determine sediments accumulation rates, geochronology, and to study metals. Its activity decline exponentially with depth, and is inversely proportional to the sedimentation rate at non-impacted ecosystem. Dating of sediments, combined with chemical profile, allow the study of the impact events in coastal zones. In the present study, we have investigated the history of metals concentrations and sedimentation rates of recent sediments (100 years) in the Cariaco Gulf, Venezuela (Fig. 1), an important fishery area at the Caribbean Sea, with industrial, harbor, agricultural and urban activities (Fig. 2).

1. See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/277588051
HISTORICAL RECONSTRUCTION OF HEAVY
METAL CONCENTRATION IN THE GULF OF
CARIACO, VENEZUELA
CONFERENCE PAPER · JANUARY 2011
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1 AUTHOR:
William Senior
Universidad Estatal de la Península de Santa …
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2. HISTORICAL RECONSTRUCTION OF
HEAVY METAL CONCENTRATION IN
THE GULF OF CARIACO, VENEZUELA
López, F. M. 1, Senior, W. J. 1, Fermín, I. M. 1, Quejido, A. 2, Ruiz-
Fernández, A.C. 3, Sánchez-Cabeza, J. A. 2, Alonso-Hernández, C.
M. 4, Gómez-Mancebo, Ma. B. 2, Suárez, D.J 1.
1 Universidad de Oriente, Venezuela. 2 Centro de Investigaciones
Energéticas, Medioambientales y Tecnológicas (CIEMAT) Spain. 3
Universidad Autónoma de México (UNAM-ICMYL), México. 4 Centro
de Estudios Ambientales de Cienfuegos (CEAC), Cuba.
INTRODUCTION
210-Pb activity is an useful technique in environmental investigation, to
determine sediments accumulation rates, geochronology, and to study metals.
Its activity decline exponentially with depth, and is inversely proportional to the
sedimentation rate at non-impacted ecosystem. Dating of sediments, combined
with chemical profile, allow the study of the impact events in coastal zones.
In the present study, we have investigated the history of metals concentrations
and sedimentation rates of recent sediments (100 years) in the Cariaco Gulf,
Venezuela (Fig. 1), an important fishery area at the Caribbean Sea, with
industrial, harbor, agricultural and urban activities (Fig. 2).
Pb
µg/g
Years
1898-1974 1975-1997 1998-2008
6
6,5
7
7,5
8
8,5
9
Hg
µg/g
Years
1898-1974 1975-1997 1998-2008
25
35
45
55
65
75
85
(X 0,001)
Cu
µg/g
Years
1898-1974 1975-1997 1998-2008
5,6
6
6,4
6,8
7,2
7,6
Sedimentation Rate
g.cm-2.yr-1
Years
1898-1974 1975-1997 1998-2008
0
0,1
0,2
0,3
0,4
0,5
0,6
-0,7 -0,4 -0,1 0,2 0,5 0,8 1,1
Factor 1
-0,7
-0,3
0,1
0,5
0,9
Factor2
AsCa
Co
Cr
Cs
Cugcm_2yr_1
Hg
K
Mg
MnMo
Na
Ni
organiccarbon
P
Pb
Si
Silt
totalN
V
Zn
Al
RESULTS
Sedimentation rates and organic carbon obtained increases with time, which seems to be related to the changes in the land use. On the other hand the metals exhibit
three different distributions: i) increase of the levels of the metal to middle 70´s (Cu, Cr, Cs). ii) Decrease in in that same period (Hg). iii) elevation in the period 1975-
1997 and diminution as of 1998 (Co, Mn, Ni, Si, V). Factorial analysis demonstrated the association of the majority metals with the sedimentation rate, and
independence of grain size (90 % silt). Also, continental contribution were observed, represented by the relation Organic Carbon-P-Total Nitrogen.
METHOD
A sediment core was collected up to 30 m depth. Dating
technique is based on decay of 210-Pb, which was
measured from 210-Po by alpha spectrometry.
Sedimentation rates were calculated from 210-Pbxs profiles,
and using the CRS model (constant rate supply).
Metal concentration was obtained by FRX, and sediment
grain size for laser difractometer.
Additionally analyses of organic carbon and total nitrogen
were realised in an elementary analyzer.
-64.3 -64.2 -64.1 -64 -63.9 -63.8 -63.7
Longitud N (Grados)
10.45
10.5
10.55
10.6
10.65
LatitudW(Grados)
Mar Caribe
Golfo de Cariaco
60º70º80º90º100º
0º
10º
30º
40º
20º
Golfo de México
Mar Caribe
Venezuela
-64.3 -64.2 -64.1 -64 -63.9 -63.8 -63.7
Longitud N (Grados)
10.45
10.5
10.55
10.6
10.65
LatitudW(Grados)
Mar Caribe
Golfo de Cariaco
60º70º80º90º100º
0º
10º
30º
40º
20º
Golfo de México
Mar Caribe
Venezuela
60º70º80º90º100º
0º
10º
30º
40º
20º
Golfo de México
Mar Caribe
Venezuela
core
Figure 1. Cariaco Gulf, Venezuela
Figure 2. Cariaco Gulf, Venezuela
Coastal Zone
Figure 3. Sedimentation rate and heavy metal. Historical distribution in sediments
of Cariaco Gulf, Venezuela
Figure 4. Factor analysis for metal, organic carbon, nutrients and sedimentation
rate distribution in Cariaco Gulf, Venezuela.
CONCLUSIONS
Two processes were identified that have influence on the distribution of the studied
variables: (i) natural input with terrestrial material of Al, Co, Cr, Mg, Mn, Si, Zn, V,
and (ii) contribution of organic matter and nutrients, probably related to the
agricultural activity of the zone. Important increases of both processes and
sedimentation rate were observed in 1980's, due, probably, to changes in the
economic activities of the area. A slight diminution of the concentrations of Pb was
observed in 1998, due to restrictions in the gasoline commercialization with Pb.
Acknowledgements
This study was supported by Internationl Atomic Energy Agency (IAEA) (Regional Project RLA/7/012)
CEAC, Cuba
España
IAEAUNAM, México