union

fw fresh weight

HC⁵ Hazardous Concentration (protecting 95% of the species) IA Independent Action -model

IC Ion Chromatography

ICP-MS Inductively Coupled Plasma Mass Spectrometry

ICP-OES Inductively Coupled Plasma Optical Emission Spectrometry JS Lake Junttiselkä

KS Lake Kirkkoselkä LJ Lake Laakajärvi

LC50 half maximal Lethal Concentration LOEC Lowest Observed Effect Concentration

MAC-EQS Maximum Annual Concentration Environmental Quality Standard MFB Multispecies Freshwater Biomonitoring® -device

NOEC No Observed Effect Concentration OC Organic Carbon

PAF Potentially Affected Fraction PJ Lake Parkkimanjärvi

PEL Probable effect level

PNEC Predicted no effect concentration SEM Simultaneously Extracted Metals SJ Lake Sysmäjärvi

SQG Sediment Quality Guideline

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SSD Species Sensitivity Distribution UEF University of Eastern Finland

WFD Water Framework Directive (in European Union) WQG Water Quality Guideline

LIST OF ORIGINAL PUBLICATIONS

This thesis is based on data presented in the following articles, referred to Roman numerals I–III.

I Väänänen K, Kauppila T, Mäkinen J, Leppänen MT, Lyytikäinen M ,

Akkanen J. (2016) Ecological risk assessment of boreal sediments affected by metal mining: Metal geochemistry, seasonality and comparison of several risk assessment methods. Integrated Environmental Assessment and Management, 12(4): 759–771.

II Väänänen K, Abel S, Oksanen T, Nybom I, Leppänen MT, Asikainen H, Rasilainen M, Karjalainen AK, Akkanen J. (2017) Toxicity of boreal lake sediments affected by metal mining: Sediment Quality Triad approach complemented with site-specific metal bioavailability and metal body residue assessment. Manuscript.

III Väänänen K, Leppänen MT, Chen XP, Akkanen J. (2018) Metal bioavailability in ecological risk assessment of freshwater ecosystems: From science to environmental management. Review article. Ecotoxicology and Environmental Safety 147:430–446.

The above publications have been included at the end of this thesis with their copyright holders’ permission.

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SSD Species Sensitivity Distribution UEF University of Eastern Finland

WFD Water Framework Directive (in European Union) WQG Water Quality Guideline

LIST OF ORIGINAL PUBLICATIONS

This thesis is based on data presented in the following articles, referred to Roman numerals I–III.

I Väänänen K, Kauppila T, Mäkinen J, Leppänen MT, Lyytikäinen M ,

Akkanen J. (2016) Ecological risk assessment of boreal sediments affected by metal mining: Metal geochemistry, seasonality and comparison of several risk assessment methods. Integrated Environmental Assessment and Management, 12(4): 759–771.

II Väänänen K, Abel S, Oksanen T, Nybom I, Leppänen MT, Asikainen H, Rasilainen M, Karjalainen AK, Akkanen J. (2017) Toxicity of boreal lake sediments affected by metal mining: Sediment Quality Triad approach complemented with site-specific metal bioavailability and metal body residue assessment. Manuscript.

III Väänänen K, Leppänen MT, Chen XP, Akkanen J. (2018) Metal bioavailability in ecological risk assessment of freshwater ecosystems: From science to environmental management. Review article. Ecotoxicology and Environmental Safety 147:430–446.

The above publications have been included at the end of this thesis with their copyright holders’ permission.

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AUTRHOR’S CONTRIBUTION

I) KV was responsible for the analyses and for writing the paper. KV, TK, JM, ML and JA planned the study and KV, TK, JM and JA conducted the sampling. ML contributed for the interpretation of sediment bioavailability assessment.

II) KV carried out the tests with V. fischeri and partly with L. variegatus. KV conducted all the analyses and wrote the manuscript. KV and JA planned the study. HA, AKK and MTL conducted the tests an analysis with C. riparius.

