Long-Term (1970−2017) Temporal Trends of Polychlorinated
Biphenyls in Fish, Settling Material, and Sediments from Populated
and Remote Sites in Rió de la Plata Estuary, Argentina
Juan Carlos Colombo,*,†,‡ Eric Demian Speranza,†,§ Malena Astoviza,† María Carolina Migoya,†,§

Carlos Norberto Skorupka,† Manuel Morrone,† Santiago Heguilor,†,§ Leandro Martín Tatone,†,§

and Claudio Bilos†

†Laboratorio de Química Ambiental y Biogeoquímica, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata,
Avenida Calchaqui km 23 500, C1888 Florencio Varela, Buenos Aires, Argentina
‡Comisioń de Investigaciones Científicas de la Provincia de Buenos Aires, Calle 526 entre 10 y 11, B1900 La Plata, Buenos Aires,
Argentina
§Consejo Nacional de Investigaciones Científicas y Tećnicas Godoy Cruz 2290, Autonomous City of Buenos Aires, Argentina

*S Supporting Information

ABSTRACT: Temporal trends of polychlorinated biphenyls
(PCBs) were studied for detritivorous fish (1996−2017) and
settling material (2002−2017) from polluted Buenos Aires
coast and for a dated sediment core (1970−2013) from the
outer Rió de la Plata estuary. In spite of contrasting
concentrations [5.3 ± 6.3 μg·g−1 dry weight (dw) for fish,
48 ± 26 ng·g−1 dw for settling material, and 1.5 ± 0.7 ng·g−1

dw for core], all three revealed exponentially decreasing trends
over time (97%, 83%, and 83%, respectively). Time trends
showed peak maxima coincident with Argentina’s period of
maximum PCB usage in 1973−1980 (80 cm depth in the
core) and pulse discharges related to PCB banning in 2001−
2002 (fish) with a lighter signature enriched in less persistent
tri- and tetrachlorobiphenyls. The log−linear PCB time trends compare well with the predicted decrease for a high emission
scenario from global emission data; the best fit was observed for the less impacted sediment core (−2%·year−1 versus −3%·
year−1 for emission scenario). Steeper slopes are observed for the more polluted settling material (−5%·year−1) and especially
for fish, in which the background decline trend tripled after the 2001 PCB pulse (from −7%·year−1 to −21%·year−1). These
PCB time trends in related environmental compartments from contrasted sites provide rare evidence for evaluating the
effectiveness of control measures in southern South America.

■ INTRODUCTION

Global concern about persistent organic pollutants (POPs),
highlighted by the Stockholm Convention treaty (2001), led to
the development of multiple monitoring programs worldwide
for the effectiveness evaluation of POP reduction based on
recommended matrices of air and breast milk.1 Yet a
considerable amount of baseline information and temporal
patterns of dichlorodiphenyltrichloroethanes (DDTs) and
polychlorinated biphenyls (PCBs) in biota and sediments
had been gathered 30−50 years prior to enactment of the
treaty. This long-term information allows a practical assess-
ment of the contamination status and efficacy of management
practices. However, these long-term data are primarily
restricted to the Northern hemisphere, where numerous
monitoring programs have been developed by national
agencies, for example, in the California coast,2 the Great
Lakes region,3−5 the Arctic,6,7 the Baltic and Swedish lakes,8,9

the Rhine and Meuse rivers,10 the Mediterranean Sea,11 and
the Asian Pacific.12 In South America, economic constraints
and political instability restricted the sustainability of
monitoring efforts, resulting in scattered and temporally
discontinuous data.13

In Argentina, the first DDT and PCB data for Rió de la Plata
fish and sediments were published in the early 1990s.14,15 Later
studies continued to monitor detritivorous fish,16−20 settling
material as a useful proxy to characterize the flocculent detritus
arriving to the bottom and associated downward PCB flux,21,22

and more recently, breast milk23 and air.24 In this paper, we
summarize previously published data and add new information

Received: August 7, 2018
Revised: September 28, 2018
Accepted: October 10, 2018
Published: October 10, 2018

Article

pubs.acs.org/estCite This: Environ. Sci. Technol. XXXX, XXX, XXX−XXX

© XXXX American Chemical Society A DOI: 10.1021/acs.est.8b04403
Environ. Sci. Technol. XXXX, XXX, XXX−XXX

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from ongoing projects in order to evaluate long-term temporal
trends of PCBs in the Rió de la Plata basin. Environmental
compartments with different accumulation/decaying patterns
and a trophic relationship; for example, detritivorous fish (21
years monitoring) and settling detrital material captured by
sediment traps in polluted Buenos Aires coast (15 years) are
compared with a dated sediment core from a mixohaline
environment from the estuary mouth to the sea, distant from
populated areas (42 years).

