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4500-year-old mining pollution in Southwestern Spain: Long-Term implications for modern mining pollution


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The Tinto river drains the Rio Tinto mining district, which comprises the world's largest known massive sulfide deposits; these orebodies have been mined from the third millenium BC to the present. The Tinto river is strongly acidic (pH, 1.5-2.5); during flood events, it transports a sandy material, including abundant detrital pyrite grains. A core drilled in the Holocene sediments of the Tinto estuary allows for investigation of recent and historical mining pollution. Two anomalous horizons have been recognized (0-1.3 m; 3-4 m). Both are characterized by very high metal content (100 times over the background) and by the presence of abundant clastic pyrite grains. The metal association (Pb, Ba, As, Cu, Zn, Sn, Tl, Cd, Ag, Hg, Au) is typical of that of the Rio Tinto pyritic ore. The upper horizon corresponds to the modern mining activity; the lower horizon has been dated at 2530 BC ( 14C AMS calibrated age). We show here that active mining occurred early (Copper Age) in the Rio Tinto area, resulting in a water-shed-scale metal contamination. We also show that anthropogenic input of metals may be accumulated and immobilized during thousands of years in estuarine sediments.
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0361-0128/00/3055/655-8 $6.00 655
Mining activity is a major source of metal contamina-
tion by toxic metals released into surface waters. Re-
newed interest in the impact of mining followed the re-
cent accident at Aznalcollar, Spain. On April 25, 1998, a
tailings spill from the mine of Aznacollar, in the southern
Iberian pyrite belt, released about 7 ×106 m3of sulfide
sludge in a tributary of the Guadalquivir river (Van Geen
and Chase, 1998), which drains the Donana national
park, the most important wildlife reserve of UNESCO in
Europa (Fig. 1). The sulfide sludge contained a mixture
of acidic waters (pH, 2–3.5) and very fine sulfide mater-
ial (<30 µm) dominated by pyrite, with about 2 percent
Zn, 0.9 percent Pb, 0.6 percent As, 0.2 percent Cu (dry
material) and abundant traces of other toxic metals such
as Tl, Hg and Cd (Table 1). The flood wave was toxic for
plankton, benthos, fish, and crab populations in the
river. One week after the spill, extremely elevated Zn
concentrations (0.6–1.2%) were found in the river sedi-
ments downstream from the mine over a distance of 40
km (Van Geen and Chase, 1998).
There is much archeological evidence of ancient min-
ing in the Iberian pyrite belt; it is well known, for exam-
ple, that the Rio Tinto orebodies have been mined at
various times since the third millennium BC (Briard,
1976; Rothenberg and Blanco Freijero, 1980). The aim
of this study was to investigate the impact of ancient
mining, at a watershed-scale, and to compare ancient
mining contamination with modern mining release. This
should allow predictions of the long-term behavior of
modern metal-contaminated sediments in this area.
The Rio Tinto Watershed
The southern Iberian pyrite belt, which belongs to the
southern part of the Iberian Variscan orogenic belt, is
the largest repository of volcanogenic massive sulfide de-
posits in the world. The pyrite belt includes more than
80 known deposits that are hosted in a Late Visean vol-
cano-sedimentary sequence. These massive pyrite de-
posits contain (mined and reserves) about 32 Mt Zn, 13
Mt Cu and 11 Mt Pb (metal tonnages, Leistel et al.,
The Rio Tinto massive sulfide district is the biggest in
its class. The Rio Tinto district comprises more than 109
t of massive pyrite ore. These super-giant deposits have
abundant base metal sulfides (Zn, Cu, Pb) and associ-
ated trace metals (Cd, As, Tl, Sn, Hg, Ag and Au; Table
1). The deposits have also had an extensive mining his-
tory. The Rio Tinto deposit has been mined since the
Copper Age, then during Tartessian and Phoenician
times (1200–500 BC), with greatest amount of activity
taking place during the Roman period (Flores, 1981).
Mining started again in the last part of the nineteenth
century and has continued to the present. These succes-
sive mining activities, from the Copper Age until the
present day, have exploited outcropping and near-sur-
face pyritic orebodies, leaving wide volumes of pyrite-
rich waste rocks and mining wastes.
Acid mine drainage resulting from the oxidation of
pyrite is especially important in the Rio Tinto mining
district. The headwaters of the Tinto river are in the area
of intense mining, which includes wide stockpiles of
pyrite-rich wastes and retention ponds of acid mine
Hydrosciences, UMR CNRS-Université Montpellier 2, 34095, Montpellier, France
GIGC, Departamiento de Geología, Universidad Huelva, 21819 Huelva, Spain
Hydrosciences, UMR CNRS-Université Montpellier 2, 34095, Montpellier, France
The Tinto river drains the Rio Tinto mining district, which comprises the world’s largest known massive sul-
fide deposits; these orebodies have been mined from the third millenium BC to the present. The Tinto river is
strongly acidic (pH, 1.5–2.5); during flood events, it transports a sandy material, including abundant detrital
pyrite grains. A core drilled in the Holocene sediments of the Tinto estuary allows for investigation of recent
and historical mining pollution. Two anomalous horizons have been recognized (0–1.3 m; 3–4 m). Both are
characterized by very high metal content (100 times over the background) and by the presence of abundant
clastic pyrite grains. The metal association (Pb, Ba, As, Cu, Zn, Sn, Tl, Cd, Ag, Hg, Au) is typical of that of the
Rio Tinto pyritic ore. The upper horizon corresponds to the modern mining activity; the lower horizon has been
dated at 2530 BC (14C AMS calibrated age).
We show here that active mining occurred early (Copper Age) in the Rio Tinto area, resulting in a water-
shed-scale metal contamination. We also show that anthropogenic input of metals may be accumulated and im-
mobilized during thousands of years in estuarine sediments.
Economic Geology
Vol. 95, 2000, pp. 655–662
Corresponding author: e-mail,
drainage waters. The name of the Tinto river (“tinto ” means
“red wine” in Spanish) clearly refers to the uncommon
brown-red color of its waters.
The Tinto river, which is 90 km long, remains strongly
acidic (pH, 1.5–2.5) from its source zone, about 400 m elev,
down to its estuary in the Ria of Huelva (Fig. 1). Its red-col-
ored waters contain high sulfate and dissolved metal contents
(Nelson and Lamothe, 1993; Elbaz-Poulichet et al., 1999).