MR and MTL conducted the L. stagnalis tests. MTL was responsible for the interpretation of the C. riparius and L. stagnalis experiments and he wrote the relevant parts of the manuscript. SA and TO ran the experiments with L.

variegatus. IN participated in data interpretation, statistical analyses and in creating the figures.

III) KV planned the manuscript together with JA. KV wrote the majority of the manuscript. CXP wrote the part dealing with China and MTL the part relating to Europe. JA acted as the main supervisor for the project.

KV = Kristiina Väänänen TK = Tommi Kauppila JM = Jari Mäkinen ML = Merja Lyytikäinen JA = Jarkko Akkanen HA = Harri Asikainen AKK = Anna K Karjalainen MTL = Matti T Leppänen MR = Maj Rasilainen SA = Sebastian Abel TO = Tähti Oksanen CXP = Chen XuePing

AUTRHOR’S CONTRIBUTION

I) KV was responsible for the analyses and for writing the paper. KV, TK, JM, ML and JA planned the study and KV, TK, JM and JA conducted the sampling. ML contributed for the interpretation of sediment bioavailability assessment.

II) KV carried out the tests with V. fischeri and partly with L. variegatus. KV conducted all the analyses and wrote the manuscript. KV and JA planned the study. HA, AKK and MTL conducted the tests an analysis with C. riparius.

MR and MTL conducted the L. stagnalis tests. MTL was responsible for the interpretation of the C. riparius and L. stagnalis experiments and he wrote the relevant parts of the manuscript. SA and TO ran the experiments with L.

variegatus. IN participated in data interpretation, statistical analyses and in creating the figures.

III) KV planned the manuscript together with JA. KV wrote the majority of the manuscript. CXP wrote the part dealing with China and MTL the part relating to Europe. JA acted as the main supervisor for the project.

KV = Kristiina Väänänen TK = Tommi Kauppila JM = Jari Mäkinen ML = Merja Lyytikäinen JA = Jarkko Akkanen HA = Harri Asikainen AKK = Anna K Karjalainen MTL = Matti T Leppänen MR = Maj Rasilainen SA = Sebastian Abel TO = Tähti Oksanen CXP = Chen XuePing

1 INTRODUCTION

Metal mining is a large, worldwide industry. When measured by total value of mineral production, China, the USA, Australia and Russia are the biggest actors (International Council of Mining & Metals 2012). In Finland, there were 45 operating mining sites in the year 2014 mining metallic minerals, carbonates, industrial minerals or commercial stone (Finnish Safety and Chemical Agency 2014). Ten of those mining sites excavate metallic minerals. The vast majority of them are located in Eastern and Northern parts of Finland. In the year 2016, the annual ore production was 28 million tons and the highest production rates were in Terrafame (previously Talvivaara) (50%) and Kevitsa (27%) mines (Tukes 2017). The life cycle of a metal mine consists of several phases; exploration, planning, construction, mine operations (ore extraction, processing and dewatering), and finally the closure of the mine (Environment Canada 2009). The length of each phase depends on the mined metal, the size and the quality of the deposit and the chosen excavation techniques.

Mining is seen as one of the most important anthropogenic sources of pollutants (Ettler et al. 2016), but there is still a lack of knowledge about its environmental effects. Environmental impacts include alterations in the landscape, and a decrease in water quality due to pit dewatering, solute transport of pollutants and acid mine drainage. Discharges of metals, half metals, salts (including sulfates), nutrients and organic matter into the surrounding environment are among the most common issues in the mining industry (Kauppila et al. 2011). Air pollution, noise, soil loss and sediment transport are also linked to mining activities (U.S. EPA 2011). In the recent years, mining-related environmental hazards have been subject to wide discussion.