■ MATERIALS AND METHODS
In this work, new information from ongoing sampling
campaigns in the Rio de la Plata estuary has been added to
previously published data covering 1996−2006,17,18,21,22 to
have updated temporal coverage of fish and settling material.
The Rió de la Plata estuary is the second largest basin of South
America (>3 million km2, 500−800 km3 of freshwater and 90
× 106 tons of solid load per year) with an abundant
ichthyomass dominated by the detritivorous fish Prochilodus
lineatus.19 This strict detritivore has been chosen for PCB
monitoring due to its special adaptations to ingest organic
matter: suckerlike mouth, gill raker filtering structure, and
numerous pyloric ceca that allow the fish to directly feed on
flocculent sewage-industrial organic matter, leading to a rapid
accumulation of fat and associated organic pollutants.19

Although P. lineatus migrates 1000−1200 km north for
reproduction, chemometric analysis of its biochemical and
pollutant profile indicated a high degree of habitat fidelity to
Buenos Aires, where the fish find an abundant and highly
energetic food supply.20 Sampling methods and general
analytical procedures have been described in previous
papers.17,18,21 Briefly, fish were obtained from local fishermen
from 1996 to 2017 along Metropolitan Buenos Aires coast, a
freshwater area affected by untreated industrial and sewage
discharges (Figure 1). Dorsolateral muscle samples were

pooled according to fish size and weight (average size, 45 ±
4.9 cm; weight, 2.7 ± 0.9 kg; n = 442 fish in 109 pools and 57
individual samples). Settling material was collected 1.5 m
below the surface in a 5−6 m water column near Buenos Aires
main sewer at Berazategui (Figure 1) during 34 trap
deployments covering 2002−2017. To minimize the capture
of resuspended bottom material in this shallow coastal area,
storm events were specifically avoided in the sampling scheme.
Due to the large anthropogenic discharges (Buenos Aires main
sewer: ∼2 million m−3·day−1) and high turbidity of the estuary,
the fixed 10 cm diameter bi- and tricylindrical traps (total
surface 157−235 cm2) deployed for 20−48 h collected a large

amount of material (total flux 140−700 g·m−2·day−1). In order
to compare temporal patterns of PCBs in a more pristine, high-
sedimentation, mixohaline, transitional environment in the
Samborombon Bay (200 km SE from Buenos Aires to the sea),
a 115 cm long sediment core was collected in the Salado River
mouth (Figure 1) in 2013 using a 10.3 cm inner diameter
poly(vinyl chloride) (PVC) tube (25), which was divided into
23 4−6 cm thick slices.
Analyses included the determination of grain size

composition (sieve and pipet method), total organic carbon
(TOC) contents by high-temperature catalytic combustion
(Thermo Finnigan Flash EA 1112), and 41 individual PCBs by
high-resolution gas chromatography and electron capture
detection (Agilent 6890N, Agilent 7890N).17,18,21,22 PCB
quantification was performed with the linear response (2, 10,
50, and 250 pg·μL−1) of 41 PCBs (IUPAC numbers 17, 18, 28,
31, 33, 44, 49, 52, 70, 74, 82, 87, 95, 99, 101, 105, 110, 118,
128, 132, 138, 149, 151, 153, 156, 158, 169, 170, 171, 177,
180, 183, 187, 191, 194, 195, 199−201, 205, 206, 208, 209; C-
QME-01, AccuStandard Inc.). PCBs 103 and 198 (Ultra) were
added to control recovery yields. Blanks included in every
eighth sample batch gave negligible results. PCB method
detection limit for the trap material ranged from 0.05 to 0.15
ng·g−1 dw; half of these values were used in case of
nondetected congeners. Repeated analysis of an internal
reference sediment from La Plata harbor in the Rió de la
Plata (21 ± 3.6 ng of PCB·g−1) indicated an average variability
of 17−22%. Method accuracy, evaluated through the analysis
of certified reference materials (sediment, NIST 1944; cod
liver oil, COD1588a), averaged 79% ± 12% for 24 individual
PCB congeners in sediments and 87% ± 16% for 22 certified
congeners in fish. For age determination of the sediment
core,25 radionuclide analyses (excess 210Pb and 137Cs as an
independent control on 210Pb-derived ages) were conducted
on 10−15 g of dried sediments by γ-spectrometry (high-purity
germanium detectors, Canberra BE3830P). The year of
deposition of sediment layers was derived from the constant
rate of supply (CRS) dating model based on unsupported
210Pb activity.25 PCB usage and high emission data for the
country were obtained from global historical emission
inventories for 22 PCB congeners from the Norwegian
Institute for Air Research.26 Descriptive statistics and
regression and correlation analyses were performed with
Excel 2010 and Python (SciPy, NumPy, and SciKit-learn).

■ RESULTS AND DISCUSSION
Yearly averaged total PCB contents in fish, settling material,
and sediment core are presented in Table 1, and temporal
trends for all data are displayed in Figure 2. Lipid content of
muscle from detritus-feeding fish from Metropolitan Buenos
Aires is high (grand mean 44% ± 23% dw, n = 166), reflecting
feeding on organic-rich, polluted anthropogenic detritus. This
produces a higher body mass gain [condition index (CI) =
(body mass)·(standard length)−3 = 3.0 ± 0.5], enhanced
hepatomegaly [hepatosomatic index (HSI) = (liver)·(body
mass)−1 × 100 = 1.4 ± 0.4], and lipogenesis, possibly
reinforced by the obesogen role of PCBs.19 In contrast, fish
from northern Parana ́ and Paraguay Rivers (>1000 km north
from Buenos Aires), with a diet based on vegetal detritus, are
lean with smaller livers (13% ± 8.4% lipids dw; CI = 2.4 ± 0.4;
HIS = 0.7 ± 0.2).20 Accordingly, fatty Buenos Aires fish show a
high bioaccumulation of PCBs with dry weight concentrations
2 orders of magnitude higher compared to the organic-rich

Figure 1. Study area and sampling locations of fish and settling
material (Buenos Aires Metropolitan coast) and sediment core
(Samborombon Bay).

