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Ecotoxicology and Human Environmental Health
The effect of various natural dissolved organic carbon on copper lability and toxicity to the tropical freshwater microalga, Chlorella sp Gabriella Macoustra, Aleicia Holland, Jennifer Stauber, and Dianne F Jolley Environ. Sci. Technol., Just Accepted Manuscript • Publication Date (Web): 29 Jan 2019 Downloaded from http://pubs.acs.org on January 30, 2019
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Environmental Science & Technology
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The effect of various natural dissolved organic carbon on copper
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lability and toxicity to the tropical freshwater microalga, Chlorella sp.
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Gabriella Macoustra1, Aleicia Holland1,2,3*, Jenny Stauber3, Dianne F Jolley1
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1University
of Wollongong, School of Chemistry, Centre for Molecular and Medical Biosciences,
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Wollongong, NSW, Australia.
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2La
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Murray Darling Freshwater Research Centre, Albury/Wodonga Campus, VIC, Australia.
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3CSIRO
Trobe University, School of Life Science, Department of Ecology, Environment and Evolution,
Land and Water, Lucas Heights, NSW, Australia
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*Corresponding author
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Postal Address: La Trobe University, School of Life Science, Department of Ecology, Environment and
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Evolution, Albury/Wodonga Campus, VIC, Australia.
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Email:
[email protected] 17
Phone number: +61 2 60249646
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Environmental Science & Technology
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Table of Contents (TOC)/Abstract Art
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Abstract
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This study adds further critical information to the limited body of knowledge on the ameliorative
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ability of Australian dissolved organic carbon (DOC), reinforcing the importance of DOC source and
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concentration as significant factors controlling the risk copper poses to organisms in freshwater
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systems. The ameliorative ability of five unstudied dissolved organic carbons (DOC), on the chronic
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toxicity of copper to the tropical alga Chlorella sp. were compared. Sensitivity to copper varied
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dramatically; EC50 values increased by up to 22-fold in the high DOC treatment compared to controls
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and more than 2-fold between DOCs at the same concentration. The analytical techniques, diffusive
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gradients in thin-films (DGT-Chelex) and Chelex-column, were used to understand whether
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differences in copper toxicity could be explained by copper lability. Labile-copper mirrored the
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trends seen in the toxicity tests; lability decreased with increasing DOC concentration and varied
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between DOCs at the same concentration. The equilibrium model, WHAM VII, was also used to
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better understand the role of the free copper ion on the toxicity observed. Disagreement between
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EC50 values derived using the WHAM-predicted free Cu2+ concentrations and agreement between
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DGT-labile and cdynmax suggest free copper is not the sole contributor to toxicity and that the source
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of the specific DOCs also play a role.
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Keywords
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WHAM, equilibrium model, diffusive gradients in thin films, chelex-column, maximum dynamic
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concentration
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Introduction
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Increasing industrialisation, urbanisation, and agricultural and mining activities have the potential to
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increase metal contaminants in aquatic systems.
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understanding of water chemistry parameters and their effect on metal bioavailability and toxicity is
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required. Dissolved organic matter (DOM), is a ubiquitous component to all natural waters and is
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one of the most important parameters influencing the bioavailability of metals1. Dissolved organic
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carbon (DOC) is operationally defined as
