Elisangela de Andrade Passos

Metal fractionation in sediments of the Sergipe River, northeast, Brazil

The sequential extraction procedure proposed by the European Community Bureau of Reference (BCR) was applied for the fractionation of Cd, Cr, Cu, Ni, Pb and Zn in sediments from the Sergipe Estuary, Brazil. The method showed satisfactory recoveries, detection limits and standard deviations for trace metals determinations in sediment samples. Cd was the metal with the greatest percentage in the exchangeable fraction. Pb and Ni were present mainly in the reducible and oxidizable fractions. Cr, Cu and Zn were predominantly associated with the residual fraction. The order of mobility of metals extracted was Pb > Cd > Ni > Cu > Cr > Zn. According to the risk assessment code (RAC), the sediments showed low to medium risk for all metals.

Metals and acid volatile sulfide in sediment cores from the Sergipe River Estuary, Northeast, Brazil

Acid volatile sulfide (AVS), simultaneously extracted metals (SEM) and metals were studied in sediment cores from the Sergipe River Estuary, Brazil. AVS and SEM concentrations were, in general, higher in the core sediments from areas which receive a higher anthropic contribution due to urban pollution. In these cores, the sulfide seemed to be the main connection for the metals. In the core obtained from the area of major marine influence, the most important binding phases for the metals seemed to be associated with organic matter and carbonates. The AVS profiles allow identification of two types of sedimentation processes in the estuary. In all cores SEM/AVS ratios were much lower than 1.

USE OF METABOLISM TO EVALUATE THE SUBLETHAL TOXICITY OF MERCURY ON FARFANTEPANEUS BRASILIENSIS LARVAE (LATREILLE 1817, CRUSTACEAN)

Abstract Penaeid shrimp are important resources for worldwide fisheries and aquaculture. In Brazil, Farfantepenaeus brasiliensis, is an important commercially exploited species and an ideal animal for studying the impairment caused by the effects of heavy metals that are often detected in coastal areas. The main purpose of this study is to detect the acute toxicity of mercury to F. brasiliensis larvae, and to investigate its effects on oxygen consumption and ammonium excretion, which have not been carried out in this species before. We examined the acute toxicity Hg to F. brasiliensis larvae revealed at 24, 48, 72 and 96-h of exposure and the medium lethal concentration (LC50) values obtained were of 0.13 mg L−1; 0.054 mg L−1; 0.047 mg L−1 and 0.045 mg L−1, respectively. Furthermore, we also found that exposure of shrimp to Hg caused an inhibition in oxygen consumption of 53.42% lower than that of the control. However, after separate exposure to Hg, elevations in ammonium excretion were obtained, which were 217.64%, higher than the control.

Regional geochemical baselines and controlling factors for trace metals in sediments from the Poxim River, Northeast Brazil

The Poxim river hydrographic sub-basin comprises four freshwater rivers, Poxim-Acu, Poxim-Mirim, Poxim and Pitanga, and is located in the East of Sergipe State, Northeast of Brazil. The present work investigates the distribution, the factors controlling concentrations, and toxicity risks of the metals Co, Cr, Cu, Li, Mn, Ni, Pb, Zn, Al and Fe, in surface sediments of the four rivers. Toxicity was evaluated using the Consensus-based Sediment Quality Guidelines for freshwater ecosystems. Spearman correlation analysis did not indicate any association of the metals with organic matter, however strong, moderate and weak correlations with aluminium, iron, and manganese, respectively, suggested that clay minerals were the main carrier of metals to sediments. Concentrations of metals in all samples were below the TEC (threshold effect concentration), indicating that for these trace metals adverse effects on aquatic biota should rarely occur. A geochemical baseline for the region was defined using lithium as reference element. Metal enrichments due to anthropogenic influence were only observed at three sites. At other sites, enrichment factors were indicative of a large predominance of naturally occurring metals in the sediments.

Assessment of trace metals pollution in estuarine sediments using SEM-AVS and ERM-ERL predictions.

This paper presents the distributions of the investigation of trace metals geochemistry in surface sediments of the Sergipe river estuary, northeast Brazil. Analyses were carried out by Flame or electrothermal atomic absorption spectrometry (FAAS or ETAAS). Principal component analysis was applied to results to identify any groupings among the different sampling sites. In order to determine the extent of contamination, taking into account natural variability within the region, metal concentrations were normalized relative to aluminium. Cr, Cu, Ni and Zn contamination was observed in sediments from the area receiving highest inputs of domestic wastes, while cadmium contamination occurred in sediments from the region affected by highest inflows of industrial effluents. Possible toxicity related to these metals was examined using the relationship simultaneously extracted metals/acid volatile sulfide and by comparing sediment chemical data with sediment quality guidelines ERL-ERM values. Results obtained using the two methods were in agreement and indicated that adverse effects on aquatic biota should rarely occur.

