Humberto González

Mercury pollution caused by a chlor-alkali plant

Since the beginning of the last decade, a chlor-alkali plant operates in Sagua la Grande, in the central part of Cuba. The factor is equipped with a treatment system for trapping Hg in the waste water, which did not always function efficiently. During 1985–1988, a first evaluatian of the environmental impact by Hg was made. Analyses of a terrestrial plant (Mimosa pudica), soils, sediments and aquatic organisms, taken from a dam upstream, that atmospheric pollution by Hg is only restricted to the factory and its surrounding. Nevertheless, the liquid wastes discharged to Sagua la Grande River, have affected aquatic systems downstream up to the estuarine zone of the river mouth. This is confirmed by the examination of core and surface sediment samples, suspended matter, awnaquatic plant (water hyacinth, Eichhornia crassipes) and a sea urchin (Lytechinus variegatus). Different control measures have now limited the Hg discharges and should bring a progressive recuperation of the affected area.

Water Hyacinth as Indicator of Heavy Metal Pollution in the Tropics.

The water hyacinth (Eichhornia crassipes) is a common aquatic plant in many tropical countries. Its ability absorb nutrients and other elements from the water has made it possible to use it for water purification purposes. Eichhornia, especially stems and leaves, have been successfully used as indicators of heavy metal pollution in tropical countries. The uptake of heavy metals in this plant is stronger in the roots than in the floating shoots. Metallothionein-like compounds have been found from roots of this species after cadmium exposure. The purpose of this investigation was to study the possibilities of using roots of water hyacinth as a biological indicator of metal pollution in tropical aquatic ecosystems.

The effect of nickel mining and metallurgical activities on the distribution of heavy metals in Levisa Bay, Cuba

Abstract The distribution of Ni, Co, Fe, Mn, Cu, Pb and Zn was investigated in surface and core sediment samples and i n the leaves of the red mangrove ( Rhizophora mangle ) from Levisa Bay, an area affected by nickel mining and metallurgical activities. The results revealed that these activities have seriously polluted the sediments, especially by Ni. Fe, Co and Mn, with concentrations decreasing with increasing distance from discharge sources. The concentrations of Fe (0.64-22.66%) and Co. Mn and Ni (7.7–324, 125–2957 and 69–4764 μ/g, respectively) were up to two orders of magnitude greater than those of non-polluted coastal areas in Cuba. Rhizophora mangle was shown to be a useful bioindicator of heavy metal pollution in the studied ecosystem.

Heavy Metals in Littoral Deposits Off Havana City, Cuba

Abstract The content of Al, Cd, Co, Cu, Fe, Hg, Mn, Ni, Pb, Zn, C org and organic matter was investigated in sediment samples taken in the littoral zone off Havana City. the results revealed three areas affected by contamination: (a) Chivo Beach with a submarine sewage outfall, (b) the mouth of the Havana Bay and (c) the estuarine area of the Almendares River. the normalization of the heavy metals contents with respect to aluminium and organic matter combined with multivariate statistical methods was found valuable for a proper interpretation of the analytical results.

Impact of nickel mining and metallurgical activities on the distribution of heavy metals in sediments of Levisa, Cabonico and Nipe Bays, Cuba

At MayarÕ zone, northeast Cuba, important lateritic deposits have been exploited since 1943. The mineral is used as raw material in a nickel-processing plant which discharges its untreated solid and liquid wastes into Levisa Bay. Similarly to the adjacent Nipe and Cabonico bays, fluvial currents from the mining areas convey a significant mineral load into this bay. To assess the environmental impact caused by the mining and the metallurgical activities, the distribution of Ni, Co, Fe, Mn, Cu, Pb and Zn was investigated in surface and core sediment samples. Uni- and multivariate statistical methods as well as different indices and pollutant factors were used to interpret results. These revealed significant environmental impacts in some areas of the three bays with high concentrations of Ni, Co, Fe and Mn, whose values are up to two orders of magnitude greater than the zone baseline levels. The metal concentrations decreased with increasing distance from discharges. A comparison with other Cuban bays and coastal zones, confirmed that the main source of metal pollution in these three bays was not urban and industrial activities, but lateritic mining and metallurgy.

Removal of Mercury from Polluted Waters by the Water Hyacinth (Eichhornia crassipes)

Abstract The uptake of mercury by water hyacinth (Eichhornia crassipes) was studied in an outdoor experiment for 25 days at different metal concentrations. the removal of mercury from the water and uptake by plants was very effective during the first hours and decreased rapidly thereafter. the uptake of mercury was directly proportional to the initial concentration in the water. the highest concentrations were found in plant roots. According to the results, water hyacinth could be used for treatment of mercurial waste waters.

Heavy Metals in Macroalgae of Havana's Northern Littoral, Cuba

Abstract Copper, iron, lead, manganese, and zinc contents were determined in various phyla of macroalgae typical of the rocky mesolittoral zone of Cuba and widely distributed in the Caribbean Region. the samples were collected in different zones along the shores of Havana City which are more or less influenced by anthropogenic activities. Differences in metal contents were observed due to seasonal variations and differences between sampling sites. of the analyzed species, only one brown alga, Padina vickersiae is considered as a suitable candidate for the monitoring of metal contamination.

Heavy Metals in Sediments and Oysters From Bluefields Bay, Nicaragua

Abstract The distribution of trace metals (Co, Cu, Fe, Mn, Ni, Pb and Zn) was investigated during a year (1994-95) in surface and core sediment samples and in the oyster (Crassotrea rhizophorae) from Bluefields Bay, Nicaragua. the aim was to assess the arthropogenic impact of potential pollutant sources, mainly Bluefields City, since domestic waste waters are discharged directly or by infiltration to the bay. Lyophilised samples were submitted to different acid digestion methods and analysed by flame atomic absorption spectrophotometry. the results showed highest contents for copper, lead and zinc near Bluefields City, with an increase in the affected area in the rainy season that is generated by greater city run off. Metal contents in oysters do not show the same distribution pattern than in sediments and were similar to those from other areas without reflecting pollution levels.