1
Soil contamination in Fildes Peninsula (King George Island,
Antarctic): Bio(availability) and Remediation strategies.
Ana Padeiro1*, Margarida C. Santos1, João Canário1
1CQE, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
Abstract
The Fildes Bay, located on Fildes Peninsula, King George Island, is characterized by its
high biodiversity, but also by the high density of scientific stations, becoming one of the
most contaminated areas of Antarctica. In order to assess the contamination and
distribution of several trace elements (Cr, Ni, Cu, Zn, As, Pb, Cd and Hg) in Fildes Bay,
soil samples were collected, The results obtained in this study point to the existence of
several contaminated hotspots mainly related to high levels of Cu, Zn, Pb, Cd, Cr and Ni.
The comparison of the contaminant distribution pattern with previous works allows
identifying the anthropogenic sources as well as proposing several remediation
strategies.
Keywords: Trace elements, contamination, human impacts, remediation, Fildes Bay, Antarctica
Introduction
In recent decades there has been an
increasing expansion, in intensity and
diversity, of human activities in Antarctica,
especially in its peninsula and surrounding
islands, which has caused serious pollution
problems, mainly near the scientific stations
(Bargagli, 2008). These problems have led
to the implementation of an environmental
protocol, the Madrid Protocol, which
designates Antarctica as a “natural reserve,
devoted to peace and science” (Art.
2). Article 3 of the Environment Protocol
sets four basic principles applicable to
human activities in Antarctica to avoid or
limit negative impacts on the environment
and ecosystems and Article 7 prohibits all
activities relating to Antarctic mineral
resources, except for scientific research
(Secretariat of the Antarctic Treaty, 2011).
Humans have occupied the Fildes Bay area
for over fifty years and in the past ten years
the average number of people living and
working in stations increased about 26%
during the summer (251 to 316) and 33% in
winter (95 to 126). It is possible to assume
that this growth in the number of occupants
of the stations will lead to a potential
increase risk for the environment (Peter, et
al., 2013). Recent studies reveal that in
some areas, near the scientific stations, the
concentrations of several trace elements
are increasing, affecting the surrounding
ecosystem (Artaxo & Rabello, 1992; Negri,
2006; Santos, et al., 2005). Bargagli (2005)
and Peter et al. (2008) state that the Fildes
region is directly influenced – although with
limits – by the current management of
waste stations, oil handling, ships and
tourism yachts in KGI and also by airborne
contaminants from South America.
2
Although there are some studies which the
concentrations of trace elements in the
Fildes Peninsula were determined, this is
the first study that provides an insight of the
source, distribution and bio(availability) of
trace elements (Cr, Ni, Cu, Zn, As, Pb, Cd
and Hg) on soil in Fildes Bay. No studies to
date have examined the availability of trace
elements in Fildes soils. Such data can help
to predict the degree of vulnerability of
Fildes soil in response to the growing
human occupation. The vulnerability of the
environment is directly proportional to the
capacity of a soil for retaining pollutants.
The environmental risks are as high as the
availability of the trace elements, which
leads to leaching and groundwater
contamination (Mendonça, et al., 2013).
Material and Methods
Site description
The Fildes Bay also known as Maxwell Bay,
located in Fildes Peninsula (62º 08´ S - 62º
14´S, 59º 02´ W - 58º 51´W) is located in
the southwest of the Island of King George
(KGI), South Shetland Island (Fig.1), and
represents one of the largest ice-free areas
in the maritime Antarctic region and it is
characterized by its high biodiversity (Peter,
et al., 2013). Collins Glacier was used as
reference site because there are no human
pressures in this site.
Figure 1- Fildes Peninsula location and map showing the sampling sites.
Sampling and Analytical methods
During the summer of 2014, surface soil
samples (the top 10 cm) were collected
around Fildes Bay (Fig.1). Sampling was
carried out with ultra-clean protocol
techniques, using acid decontaminated
material and wearing latex gloves. Samples
were collected with a decontaminated
plastic spatula, stored in zip sealed plastic
bags and also dried at 40°C. After dried,
sediments where sieved and only the
fraction <2 mm was used for analysis, to
avoid the dilution of contents by coarse
material.