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(8.3% ± 4.5% TOC) settling material collected by the traps
(0.11−35, 5.8 ± 7.0 μg·g−1 dw versus 7.0−154, 50 ± 34 ng·g−1

dw, respectively).
The less polluted sediment core from Samborombon Bay

shows homogeneous grain size composition and lower TOC
contents (sand, 1.9% ± 1.3%; silt, 27% ± 9.3%; clay, 71% ±
9.3%; TOC, 2.2% ± 0.6%), revealing very low baseline PCB
concentrations for the basin at 30-fold below Buenos Aires’
trap material values (0.6−3.8, 1.5 ± 0.7 ng·g−1 dw). As
expected, the differences between lipid- and organic carbon-
based PCB concentrations are lower but still show the same
pattern, with fish averaging 20 times higher than the trap
material value which, in turn, is 7 times higher than the
sediment core average (11 ± 13 μg·g−1 lipid for fish, 478 ±
384 and 71 ± 27 ng·g−1 TOC for settling material and
sediment core, respectively).
In spite of the large differences in PCB concentrations, the

variability of the data [relative standard deviation (RSD) 120%

for fish and ∼50% for settling material and sediment core]
includes significant exponentially decreasing trends over time
in all three environmental compartments (r2 = 0.57−0.89, p <
0.001; Figure 2). When the decrease from peak maxima to
more stable final periods of the time series is considered
(December 2001 to 2008−2017 for fish, 2002−2005 to 2015−
1017 for settling material, and 1980 to 2011−2012 for
sediment core), the exponential decrease in total PCBs
averages 97% for fish (from 21 to 0.7 μg·g−1 dw), 83% for
settling particles (from 76 to 13 ng·g−1 dw), and 82% for
sediment core (from 3.8 to 0.7 ng·g−1 dw). The initial lower
concentrations and peak maxima observed in fish and sediment
core data introduce significant variability in the time series.
The time trend of fish data shows a large variability

associated with a peak maximum by the end of 2001 when
PCB phase-out associated with a severe economic crisis, illegal
dumping, and heavy rains resulted in a strong pulse of PCBs
into the estuary.17,18 Effectively, PCBs from transformer oil

Table 1. Annual PCB Averages and Compositional Ratios for Fish, Settling Material, and Sediment Corea

fish (μg·g−1) settling material (ng·g−1) sediment core (ng·g−1)

year dry wt fresh wt lipid wt 3−4/6 CB n dry wt TOC wt 3−4/6 CB n dry wt TOC wt 3−4/6 CB

1970 1.35 49.5 0.13
1972 1.08 66.2 0.44
1974 1.30 78.0 0.39
1976 2.00 96.0 0.37
1978 1.56 75.8 0.16
1980 3.77 139.1 0.09
1982 2.67 91.7 0.26
1983 2.26 59.0 0.00
1985 1.97 79.6 0.00
1987 1.92 73.6 0.00
1989 1.43 78.5 0.00
1991 1.72 91.6 0.00
1993 1.57 50.0 0.00
1995 1.26 88.4 0.00
1996 5.9−6.6 2.2−2.6 17.1−27.6 0.49 2
1997 1.77 116.6 0.12
1998
1999 7.1 ± 2.6 3.2 ± 1.5 8.8 ± 1.9 0.46 5
2000 6.1 ± 2.7 2.7 ± 1.5 8.7 ± 2.3 0.40 9 1.45 86.5 0.00
2001 4.7 ± 1.9 2.2 ± 1.3 7.8 ± 3.3 0.56 10
12/2001 21 ± 12 8.5 ± 5.8 47 ± 22 1.04 3
2002 17 ± 4.9 7.0 ± 1.9 39 ± 28 0.64 13 79.6 491 0.19 1 1.02 46.3 0.06
2003 16 ± 6.0 7.3 ± 3.7 24 ± 7.0 0.40 16 57−68 334−1627 0.47 2
2004 11 ± 4.6 3.8 ± 2.2 20 ± 5.0 0.35 12 87 ± 34 1976 ± 1591 0.19 6 0.92 53.9 0.00
2005 5.2 ± 2.9 2.1 ± 1.5 12 ± 2.9 0.30 9 76 ± 33 1286 ± 903 0.38 4
2006 2.9 ± 2.0 1.1 ± 0.9 11 ± 4.5 0.29 12 39 ± 22 580 ± 238 0.78 4 1.06 61.8 0.00
2007 1.7 ± 0.8 0.5 ± 0.3 8.3 ± 6.5 0.31 10
2008 0.8 ± 0.5 0.2 ± 0.1 3.1 ± 1.5 0.42 3 44 466 0.76 1 0.96 58.7 0.00
2009 0.9 ± 0.3 0.3 ± 0.1 2.8 ± 1.4 0.28 8 0.84 42.2 0.00
2010 0.8 ± 0.6 0.2 ± 0.2 2.7 ± 1.7 0.34 9
2011 0.5 ± 0.3 0.2 ± 0.1 2.3 ± 1.9 0.45 17 0.60 31.3 0.00
2012 0.6 ± 0.3 0.2 ± 0.1 2.0 ± 0.7 0.39 12 37 ± 5.1 349 ± 125 1.23 4 0.75 24.6 0.00
2013 0.7 ± 0.4 0.2 ± 0.1 2.1 ± 0.7 0.42 9 45 ± 32 384 ± 200 1.08 4
2014 0.4−0.5 0.13−0.14 1.2−2.1 0.46 2 21−31 720−1060 0.34 2
2015 0.52−0.54 0.1−0.2 1.5−1.8 0.47 2 15 ± 7.7 692 ± 164 0.25 3
2016
2017 0.8 ± 0.4 0.3 ± 0.2 1.9 ± 0.6 0.42 3 11 ± 5.8 827 ± 425 0.54 3
total 166 34