In Finland, this is mainly a result of the environmental disasters in Talvivaara Mine (nowadays Terrafame Ltd), starting with a leakage from a gypsum waste pond, which lead to the release of metal-rich waters into the surrounding environment in November 2012 (The Finnish Association for Nature Conservation 2016).

All metals are potentially toxic, and therefore the environmental (and health) effects of metal discharges should be known better. At the moment, information about adverse effects is focused on the common metals; Cu, Ni, Pb and Zn. The majority of the toxicity studies are conducted in standard laboratory conditions (neutral pH, room temperature, average water hardness), and therefore the results may not be directly applied in the natural environment. This is a concern especially in Fennoscandia, where water quality is far from the European average. The freshwaters in Fennoscandia are particularly soft, high in organic carbon content and often acidic (Hoppe et al. 2015). All of these aspects affect metal toxicity and therefore, the standard risk assessment methods cannot necessarily be used.

Ecological risk assessment (ERA) is an important administrative process, which evaluates the adverse effects of compounds in the environment. ERA consists of several phases: hazard characterization, exposure assessment, effect assessment, risk

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1 INTRODUCTION

Metal mining is a large, worldwide industry. When measured by total value of mineral production, China, the USA, Australia and Russia are the biggest actors (International Council of Mining & Metals 2012). In Finland, there were 45 operating mining sites in the year 2014 mining metallic minerals, carbonates, industrial minerals or commercial stone (Finnish Safety and Chemical Agency 2014). Ten of those mining sites excavate metallic minerals. The vast majority of them are located in Eastern and Northern parts of Finland. In the year 2016, the annual ore production was 28 million tons and the highest production rates were in Terrafame (previously Talvivaara) (50%) and Kevitsa (27%) mines (Tukes 2017). The life cycle of a metal mine consists of several phases; exploration, planning, construction, mine operations (ore extraction, processing and dewatering), and finally the closure of the mine (Environment Canada 2009). The length of each phase depends on the mined metal, the size and the quality of the deposit and the chosen excavation techniques.

Mining is seen as one of the most important anthropogenic sources of pollutants (Ettler et al. 2016), but there is still a lack of knowledge about its environmental effects. Environmental impacts include alterations in the landscape, and a decrease in water quality due to pit dewatering, solute transport of pollutants and acid mine drainage. Discharges of metals, half metals, salts (including sulfates), nutrients and organic matter into the surrounding environment are among the most common issues in the mining industry (Kauppila et al. 2011). Air pollution, noise, soil loss and sediment transport are also linked to mining activities (U.S. EPA 2011). In the recent years, mining-related environmental hazards have been subject to wide discussion.

In Finland, this is mainly a result of the environmental disasters in Talvivaara Mine (nowadays Terrafame Ltd), starting with a leakage from a gypsum waste pond, which lead to the release of metal-rich waters into the surrounding environment in November 2012 (The Finnish Association for Nature Conservation 2016).

All metals are potentially toxic, and therefore the environmental (and health) effects of metal discharges should be known better. At the moment, information about adverse effects is focused on the common metals; Cu, Ni, Pb and Zn. The majority of the toxicity studies are conducted in standard laboratory conditions (neutral pH, room temperature, average water hardness), and therefore the results may not be directly applied in the natural environment. This is a concern especially in Fennoscandia, where water quality is far from the European average. The freshwaters in Fennoscandia are particularly soft, high in organic carbon content and often acidic (Hoppe et al. 2015). All of these aspects affect metal toxicity and therefore, the standard risk assessment methods cannot necessarily be used.

Ecological risk assessment (ERA) is an important administrative process, which evaluates the adverse effects of compounds in the environment. ERA consists of several phases: hazard characterization, exposure assessment, effect assessment, risk

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characterization and risk assessment (Luoma and Rainbow 2008). Wide scientific knowledge and comprehensive regulatory tools are needed for conducting ERA. For metals, the practices in different parts of the world vary greatly. In most countries, metal emissions to the environment are monitored regularly, and the discharge limits are set in the environmental permits, granted by regional administration. The acceptable metal concentrations in the environment are defined in environmental quality guidelines (EQS), such as water quality guidelines and sediment quality guidelines. Occasionally, the goals of guidelines are not met, and too high concentrations of chemicals accumulate in the sediment. In these cases, there is a need to remediate the contaminated site. There are several ways to conduct the remediation. Traditional remediation methods include sediment dredging and banking or capping methods (U.S. EPA 2005a; Manap and Voulvoulis 2015).

