Jorge Stripeikis

Seaweeds in the assessment of heavy metal pollution in the Gulf San Jorge, Argentina

Abstract The content of cadmium, lead, chromium, copper and zinc in algal samples from the Southern Atlantic coasts was determined by atomic absorption spectrometry. Algal population samples of Ulva lactuca , Enteromorpha prolifera and Porphyra columbina from Gulf San Jorge, Argentina, were collected, composited and pooled. Two stations with different exposure degree to human activities, Punta Borja and Punta Maqueda, were selected as sampling points. Freeze-dried algal powders of entire plants were digested in a microwave oven before spectroscopic analysis. This sample preparation program allowed the detection of lower levels of metals than the conventional wet digestion procedure. The content of total cadmium, lead, chromium, copper and zinc in filtered seawater from the collection sites was also determined in order to study metal concentration and distribution in the different algal species. Taking into account their toxicities, operational speciation of cadmium and lead was also carried out in order to compare metal accumulation in seaweeds under different environmental conditions.

Cd, Cu and Zn concentrations in sediments and the invasive bivalves Limnoperna fortunei and Corbicula fluminea at the Río de la Plata basin, Argentina

Cd, Cu and Zn content in sediments and bivalves (Limnoperna fortunei and Corbicula fluminea) were studied in the lower 500 km stretch of the Paraná River and in the right margin of the Río de la Plata Estuary. Both bivalves species showed higher metal contents at the Paraná River, possibly related to water chemistry. The Paraná water is circumneutral and soft, while the Río de la Plata coastal water is alkaline, hard, with a higher organic content. Bivalves sampled at the thermal effluent of the Atucha Nuclear Power Plant, at the Paraná River, showed the highest metal content, either from increased absorption at the higher water temperatures (12 °C higher than the river water) or from metal corrosion of the power plant cooling system. L. fortunei and C. fluminea appeared to be successful biomonitor organisms for Cd pollution in the basin, while Cu and Zn content in bivalve tissues was apparently not related to metal load.

On-line copper and iron removal and selenium(VI) pre-reduction for the determination of total selenium by flow-injection hydride generation-inductively coupled plasma optical emission spectrometry

Abstract Selenium was determined in samples with high copper and iron contents by hydride generation-inductively coupled plasma optical emission spectrometry (HG-ICP-OES) after flow-injection (FI) on-line copper and iron removal and selenium(VI) reduction. A Dowex 1X-8 anion-exchange microcolumn was used for the separation of selenium from copper and iron as their chloro-complexes. Se(VI) was then reduced on-line by heating a PTFE coiled reactor (150 cm long, 0.7 mm i.d.) in a 100°C water bath. After reduction of Se(VI), a 900-μl sample was injected into the carrier stream containing hydrochloric acid and sodium tetrahydroborate to generate the hydride. A limit of detection of 0.4 μg l −1 (RSD 2.3% for 20 μg l −1 selenium) was obtained. The application of the method to Geochemical Standard Reference Samples and copper metal reference materials (MBH) demonstrated that results were in good statistical accordance with certified values.

Fully Automatic On-line Separation Preconcentration System for Electrothermal Atomic Absorption Spectrometry: Determination of Cadmium and Lead in Sea-water

An automatic separation preconcentration system coupled to an electrothermal (graphite furnace) atomic absorption spectrometer is described. The preconcentration step is performed on a chelating resin microcolumn (Chelex-100) placed in the injection tip of the autosampler. A time based manifold with two- and three-way solenoid valves commanded by an eight channel microcomputer programmable controller is used for column conditioning, preconcentration and washing steps; no manual operations are involved. Elution is performed by the programmable graphite furnace autosampler and achieved in only one step. Operations involving complete and partial injection of the eluate into the graphite furnace are also discussed. The system was applied to the determination of Cd and Pb in near shore sea-water from Patagonia, Argentina. Detection limits of 1 and 8 ng l-1 were obtained for Cd and Pb respectively. Analysis of a certified reference material (CASS-3) showed good agreement with the certified values.

Hybrid mesoporous materials for on-line preconcentration of Cr(VI) followed by one-step scheme for elution and colorimetric determination at ultratrace levels.