aSome values are given as arithmetic mean ± standard deviation. 3−4/6 CB is the tri+tetra/hexachlorobiphenyl ratio. 12/2001 indicates December
2001 peak concentration in fish after massive dumping.

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residues discharged in heavily polluted channels and ports were
efficiently washed out to the estuary, producing concomitant
extreme PCB concentrations in fish from December 2001
(13−35 μg·g−1 dw; Figure 2). A similar situation has been
suspected to explain PCB increases in Meuse River eels in
2000 after the Belgium dioxin crisis.10 The large variability of
Buenos Aires’ fish averages for December 2001 and the years
2002 and 2003 (Figure 2) reflects mixing of fish with different
exposures. In fact, from December 2001 to 2003, 29 out from
32 fish samples ranged from 13 to 35 μg of PCB·g−1 dw (mean
18 ± 5.4 μg·g−1 dw), tripling the already high previous PCB
concentrations of fish from this polluted area (from 1996 to
October 2001, 5.8 ± 2.4 μg·g−1 dw; n = 26), whereas only
three animals maintained similar concentrations in 2001−2003
(6.4 ± 0.5 μg·g−1 dw). The dampening of this PCB pulse in
fish appears to be largely completed approximately in 2006−
2007. While depuration/elimination kinetics might play a role
in this decrease, the exceptionally high muscle lipid depot of
the fish, which is maintained even during migration efforts
when visceral fat is consumed, act basically as a long-term
reservoir for persistent pollutants, minimizing their remobiliza-
tion.20 Thus, the most likely explanation of PCB attenuation in
fish is the general population turnover, where heavily polluted
fish are progressively replaced by less contaminated specimens

from subsequent cohorts. According to the most recent local
fishery study,27 the age-class distribution of this fish is maximal
between 2 and 6 and 9−10 years, supporting the interpretation
of a relatively rapid 6−7 year replacement of fish after the
2001−2002 PCB pulse. From 2008 to 2017, PCB concen-
trations stabilized as shown by the nonsignificant fit of the
linear trend (0.68 ± 0.16 ng·g−1 dw; r2 = 0.16, p > 0.28; Figure
2, inset), suggesting that 7 years after the official phase-out of
PCBs, fish approached a new steady state, at levels 9 times
lower than the prepulse PCB concentrations. These results
indicate that despite the typically large variability of fish data,
this dominant and highly specialized detritivorous fish, with a
very short trophic chain based on anthropogenic organic
matter, provides useful and reliable information to evaluate the
effectiveness of management practices related to the Stock-
holm Convention.
Although the time series of settling material has a limited

time coverage that begins just after the major PCB pulse
observed in fish (August 2002), the highest concentrations in
the trap material match the time frame of fish maximum
(2002−2005) with a significant decrease afterward. Effectively,
the average PCB concentration in the trap material during
2002−2005 (80 ± 29 ng·g−1 dw) decreased 2−3-fold after
2008 and displayed a larger relative variability (31 ± 20 ng·g−1

dw). Shorter time series (1984−1991) of settling material in
Lake Superior presented an even faster decrease over time.28

During the 2008−20017 period, annual PCB averages of
settling material continue decreasing (from 37−45 to 11−15
ng·g−1 dw; r2 = 0.69, p < 0.05 for the linear regression),
contrasting with the more stable fish pattern (Figure 2, inset).
This may be attributed to the direct impact of input discharges
on the trap material, in contrast to fish, where the pattern is
also influenced by bioaccumulation/depuration kinetics,
longevity, migration, and population dynamics. Organic
carbon-normalized PCB concentrations in settling material
also show a maximum in 2004−2005 and lower values
afterward (from 1300−2000 to 350−890 ng·g−1 TOC; Table
1) but during 2014−2017, concentrations increases signifi-
cantly due to the average 5-fold reduction of TOC (9.9% ±
3.5% to 2.1% ± 0.8%) related to the construction of a
wastewater treatment plant, resulting in a nonsignificant
exponential fit of TOC-based concentrations and years (r2 =
0.11, p = 0.32) . These results indicate that the main Buenos
Aires sewer is a significant source of TOC but not of PCBs and
confirms the flaws of TOC-normalized data for time trend
analysis.8