The mean discharge is relatively small—about 15 m3/s, rang-
ing from 1 to 100 m3/s depending on seasonal variations, in-
cluding dry periods and rainy periods with floods. The Tinto
river sediments are gray sands, including quartz and slate el-
ements and abundant detrital pyrite grains that are weakly
weathered and slightly rounded.
Methods and Materials
A core was drilled (lat. 37°18'16", long. 6°48'10"), down to
the bedrock, through the Holocene sediments of the upper
part of the Rio Tinto estuary (Fig. 1). This zone corresponds
today to a flood plain that is usually dry, being 1.15 m above
the mean high-water level. The core, 7 cm diameter, is about
15 m in length. Core recovery was relatively good (92%) and
the core material was only moderately disturbed and frag-
mented; consequently, there is no uncertainty in depth con-
trol. Core material was protected in a PVC sheath. It was
sawed longitudinally in four parts for lithological, geochemi-
cal, and dating studies, and the last part was kept as reference.
Lithology was studied both using optical microscopy and
scanning electronic microscopy to investigate the sulfide
phases. Twenty samples of core material (30–50 g dry mater-
ial) were selected for major and trace elements analysis (Fig.
Present sediments from the Tinto river were collected ran-
domly within the uppermost 5 cm. They were dried before
examination by SEM, then analyzed (30–50 g) for major and
trace elements. The sulfide sludge from Aznalcollar was col-
lected along the banks of the Guadiamar river one day after
the spill.
The geochemical analyses for major (including S, CO2,and
organic C) and trace elements (including Cl and Hg) were
done by X-RAL laboratories (Don Mills, Ontario, Canada)
and at the Montpellier University, using XRF (X-ray fluores-
cence), NAA (neutron activation analysis), ICP-MS (induc-
tively coupled plasma-mass spectrometry) and AA (Atomic
Absorption) spectrophotometry.
The SEM investigations were performed with a Hitachi S-
4500 instrument coupled with an energy-dispersive X-ray
spectrometer (EDS); detection limits were about 0,1 percent,
with a precision within 20 percent.
Activation mass spectrometry (AMS) radiocarbon dating
was performed by Beta Analytic, Inc. (Miami). The analyzed
sediment samples (35–75 g) contained enough organic carbon
(0.5–1%) to ensure accurate analysis and all analytical steps
went normally (graphitization and AMS radiocarbon count-
ing); a charcoal fragment (4.3 g) was picked for complemen-
tary analysis. The conventional 14C ages were calibrated to
calendar years using the Pretoria Calibration Procedure
based on tree-ring data as calibration curves (dendrocalibra-
tion); the calibrated ages are given BC ages with 95 percent
The 210Pb determinations were done on the uppermost 30
cm of the core in order to determine the chronology of pollu-
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Mining areas
drill hole
Rio Tinto
Mine Aznalcollar
Guadiamar river
Tinto river
Odiel river
Guadalquivir river
6° 206° 40
37° 20
37° 00
30 km
Fig. 1. Sketch map (southwest Spain) showing the location of the Rio
Tinto and of the Aznalcollar mining areas and the location of the core drilled
in the upper estuary of the Tinto river (Huelva ria).
TABLE 1. Metal Contents of the Two Anomalous Horizons of the Core and Comparizon with the Normal Estuarian Sediments of the Core
Zn Cu Pb As Cd Sn Ag Tl Hg Au Ba
Rio Tinto massive sulfide ore (avg)120,000 7,000 7,000 2,000 150 350 45 35 40 0.8 Unknown
Pyritic tailings of Aznalcollar (spill) 21,200 2,120 8,500 6,100 31 22 50 103 Unknown 0.06 70
Pyrite-rich sand from the Tinto river 3,200 950 1,200 3,900 57 20 14 24 12 0.07 2,900
Upper pyrite-rich sand horizon (core) 300 760 5,300 1,400 9 100 17 18 5.1 0.2 3,400
Lower pyrite-rich sand horizon (core) 240 400 2,500 900 6 45 10 12 3.0 0.1 1.600
Normal estuarian black mud (core) 67 24 7 12 <1 2 0.9 0.4 0.04 0.003 230
All values given in ppm
Metals concentrations in the sands from the upper part of the Tinto river, in Rio Tinto massive pyrite ore, and in pyrite sludge released from the Aznal-
collar spill are given for comparizon with the anomalous horizons of the core
1 Leistel et al, 1993
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Tl Cu
ppm (g/t)
110 100 1000
110 100 1000
ppm (g/t)
radiocarbon age
plant fragments
authigenic pyrite (pyritospheres)
detrital pyrite grains
1 ppm
1000 ppm = 0.1 %
FIG. 2. Description, age dates and metal concentrations of the core. The lithostratigraphic sequence corresponds to an
estuarine evolution, ending with an erosional hiatus (flood plain). The 14C AMS radiocarbon dates (given as calibrated BC
ages) agree with an Holocene transgressive cycle; the 210Pb data from the uppermost part indicate present sediments. Two
horizons show metal concentrations (ppm) that are two orders of magnitude over background. Both metal-contaminated
horizons include abundant clastic pyrite grains.
tion associated with modern mining (Davis et al., in press);
analyses were conducted at Florida State University by W.
Burnett and associates.
From bottom to top, the following materials are present in
the core (Fig. 2): (1) coarse detrital sediments (fluvial channel
and fluvial bar); (2) shelly and sandy black muds, including
shell-rich horizons with authigenic pyritic nodules (estuarine
accretion bodies); (3) muddy sands with shell fragments (es-
tuarine channel); (4) alternating yellow sands and dark green
muds (channel margins); and (5) yellow sands of the flood
plain at the top of the core. This uppermost horizon results
from flood deposits that may be strongly erosional, as sug-
gested by the lithologic break and the sharp discontinuity
with the underlying muddy horizon. Almost every year there
is a major flood from the Tinto river, eroding and/or deposit-
ing up to 50 cm of sandy material on the flood plain.