3
Digestion of the samples was carried out to
destroy organic matter and to dissolve
suspended solids. Samples were digested
in Aqua Regia (HCl, 36 %; HNO3, 60 %,
3:1) and HF (40 %) in Teflon bombs (100
ºC for 1 h) (Loring and Rantala, 1992),
evaporated to near dryness and dissolved
with HNO3 (1 %).
Tests of bioavailability were conducted with
Immobilised Phaeodactylum tricornutum in
alginate. Immobilised P.tricornutum was
incubated, with water and soil collected at
Fildes bay, in polyethylene devices. Control
and test incubation devices were produced
according to Cabrita et al. (2013); a control
device comprised a zip-lock transparent
polyethylene bag filled with Immobilised P.
tricornutum with f/2, preventing contact with
Fildes Bay water or water and soil, whereas
a test one consisted of a drilled zip-lock
transparent polyethylene bag filled with
Immobilised P. tricornutum, that allowed the
contact with Fildes Bay water or water and
soil. At each experiment day, both control
and test incubation devices were always
used.
Leaching simulation tests were performed
for the partitioning of particulate trace
elements into the exchangeable fractions
using H2O Millipore, shaking for 6 h.
Analyses of trace elements (Cr, Ni, Cu, Zn,
As, Pb and Cd) in all samples were done by
ICP–MS. Hg determination in soil samples
were done by atomic absorption using a
direct mercury analyzer
QA/QC Control: International certified
standards (MESS-3, TH2 and 414-
Plancton) were used to ensure the
accuracy of our procedure. For all
parameters, obtained values were
consistent within the ranges of certified
values. Analytical variability and
homogeneity of soils samples (calculated
as standard deviation of duplicates, with
values below 15%) were considered
satisfactory.
Results and discussion
Trace elements content
The ranges of values measured for the 8
elements in Fildes Bay and Collins Glacier
are shown in Table 1. The element content
(μg g-1; Hg mg g-1) in Fildes Bay were 15-
263 Cr, 12-141 Ni, 56-179 Cu, 68-949 Zn,
13-23 As, 3-418 Pb, 0,2-1,2 Cd and 0,005-
0,37 Hg. These concentrations are higher
than the values found for the Collins Glacier
(reference site - without anthropogenic
impacts), 28-31 Cr, 12-18 Ni, 49-70 Cu, 56-
87 Zn, 12-18 As, 5-7 Pb, 0,2 Cd and 0,006
Hg.
Table 1- Ranges of element concentration (μg g-1; Hg mg g-1) in Fildes Bay soil samples.
Local Cr Ni Cu Zn As Pb Cd Hg
Fildes Bay 15-263 12-141 56-179 68-949 13-23 3-418 0,2-1,2 0-0,37
Collins Glaciar 28-31 12-18 49-70 56-87 12-18 5-7 0,2 0,006
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Trace elements distribution
Figure 2 – Element distribution (μg g-1; Hg mg g-1) in Fildes Bay and the representation (through the hoop) of the average concentration of each element in the reference soil (glacial Collins).
With the observation of Fig. 2 it is possible
to see that samples of Fildes Bay have
higher values than those found in Collins
Glacier. The concentrations of As and Hg
are those with lower amplitude across the
Bay. Therefore, except for sample 14
relative to the mercury which has a 21
times higher concentration than the others,
it is expected that levels of these elements
are mostly of geologic origin. The
distribution of the remaining elements
follows the distribution of waste sites
(without protection for the ecosystems) that
exist in the Bay, as well as locations
affected by oil substances in the case of Pb
and Cd, in particular in areas with fuel
storage tanks. The distribution of Ni and Cr
shows a significant correlation (rs = 0.92, P
<0.05), as well as Pb and Cd (rs = 0.81, P
<0.05), which indicates the same source of
contamination for the correlated elements.
Fig. 3 allows a better understanding of that,
since it allows the comparison of sampling
sites with local waste disposal and spill or
fuel storage.
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Figure 3 - Distribution of waste disposal and fuel storage and/ or spills in Fildes Bay (Adapted from Peter, et al. 2013).