The sediment core collected in the distant, more pristine,
and mixohaline Samborombon Bay covers an extended 42-year
time frame with 1−2 orders of magnitude lower PCB
concentrations than Buenos Aires’ settling particles and a
different temporal pattern than fish and trap material. The
sediment core presents a PCB maximum at 80 cm depth (3.8
ng·g−1 dw) dated to 1980, which is in good agreement with
Argentina’s period of maximum PCB usage of 200−350 tons·
year−1 from 1973 to 198026 but does not reflect the 2001−
2002 pulse maximum of Buenos Aires’ fish. This suggests that
this remote area reflects background inputs related to the
general magnitude of PCB usage in the country rather than
local pulses from the most industrialized and populated area,
where the very high sedimentation rates (5.0 ± 1.7 cm·
year−1)21 and associated PCB fluxes (26 ± 19 μg·m−2·day−1)21

favor the rapid burial of hydrophobic pollutants near main
sources. Similar to trap material, the more recent surficial PCB

Figure 2. Temporal trends of PCBs in fish, settling material (traps),
and sediment core from the Rió de la Plata estuary. (○) Individual
measures; (●) arithmetic year averages ± standard deviations.
Exponential decrease trends (dashed lines) are displayed after 2001
for fish and after 1980 for sediment core. Recent linear trends are
shown for the 2008−2017 period (top, inset).

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concentrations in the core suggest a decreasing trend, but it is
statistically nonsignificant due to few data points (∼1 to 0.6
ng·g−1 dw; r2 = 0.63, p < 0.20; Figure 2, inset). As observed for
settling material, the TOC-normalized sediment core concen-
trations also decrease from 1980 to 2012 (from 139 to 25 ng·
g−1 TOC, Table 1) but show a poorer yet significant
exponential fit (r2 = 0.52, p < 0.001 for TOC and r2 = 0.89,
p < 0.001 for dw data), thus supporting the use of dry weight
concentrations in time trend analysis.
Log−linear PCB time trends in fish, settling material, and

sediment core from the Rió de la Plata are compared with
usage/emission patterns and Argentina’s management mile-
stones in Figure 3. In general, all three environmental

compartments compare well with the predicted decline
emission scenario with a best fit for the remote environment,
away from major pollution sources. The log−linear slope of
this more pristine sediment core (−2%·year−1, p < 0.001) is
lower than the decline slope derived for the high-emission
scenario (−3%·year−1). More polluted settling material from
Buenos Aires present higher slopes (−5%·year−1, p < 0.001)
and especially fish data, whose slope shows a 3-fold increase
after the 2001 pulse (−7%·year−1, p < 0.001, excluding the
2001 peak to −21%·year−1, p < 0.001). Overall, Rió de la
Plata’s declining PCB trends are comparable to those reported
for other environments (2−5%·year−1 for sediments and 2−
11%·year−1 for fish) with a proportionally higher decrease for
settling particles compared to the core and especially for fish
after the 2001 PCB pulse. Table S1 provides Rió de la Plata dry
weight-, fresh weight-, and lipid-based declining PCB trends
compared to other environments. The 1980−2012 decrease of
PCBs in Rió de la Plata sediment core is comparable to that
reported for a core covering 1968−1990 in the Stockholm
Archipelago8 and 3 times lower than a 1940−1990 Baltic core’s
declining trend.8 PCB burial and sediment core slopes are
significantly influenced by sedimentation rates and resuspen-
sion.8 The high sedimentation rate estimated for the Salado
core from 210Pb data (2.62 cm·year−1)25 indicates a relatively
rapid burial of the PCB signal, and the uniformly fine texture of
the core (clay, 71% ± 9.3%; silt, 27% ± 9.3%) suggests that
resuspension and mixing with coarser material is probably not

relevant. As observed in Rió de la Plata data, the Baltic
temporal PCB trends also show consistently lower slopes for
sediment cores compared to biota.8

Settling material from Buenos Aires showed a higher PCB
decrease trend from 2002 to 2017 compared to the Rió de la
Plata core but lower than the 1984−1991 temporal decline
reported for Lake Superior,28 where trap material PCB
concentrations were more than an order of magnitude higher
with total mass fluxes 3 orders of magnitude lower than Buenos
Aires coastal area.22 Excluding the 2001−2002 pulse, PCB
decline in Buenos Aires’ fish is on the high end of the 2−11%·
year−1 range observed for most locations.4,8,29,30 After the
2001−2002 pulse, the 3-fold increase in PCB decline is
comparable only to the extreme 1975−2010 PCB reduction
reported for Lake Michigan salmon.31 Contrasted scenarios are
observed in the time trends relative to management practices.
Fish data show paradoxical results, with a 3-fold PCB increase
after their banning in 2001−2002 with a subsequent rapid
decline. On the other hand, construction of the wastewater
treatment plant effectively contributed to an average 5-fold
reduction of trap TOC with lower dry weight PCB contents.
Figure 4 presents the average composition of PCBs in fish,