Presence of metal-rich horizons
The trace metal contents in the Holocene estuarine sedi-
ments (Fig. 2, Table 1) are similar to averaged continental
sediments (Taylor and McLennan, 1985). The highest con-
tents are in organic carbon-rich sediments containing diage-
netic pyrite (Fig. 3D) overgrowing plant debris or shell frag-
ments. Against this normal geochemical background two
remarkable horizons (0–1.3 m and 3–4 m) are characterized
by metal concentrations that are two orders of magnitude
higher than those of the other layers (Fig. 2). These horizons
contain 2,500 to 5,300 ppm Pb and 900 to 1,400 ppm As, re-
spectively. In both cases the same metal association is present,
composed of high Pb, Ba, As-Cu, Zn-Sn, Tl-Cd, Ag, Hg-Au,
in decreasing order of importance.
SEM observations (Fig. 3)
The two anomalous horizons are also remarkable for their
mineralogic composition. They consist mainly of light yellow
sands and silts, including abundant clastic pyrite grains (2–12
wt %). The pyrite grains are small and well sorted (20–50
µm); they correspond to angular fragments of subhedral
pyrite grains (Fig. 3A2) that have been only slightly rounded,
and which exhibit only rare dissolution pits and cracks. The
only oxidized material consists of ochre fragments in the silt
layers. EDS-SEM investigations suggest that galena is pre-
sent as small accessory grains (1–5 µm), partly included in
pyrite; rare gold inclusions (0.5 µm) are also present in pyrite.
The high barium content is clearly explained by the presence
of lamellar fragments of barite in the pyrite-rich sands. Cassi-
terite is present as small, perfectly euhedral crystals (10 µm),
explaining the high Sn contents (40–100 ppm Sn).
The lower horizon (0.5–1.2% organic carbon) contains
black plant fragments that often display woody cellular tex-
tures (Fig. 3C). These charcoal fragments are very small and
well sorted (0.1–1.2 mm). A few small globules (30–500 µm)
of vesicular glass, with smooth surfaces, are also present in
this horizon (Fig. 3B). EDS-SEM analysis suggests they con-
sist either of a Fe-Si glass, with traces of sulfur, or of a carbon-
iron material with small contents of copper and sulfur
(0.1–1%). These compositions, which differ from those of
natural vesicular glasses, such as lavas, are similar to those of
scorias and slags from metallurgical furnaces.
Dating results
The four 14C calibrated ages (BC) obtained are consistent
with the relative stratigraphic position of the analyzed sam-
ples (Fig. 2) : 6,000 ±140 yr for the base of the estuarine ac-
cretion bodies (12.5 m); 3,600 ±100 yr for the base of the es-
tuarine channel (7.5 m); 2,530 ±70 yr for the lower
metal-contaminated horizon (4 m) and 1,930 ±–55 yr for the
floor of the uppermost metal-contaminated horizon (1.3 m).
The 210Pb concentrations along the uppermost 30 cm of the
core (Davis et al., in press) are strikingly constant and rela-
tively high (8 ± –2 Bq/kg).
Evolution of the Holocene depositional environment
The lithostratigraphic sequence and the 14C ages corre-
spond fairly well to the Holocene transgression that started in
the Huelva area about 8,000 BC, filled up the estuary, and
ended with a stabilization of the sea level about 3,000 BC
(Borrego et al., 1999). The transgression is connected with a
deglacial sea-level rise (Mannion, 1997). From 14C radiodat-
ing, it appears the sedimentation rates of the estuarine sedi-
ments were between 1 and 7 mm/yr.
The two metal-contaminated horizons correspond to well-
sorted sandy flood deposits. The lower horizon results from
input of fluvial sands during a progradation stage in the estuar-
ine system; the overlying muddy and shelly horizon corresponds
to tidal sediments along channel margins. The upper horizon re-
sults from discontinuous input of fluvial sands over the surface of
the flood plain—which is usually dry—during seasonal floods.
Geochemical and mineralogical evidence for
metal contaminations from the Rio Tinto mineralization
The metals present in these two anomalous horizons reflect
fairly well those of the Rio Tinto sulfide ore, including base
and trace metals (Table 1). For example, the relatively high
Au content of the pyritic horizons (0.1–0.2 ppm) is in agree-
ment with the presence of gold in the Rio Tinto mineraliza-
tion (0.5–1.5 ppm); SEM observations reveal that gold inclu-
sions are present in the detrital pyrite grains. The abundance
of barium, and the presence of barite detrital grains, may be
explained by the fact that barite is a common gangue mineral
of the sulfide ores. The relatively high Sn concentrations and
the presence of cassiterite grains are in agreement with the
presence of cassiterite in the Rio Tinto ore. The arsenic con-
centrations in detrital pyrite grains, which have been picked
up from the core, range from 1 to 2 percent As, explaining the
high arsenic contents of the pyrite-rich horizons.
However, the order of abundance is not exactly the same.
For example, Zn and Cd concentrations are low compared to
the other base metals (Pb, Cu) in the pyrite-rich sands. This
may be explained either by the fact that Zn and Cd are rela-
tively more easily soluble in surface waters or that sphalerite
was not abundant in the transported pyritic material.
The pyrite grains from the two metal-contaminated hori-
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20 µm
20 µm
20 µm
20 µm
20 µm
20 µm
50 µm
20 µm
20 µm
A1 A2
B1 B2
A- Clastic pyrite
B- Slags
C- Wood fragment D- Authigenic pyrite
actual 4,500 yr old
FIG. 3. Scanning electronic microscopic (SEM) images. A. (A1) Clastic pyrite grains, displaying subhedral to angular
shapes, from the present sands of the Tinto river. (A2) Pyrite grains from the lower metal-contaminated horizon of the core
(dated at 2530 ±70 BC) are similar in shape and size to the clastic pyrite grains from the present sands of the Tinto river (A1);
note the presence of a barite fragment. B. (B1) Slag droplet from the lower metal-contaminated horizon; its composition is
that of a Si-Fe glass with minor contents of sulfur (0.1–1% S). (B2) Vesiculated slag fragment, from the lower metal-conta-
minated horizon, showing a C-Fe-O composition with minor contents of copper, sulfur and silica (0.1–1%). The analytical
data were performed using an energy-dispersive X-ray spectrometer (EDS). C. Wood fragments (charcoal) are relatively
abundant (1%) in the lower metal-contaminated horizon (dated at 2530 ±70 BC) D. Authigenic pyrite crystallizing as agre-
gates of pyritospheres in shell or plant fragments from the lower part of the core (black muddy estuarine sediments); note
the difference in shape and size compared to the detrital pyrites (A1, A2).