However, the costs are high and these methods seriously disturb the local ecosystems heavily. Recently, more elaborate and less disturbing bioavailability-reducing methods have been developed. In the future, they could replace the current methods.

In Finland, the regulation of metal emissions is rather limited. European Union Water Framework Directive has set maximum allowable concentrations for four metals, but for other metals, each country may decide their own guidances (European Commission 2013). There is no EU-wide mandatory regulation for sediment quality, but some EU member countries have set their own sediment regulation. In Finland, such guidance does not exist. Since the ecosystems are versatile and there are several anthropogenic activities leading to metal pollution, the evaluation of metal toxicity and ecological risks is challenging and there are still wide data gaps in knowledge about the behavior of metals. On the other hand, environmental administration needs simple and easily interpreted methods for routine monitoring.

1.1 AIMS OF THE STUDY

The aims of this study were to evaluate the risks of metal mining in boreal lake ecosystems, and to improve the ecological risk assessment of metals. One of the key aspects was to evaluate the usability of different methods in local conditions. Since there are no sediment quality guidelines in Finland, special attention was given to the applicability of the risk assessment methods used in other geographic areas.

Special interest was also given on how the seasonal changes affect metal bioavailability and toxicity.

The specific goals of this projects were to

1) Analyze the metal concentrations in several matrices (water, sediment, sediment pore water, benthic organisms and fish) in boreal freshwaters affected by metal mining (I),

2) Assess metal bioavailability and toxicity (I, II), including the studies of possible effects from seasonal changes,

3) Evaluate and compare the suitability of different ecological risk assessment and metal bioavailability evaluation methods (I, II, III),

4) Review the current methods and practices of metal ERA in different parts of the world in order to reveal the current shortcomings and the best practices (III), and

5) Test suitable adsorbent materials for remediating metal-contaminated sediment.

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characterization and risk assessment (Luoma and Rainbow 2008). Wide scientific knowledge and comprehensive regulatory tools are needed for conducting ERA. For metals, the practices in different parts of the world vary greatly. In most countries, metal emissions to the environment are monitored regularly, and the discharge limits are set in the environmental permits, granted by regional administration. The acceptable metal concentrations in the environment are defined in environmental quality guidelines (EQS), such as water quality guidelines and sediment quality guidelines. Occasionally, the goals of guidelines are not met, and too high concentrations of chemicals accumulate in the sediment. In these cases, there is a need to remediate the contaminated site. There are several ways to conduct the remediation. Traditional remediation methods include sediment dredging and banking or capping methods (U.S. EPA 2005a; Manap and Voulvoulis 2015).

However, the costs are high and these methods seriously disturb the local ecosystems heavily. Recently, more elaborate and less disturbing bioavailability-reducing methods have been developed. In the future, they could replace the current methods.

In Finland, the regulation of metal emissions is rather limited. European Union Water Framework Directive has set maximum allowable concentrations for four metals, but for other metals, each country may decide their own guidances (European Commission 2013). There is no EU-wide mandatory regulation for sediment quality, but some EU member countries have set their own sediment regulation. In Finland, such guidance does not exist. Since the ecosystems are versatile and there are several anthropogenic activities leading to metal pollution, the evaluation of metal toxicity and ecological risks is challenging and there are still wide data gaps in knowledge about the behavior of metals. On the other hand, environmental administration needs simple and easily interpreted methods for routine monitoring.