settling material, and sediment core and its annually averaged
variability. Overall, hexachlorobiphenyls predominate in all
three compartments but especially in the remote sediment
core, which shows a heavier PCB signature (6CB, 36% ± 3.4%
in fish, 35% ± 9.9% in trap material, and 49% ± 7.8% in core).
Fish and settling material from Buenos Aires’ coast display a
similar and lighter PCB pattern, evidence of the impact of
fresher discharges enriched in less persistent tri-, tetra-, and
pentachlorobiphenyls, with a more homogeneous signature in
fish. Pentachlorobiphenyls are the next most abundant
congeners in fish and settling material, followed by
heptachlorobiphenyls (5CB, 23% ± 5.0% and 24% ± 3.1%;
7CB, 21% ± 4.7% and 18% ± 6.2%, respectively), but this
trend is reversed in the sediment core (5CB, 17% ± 7.7%;
7CB, 21% ± 4.4%). Tri- and tetrachlorobiphenyls are variable
in all three environmental compartments (3−4CB, 15% ±
4.6% in fish, 17% ± 6.8% in traps, and 3.5% ± 5.3% in core)
with higher proportions during peak PCB concentrations. This
is especially evident in fish, where they account for 27% of total
PCBs with the highest 3−4/6 chlorobiphenyl ratio (∼1)
during the December 2001 PCB peak, denoting the input of
fresh residues. Afterward, tri- and tetrachlorobiphenyls
decrease progressively in fish until 2005−2006 (to 10−11%),
with a steeper decline of the 3−4/6 CB ratio (to ∼0.3). This
pattern is also evident in the sediment core, which shows
increased proportions of 3−4 CBs from 1972 to 1982 (10−
15% of total PCBs) with higher 3−4/6 chlorobiphenyl ratios
(∼0.4) during the period of maximum PCB usage in
Argentina, whereas lower chlorinated congeners almost
disappear in upper sediment layers, which show very low 3−
4/6 CB ratios (<0.1). The relationship of lighter PCB
signatures during peak contamination episodes and progressive
attenuation of the signal due to increased volatility and
degradation of lighter chlorinated PCBs has also been reported
for Swedish lakes.9 Settling material shows variable PCB
composition with an apparent increase in lower chlorinated
congeners and highest 3−4/6 chlorobiphenyl ratios between
2006 and 2013, with intermediate concentrations.
Summing up, PCB time trends in detritivorous fish and

settling material from the polluted Buenos Aires coastal area
and a more pristine, dated sediment core from the mixohaline

Figure 3. Temporal trends of total PCBs (log basis) in fish, settling
particles (traps), and sediment core compared with usage and high-
emission scenarios and management milestones (HWL, hazardous
residue law, 1991; Sign, Stockholm Convention signature, 2001; Ban,
PCB banning, 2002; Rat, Stockholm Convention ratification, 2005;
NIP, National Implementation Plan, 2007; WWTP, wastewater
treatment plant, 2014). Annual percentage decreases are indicated
by the slopes of the log−linear trends.

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outer Rió de la Plata estuary provide rare and valuable
evidence of consistent, exponentially decreasing trends over
time in southern South America. Temporal patterns showed
peak maxima associated with Argentina’s period of maximum
PCB usage in 1973−1980 in the longer time series represented
by the sediment core and pulse discharges related to PCB
banning in 2001−2002 in the fish, with a lighter signature
enriched in less persistent tri- and tetrachlorobiphenyls. The
log−linear PCB time trends in all three compartments
compare well with those reported for the Northern hemisphere
with an annual decrease of 2−5% for sediments and 2−11% for
fish. A higher PCB decline is observed for settling material
compared to the core and especially for fish after the 2001
pulse, which showed a rapid 21%·year−1 reduction until 2006−
2007.

■ ASSOCIATED CONTENT
*S Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.est.8b04403.

One table comparing PCB time trends in sediments and
fish from different environments (PDF)

■ AUTHOR INFORMATION

Corresponding Author
*E-mail: colombo@fcnym.unlp.edu.ar.

ORCID
Juan Carlos Colombo: 0000-0001-7881-6577
Notes
The authors declare no competing financial interest.

■ ACKNOWLEDGMENTS
This work was supported by the Argentinean National
Scientific and Technical Research Council (CONICET),
Agency of Scientific and Technical Promotion (ANPCyT,
FONCyT), the Buenos Aires Scientific Research Commission
(CIC), and the National University of La Plata (UNLP). The
manuscript benefited from the constructive criticism of three
anonymous reviewers; English language was improved by the
detailed reading of Manuel Colombo.

