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This study explores a century-long sedimentary record of Hg and Pb pollution in the Sagua estuary of Cuba using 210Pb and 137Cs chronology. The research delves into pollution sources, sediment quality, and economic impacts on contamination levels, revealing significant anthropogenic inputs and the influence of industrial and economic developments from 1920 to 1980. The findings highlight the need for further investigations on mercury distribution in edible organisms to assess risks to local populations.
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“To predict the future of coastal areas is necesary to know how was it in past”
One century sedimentary record of Hg and Pb pollution in the Sagua estuary (Cuba) derived from 210Pb and 137Cs chronology Díaz-Asencio M. Alonso-Hernández C.M., Bolanos-Álvarez Y., Gómez-Batista M. , Morabito R., Hernández-Albernas J.I., Eriksson M., Sanchez-Cabeza J.A. Centro de Estudio Ambientales de Cienfuegos, Cienfuegos, Cuba. ENEA-C.R.E. Casaccia, PROT-CHIM, Roma, Italy. Centro de Investigaciones y Servicios Ambientales, Villa Clara, Cuba. IAEA Marine Environment Laboratories, Monaco.
Pollution sources Hg Pb Urbanwaste Dum 1972 Hg Alacranes Dam Chlor-alkali plant
Chlor-alkali plant 1979 Hg Mercury cell
Sampling Bahía de Santa Clara (15 m)
High-resolution gamma spectrometry Grain size Mercury analysis X-Ray Fluorescence (XRF) SPECTOR X-LAB PRO 2000 system
210Pb Accumulation rate: 0.17 ± 0.04 g cm-2y -1 (0.52 ± 0.13 cm y-1) 137Cs Accumulation rate 0.18 ± 0.07 g cm-2 y-1 (0.52 ± 0.09 cm y-1)
Pb (µg.g-1) This period coincides with a strong economic contraction in Cuba Pb pollution Based onEnrichment Factor (EF): EF=(Ms/Als)/(Mb/Alb) where M and Al represent the trace metal and aluminium concentrations, respectively; and, the subscripts s and b refer to sample and background values.
1988 The sediment quality of Sagua la Grande estuary suggests the presence of a significant contamination Total Hg (µg g-1) Hg (ppm)
Conclusions • The observed sedimentation rate was 0.171 ± 0.04 g cm-2 year-1, corresponding to a sediment accumulation rate of 0.52 ± 0.13 cm year-1. The 137Cs profile corroborated these estimates. • The Hg (concentrations up to 2.7 µg g-1) and Pb (concentrations up to 22 µg g-1) depth profiles showed important anthropogenic inputs to the coastal environment. The incomplete treatment of the residual from the chlor-alkali plant and the increment of Sagua la Grande city population are the main human activities that determine the time evolution of Hg and Pb in these sediments. • The observed Pb fluxes to sediments may reflect the overall development of Cuba. While industrial and economical expansion was continuous in the 1920-1980 period, a certain economical contraction was observed in the 90s, in good agreement with the collapse of the soviet economy and the commercial embargo to the country. • The present study showed high mercury contamination in sediments of Sagua la Grande estuary. Further studies on the uptake and distribution of Hg in edible organisms will be necessary for evaluating the risk for the local populations.