1.1 AIMS OF THE STUDY

The aims of this study were to evaluate the risks of metal mining in boreal lake ecosystems, and to improve the ecological risk assessment of metals. One of the key aspects was to evaluate the usability of different methods in local conditions. Since there are no sediment quality guidelines in Finland, special attention was given to the applicability of the risk assessment methods used in other geographic areas.

Special interest was also given on how the seasonal changes affect metal bioavailability and toxicity.

The specific goals of this projects were to

1) Analyze the metal concentrations in several matrices (water, sediment, sediment pore water, benthic organisms and fish) in boreal freshwaters affected by metal mining (I),

2) Assess metal bioavailability and toxicity (I, II), including the studies of possible effects from seasonal changes,

3) Evaluate and compare the suitability of different ecological risk assessment and metal bioavailability evaluation methods (I, II, III),

4) Review the current methods and practices of metal ERA in different parts of the world in order to reveal the current shortcomings and the best practices (III), and

5) Test suitable adsorbent materials for remediating metal-contaminated sediment.

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2 METALS IN THE AQUATIC ENVIRONMENT

Metals are a group of elements that are found everywhere in nature. Metals are defined as elements with a lustrous appearance and good conductivity of electricity and heat (Luoma and Rainbow 2008). They usually participate in chemical reactions as cations. Most of the elements in the periodic table of the elements can be defined as metals. Metals share few unique properties, especially when occurring in nature.

Even though metals are toxic at high exposures, some of the metals are essential for life processes in small quantities (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Sn and Sb) (Luoma and Rainbow 2008). Metals are unique in the way that they are not biodegradable like organic compounds. The naturally occurring concentrations of different metals and metalloids vary spatially. These background concentrations of metals are usually highest in the areas which are of interest to the mining industry.

In freshwater ecosystems, metals are distributed between biota, water, sediment particles and sediment pore water. Pollutants have a tendency to accumulate in bed sediments, and this accumulation may lead to increased exposure and toxicity in aquatic organisms (Besser et al. 2015). Sediment is the matter on the bottom of a water body, consisting of soil (organic matter and minerals), sand and water (U.S. EPA 1998). The solids consists of sand (Ø>60 µm), silt (2–60 µm) and clay (<2 µm) (Reible 2014). The top layer (0–10 cm) of the sediment is considered to be the biologically most active part, resembling current conditions (Fisher 1982; Mäkinen and Lerssi 2007). In fresh waters, sediment acts as habitant for various types of macroinvertebrates, such as insect larvae, crustaceans, oligochaetes and molluscs (Fisher 1982). There are diverse exposure pathways along which sediment-associated contaminants could end up to benthic organisms; most often from pore water, food particles in sediment and from overlying water (Batley et al. 2005). Overlying water is the water phase at the bottom of a waterbody, just above the sediment-water interphase. The importance of the sources depends on the behavior of the organism, such as its feeding and burrowing habits.

2.1 METAL BIOAVAILABILITY AND TOXICITY

There are different chemical forms for metals, each having specific properties and this is referred to as metal speciation. The mechanistic understanding of the behavior of metals in aquatic ecosystems has advanced, and the significance of metal speciation and bioavailability has been noted (Calace et al. 2006). Metals can occur as free ions (M^1–2+), as part of an inorganic metal-ion pair (e.g., M-OH⁺. M-Cl⁺, M-CO³) or bound to organic compounds or to biotic surfaces (Smith et al. 2002; Vink 2009).

Bioavailability is a key concept when evaluating the risks of metals, since the bioavailable metal fraction is the fraction causing adverse effects (= toxicity) to

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2 METALS IN THE AQUATIC ENVIRONMENT

Metals are a group of elements that are found everywhere in nature. Metals are defined as elements with a lustrous appearance and good conductivity of electricity and heat (Luoma and Rainbow 2008). They usually participate in chemical reactions as cations. Most of the elements in the periodic table of the elements can be defined as metals. Metals share few unique properties, especially when occurring in nature.