Leaching simulation
The percentages of the element extracted
by water were calculated by:
%𝑀𝐸 =[𝑀]𝑒𝑥𝑡𝑟𝑎𝑐𝑡𝑒𝑑 × 𝑉
[𝑀]𝑇𝑜𝑡𝑎𝑙 × 𝑚𝑆𝑜𝑖𝑙 × 100
Where [M]extracted is the concentration of
element extracted from the soil (µg L-1); V
the volume of milipore water (L); [M]Total is
the
concentration of element in the soil (g);
Msolo is the mass of soil used is the
experiment.
The main objective of this test was to
simulate the leaching/runoff caused by
rainfall and glacier melt in Fildes Bay. From
Table 2 it can be seen that only a tiny
fraction of total elements that are found in
soils is extractable.
Table 2 – Percentage range of element removal by Millipore H2O (contact for 6h with stirring)
Cr Ni Cu Zn As Pb Cd
0,02-0,09 0,02-0,19 0,05-0,38 0,04-1,04 0,16-0,86 0-0,04 0,5-2,01
Trace elements bioavailability
Figure 4 shows the mean and standard
deviation of the concentration of Cr, Ni, Cu,
Zn, Cd and Pb in P. tricornutum cells in the
water and soil from study site, as well as
the controls.
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Figure 4 -Incorporation of trace element in cells of P. tricomutum during testing of bioavailability. Incubation: a) Collins water + C2 Soil; b) Fildes water + 27 Soil; c) Fildes water + 35; d) Fildes water + 75 soil.
With the exception of Pb in microalgae
incubated with soil 35, the accumulation of
Cr, Ni, Cu, Zn, As, Cd, and Pb in the
immobilised P. tricornutum cells exposed is
significantly (p<0.05) higher than the
concentration in control cells.
In order to assess the amount of element
incorporated into the cell was calculated the
% of Element removal by,
%𝑅𝑀𝐴 =𝑀𝐸𝐴𝑙𝑔𝑎𝑒 × 𝑚𝑎𝑙𝑔𝑎𝑒
𝑀𝐸𝑆𝑜𝑖𝑙 × 𝑚𝑆𝑜𝑖𝑙
where ME is the element concentration (µg
g-1) and m the mass (g)
All elements have bioavailable fractions,
although, as expected, with different levels
of incorporation by the cells. The Zn was
the element that showed a greater
incorporation by the algae in all soils, with a
maximum of 25%. The maximum
percentage removal achieved for Zn and Pb
is much higher than other elements,
suggesting the possibility of anthropogenic
contribution.
Table 3 – Percentage range of element removal by microalgae.
Cr Ni Cu Zn As Pb Cd
1,4-4,3 1,8-3,2 1,1-3,5 3,9-25 0,8-1,2 2,7-24 1,7-5,3
Conclusion
The concentration and distribution of the
trace elements analyzed in the soil samples
of Fildes Bay clearly evidence the negative
impact of human presence. A significant
correlation was found between the
concentrations of Cr and Ni, where high
concentrations were found near the waste
disposal sites. A significant correlation was
also found between Pb and Cd
concentrations, where higher
concentrations were found in samples near
the fuel tanks. The distribution of Zn seems
to be related to both, fuel tanks and waste
disposal.
The simulation of leaching and the
bioavailability tests indicate that the
elements in soils are mainly in the
particulate fraction, and therefore transport
by the suspended particles. Once the
particles reach the bay deadsorption takes
place (owing to the high ionic strength and
complexing capacity of the salt water) thus
increasing the concentration of the
7
elements. By the bioavailability tests it was
concluded also that, except for As and Hg,
all elements are biologically available. We
concluded that it is urgent that measures for
soil rehabilitation are taken in Fildes Bay,
especially with respect to contamination by
Cr, Ni, Pb, Cd, Cu and Zn. Thought further
research is needed in order to fully access
the contamination a brief research allowed
to suggest that the remediation measures
that may be more adequate in the area are
the chemical fixation (using
orthophosphates) and the permeable
reactive barrier.
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Obtido em 6 de Abril de 2014, de
ats: http://www.ats.aq/e/ep.htm