actual A - Clastic pyrite 4,500 yr old
B - Slags
C - Wood fragment D - Authigenic pyrite
zons are angular clastic pyrite grains (Fig. 3A2) that may be
slightly rounded and corroded. They are clearly different in
shape and size from the authigenic pyrite crystals and the
spherulitic agregates of pyrite (Fig. 3D) that are present in
the shelly black mud horizons of the core (Fig. 2). The only
obvious source of pyrite in the catchment zone of the Tinto
river is the Rio Tinto mining area. There are outcropping
massive pyrite orebodies, with subhedral pyrite grains similar
in shape and size to those of the anomalous horizons of the
core, and huge stockpiles of pyrite-rich tailings and wastes
from modern mining activity. The pyrite grains are very abun-
dant in the present surface sands collected along the bed and
the banks of of the Tinto river: in the immediate vicinity of
the mine area, there are pyritic sands containing up to 60 wt
percent pyrite, and downstream from the coring location, the
estuarian sediments still contain 1 to 10 wt percent pyrite.
The pyrite-rich sediments of the Tinto river display very high
concentrations of toxic metals (0.5% As, 0.5% Pb, 0.3% Zn,
0.2% Cu; Table 1). These high metal contents can be ascribed
to pyrite (this is the case for As) or to discrete Pb-Zn-Cu sul-
fide phases associated with or included in pyrite. The clastic
pyrite grains from the surface sands along the Tinto river are
similar in shape and size (Fig. 3A1) to those from the metal-
contaminated horizons at depth in the core, providing evi-
dence that pyrite grains may be transported by the Tinto river
from the Rio Tinto mining zone to the estuarine zone. Con-
sidering the hydric flow during seasonal flood events and the
average geometry of the Tinto river, the rate of sediment
transport can be roughly calculated: the time for the trans-
portation of the pyrite grains—from the source zone to the
estuary—may be from 15 to 45 hours. Consequently, the
pyrite grains may be deposited very quickly in the estuarine
sediments without having suffered any weathering during
their transportation. The same shape and size of pyrite grains
characterize the pyritic sludge released within a few hours by
the Aznalcollar tailings spill in the Donana national park, 40
km downsream (Fig. 1).
These geochemical and mineralogical observations are the
first indication that the two anomalous horizons correspond
to input of pyrite-bearing and metal-rich sands resulting from
mining activity in the Rio Tinto source region.
Age of the upper metal-contaminated horizon
The impact of intensive modern mining activity that started
130 yr ago has been clearly recorded in shelf surface sedi-
ments of the Gulf of Cadiz (Van Geen et al., 1997). The upper
metal-contaminated horizon of the core may correspond to
this modern mining. The uppermost 30 cm of the core have
high and constant 210Pb concentrations; this means that the
upper part of the upper contaminated horizon was deposited
a short time ago, probably during recent flood events. How-
ever, considering the discontinuous sedimentary and/or ero-
sional history of the flood plain of the upper estuary, we are
not sure that this 1.3-m-thick pyrite-rich horizon corresponds
in its entirety to the modern mining period. A 14C AMS ra-
diocarbon dating was performed on an ochre layer, just below
the upper horizon (Fig. 2). The ochre has an age of 1930 ±50
BC (calibrated age). This is consistent with the chronostratig-
raphy of the core but indicates that the upper part of the
Holocene sequence has been eroded before or during the de-
position of the upper, metal-contaminated horizon.
Age of the lower metal-contaminated horizon
The lower horizon has been dated at 2530 ±70 BC (AMS
14C calibrated age). The analyzed sample (pyrite-rich sand)
contains 1 percent organic carbon. Tiny black fragments of
charcoal are the only possible organic carbon source; there
are no shell fragments or carbonate (<0.1%). Dating of a sin-
gle charcoal material, picked up 10 cm below the first dated
sample, has given a 500-yr older age (3015 ±70 yr BC), which
could indicate derivation from a 500-yr-old tree (“old wood
effect”) or material derived from an older layer. Although the
ancients may have been burning old wood in their furnaces,
this is unlikely to have significantly affected the observed 14C
stratigraphy of the core. The logical progression of 14C dates
down the core suggests that resedimentation processes in the
estuary have not resulted in major disturbances in in the
These ages correspond to the Copper Age in the western
Mediterranean area and confirm that active mining started
early in the Rio Tinto district.
The presence of small droplets and fragments of likely slags
(vesicular glasses with Fe-Si or C-Fe compositions and up to
0.5% copper and sulfur) in the lower horizon (Fig. 3B), is
compelling evidence for contemporaneous metallurgical ac-
tivity. In the same way, the presence of tiny and well-sorted
charcoal fragments may reflect the common use of small
charcoal fragments during metallurgical treatments.
Copper Age mining and metallurgy in the Rio Tinto area
The oldest findings indicate that metallurgical activities in
the region date from 2700 BC (Rothenberg and Blanco Frei-
jero, 1980). Except for a few metal tools in some graves and
scarce traces of mining excavations and ovens, there has been
little evidence of important Copper Age mining activity in the
Rio Tinto district. However, the Almerian Copper Age civi-
lization (3000–2200 BC) is well known in eastern Andalusia,
Spain, for the important development of copper mining and
metallurgy (i.e., in the fortified site of Los Millares, Almeria).
Similar activity was likely taking place in western Andalusia,
notably in the Rio Tinto area (Briard, 1976). Unfortunately,
the subsequent mining periods probably erased most of the
Chalcolitic mining and metallurgical works. The Romans
started their mining activity from the Tartessian-Phoenician
works, and active mining today recovers gold (1–1.5 ppm)
from the Roman mining wastes.
