Jorge Eduardo Marcovecchio

Tissue distribution of heavy metals in small cetaceans from the Southwestern Atlantic Ocean

Abstract Tissue distribution of heavy metals (total mercury, cadmium, zinc and copper) were studied in specimens of Bottlenose Dolphin (Tursiops gephyreus), Franciscana Dolphin (Pontoporia blainvillei) and Pigmy Sperm Whale (Kogia breviceps) stranded in SW Atlantic beaches in Argentina. Heavy metal determinations were carried out by atomic absorption spectrophotometry. Liver is the most important Hg, Zn, and Cu accumulator organ in the studied specimens, while kidney is so for Cd. The importance of the trophic habits and ecological characteristics of each species related to corresponding heavy metal concentrations was emphasized, as well as the animal age vs. pollutant contents relationship. Based on these results the suitability of using these small cetaceans species as ‘heavy metals bioindicators’ in the considered environment was discussed.

Distribution and Geochemical Partitioning of Heavy Metals in Sediments of the Bahía Blanca Estuary, Argentina

Abstract A long-term study programme has evaluated heavy metals in the Bahía Blanca estuary, considering occurrence, concentration and distribution in the estuarine sediments, as well as their corresponding geochemical partitioning in the <62 µm grain size fraction of the sediment. Total concentrations of heavy metals (Cd, Zn, Cu, Cr, Pb, Fe) have been determined through flameless atomic absorption spectrophotometry (AAS). Geochemical partitioning of these metals was determined following a sequential extraction technique. Furthermore, heavy metal distribution was studied against organic matter concentration within the sediments. The results allow the characterization of the spatial distribution of the metals, together with their accumulation areas and potential sources. Bahía Blanca estuarine sediments have low to medium heavy metal concentrations. The geochemical partitioning indicated that many bioavailable species occur within the system, including those of highly toxic elements such as cadmium. Moreover, a theoretical scheme of transference of these metals to other compartments within the system was proposed. Finally, the environmental status of the estuary was addressed within the described framework.

Determination of heavy metal concentrations in biota of Bahia Blanca, Argentina

Abstract Total mercury, cadmium and zinc in the muscles of 19 species of marine organisms (fish and crustaceans) from the Bahia Blanca Estuary, Argentina, were determined for the period 1985–1986. In the lower organisms, total mercury values were not higher than international standards for human consumption, but the levels in the top predators exceeded these standards. Cadmium concentrations were very low at all trophic levels. The zinc contents were the standards accepted as suitable for human consumption. The bioaccumulation and biomagnification processes for total mercury through the analyzed trophic web were verified, while for cadmium and zinc, only the bioaccumulation process was detected. Some of the organisms in this ecosystem appear to be good bioindicators of trace metal pollution, and can be used for future evaluations of the status of a particular evironment.

Metal accumulation in tissues of sharks from the Bahía Blanca estuary, Argentina

Abstract Total mercury, cadmium, and zinc accumulation was studied in muscle and liver of three species of shark from the Bahia Blanca estuary, Argentina. The mercury concentrations were similar in both muscle (range: 0·77–2·99 μg/g) and liver (0·79–2·26 μg/g) of the analyzed species. Concentrations of cadmium and zinc were higher in liver than in muscle. The frequency distributions of metal concentrations were found to be log-normal. The metal concentrations increased proportionally to the total length of the sharks. Significant differences—attributable to location in the estuary—in metal concentrations were not found. Dietary differences among species of shark seemed to be the most important causes for differences in their metal concentrations.

Environmental contamination and marine mammals in coastal waters from Argentina : an overview

Environmental contamination become an increasing global problem. Different scientific strategies have been developed in order to assess the impact of pollutants on marine ecosystems. The distribution of toxic contaminants in tissues of different marine mammal species--both cetaceans and pinnipeds--has been studied in many ecosystems, as well as several related ecological processes, like pollutant accumulation or transfer through the food web. A research program directed towards evaluating the occurrence of pollutants in marine mammals from the coastal waters of Argentina (southwestern Atlantic Ocean) has been developed since 1985, and includes the study of heavy metal contents in stranded or incidentally caught animals. The marine mammal species studied during this period were: the seals Otaria flavescens and Arctocephalus australis, and small cetaceans Tursiops gephyreus, Pontoporia blainvillei, Kogia breviceps and Ziphius cavirostris. In most of the cases, high contents of heavy metals (total mercury, cadmium, zinc, and copper) have been recorded. Moreover, liver showed the maximum capability for accumulation of heavy metals in all studied species. The biological and ecological characteristics of each species of the above-mentioned marine mammals (feeding habits, age, migratory pathways, or sex) contributed to the understanding of the metal sources. Considering the results as obtained during the study period it can be assumed that: (1) The global distribution of toxic contaminants also affects the southwestern Atlantic Ocean ecosystems, and (2) Marine mammals could be appropriate bioindicator species in order to assess this kind of environmental problem.