■ REFERENCES
(1) Stockholm Convention: Protecting human health and the
enviromnemt from persistent organic pollutants; United Nations
Environment Programme; chm.pops.int.
(2) Melwani, A. R.; Davis, J. A.; Gregorio, D.; Jin, J.; Stephenson,
M.; Maruya, K.; Crane, D.; Lauenstein, G. Mussel Watch Monitoring in
California: long-term trends in coastal contaminants and recommenda-
tions for future monitoring; SFEI Contribution 685; San Francisco
Estuary Institute, Richmond, CA, 2013; https://www.waterboards.ca.
gov/water_issues/programs/swamp/docs/mussel_watch/pdf1_msl_
lngtrm_trnd_2013.pdf.
(3) Swackhamer, D. L. Aquatic processes and systems in perspective
- The past, present, and future of the North American Great Lakes:
what lessons do they offer? J. Environ. Monit. 2005, 7, 540−544.
(4) Bhavsar, S. P.; Jackson, D. A.; Hayton, A.; Reiner, E. J.; Chen, T.;
Bodnar, J. Are PCB Levels in Fish from the Canadian Great Lakes Still
Declining? J. Great Lakes Res. 2007, 33, 592−605.
(5) Bentzen, E.; Mackay, D.; Hickie, B. E.; Lean, D. R. S. Temporal
trends of polychlorinated biphenyls (PCBs) in Lake Ontario fish and
invertebrates. Environ. Rev. 1999, 7, 203−223.
(6) Braune, B. M.; Outridge, P. M.; Fisk, A. T.; Muir, D. C. G.;
Helm, P. A.; Hobbs, K.; Hoekstra, P. F.; Kuzyk, Z. A.; Kwan, M.;
Letcher, R. J.; Lockhart, W. L.; Norstrom, R. J.; Stern, G. A.; Stirling,
I. Persistent organic pollutants and mercury in marine biota of the
Canadian Arctic: An overview of spatial and temporal trends. Sci.
Total Environ. 2005, 351−352, 4−56.
(7) Riget́, F.; Bignert, A.; Braune, B.; Stow, J.; Wilson, S. Temporal
trends of legacy POPs in Arctic biota, an update. Sci. Total Environ.
2010, 408, 2874−2884.
(8) Olsson, M.; Bignert, A.; Eckheĺl, J.; Jonsson, P. Comparison of
Temporal Trends (1940s−1990s) of DDT and PCB in Baltic
Sediment and Biota in Relation to Eutrophication. Ambio 2000, 29,
195−201.
(9) Nyberg, E.; Danielsson, S.; Eriksson, U.; Faxneld, S.; Miller, A.;
Bignert, A. Spatio-temporal trends of PCBs in the Swedish freshwater
environment 1981−2012. Ambio 2014, 43, 45−57.
(10) De Boer, J.; Dao, Q. T.; van Leeuwen, S. P. J.; Kotterman, M. J.
J.; Schobben, J. H. M. Thirty year monitoring of PCBs, organo-
chlorine pesticides and tetrabromodiphenylether in eel from The
Netherlands. Environ. Pollut. 2010, 158, 1228−1236.
(11) Gomez-Gutierrez, A.; Garnacho, E.; Bayona, J. M.; Albaiges, J.
Assessment of the Mediterranean sediments contamination by
persistent organic pollutants. Environ. Pollut. 2007, 148, 396−408.

Figure 4. (Top panel) Average PCB composition in fish, settling
material, and sediment core and annually averaged variability for
(second panel) fish, (third panel) settling material, and (bottom
panel) sediment core from the Rió de la Plata estuary. PCBs are
grouped by Cl contents in tri-tetra- (3−4CB), penta- (5CB), hexa-
(6CB), hepta- (7CB). and octa−decachlorobiphenyls (8−10 CB).
The lower/higher chlorinated 3−4/6 CB ratio is also shown.

Environmental Science & Technology Article

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Environ. Sci. Technol. XXXX, XXX, XXX−XXX

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http://pubs.acs.org/doi/abs/10.1021/acs.est.8b04403
http://pubs.acs.org/doi/suppl/10.1021/acs.est.8b04403/suppl_file/es8b04403_si_001.pdf
mailto:colombo@fcnym.unlp.edu.ar
http://orcid.org/0000-0001-7881-6577
http://chm.pops.int
https://www.waterboards.ca.gov/water_issues/programs/swamp/docs/mussel_watch/pdf1_msl_lngtrm_trnd_2013.pdf
https://www.waterboards.ca.gov/water_issues/programs/swamp/docs/mussel_watch/pdf1_msl_lngtrm_trnd_2013.pdf
https://www.waterboards.ca.gov/water_issues/programs/swamp/docs/mussel_watch/pdf1_msl_lngtrm_trnd_2013.pdf
http://dx.doi.org/10.1021/acs.est.8b04403


