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Título: Anthropogenic microparticles as heavy metal vectors: implications
for marine contaminantion and food webs

Área Científica: Ciências da Terra e do Ambiente
Sub-área: Ciências do Ambiente

Sumário (max. 150 palavras):
Coastal areas have a great ecological value as ecosystem services providers
[1,2,3]. An important role has been admitted by the inclusion of these
ecosystems in the Water Framework Directive (WFD) and in the Marine
Strategy Framework Directive (MSFD) [6]. Heavy metals (HMs) have been
widely studied in these systems [1,4,5,6,7,8]. Anthropogenic microparticles
(MPs) are the new concern while evaluating ecological status of marine
systems travelling along the hydrodynamic gradient carrying HMs [12]. This
project will provide answers in the remediative role of these ecosystems as
MPs and HMs sinks. This travel through coastal gradients also subjects MPs
to a physic-chemical gradient shaping the sorption/desorption of HMs to MPs
surface [12], entering the food chain [13]. HMs-MPs couples versus single
effects in different trophic levels, acquires additional meaning under the
MSFD scope in commercially exploited species. This multi-disciplinary
approach intent to fill the gaps between HMs-MPs at the ecosystem level.

Estado da Arte (max. 500 palavras):
HMs are well-known contaminants with recognized effects in marine MOs,
plants and animals [6,7,11]. Estuarine ecosystems are key ecosystems for
the remediation of marine systems [8,9,10] provided by salt marshes acting
as active sinks of pollutants [1,4,5].Estuarine hydrodynamics, settle passive
particles charged with HMs on salt marshes, promoting sedimentation [2,3].
MPs are no different and exhibit a passive Lagrangean drift [8]. Studies
regarding anthropogenic MPs have increased [14] and this also caught
attention in conventions and directives. Mankind uses about 240M tons of
plastic discarding these materials into the marine environments [20]. This
debris undergoes degradation into smaller particles [14]. Plastics are
persistent pollutants ending up on the bottom of all kind of marine
environments [14]. The widespread has prompted several agencies (UN,
IOC, EU, NOAA) even the OSPAR convention to improve our understanding
about how MPs contamination is, accumulation, sources and impacts. In
addition to their aesthetic impacts, MPs are threatening animals by
accumulation and entanglement [15], and it can be easily mistaken as food
[20]. HMs-MPs interactions hadn’t been considered because polymers were
mentioned to be inert towards metal ions [12] although the association
mechanism is unclear, involve adsorption of ions to polymers and adherence
of metal-bearing mineral particles to MPs surface [12]. Buoyancy of pellets
ensures MPs exposition to high HM concentrations in the surface microlayer.
In marine environments can travels considerable distances being potentially
available to animals [17] and is even more unknown in systems very marked

physic-chemical gradient changing ion solubility [14]. If one considers
predicted physic-chemical changes derived from climate change [8] the
scarcity data on HMs-MPs interaction is even higher. If their static behavior
while HMs vectors has a high degree of uncertainty, their dynamics while
passive particles transported along a coastal system is almost case-specific.
Numerical modellings coupled to in situ data contribute efficiently
particulate HMs trajectories along the system [8] and also be applied to MPs
due to their Langrangean behavior [16]. Stable isotopes can establish mass
and energy balances along food webs providing insights on contaminant
flows. IsoWeb model, estimates diet proportions of all consumers in a food
web based on stable isotope information, taking into account variation in
trophic enrichment factors among different consumer-resource links [18].
The knowledge about how different food webs and its elements incorporate
persistent contaminants is yet to be known. MPs ingestion has physical
impacts and physiological consequences on the population fitness [13].
Biochemical markers can characterize the contaminant fraction and
integrate effects of contaminants experienced by organisms [19]. They are
powerful tools to measure xenobiotic effects [19]. In sum, the acquisition of
knowledge proposed by this PhD plan, intents to suppress the major gaps in
this area [20]. A clear view of the MPs contamination history for the target
systems coupled with hydrodynamic approach will provide answers to these
gaps. Their Interactions with HMs, MOs and animals is essential for
understanding ecological impacts, MSFD sensu and proving technical
information for impact assessment and scientific knowledge to answer
questions demonstrated by the literature review.