Even though metals are toxic at high exposures, some of the metals are essential for life processes in small quantities (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Sn and Sb) (Luoma and Rainbow 2008). Metals are unique in the way that they are not biodegradable like organic compounds. The naturally occurring concentrations of different metals and metalloids vary spatially. These background concentrations of metals are usually highest in the areas which are of interest to the mining industry.

In freshwater ecosystems, metals are distributed between biota, water, sediment particles and sediment pore water. Pollutants have a tendency to accumulate in bed sediments, and this accumulation may lead to increased exposure and toxicity in aquatic organisms (Besser et al. 2015). Sediment is the matter on the bottom of a water body, consisting of soil (organic matter and minerals), sand and water (U.S. EPA 1998). The solids consists of sand (Ø>60 µm), silt (2–60 µm) and clay (<2 µm) (Reible 2014). The top layer (0–10 cm) of the sediment is considered to be the biologically most active part, resembling current conditions (Fisher 1982; Mäkinen and Lerssi 2007). In fresh waters, sediment acts as habitant for various types of macroinvertebrates, such as insect larvae, crustaceans, oligochaetes and molluscs (Fisher 1982). There are diverse exposure pathways along which sediment-associated contaminants could end up to benthic organisms; most often from pore water, food particles in sediment and from overlying water (Batley et al. 2005). Overlying water is the water phase at the bottom of a waterbody, just above the sediment-water interphase. The importance of the sources depends on the behavior of the organism, such as its feeding and burrowing habits.

2.1 METAL BIOAVAILABILITY AND TOXICITY

There are different chemical forms for metals, each having specific properties and this is referred to as metal speciation. The mechanistic understanding of the behavior of metals in aquatic ecosystems has advanced, and the significance of metal speciation and bioavailability has been noted (Calace et al. 2006). Metals can occur as free ions (M^1–2+), as part of an inorganic metal-ion pair (e.g., M-OH⁺. M-Cl⁺, M-CO³) or bound to organic compounds or to biotic surfaces (Smith et al. 2002; Vink 2009).

Bioavailability is a key concept when evaluating the risks of metals, since the bioavailable metal fraction is the fraction causing adverse effects (= toxicity) to

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organisms. In general, free metal ions are the most toxic and the most bioavailable form of metal. There are several ways of defining bioavailability. According to Semple et al. (2004), a bioavailable chemical is one that is freely available to cross the cellular membrane of an organism in the given habitat. A more detailed definition of bioavailability is given by Spacie et al. (1995):

...the portion of the total quantity of concentration of a chemical in the environment or a portion of it that is potentially available for biological action, such as uptake by and aquatic organism… environmental bioavailability is the portion of chemical in an available form which the organism encounters that it actually absorbs.

There is still a lack of consensus when it comes to defining the term bioavailability. Some of the definitions include the metal uptake by organisms, while others focus only on the environmental conditions (the portion that could be taken up). Besides the above-mentioned definition, another, widely used definition is:

bioavailability is the metal exposure or uptake to organism from all the possible uptake sources (Ehlers and Luthy 2003; Luoma and Rainbow 2008).

The bioavailable metal fraction (often metal cations, but also neutral and anionic species) rather than metal total concentrations, represents the potentially toxic metal fraction (e.g,. Morel 1983; Morel and Hering 1993). Metal bioavailability is a complex phenomenon, controlled by many processes. In aquatic freshwater ecosystems, there are several water quality parameters that control the bioavailability, including pH, organic carbon content, water hardness, dissolved oxygen and sulfides (Luoma and Rainbow 2008). Bioavailability is controlled by competition with other cations for metal binding sites, metals in colloidal forms and metal complexation by organic ligands (Fortin et al. 2010; van Dam et al. 2010; Gandhi et al. 2011). Ligands, in general, are molecules attached to metal. The processes behind metal bioavailability are slightly different in the sediment compartment. A part of the metal sinks to the sediment, but sediment is not necessarily a permanent sink. When the environmental conditions change, metals can be released back into the water, where they may induce toxicity. In sediments, metals are mainly soluble or ion-exchangeable, or bound to Fe and/or Mn oxides, sulfides, organic matter and carbonates (Hou et al.