1. We show here a new record of watershed-scale impact of
early mining, over a distance of about 100 km. A 4,500-yr-old
(2530 BC) metal contamination, caused by Copper Age min-
ing, has existed in southern Spain. Notwithstanding the re-
cent accident at Aznalcollar, it is possible that long-term re-
lease of metals from ancient mining operations that have not
received the benefit of modern remediation may be a more
serious problem than the impact of much larger, modern-day
2. Anthropogenic input of metals may remain immobilized
for millennia in estuarine sediments. Most metals can be
locked as sulfides in estuarine sediments where anoxic condi-
0361-0128/98/000/000-00 $6.00 660
tions (organic matter, fast sedimentation rates) can enhance
the formation of authigenic sulfides and/or prevent the oxida-
tion of detrital sulfides. Considering the recent spill of pyrite
tailings at Aznalcollar, these findings may have implications
for modern mining. Part of the sulfide-rich material recently
discharged into the Guadiamar river (Fig. 1) might remain
stored in the Guadalquivir estuarine sediments for millenia.
Precautions must be taken to prevent any change in the estu-
arine system, particularly oxidation (by draining, dredging, or
erosion) of these potentially highly toxic or deleterious mate-
3. Sulfide grains can be quickly transported far away from
their source zone, during flood events, without having suf-
fered weathering. This kind of metal transportation in surface
waters, often neglected, can be of great importance, locally.
This work was funded by the European Commission
(DGXII) under contract TOROS (Tinto Odiel Ocean River
System), Environment and Climate Programme (ELOISE);
for more information see the website <
We are grateful to Lex van Geen and to an anonymous
member of the Editorial Board, who helped us considerably
to improve this manuscript.
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... basin (Rio Tinto district) going back to the Roman period (Leblanc et al., 2000). Similar studies on the Rio Tinto River estuarine floodplain sediments (Borrego et al., 2004), and terrace deposits (Cáceres et al., 2013), verify the power of overbank sediments to depict the palaeo-geochemistry of the upstream catchment basin. ...
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This Manual presents, a comprehensive overview of the standardised methods to be employed across the land surface of the Earth to map the distribution of chemical elements in rock, soil, sediment and water
... Mining activities, closely linked to the exploitation of natural resources, have occurred in several regions of the world since classical times (Radivojević et al. 2019). In South Iberia, for instance, pollution from anthropogenic sources caused by the mining of metal sulfide ores has occurred since at least 3250-3000 BCE (the Copper Age; Emslie et al. 2015Emslie et al. , 2019Leblanc et al. 2000;Rovira 2002). By that time, northern Iberian communities had undergone a crucial historical trajectory regarding mining activity (e.g., de Blas 1996de Blas , 2005Martínez-Cortizas et al. 2002, 2012. ...
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We analyze potential Late Holocene metal contamination along a sediment core collected in the distal zone of Ria de Vigo (North Spain). Statistical treatment of the dataset based on a multiproxy approach enabled us to identify and disentangle factors influencing the depositional processes and the preservation of the records of this activity in the area over the last ≈3000 years bp. Some layers of the analyzed core have significant enrichment in Cu and a moderate enrichment in Ag, Mo, As, Sb, S, Zn, Ni, Sn, Cd, Cr, Co, Pb, and Li. The enrichment of these elements in some layers of this core may be related to mining activities that have taken place since classical times in the region. Successive phases of pollution were identified along the core KSGX24 related to the Late Bronze Age (≈3000–2450 years bp), Iron Age (≈2450–1850 years bp), Roman times (≈1850–1550 years bp), Middle Ages (≈1250–500 years bp), and industrial and modern (≈250–0 years bp) anthropic activities. The protection of the Cies Islands, the erosive and transport capacity of the rivers in the region, oscillations of the oceanographic and climatic regime, atmospheric contamination, and diagenetic sedimentary processes might have contributed to the accumulation and preservation of this record in the distal region of the Ria de Vigo. The studied core shows that the industrial and preindustrial anthropic impacts caused an environmental liability and contributed to the presence of moderate to heavy pollution of various metals in surface and subsurface sediment layers in the distal sector of the Ria de Vigo, which could be a hazard to biota.
... Acid Mine drainage (AMD) during the mining process will increase the acidity of surrounding rivers and lakes, which has a great impact on the survival of aquatic organisms. In 2000, a study by Leblanc, M. et al. [33] found that the Tinto River region in southwestern Spain was heavily polluted by mining operations. The Tinto River which is called the "Red River" by locals has a pH of 1.5 to 2.5, is highly acidic and heavily contaminated with heavy metals. ...
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With the development of technology, the concepts of “green” and “sustainable” have gradually been popularized in all walks of life. With the continuous development of the world mining industry, the efficiency of resource development in various countries has been improved, but mining activities and production will undoubtedly bring many environmental pollution problems. As a mining power, China is one of the first countries to put forward the concept of “green mining”. Over the years, as people emphasize safety and environmental protection, green mining technology has become the hot topic. At the same time, groundwater pollution caused by mining has become the focus of China’s “green mine construction”: with the continuous development of mining, mining activities and production will also undoubtedly bring significant environmental pollution. The environmental pollution of the mined area has a vital influence on the surrounding environment. The pollutants mainly come from mining operations and production of the mineral processing industry, including process wastewater, gas waste, smelting slag, etc., which are all acidic. Acid mine drainage (AMD) occurs in the process of mining production, due to the structure of minerals and the complex reactions between oxygen and minerals, and results in heavy metal ions leaching into groundwater. Once the groundwater is polluted, it will slowly flow to the surrounding area, resulting in the migration and diffusion of pollutants in the groundwater, affecting the surrounding rivers, farmland, and drinking water for residents. In recent years, environmental damage caused by groundwater pollution from underground mines in Shijiazhuang, China, and Selangor, Malaysia, has had a negative impact on rivers, farmland, and human health. At the same time, the paper introduces many key technologies of green mine construction, such as the backfill mining method. In cooperation with China Road & Bridge Corporation, this paper also introduces the progress in the reuse of mining waste, especially the use of mining waste as aggregate to prepare concrete materials for road and bridge construction. This information article introduces the development status of green mine construction in China and briefly reviews the key technologies of green mine construction in China.
... The results obtained in this work from the sediments of the La Fontanilla cove (Tinto Estuary, SW Spain) show that the REE concentration distribution can be related to the depositional environment; nevertheless, the input of rare earths into sediments may have been modified by anthropogenic activities, such as mining/industrial inputs that led to favorable upward environmental conditions, i.e., to the dissolution of phases carrying REE (pyrite and other ore deposits). The old marshes, ebb-tide channels, lagoons, and freshwater ponds are constituted by clayey silts that present the highest REE contents, particularly around 4.5 kyr BP in the three cores and near the surface in Cores B and C. It should be noted that high contents of Cu, Pb, and As have also been detected in nearby cores studied by [95] and correlated with the first mining activities, as well as the recent mining and industrial wastes (1850-2000); in both polluted horizons, important percentages of pyrite (2-12%) were found. ...