(12) Tanabe, S.; Iwata, H.; Tatsukawa, R. Global contamination by
persistent organochlorines and their ecotoxicological impact on
marine mammals. Sci. Total Environ. 1994, 154, 163−177.
(13) Barra, R.; Colombo, J. C.; Eguren, G.; Gamboa, N.; Jardim, W.
F.; Mendoza, G. Persistent organic pollutants (POPs) in Eastern and
western South American countries. Rev. Environ. Contam. Toxicol.
2006, 185, 1−33.
(14) Colombo, J. C.; Khalil, M. F.; Arnac, M.; Horth, A. C.;
Catoggio, J. A. Distribution of chlorinated pesticides and individual
polychlorinated biphenyls in biotic and abiotic compartments of the
Rió de la Plata, Argentina. Environ. Sci. Technol. 1990, 24, 498−505.
(15) Colombo, J. C.; Bilos, C.; Campanaro, M.; Presa, M. J. R.;
Catoggio, J. A. Bioaccumulation of polychlorinated biphenyls and
chlorinated pesticides by the Asiatic Clam Corbicula fluminea: its use
as sentinel organism in the Rió de la Plata estuary, Argentina. Environ.
Sci. Technol. 1995, 29, 914−927.
(16) Colombo, J. C.; Bilos, C.; Lenicov, M. R.; Colautti, D.;
Landoni, P.; Brochu, C. Detritivorous fish contamination in the Rió
de la Plata estuary. A critical accumulation pathway in the cycle of
anthropogenic compounds. Can. J. Fish. Aquat. Sci. 2000, 57, 1139−
1150.
(17) Colombo, J. C.; Cappelletti, N.; Migoya, M. C.; Speranza, E.
Bioaccumulation of anthropogenic contaminants by detritivorous fish
in the Rió de la Plata estuary: 2- Polychlorinated Biphenyls.
Chemosphere 2007, 69, 1253−1260.
(18) Colombo, J. C.; Cappelletti, N.; Williamson, M.; Migoya, M.
C.; Speranza, E.; Sericano, J.; Muir, D. C. G. Risk ranking of multiple-
POPs in detritivorous fish from the Rio de la Plata. Chemosphere
2011, 83, 882−889.
(19) Speranza, E. D.; Tatone, L. M.; Cappelletti, N.; Colombo, J. C.
Cost-benefit of feeding on anthropogenic organic matter: lipid
changes in a detritivorous fish (Prochilodus lineatus). Ichthyol. Res.
2013, 60, 334−342.
(20) Speranza, E. D.; Cappelletti, N.; Migoya, M. C.; Tatone, L. M.;
Colombo, J. C. Migratory behavior of a dominant detritivorous fish
(Prochilodus lineatus) evaluated by multivariate biochemical and
pollutant data in the Parana-́ Rió de la Plata Basin. J. Fish Biol. 2012,
81, 848−865.
(21) Colombo, J. C.; Cappelletti, N.; Barreda, A.; Migoya, M. C.;
Skorupka, C. N. Vertical fluxes and accumulation of PCBs in coastal
sediments of the Rió de la Plata estuary, Argentina. Chemosphere
2005, 61, 1345−1357.
(22) Colombo, J. C.; Cappelletti, N.; Speranza, E.; Migoya, M. C.;
Lasci, J.; Skorupka, C. N. Vertical fluxes and organic composition of
settling material from the sewage impacted Buenos Aires coastal area,
Argentina. Org. Geochem. 2007, 38, 1941−1952.
(23) Della Ceca, L.; Cappelletti, N.; Migoya, M. C.; Colombo, J. C.
PCDDs/PCDDFs in human breast milk from Argentina. Organo-
halogen Compd. 2015, 77, 198−201.
(24) Astoviza, M. J.; Cappelletti, N.; Bilos, C.; Migoya, M. C.;
Colombo, J. C. Airborne PCB patterns and urban scale in the
Southern Rió de la Plata Basin, Argentina. Sci. Total Environ. 2016,
572, 16−22.
(25) Schuerch, M.; Scholten, J.; Carretero, S.; García-Rodríguez, F.;
Kumbier, K.; Baechtiger, M.; Liebetrau, V. The effect of long-term
and decadal climate and hydrology variations on estuarine marsh
dynamics: an identifying case study from the Rió de la Plata.
Geomorphology 2016, 269, 122−132.
(26) Breivik, K.; Sweetman, A.; Pacyna, J. M.; Jones, K. C. Towards
a global historical emission inventory for selected PCB congeners - A
mass balance approach 1. Global production and consumption. Sci.
Total Environ. 2002, 290, 181−198.
(27) Espinach Ros, A.; Demonte, L. D.; Campana, M.; Trogolo, A.;
Domańico, A.; Cordiviola, E. Estimacioń de edades y crecimiento. In
Proyecto Evaluacioń del Recurso Sab́alo (Prochilodus lineatus) en el
Parana.́ Informe de los resultados de la segunda etapa - 2006−2007.
Secretariá de Agricultura, Ganaderiá, Pesca y Alimentos, Subsecretariá
de Pesca y Acuicultura, 2008; https://www.agroindustria.gob.ar/
sitio/areas/pesca_continental/informes/baja/_archivos//000000_

Informes%20del%20proyecto%20evaluaci%C3%B3n%20biol%C3%B3
gica%20y%20pesquera%20de%20especies%20de%20inter%
C 3%A 9 s % 2 0 d e p o r t i v o % 2 0 y% 2 0 c om e r c i a l / 0 6 0 0 0 0 -
Segundo%20informe%20del%20proyecto%20de%20evalua
ci%C3%B3n%20del%20recurso%20del%20s%C3%A1balo%20(2006-
2007).pdf.
(28) Jeremiason, J. D.; Eisenreich, S. J.; Baker, J. E.; Eadie, B. J. PCB
Decline in Settling Particles and Benthic Recycling of PCBs and PAHs
in Lake Superior. Environ. Sci. Technol. 1998, 32, 3249−3256.
(29) Szlinder-Richert, J.; Barska, I.; Mazerski, J.; Usydus, Z. PCBs in
fish from the southern Baltic Sea: Levels, bioaccumulation features,
and temporal trends during the period from 1997 to 2006.Mar. Pollut.
Bull. 2009, 58, 85−92.
(30) French, T. D.; Petro, S.; Reiner, E. J.; Bhavsar, S. P.; Jackson, D.
A. Thirty-Year Time Series of PCB Concentrations in a Small
Insectivorous Fish (Notropis Hudsonius): An Examination of Post-
1990 Trajectory Shifts in the Lower Great Lakes. Ecosystems 2011, 14,
415−429.
(31) Rasmussen, P. W.; Schrank, C.; Williams, M. C. W. Trends of
PCB concentrations in Lake Michigan coho and chinook salmon,
1975−2010. J. Great Lakes Res. 2014, 40, 748−754.

Environmental Science & Technology Article

DOI: 10.1021/acs.est.8b04403
Environ. Sci. Technol. XXXX, XXX, XXX−XXX

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