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Microplastics as Vectors for Environmental Contaminants : Exploring Sorption,
Desorption, and Transfer to Biota
Hartmann, Nanna B.; Rist, Sinja; Bodin, Julia; Jensen, Louise Helene Søgaard; Nørgaard Schmidt, Stine;
Mayer, Philipp; Meibom, Anders; Baun, Anders
Published in:
Integrated Environmental Assessment and Management
Link to article, DOI:
10.1002/ieam.1904
Publication date:
2017
Document Version
Peer reviewed version
Link back to DTU Orbit
Citation (APA):
Hartmann, N. B., Rist, S., Bodin, J., Jensen, L. H. S., Nørgaard Schmidt, S., Mayer, P., Meibom, A., & Baun, A.
(2017). Microplastics as Vectors for Environmental Contaminants : Exploring Sorption, Desorption, and Transfer
to Biota. Integrated Environmental Assessment and Management, 13(3), 488-493.
https://doi.org/10.1002/ieam.1904
Microplastics as contaminant vectors – exploring the processes – Postprint version
Page 1 of 17
Microplastics as vectors for environmental contaminants: Exploring
sorption, desorption, and transfer to biota
Accepted for publication in: Integrated Environmental Assessment and Management
DOI:10.1002/ieam.1904
Nanna Bloch Hartmann
†, *
, Sinja Rist
†
, Julia Bodin
‡
, Louise Helene Søgaard Jensen
‡
, Stine
Nørgaard Schmidt
†
, Philipp Mayer
†
, Anders Meibom
‡
, Anders Baun
†
†
Technical University of Denmark, Department of Environmental Engineering, Bygningstorvet
B115, DK-2800 Kgs Lyngby, Denmark
‡
Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental
Engineering at Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne,
Switzerland.
* corresponding author , nibh@env.dtu.dk
Microplastics as contaminant vectors – exploring the processes – Postprint version
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ABSTRACT
The occurrence and effects of microplastics (MPs) in the aquatic environment are receiving
increasing attention. In addition to possible direct adverse effects on biota, their potential role as
vectors for hydrophobic organic chemicals (HOCs), compared to natural pathways, is a topic of
much debate. It is evident, however, that temporal and spatial variations of MP occurrence do (and
will) occur. To further improve the estimations of the role of MPs as vectors for HOC transfer into
biota under varying MP concentrations and environmental conditions, it is important to identify and
understand the governing processes. Here, we explore HOC sorption to and desorption from MPs
and the underlying principles for their interactions. We discuss intrinsic and extrinsic parameters
influencing these processes, and focus on the importance of the exposure route for diffusive mass
transfer. Also, we outline research needed to fill knowledge gaps and improve model-based
calculations of MP-facilitated HOC transfer in the environment.
Keywords
Microplastics, contaminants, hydrophobic organic chemicals (HOCs), exposure, transfer,
ecotoxicity
Microplastics as contaminant vectors – exploring the processes – Postprint version
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I. INTRODUCTION
Interactions between microplastics (MPs) and organic contaminants take place before, during,
and after their release to natural environments. These interactions occur as a result of product
formulation (e.g., by addition of plasticisers and preservatives) as well as unintentionally, in e.g.,
wastewater, urban runoff, and landfill leachate containing complex mixtures of other environmental
contaminants. Recent studies have demonstrated the ability of MPs to carry environmental
contaminants (e.g. Rochman et al. 2013; Velzeboer et al. 2014). This has led to the hypothesis that,
in addition to direct effects of interactions with biota, MPs may also play a role in aquatic
ecotoxicology as vectors for toxic substances.
The role of MPs as contaminant vectors has been the topic of experimental studies and review
papers, both supporting and challenging this hypothesis. Some argue that plastic debris and HOCs
form complex cocktails that increase the overall bioavailability of HOCs to aquatic organisms and
ultimately to humans (Vethaak and Leslie 2016). This hypothesis has been challenged with the
argument that plastics play a minor role as contaminant vectors compared to natural particles, such
as suspended organic particulates and natural prey, because of their relatively low abundance in the
environment (Koelmans et al. 2016). Based on data from published studies, calculations have been
made to assess the overall relative importance of MPs as contaminant vectors compared to other
naturally occurring sorbents (Koelmans et al. 2016; Bakir et al. 2016). Models of increasing
complexity have been developed and applied, taking into account the partition ratios between solid
phases (including plastic) and water, MP age distribution, the relative abundance and ingested
amounts of MPs (Koelmans et al. 2016) as well as the role of gut surfactants, pH, and temperature
on HOC desorption (Bakir et al. 2016). With increasing plastic production and use in society,
environmental occurrence of MPs will inevitable increase in the future (temporal increase) and also
vary depending on specific local-scale conditions (spatial variations). Expanding our fundamental
understanding of the processes involved in MP facilitated transport of contaminants is therefore
Microplastics as contaminant vectors – exploring the processes – Postprint version
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necessary, allowing us to develop more accurate models and thereby evaluate the role of this
process under varying and case-specific conditions.
A conceptual overview of the topics covered in this paper is illustrated in Figure 1. In the
following sections, we describe the processes governing the interactions between MPs and HOCs
and their subsequent uptake into aquatic organisms, including HOC sorption to and desorption from
MPs and parameters affecting HOC distribution. We discuss the impact of different uptake routes
on MP-facilitated HOC transfer into biota, including direct MP contact exposure (internal and
external). Finally, we point to knowledge gaps and research required for a more comprehensive
understanding and modelling of these processes.
Figure 1. Overview of the topics covered in this paper: I) HOC sorption to and desorption from MPs; II) The influence
of intrinsic and extrinsic properties on HOC distribution to MPs; III) Transfer of HOCs between MPs and biota,
including direct contact transfer; IV) The role of in situ and laboratory studies when exploring these processes; and, V)
Outlook on knowledge gaps and future research directions
