Noemí R. Verrengia Guerrero

Trace metal levels in Prochilodus lineatus collected from the La Plata River, Argentina

Most of the industrial, urban and sewage discharges are released into the La Plata River, Argentina without any previous treatment. However, few works have investigated the extent of metal contamination. The aim of this study was to assess the levels of cadmium, copper, lead and zinc in liver and gills of adults Prochilodus lineatus collected from three sampling stations along the coast of the La Plata River: Berazategui, Berisso and Atalaya (from north to south). Samplings were performed during 2002 and 2004. Berazategui and Berisso were located nearby the main ducts that discharge the urban and domestic waste disposal from the cities of Buenos Aires and La Plata, respectively. The third station, Atalaya, was free of sewage discharges. Levels of cadmium and copper in liver were always higher than those found in gills. Instead, for lead and zinc, high levels were observed either in liver or gills, depending on the sampling station and the sampling period. In both tissues, the concentrations of metals did not differ significantly between male and female fish. In liver samples, the concentrations of cadmium, copper and zinc tended to increase from north to south. Instead, the levels of lead followed an opposite pattern. No clear tendencies were observed in gill samples. The data may be useful as reference levels of metal contaminants in P. lineatus, the most important fish species in the La Plata River system.

Tributyltin bioaccumulation and toxic effects in freshwater gastropods Pomacea canaliculata after a chronic exposure: field and laboratory studies

Freshwater samples and gastropod mollusks (Pomacea canaliculata) were collected at 5 sampling stations located along the lower Río de la Plata basin, Argentina, to assess the extent of tributyltin (TBT) contamination. Determined data revealed the presence of TBT and some of its breakdown products (dibutyltin: DBT, and monobutyltin: MBT) in all freshwater samples and also in soft tissues of P. canaliculata gastropods. Chronic bioassays (6 months) were performed using female gastropods that had been reared under laboratory conditions and exposed to a similar TBT concentration than the value determined in freshwater samples (1 µg L−1). The aims of this study were to evaluate the extent of TBT accumulation, the tissue distribution, and the effects on selected biomarkers (activity of superoxide dismutasa: SOD, activity of catalase: CAT, levels of total glutathione: t-GSH, lipid peroxidation, and activity of acetylcholinesterase: AChE). Gonads presented the highest accumulation, followed by the cephalopedal region, albumin gland, and finally hepatopancreas. Both metabolites, DBT and MBT, were also found. All exposed female animals presented development of a penis reflecting the potential of TBT as an endocrine disrupting chemical for this gastropod species. Results on the selected biomarkers confirmed additional adverse effects induced by TBT. An increase in CAT activity and changes in t-GSH levels are indicative of alterations on the cellular redox status. The inhibition of AChE could reflect signs of neurotoxicity. Altogether, these results reveal a negative impact on the health of this gastropod population.

Investigating Arsenic Bioavailability and Bioaccumulation by the Freshwater Oligochaete Lumbriculus variegatus

The complex and variable composition of natural sediments makes it difficult to predict the bioavailability and bioaccumulation of sediment-bound contaminants. Several approaches, including an experimental model using artificial particles as analogues for natural sediments, have been proposed to overcome this problem. For this work, we applied this experimental device to investigate the uptake and bioaccumulation of AsIII by the freshwater oligochaete Lumbriculus variegatus. Five different particle systems were selected, and particle–water partition coefficients for AsIII were calculated. The influence of different concentrations of commercial humic acids was also investigated, but this material had no effect on bioaccumulation. In the presence of particulate matter, the bioaccumulation of AsIII by the oligochaetes did not depend solely on the levels of chemical dissolved but also on the amount sorbed onto the particles and the strength of that binding. This study confirms that the use of artificial particles may be a suitable experimental model for understanding the possible interactions that may occur between contaminants and particulate matter. In addition, it was found that the most hydrophobic resin induced an increase in arsenic bioavailability, leading to the highest bioaccumulation to L. variegatus compared with animals that were exposed to water only.

Investigating the Uptake and Some Subcellular Effects of Manufactured GoethiteNanoparticles on Lumbriculus variegatus

Investigating the Uptake and Some Subcellular Effects of Manufactured Goethite Nanoparticles on Lumbriculus variegatus The aims of this work were: 1) to investigate whether the freshwater oligochaete Lumbriculus variegatus incorporates manufactured goethite nanoparticles (NPs) after an acute exposure; 2) to evaluate the influence of a solution of humic acids (HA) on the uptake of NPs; 3) to investigate the effects of these NPs on several biomarkers related to the generation of reactive oxygen species (ROS). NPs were analyzed by transmission electron microscopy. To evaluate the uptake, animals were exposed to 10 mg NPs L-1 for 48 h and then depurated for different periods (0;4;16, and 24 h). Iron concentrations were measured by atomic absorption spectrophotometry. Biomarker parameters were determined in oligochaetes exposed to a suspension containing 10 mg NPs L-1 for 48 h without depuration. Oligochaetes depurated for 4 h presented higher levels of Fe in their whole body tissues than control organisms. However, values returned to control levels when the oligochaetes were depurated for periods longer than 16 h, suggesting that organisms may transitorily incorporate the NPs in their digestive tract and/or superficially adsorbed them but they could not absorb the NPs. Exposures for periods longer than 48 h did not increase the Fe body burden. The presence of a 20 mg L-1 of humic acid solution prevented the NPs uptake. Several biomarker parameters related to the generation of reactive oxygen species were assessed. The activity of the enzyme superoxide dismutase and levels of total glutathione were higher in animals exposed to the NPs for 48 h than in controls. However, the catalase activity and the determination of the total scavenger capacity (TOSC assay) were not modified.The release of manufactured nanomaterials to the aquatic environment may elicit some subcellular responses even when the NPs are not absorbed by the organisms.