Dissolved Nutrient Availability during Winter Diatom Bloom in a Turbid and Shallow Estuary (Bahía Blanca, Argentina)

Abstract The inner zone of Bahía Blanca Estuary is a shallow, well-mixed, highly turbid, and nutrient-rich temperate ecosystem. The phytoplankton annual cycle is characterized by a recurrent winter/early-spring diatom bloom. From May to August 2002 a research program aimed to describe the potential relations between the dynamics of phytoplankton and nutrients was carried out. Phytoplankton composition, abundance, chlorophyll a (Chl a), and dissolved inorganic nutrients (nitrate, nitrite, ammonium, phosphate, and silicate) were measured. The species involved were classified in blooming (including Thalassiosira spp. and Chaetoceros spp.) and nonblooming species (including other diatoms and dinoflagellates). The results show: (1) a prebloom period, which includes low biomass values and a strong decrease of NO3−; (2) an initial bloom period characterized by high diatom abundance and Chl a, a marked dominance of Thalassiosira curviseriata, and a strong decrease of NH4+; (3) an intermediate bloom period of high abundance, codominance of blooming species, and a strong decrease of PO43−; and (4) a final bloom period with a decrease in abundance of blooming species and a general nutrient recovery. Thalassiosira curviseriata seems to be a species associated with high nutrient stock and low light intensity. Its growth, mainly concurrent with DIN decrease, was related to new production in this area. The obtained data suggest that low phosphate concentrations, more than DIN and silicates, contributed to the diatom bloom collapse. According to our results, this high production during winter can be explained as a net growth of phytoplankton because of a successful low light- and temperature-acclimated species, possibly favored by low predation and high nutrient availability.

Heavy metal concentrations in litteral sediments from the Beagle Channel, Tierra del Fuego, Argentina

For the first time the concentration of trace metals (Fe, Pb, Cu, Zn, Cd and total Hg) of sediments from the coastal zone of the Beagle Channel (Tierra del Fuego, in Southern Argentina) were measured. Atomic absorption spectrophotometry was utilized in order to determine the metal contents. The level of metals as observed in the sediments was recognized as the natural background, even though the use of normalization of lead, copper, and zinc to iron allowed the identification of the main sources of metal pollution for this environment. In order to develop future environmental monitoring programmes for the area of Ushuaia city and the Beagle Channel, the present results need to be considered.

Distribution of Heavy Metals in Surface Sediments from an Antarctic Marine Ecosystem

The concentrations of lead, cadmium, copper,chromium, iron, manganese and zinc in surfacesediments collected from Potter Cove, in the 25de Mayo Island (King George Island), Antarctica, andits drainage basin, were measured by atomic absorptionspectroscopy. The obtained results were use todetermine the areal and vertical distribution of themetals of in the Cove and potential sources of thesemetals to this environment. The geochemical datasuggest that most of the metals found in Potter Coveconstitute a redistribution of autochthonous materialswithin the ecosystem. Therefore, the metalconcentrations can be considered to be present atnatural background levels in surface sediments.

Cadmium, zinc and total mercury levels in the tissues of several fish species from La Plata river estuary, Argentina

A survey of the concentrations of heavy metals — cadmium, zinc and total mercury — in the tissues of fifteen fish species from Samborombón Bay, La Plata river estuary, in Argentina, has been carried out. Liver appeared to be the main organ accumulating cadmium and zinc, while both liver and muscle showed a similar ability for accumulating mercury. The bioaccumulation process was verified for the three metals analyzed, even though low concentrations have been determined. The biomagnification process of the metals studied was not verified in this environment. The highest metal concentrations were recorded in Mugil liza, and particulate matter and sediments — which are closely related to its trophic and ecological habits — seemed to be the main source of metals for this species. Both Micropogonias furnieri and Mugil liza were recognized as possible indicator species for future monitoring programmes for heavy metals in Samborombón Bay. Considering the present results, this area of La Plata river estuary is characterized as a non-polluted environment.

Bio-magnification of total mercury in Bahia Blanca estuary shark

Les grands predateurs tels que Mustelus schmitti semblent etre de bons indicateurs biologiques de la pollution