Objectivos (max. 300 palavras):

Descrição Detalhada (max. 1000 palavras):
Facing the lack of knowledge on the interactions between MPs and the wellknown HM contaminants present in the Tagus and in Madeira coastal areas,
a multi-disciplinary approach will be undertaken, from geology to
hydrodynamics, passing by animal physiology and ecotoxicology and marine
chemistry. These two marine systems have contrasting contamination
histories. Tagus industrial history is well known and it’s markedly recorded in
several research papers and in the sediment record. On the other hand,
Madeira archipelagos is away from any kind of industrial activity but it’s
highly affected by a large volume of marine traffic. This intense ship
movement will introduce some contamination sources to this marine
ecosystem, such as metal release from anti-fouling paints or MPs generation
from marine litter introduction. First, to understand the present pollution of
our estuaries, there is the need to unravel the past history of MP
contaminations, similarly to what is known for HMs. Salt marshes are known
to constitute good records of the contamination history of an estuary, as
they act as sinks integrating in their sediments contaminants and drifting
material. Different salt marshes located along the Tagus estuarine shoreline

will be sampled for sediment cores in order to establish a chronology based
on the 137Cs dating. This will allow understanding when MPs started to
appear in the estuarine system with different levels of anthropogenic
pressure and simultaneously their relationships with the HM contamination
between 1900 and the sampling date. The same approach will be employed
in Madeira coastal area. Alongside this historical reconstruction, it’s also
important to understand the present status of contamination of both marine
systems. While sediments are good historical records for contaminants, the
water column can provide real-time Information. Sampling MPs present in
the water column surface within a pre-established sampling grid will provide
powerful insights to feed hydrodynamic models. The HM contamination in
the water column and in the drifting MPs will be assessed, in order to
understand their role as vectors of chemical contamination. MPs behave as
drifting Lagrangean particles and thus have their movement controlled by
the system hydrodynamic features. This approach will allow identifying
possible sources and destinations of the MPs and associated contaminants.
Simultaneously, a chemical approach will be undertaken, analyzing the
dissociation and adsorption processes of HMs from MPs using Langmuir and
Freundlich models, providing insights on the chemical equilibrium of the
contaminants present in the dissolved phase and in the particulate phase,
namely in the MPs. This merger of hydrodynamic and chemical models, will
provide a map of the contaminant transport and dissolution along the
physic-chemical gradient modeled mostly by salinity, and thus the
availability and transport of the different chemical contaminants as well as
the MPs hazardous characteristics as contaminant carriers. Fishes and
macroinvertebrates can play a key role in the ecosystem-contaminant
interactions. These are important to consider in terms of MPs mass balances
and associated contaminants. Fishes and invertebrates will be sampled and
their MPs content determined both incorporated in the muscle and in their
stomach. Comparing animals from similar sites and with different MPs
concentrations, it is expected to establish a relationship between MPs and
HMs concentrations in the animals, in order to understand the effect of the
MPs as contamination vectors. This is important in terms of economically
exploitable species such as mussels, mollusks and barnacles. Additionally,
biological invasions by non-indigenous species (NIS) are considered one of
the greatest environmental and economic threats to global biodiversity.
Studies have been indicating that NIS are more resistant to several types of
stresses. Comparing different MPs concentrations between NIS and sister
native species could provide key and novel insights. The analysis of the
d13C and d15N stable isotopes coupled with isotope-based trophic models
(IsoWeb) allows a better understanding the energy and mass flow along the
estuarine trophic web, and thus the potential MPs and contaminant transfers
between trophic levels. This will lately be coupled with animal manipulation
experiments. Nevertheless, marine environments are subjected to physicchemical gradients, with known effects on the adsorption/desorption of
contaminants between the particulate (SPM and MPs) and dissolved phases.
Using controlled mesocosmos, several at present and predicted pH, salinity
and temperature conditions will be simulated using estuarine water and
controlled MPs (with different morphologies and materials) and contaminant
concentrations in order to assess the effect of the present and future
estuarine gradients on the MPs carrier capacity. Using a similar mesocosmos