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The Tinto and Odiel rivers (SW Spain) drain from a vast sulfide mining district and join at a 20-km-long estuary that enters the Atlantic Ocean. In this work, the contents of rare earth elements (REE) and fractionation in Neogene–Holocene sediment cores from La Fontanilla cove (Tinto estuary) were studied. The sediments were collected from a depth of 18 m at different distances from the recent river flow and were analyzed for new information on the temporal development of the REE load in the sediment column. Results show that the å REE is higher in the finer sediments and during periods of mining activity from prehistoric to recent times. Marine influence appears to increase the light REE (LREE) relative to the heavy REE (HREE). The REE patterns of these estuarine sediments show convex curvatures in the MREE relative to the LREE and HREE, indicating the presence of acid-mixing processes between the fluvial waters affected by acid mine drainage (AMD) and seawater, as well as the precipitation of poorly crystalline mineral phases. Significant positive Eu anomalies were found in ebb-tide channels and marsh deposits, which can reflect the mineralogical composition and/or a strong localized salinity gradient combined with organic matter degradation. Sedimentological characteristics of the deposits appear to play the main role in accumulation and fractionation of the REE.
... Copper (Cu) is a metal naturally present mainly in the forms of sulphides, oxides, and carbides and to a lesser extent can also exist in pure metal form. Copper has been used by humans for thousands of years, but the mining and processing of its ores can be a significant source of environmental contamination [61,62]. On one hand, copper, from a biological point of view, is one of the so-called essential elements; it is involved in the function of many enzymes and in the catalysis of significant enzymatic processes such as cellular respiration or the formation of neurotransmitters [63]. ...
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This study summarizes all the results of sampling campaigns carried out between 2018 and 2021 in 13 settlements of the Tumanyan and Stepanavan regions of Lori Province. The survey was conducted with the cooperation of three non-profit organizations: Arnika, Centre for Community Mobilization and Support (CCMS), and EcoLur. The individual surveys generated a large dataset covering a wide range of sampled matrices including environmental samples of soil, sediment, and household dust, and food samples such as domestic chicken eggs, fish, homemade cheese, and crops grown by local private farmers were collected from these localities. Biological samples such as urine, hair, and nails were also taken from local residents. The Tumanyan and Stepanavan regions are characterized by rich mineral reserves. For many years, copper, molybdenum, gold, silver, and other precious and non-ferrous metals have been mined and continue to be mined here, which implies their increased content in environmental components. However, in addition to the natural high background, these elements are actively distributed in the environment by the mining and metallurgical industries. Such industrial practices affect the surrounding environment and the living conditions of local people who are directly exposed to metals for a long time. As a consequence, the adverse change in the living environment is felt by people either directly on their health or on the quality of the farming environment. As part of this study, analyses were carried out for the presence of heavy metals such as copper (Cu), zinc (Zn), lead (Pb), arsenic (As), cadmium (Cd), and others, as well as for the presence of persistent organic pollutants (POPs). The aim of this study was to map the occurrence and distribution of heavy metals and POPs in components in the vicinity of the potential polluting points of the Tumanyan and Stepanavan regions, and to determine the burden of contaminants on the local population in a territory with a population of 40,000.
... This mining region run from the northwest of Seville (Spain) to the Lousal area near Grandola (Portugal) (Sáez et al. 1996;Tornos et al. 2009;Inverno et al. 2015). From antiquity (about 3000 BC), IPB has been exploited for its deposits of copper, gold, silver, and other metals (Leblanc et al. 2000;Olías and Nieto 2015). More than 80 mines are distributed in the region, although most of them were abandoned (Grande 2016). ...
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Odiel river basin is located in the Iberian Pyritic Belt (IPB) and mostly of its tributaries are severely affected by acid mine drainage (AMD). It is originated when pyritic minerals from abandoned mines, especially mineral residues from waste rock dams, get in contact with air and water. Fifteen sampling points were chosen to analyze interactions between diatom communities and water hydrogeochemistry. Considering physicochemical characteristics, sampling points were assigned as highly, moderately, and unpolluted by AMD. No correlation was observed between ecological diversity indexes and physico-chemical parameters. However, a dependency relationship between diatom species distribution and specific pH, conductivity, redox potential, sulfate, and metal concentrations was observed. Cluster analysis based on Pearson correlation and rs values of the non-parametric Spearman correlation allowed to identify Pinnularia acidophila, Pinnularia subcapitata var. elongata, and Eunotia exigua as the main bioindicators of AMD-polluted Odiel streams. Finally, a principal component analysis led to associate the most abundant diatoms species to specific physico-chemical parameters.
... Медь (Cu) присутствует в природе в основном в виде сульфидов, оксидов и карбидов и, в меньшей степени, в чистой форме металла. Медь использовалась людьми в течение тысяч лет, в то время как добыча и переработка ее руд может быть значительным источником загрязнения окружающей среды [60,61]. ...
Technical Report
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В исследовании обобщены результаты кампаний по отбору и анализу проб, проведенных в период с 2018 по 2021 год в 13 населенных пунктах Туманянского и Степанаванского регионов Лорийской области. Это исследование было проведено некоммерческими организациями - чешской природоохранной НПО “Арника”, НПО “Центр общинной мобилизации и содействия” из Алаверди и Информационной НПО “ЭкоЛур” из Еревана. В результате исследований был получен большой набор данных, охватывающий широкий спектр анализируемых матриц. Пробы включали компоненты окружающей среды: почвы, донных отложений, бытовой пыли, а также пробы продуктов питания, таких как куриные яйца, рыба, домашний сыр и сельскохозяйственные культуры, выращенные местными фермерами. В дополнение, у местных жителей были отобраны биологические образцы, такие как моча, волосы и ногти. Цель исследования состояла в том, чтобы составить карту встречаемости и распределения тяжелых металлов и СОЗ в компонентах окружающей среды в окрестностях потенциальных загрязняющих точек Туманянского и Степанаванского регионов, и определить степень нагрузки загрязняющих веществ на местных жителей на территории с 40000-ым населением.
