Nahuel Francisco Schenone

Heavy metals and trace elements in muscle of silverside (Odontesthes bonariensis) and water from different environments (Argentina): aquatic pollution and consumption effect approach

The concentrations of As, Ag, B, Ba, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hg, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Rb, Sb, Se, Sn, Sr, Te, Ti, U, V and Zn were determined in water and silverside (Odontesthes bonariensis) muscle samples from four important commercial fishing sites (Argentina) by ICPMS. Trace element concentrations in water with well-documented human health effects were above the recommended maximum levels established by Argentinean and international guidelines for the aquatic biota protection in three sampling sites (e.g. As: 28.4-367 μg L(-1); Cd: 0.17-1.05 μg L(-1); Hg: 0.07-0.63 μg L(-1); Zn: 71.3-90.0 μg L(-1)). High concentrations of As, Hg and Pb (0.03-0.76; 0.03-0.42 and 0.04-0.19 mg kg(-1) wet weight, respectively) were found in silverside muscle. Fishing communities associated with contaminated environments are likely to have higher consumption rates and are thus more likely to be exposed to higher concentrations of the toxic elements (As, Hg and Pb).

Trace metal contents in water and sediments in Samborombón Bay wetland, Argentina

Samborombón Bay is the most extensive myxohaline wetland of Argentina. This Ramsar site is considered a priority area for the conservation of biodiversity in the country. Numerous rivers and channels that drain the Pampean plain, such as the Salado River and the channels Lower Salado, 15, 9, A, 1, and 2, cross this wetland and flow into Samborombón Bay. Trace metal concentration (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) in water and sediments were determined in low and high water periods. In the first case, contents were higher than the Guide Levels for the Protection of the Aquatic Biota (GLPAB) in most of the sampling stations. In high water period, only As and Zn were detected. Relevant physico-chemical parameters were analyzed by a principal component analysis (PCA). Trace metal concentrations in sediments suggest, as a whole, that this wetland has been so far exposed to low to moderate levels of anthropic influence. It must be emphasized however, that the presence of metals in both the water and sediments of this bay might have negative effects on the biota and on the regional trophic web.

The removal of fluoride from aqueous solution by a lateritic soil adsorption : kinetic and equilibrium studies

The use of natural sorbents to remove fluoride from drinking water is a promising alternative because of its low-cost and easy implementation. In this article, fluoride adsorption on a latosol soil from Misiones province (Argentina) was studied regarding kinetic and equilibrium aspects. Experiments were conducted in batch at room temperature under controlled conditions of pH 4-8) and ionic strength (1-10mM KNO3). Experimental data indicated that adsorption processes followed a PSO kinetic where initial rates have showed to be influenced by pH solution. The necessary time to reach an equilibrium state had resulted approximately 30min. Equilibrium adsorption studies were performed at pH 8 which is similar to the natural groundwater. For that, fluoride adsorption data were successfully adjusted to Dubinin-Ataskhov model determining that the fluoride adsorption onto soil particles mainly followed a physical mechanism with a removal capacity of 0.48mgg-1. Finally, a natural groundwater was tested with laterite obtaining a reduction close to 30% from initial concentration and without changing significantly the physicochemical properties of the natural water. Therefore, it was concluded that the use of lateritic soils for fluoride removal is very promising on a domestic scale.

Short spatial and temporal scale patterns of fish assemblages in a subtropical rainforest mountain stream

The fish fauna of a subtropical mountain stream in Argentina was surveyed for the first time. The abundance and occurrence of species were explored considering variation in hydrology, seasonality and the abiotic environment. We collected 221 individuals of 23 species from 10 families and four orders. Small sized species and small individuals dominated the fish fauna. The small characid Astyanax saguazu was the most conspicuous species. Hydrology, seasonal changes in water temperature and variation in water conductivity affected the abundance and distribution of fish. Hypobrycon maromba is recorded in Argentina for the first time.

Molecular and taxonomic characterisation of introduced specimens of Poecilia reticulata in the lower Paraguay River basin (Cyprinodontiformes: Poeciliidae)

Fil: Rosso, Juan Jose. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Fundacion Bosques Nativos Argentinos para la Biodiversidad; Argentina