approach the stomach content of some animals (fishes and invertebrates)
will be simulated. Our major goal is to understand the desorption rates of
the contaminants from the MPs surface to the digestive environment and to
the animal cells. This will provide new insights on the MPs impact in the
animal contaminant burden. Exposing representative species with different
feeding habits to different types of contaminated and non-contaminated
MPs, created in a controlled environment will provide data on the
physiological fitness of these animals towards the exposure to contaminants
both carried by MPs and by simple water/sediment ingestion. At this level
several condition and physiological biomarkers will be employed ranging
from genotoxicity and proteomic analysis to typical enzymatic biomarker
assessment. Since there exists a large number of commercially exploited
species potentially affected by MPs contaminations, also their ability to be
depurated will be tested maintaining the animals in a controlled
environment without any levels of contamination. This is very important in
terms of food security and public health, as these MPs particles are not
currently monitored in these economically exploited species and thus their
presence can present a threat to the human consumers, not only by the
coupled-contaminants but also as contaminants itself. With these multidisciplinary approaches the present consortium intents to provide science
answers, but also guidance document for the management and protection of
marine ecosystems to be presented to the stakeholders and authorities. Also
within the scope of the WFD and MSFD these insights acquire an increased
importance as they will provide recommendations for both monitoring and
mitigation programs of priority substances (HMs-MPs) considered key
features within the ecological quality status assessment imposed by both
directives.

Referências (max. 20):
1. Caçador, I., C. Vale and F.M. Catarino, 1996. Accumulation of Zn, Pb, Cu,
Cr and Ni in Sediments Between Roots of the Tagus Estuary Salt Marshes,
Portugal. Estuarine, Coastal and Shelf Science 42:393-403
2. Salgueiro, N. & I. Caçador (2007). Short-term sedimentation in Tagus
estuary, Portugal: the influence of salt marsh plants. Hydrobiologia 587:185193.
3. Duarte, B., Caçador, I., Marques, J.C. and Croudace, I., 2013. Tagus
Estuary salt marshes feedback to sea level rise over a 40-year period:
insights from the application of geochemical indices. Ecological Indicators
34, 268-276.
4. Caçador, I., Caetano, M., Duarte, B., Vale, C. 2009. Stock and losses of
trace metals from salt marsh plants. Marine Environmental Research, 67,
75-82.
5. Duarte, B., Caetano, M., Almeida, P., Vale, C., Caçador, I., 2010.
Accumulation and biological cycling of heavy metal in the root-sediment

system of four salt marsh species, from Tagus estuary (Portugal).
Environmental Pollution 158, 1661-1668.
6. Santos, D., Duarte, B. and Caçador, I., 2014. Unveiling Zn
hyperacumulation in Juncus acutus: implications on the electronic energy
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7. Pedro, S., Duarte, B., Castro, N., Almeida, P.R., Caçador, I. and Costa, J.L.,
2015. The Lusitanian Toadfish as biomonitor of estuarine sediment metal
burden: the influence of gender and reproductive metabolism. Ecological
Indicators 48, 370-379.
8. Duarte, B., Valentim, J.M., Dias, J.M., Silva, H., Marques, J.C. and Caçador,
I., 2014. Modelling Sea Level Rise (SLR) impacts on salt marsh detrital
outwelling C and N exports from an estuarine coastal lagoon to the ocean
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Estuary (Portugal), during a flood episode. Marine Pollution Bulletin 64,
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17. Tourinho, P.S., Ivar do Sul, J.A., Fillmann, G., 2010. Is marine debris
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