... The following discussion for the Spanish and Portuguese Río Tinto River is based on publications by Ariza (1998), Chacon-Baca et al. (2021), Grande et al. (2014), Leblanc et al. (2000), Nieto et al. (2007), Olías et al. (2020), Olías and Nieto (2015), Olías et al. (2004), Ruiz Cánovas et al. (2019, Sainz and Loredo (2005), Salkield (1987), and Torre et al. (2014). ...
This chapter describes case studies about pollution sources, tailings dam failures and potential remediation options in rivers/streams. These case studies are supported with images of mining influenced water courses. All the sites described in the case studies are in mining areas of outstanding importance to human's mining history or point to mining accidents of global importance. Each section uses existing literature to present the stresses and negative effects to the aquatic ecosystem, and potential solutions to resolve or remove these. It can be shown that some mine sites can be remediated with existing technology, while others will remain changed for a very long time, if not permanently.
The Iberian Pyrite Belt (IPB), in the southwest of Europe, is one of the largest sulfide metallogenetic provinces in the world which is characterized by high levels of AMD pollution in a large extent of its fluvial network. The main objective of this work is the characterization of the processes controlling the water chemistry as well as the evolution and natural attenuation processes of waters from two different AMD producing focus, with a common paragenesis (San Telmo and El Carpio mines). Both joining into the same fluvial network. The present work allowed to comply the main objective, detecting the existence of the natural attenuation process for these two mining watercourses, which are globally controlled by different chemical and biological processes and individually affected by dissolution, hydrolysis, precipitation, co-precipitation processes, being the biological indicators dominated by algae from Euglena and Klebsormidium genera very important in the natural attenuation phenomena.
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In the mining-impacted Rio Tinto, Spain, Fe-cycling microorganisms influence the transport of heavy metals (HMs) into the Atlantic Ocean. However, it remains largely unknown how spatial and temporal hydrogeochemical gradients along the Rio Tinto shape the composition of Fe-cycling microbial communities and how this in turn affects HM mobility. Using a combination of DNA- and RNA-based 16S rRNA (gene) amplicon sequencing and hydrogeochemical analyses, we explored the impact of pH, Fe(III), Fe(II) and Cl ⁻ on Fe-cycling microorganisms. We showed that the water column at the acidic (pH 2.2) middle course of the river was colonized by Fe(II) oxidizers affiliating with Acidithiobacillus and Leptospirillum. At the upper estuary, daily fluctuations of pH (2.7-3.7) and Cl ⁻ (6.9-16.6 g/L) contributed to the establishment of a unique microbial community, including Fe(II) oxidizers belonging to Acidihalobacter , Marinobacter and Mariprofundus identified at this site. Furthermore, DNA- and RNA-based profiles of the benthic community suggested that acidophilic and neutrophilic Fe(II) oxidizers (e.g., Acidihalobacter , Marinobacter and Mariprofundus ), Fe(III) reducers (e.g., Thermoanaerobaculum ) and sulfate-reducing bacteria drive the Fe cycle in the estuarine sediments. RNA-based relative abundances of Leptospirillum at the middle course as well as abundances of Acidohalobacter and Mariprofundus at the upper estuary were higher, compared to DNA-based results, suggesting potentially higher level of activity of these taxa. Based on our findings, we propose a model of how tidal water affects the composition and activity of the Fe-cycling taxa, playing an important role in the transport of HMs (e.g., As, Cd, Cr and Pb) along the Rio Tinto. Importance The estuary of the Rio Tinto is a unique environment in which extremely acidic, heavy metal- and especially iron-rich river water is mixed with seawater. Due to the mixing events, the estuarine water is characterized by a low pH, almost sea water salinity and high concentrations of bioavailable iron. The unusual hydrogeochemistry maintains unique microbial communities in the estuarine water and in the sediment. These communities include halotolerant iron-oxidizing microorganisms which typically inhabit acidic saline environments and marine iron-oxidizing microorganisms, which, in opposite, are not typically found in acidic environments. Furthermore, highly saline estuarine water favored the prosperity of acidophilic heterotrophs, typically inhabiting brackish and saline environments. The Rio Tinto estuarine sediment harbored a diverse microbial community with both, acidophilic and neutrophilic members that can mediate the iron cycle, and in turn, can directly impact the mobility and transport of heavy metals in the Rio Tinto estuary.
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 Mining of massive sulfide deposits in southwestern Spain extending back to the Copper and Bronze Ages has resulted in the pollution of the Rio Tinto fluvial-estuarine complex, the site of Columbus' departure for the New World in 1492. Additional sources of potential pollution include the large industrial complex at Huelva near the lower portion of the estuary. Extensive analysis of surface sediment samples and cores has established that there are no geographic trends in the distribution of the pollutants, which include Cu, Fe, Pb, Zn, Ti, Ba, Cr, V and Co. These data have, however, demonstrated that tidal flux within the estuary carries phosphorus and perhaps other elements from the industrial complex at Huelva to the tidal limit of the system, several kilometers upstream from the discharge site. Radiometric analysis of short cores shows that sedimentation rates over at least the past couple of centuries have been about 0.3 cm/year. These data and that from a single deep core demonstrate that the estuary was polluted from mining activity long before the large-scale operations began in the late nineteenth century.
Presents a broad-based synopsis of how natural and cultural agents have transformed the Earth's surface over the past 3 million years. Two main parts cover firstly temporal aspects of environmental change: the Quaternary, the evolution of modern humans, animal domestication and the spread of agriculture; and secondly, changes over the last 200 years due to industrial development and agriculture and more recently, changes due to tourism, recreation and biotechnology. There are 9 chapters: environmental change: agents, processes and the Quaternary; environmental change in the late- and post-glacial periods; prehistoric communities as agents of environmental change; environmental change in the historic period; post-1700 industrialisation; impact of agriculture in the developed world; impact of agriculture in the developing world; forestry, recreation, tourism, sport and biotechnology; and conclusion and prospects. -M.Dean
A metal-enriched seawater plume entering the western Mediterranean Sea through the Strait of Gibraltar originates 300 km to the west in the Rio Tinto estuary of southwestern Spain. Mining of Rio Tinto ore, one of the largest metal-rich sulfide deposits in the world, started well before Roman times. Contemporary Rio Tinto waters draining the region are highly acidic (pH 2.5) with dissolved cadmium, zinc, and copper concentrations 105-106 times higher than in uncontaminated surface water of the Gulf of Cadiz. Two dated sediment cores from the Spanish continental shelf show that metal inputs to the region increased with the onset of intensive mining activities during the second half of the 19th century. Although the impact of mining may have decreased over the past few decades, the Tinto river and estuary remain highly contaminated.