2013). Also, the physical-chemical attributes of pore water and overlying water influence the metal bioavailability in sediment. These attributes include pH, redox- potential and sulfides (Zhang et al. 2014).

2.1.1 Methods for evaluating metal speciation and bioavailability

One of the earlier models leading to studies on metal speciation is the Free Ion Activity Model (FIAM) (Morel 1983; Morel and Hering 1993; Campbell 1995). The theory is based on an assumption that biological adverse effects arise from free metal ions rather than from the total concentration of the metal. The Equilibrium

Partitioning model (EqP) incorporates the interaction between sediment, pore water and organisms (Ankley et al. 1996). If the concentration of metal in one of the phases is known, the concentrations in other phases can be calculated from that. The model proposes that metals in the pore water are the primary route by which contaminants enter biota in aquatic environments (Burton et al. 2005). Metal concentrations in pore water could, therefore, be used as an estimate of bioavailable metal fraction. These models are still used as a base for more advanced, thermodynamically based methods and software (e.g., MITEQA2 and PHREEQC, WHAM).

Several methods can be used for evaluating metal bioavailability. Dissolved and colloidal metal fractions (filtered Ø 0.45 µm) may be chemically analyzed using inductively coupled plasm mass spectrometry (ICP-MS), inductively coupled plasm atomic emission spectroscopy (ICP-AES), atomic adsorption spectroscopy (AAS) or voltammetric determination (European Commission 2009a). These methods can also be used for analyzing sediment pore waters. Before analysis, pore waters need to be extracted either in situ (peepers, suction, vacuum filtration) or ex situ (centrifugation, squeezing, pressurization, vacuum filtrations) (ASTM International 2004). A traditional chemical method for evaluating bioavailability in sediment is stepwise sequential extraction (Tessier et al. 1979). In extractions, metals are categorized according to their binding capacity (exchangeable, carbonate-bound, bound to Fe/Mn oxides, bound to organic materials and residual metals). The most readily exchangeable fraction represents the bioavailable metal fraction. Another chemical method for analyzing bioavailability in sulfide-rich sediments is SEM-AVS (simultaneously extracted metals – acid volatile sulfides) method (Di Toro et al. 1992;

Di Toro et al. 2005; Ribeiro et al. 2013). It is assumed that in anaerobic conditions, reactive metals (SEM) bind to reactive sulfide (AVS) and, hence, are not available for the organisms (= bioavailable). This solid phase sulfide that complexes with metals results from the reduction of SO⁴ in anaerobic conditions. The precipitates formed lower the bioavailability of the metals (De Jonge et al. 2012). If the amount of AVS is higher than ∑SEM (Cd, Cu, Ni, Pb, Zn), no toxicity is expected. Organic carbons have bioavailability-reducing features similar to those of sulfides, and therefore, the accuracy of the SEM-AVS results can be improved by adding the evaluation of complexes between metals and organic carbon (OC). It is applied by normalizing the SEM-AVS results to OC. Toxicity is not expected if ∑SEM is less than 150 µmol/g f^oc (Burton et al. 2007).

Passive samplers are modern tools for evaluating the bioavailable fraction of chemicals in the environment. There are two differing operative principles in passive samplers; they may either continuously accumulate bioavailable and/or labile chemicals from the environment, or they are based on chemical equilibrium between the sampler and the environment (Vrana et al. 2005). Passive samplers for metals are often the former ones with continuous accumulation and equilibrium-based samplers are more commonly used with organic compounds. Diffusive Gradients in Thin Films (DGT) are among the most common methods for measuring labile metals

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