Evaluation of trace metal levels in surface sediments of the Sergipe River Hydrographic Basin, Northeast Brazil

The distributions of Co, Cr, Cu, Mn, Ni, Pb, Fe and Al were investigated in surface sediments collected at 19 sites in the Sergipe River Hydrographic Basin of Northeast Brazil. A regional geochemical baseline (RGB) was defined using iron as a reference element. Enrichment factors (EF) and geoaccumulation indices (Igeo) were used to determine the extent of anthropogenic metal pollution. EF values showed that sediments from sites 1, 5 and 13 could be considered contaminated by Pb, Cr and Cu, respectively. Igeo values showed that only site 13 could be considered contaminated. For other sites, results indicated that naturally occurring metals predominated in the sediments. Possible toxicity related to these metals was examined using the comparing sediment chemical data with sediment quality guidelines (SQG) PEC-TEC values. Principal component analysis (PCA) clearly separated the sites into two groups and hierarchical cluster analysis (HCA) confirmed the interpretations made from the PCA results.

Concentrações e associações geoquímicas de Pb e Zn em sedimentos do rio São Francisco impactados por rejeitos da produção industrial de zinco

Surface sediments from the River Sao Francisco were analyzed to investigate the impact, due to the presence of metals (Cd, Cu, Pb, Zn) in wastes from a metallurgical industry in the city of Tres Marias/MG, Brazil. The concentrations and geochemical associations of Pb, Zn and trace metals associated with the minerals employed in zinc production were measured. Sediments close to discharge locations were highly contaminated with Pb (332-512 μg g-1) and Zn (7872-10780 μg g-1), with values decreasing rapidly due to dilution and hydraulic sorting. Evaluation of toxicity according to the Consensus-based Sediment Quality Guidelines indicated for Cd, Pb and Zn a high probability of adverse effects on aquatic biota at these sites.

Characterization of dissolved organic matter in the Piauí river estuary, Northeast Brazil

Fluorescence spectroscopy and dissolved organic carbon (DOC) measurements were used to characterize the dissolved organic matter (DOM) in the Piaui River estuary, a tropical estuary situated in the State of Sergipe, Northeast Brazil. Fluorescence intensities were greater during the rainy period than the dry period, demonstrating that variability in the fluorescence properties of the DOM was determined mainly by the fluvial discharge and the dilution processes occurring in the estuary. During the rainy period, tryptophan-like and humic substances were the main components of the DOM, while during the dry period there was a significant increase of protein-like constituents. Relationships identified between fluorescence intensities and salinity were indicative of non-conservative behavior of the fluorescent DOM. DOC showed behavior that was conservative during the dry period, and non-conservative during the rainy period, with production of DOC in the upper reaches of the estuary. The complexation of DOM with Cu(II), studied using the fluorescence suppression technique, showed the complexation potentials of protein, tryptophan and humic type fluorophores.

Determination of Zn in Dry Feeds for Cats and Dogs by Energy-Dispersive X-Ray Fluorescence Spectrometry

This work describes an analytical method for Zn determination in dry feeds for cats and dogs by energy-dispersive X-ray fluorescence (EDXRF). Samples of dry feed were powdered and prepared in the form of pellets for direct analysis by EDXRF. The LOQ (10σ) was 0.4 mg/kg. The samples were also analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES) as an independent comparative method. Application of a paired t-test showed no significant differences between Zn concentrations obtained by EDXRF and ICP-OES (at a 95% confidence level). Analysis of variance was also applied to the results and revealed no significant differences between the two techniques (at a 95% confidence level). The precision, expressed as the RSD (n = 3), was RSD < 4.55%. This analytical method provides a simple, rapid, accurate, and precise determination of Zn in dry feeds for cats and dogs by EDXRF as direct, solid-sample analysis.

Distributions of trace metals in sediment cores from a hypertrophic reservoir in northeast Brazil

The distributions of Al, Cu, Co, Cr, Fe, Mn, Ni, Pb and Zn were measured in two sediment cores obtained from the Macela Reservoir in Northeast Brazil. Principal component analysis (PCA) clearly separated both the cores and the sections corresponding to different depths. The concentrations of Cu, Cr, Mn and Zn were highest in the upper sections (0-20 cm), and were significantly correlated with the total organic carbon (Corg) content. The concentrations of Co, Pb and Ni were highest in the lower sections (25-45 cm), and showed strong correlations with aluminum. Cu, Cr, Mn and Zn were derived from anthropogenic sources, while Co, Ni and Pb were of natural origin. Toxicity assessment based on the threshold effect level (TEL) and probable effect level (PEL) values listed in the Canadian Sediment Quality Guidelines (SQG) showed that Cu, Pb and Zn rarely cause any adverse effects, while Ni was likely to cause frequent effects in the biota of the reservoir. The toxicity of Cr was uncertain.