The retaining wall of a tailings reservoir collapsed at a zinc mine in Spain last spring, releasing into the watershed possibly nearly as much zinc as the mine produces annually. The accident happened April 25,1998, at the Los Frailes mine near Aznalcollar in southern Spain, sending ˜5 x 106m3 of acid sludge into the Guadiamar River. Based on a suite of water and river bank sediment samples collected downstream of the spill on May 1-3, 1998, an estimated 40,000 to 120,000 tons of Zn was added to the watershed. This is comparable to the annual production capacity of the mine of 125,000 tons. While the scale of the accident was certainly very large, an equivalent amount of Zn has been reaching the adjacent Tinto-Odiel estuary every 1-2 years as a result of mining since the middle of the 19th century. Emergency dikes were built shortly after the accident to prevent contamination of Donana National Park, an important wildlife reserve 40 km to the south of the mine. The composition of samples collected north of the park suggest this diversion was effective.
This book describes the composition of the present upper crust, and deals with possible compositions for the total crust and the inferred composition of the lower crust. The question of the uniformity of crustal composition throughout geological time is discussed. It describes the Archean crust and models for crustal evolution in Archean and Post-Archean time. The rate of growth of the crust through time is assessed, and the effects of the extraction of the crust on mantle compositions. The question of early pre-geological crusts on the Earth is discussed and comparisons are given with crusts on the Moon, Mercury, Mars, Venus and the Galilean Satellites.
A metal-enriched seawater plume entering the western Mediterranean Sea through the Strait of Gibraltar originates 300 km to the west in the Rio Tinto estuary of southwestern Spain. Mining of Rio Tinto ore, one of the largest metal-rich sulfide deposits in the world, started well before Roman times. Contemporary Rio Tinto waters draining the region are highly acidic (pH 2.5) with dissolved cadmium, zinc, and copper concentrations 10^5–10^6 times higher than in uncontaminated surface water of the Gulf of Cadiz. Two dated sediment cores from the Spanish continental shelf show that metal inputs to the region increased with the onset of intensive mining activities during the second half of the 19th century. Although the impact of mining may have decreased over the past few decades, the Tinto river and estuary remain highly contaminated.
The Tinto and Odiel rivers drain 100 km from the Rio Tinto sulphide mining district, and join at a 20-km long estuary entering the Atlantic Ocean. A reconnaissance study of heavy metal anomalies in channel sand and overbank mud of the river and estuary by semi-quantitative emission dc-arc spectrographic analysis shows the following upstream to downstream ranges in ppm (μg g−1): As 3,000 to Rio Tinto sulphide lode sources (Pb, Cu, Zn) and industrial activities within the estuary (Fe, Cr, Ti). Because heavy metal contamination of Tinto-Odiel river sediment reaches or exceeds the highest levels encountered in other river sediments of Spain and Europe, a detailed analysis of metals in water and suspended sediment throughout the system, and epidemiological analysis of heavy metal effects in humans is appropriate.
Nutrient (nitrate, phosphate, silica) and dissolved metal (Al, Cu, As, Cd, Ni, Zn, Fe, U) distributions were studied in the mixing zones of the Tinto and Odiel rivers which drain the South Iberian pyrite belt. Phosphate distribution is strongly influenced by discharges from the fertiliser industry, especially in the Tinto mixing zone. The increase of silica content in this zone is related to a release of biogenic silica from diatoms. Nitrate concentrations which are influenced by urban and industrial effluents showed an important maximum in the early stages of mixing in the Tinto (as do the metals). Compared to the Odiel river, the metal concentrations in the Tinto river reached higher values in relation to more intensive mining activities. Dissolved Fe, Mn, Al, Cu, Cd and Zn concentrations were correlated in the mixing zones of both rivers. This suggests that they have the same source and are subjected to the same controlling processes in the estuary. A maximum concentration for these metals was observed in the early stage of mixing in the Tinto and reflects a decrease of redox in a low pH (<3) environment. Downstream in the Odiel system, metals showed a slight removal. Dissolved uranium, present at a low level (0.05 μmol l−1) in the rivers, is introduced by the phosphate fertiliser industry in the estuary and trapped in sedimentation areas. As a consequence, waters of the Gulf of Cadiz have a U content similar to that of the open seawater.
Six estuarine facies were distinguished recording the Holocene history of sea level rise relating according to the start and development of the Holocene transgression which flooded the coast of Huelva: Facies 2 (gravels), Facies 3 (grey clayey silts), Facies 5 (well sorted sands), Facies 4 (silty sands), Facies 5 (black clayey silts), and Facies 6 (red muds). This group overlies Neogene sediments (Facies 1). Three faunal assemblages (Open bay (OB), Central estuary (CE), and Wave domination (WD)) including remains of macrofauna, foraminifers and ostracods plus depositional features, are identified in a sedimentological log constructed from a borehole with a continuous core, sunk in the central basin of the Odiel River estuary, Huela coast, SW. Spain. The OB assemblage requires shallow and protected zones controlled by low energy tidal currents; the CE assemblage is located within an intertidal zone, where reworked marine forms of foraminifers, ostracods and scattered macrofauna co-exist with small estuarine foraminifers and ostracods; the WD assemblage comprises tests of marine macrofauna with fractured shells plus large marine foraminifers and estuarine ostracods. During the first stage of continuous sea level rise (8720±260 BP to 5390±155 BP), estuarine accretion, high energy tidal currents and wave action took place successively, allowing the development of the OB, CE and WD assemblages. The second stage (5390±155 BP to Present), with a stabilized sea level, comprised a vertical decrease of energy, with tidal currents favouring deposition in shallow tidal channels and marsh zones, leading to less energetic CE assemblages within the estuarine central basin. High sediment supply resulted in deposition during this stage, which shows a regressive nature.