An hybrid mesoporous material synthesised in our laboratories for solid phase extraction (SPE) in flow through systems has been used for analytical purposes. The solid was obtained from mesoporous silica MCM-41 functionalized with 3-aminopropyltriethoxy silane by Sol-Gel methodology. In order to exploit the large sorption capacity of the material together with the possibility of modeling it for anions retention, a microcolumn (MC) filled with the solid was inserted in a flow system for preconcentration of Cr(VI) and its determination at ultratrace levels in natural waters. The analytical methodology involved a reverse flow injection system (rFI) holding a MC filled with the solid for the analyte extraction. Elution and colorimetric detection were carried out with 1-5 diphenylcarbazide (DPC) in sulfuric acid. DPC produced the reduction of Cr(VI) to Cr(III) together with the generation of a cationic red complex between Cr(III) and 1-5 diphenylcarbazone which was easily eluted and detected with a visible spectrophotometer. Moreover, the filling material got ready for the next sample loading remaining unspoiled for more than 300 cycles. The effect of several variables on the analytical signal as well as the influence of cationic and anionic interferences were discussed. Particular attention was given to sulfuric acid interference since it is the required media for the complex generation. Under optimal conditions, 99.8% of Cr(VI) recovery was obtained for a preconcentration time of 120s (sample and DPC flow rates=1 mL min(-1)) and an elution volume of 250 micro L. The limit of detection (3s) was found to be 0.09 microg L(-1) Cr(VI) with a relative standard deviation (n=10, 3 microg L(-1)) of 1.8. Since no Cr(III) was retained by the solid material and Cr(VI) was completely adsorbed, electrothermal atomic absorption spectrometry (ET AAS) determinations of Cr(III) were also performed by simply measuring its concentration at the end of the microcolumn after Cr(VI) retention by the mesoporous solid. Applications to the determination of Cr(VI) and Cr(III) in natural waters and the validation of the methodology were also studied.

Condition index and growth rates of field caged Corbicula fluminea (Bivalvia) as biomarkers of pollution gradients in the Paraná river delta (Argentina)

In 1995-1996, Corbicula fluminea was collected at monthly intervals at two sites in the delta of the lower Paraná river (Argentina), at the confluence of the San Antonio and Vinculación rivers, and from the Paraná de las Palmas river close to its outlet into the Río de la Plata estuary. The San Antonio site is located in the vicinity of sources of industrial and sewage effluents, whereas the more remote Paraná de las Palmas river sampling location is considerably less polluted. Growth rates of caged individuals at the two sites also monitored during the same period, and Cu, Cd, Pb and Zn were measured monthly in the water and in tissue of animals. Throughout the year concentrations of all metals in water, as well as Pb and Zn in tissue, varied irregularly and their levels at the two sites were roughly similar; on the other hand, Cu and Cd in tissue of animals from the polluted site were consistently and significantly higher than in those from the remote site. Changes in the size-frequency of clams from Paraná de las Palmas river throughout the period surveyed clearly indicated a highly structured population with a single well defined reproduction period in October-November. In contrast, shell lengths at San Antonio changed very little throughout the 13 month period, with over 88% of the clams varying between 18 and 20 mm in length; no discernible cohorts were recorded. Growth rates of caged clams were very significantly lower at the polluted site, with the remote site latter yielding comparable values to those obtained from the remote site cohort analysis data. Highest growth rates (around 10 mm) were attained by the smallest (about 7-8 mm) clams reared in Paraná de las Palmas river waters, whereas 23 to 25 mm organisms maintained in San Antonio waters grew only 2 to 3 mm in the same period. Of the 57 animals which survived throughout the caging experiment, those below 10 mm at the outset increased, on average, 8.2 mm in length after 13 months, whereas clams less than10 mm in length grew only 4.2 mm. The condition index (i.e., dry tissue weight divided by shell length) of clams from San Antonio was consistently about 50% lower than that of clams from the Paraná de las Palmas river.It is concluded that delayed growth, poorer condition index, and the abnormal population structure at San Antonio are due to enhanced pollution in this area as compared with the Paraná de las Palmas river, and that all three traits constitute a more useful biomarker of

Trace metal concentrations in coastal marshes of the Lower Paraná River and the Río de la Plata Estuary

Cu, Cr, Pb, Zn and Fe in water, sediment and tissue of the emergent macrophyte Schoenoplectus californicus were studied in three coastal environments differing in aquatic chemistry and tide amplitude: a deltaic floodplain marsh, a coastal vegetated strip of the river and a tidal marsh at the south margin of the Río de la Plata Estuary. Metal content in water was not significantly different between the river and the floodplain marsh. Metal content in sediments showed higher values in the marshes than in the river, suggesting a retention in the marsh. Except for Cu, the highest metal content in sediments and water was observed in the tidal marsh. Pb in plants was undetectable. Metal content was higher in rhizomes, except Cr, which was mainly stored in stems. Rhizome metal content was higher in the river, probably related to the higher redox potential of its sediments. Inflorescence metal content was higher in the marshes: the highest Zn, Cr and Fe contents were measured in the tidal marsh; the highest Cu content was in the floodplain marsh, together with the highest organic matter content of the sediments. Zn, Cr and Fe increased in standing drying stems and in inflorescences in late fall. Inflorescences showed the highest metal content after seeds had been released.

Oral aluminum administration to rats with normal renal function. 2. Body distribution

Aluminum (Al) has no known physiological function and is not considered an essential dietary compound. Nowadays, it is recognized as an element that can produce adverse effects on biological systems. The present study determined Al partitioning in the body compartments of rats that have been orally exposed for 15 weeks. Three experimental groups were studied: Controls (C, n=19), TAl-1 (n=10) rats receiving daily doses of Al citrate (1.0 mmol/g body weight) by gavage and TA1-2 (n=13), receiving Al citrate with the drinking water (100 mmol/ l). At the end of the experimental period, the Al contents of organs and sera were determined. Results are expressed as median and range values. Comparing the TAl-2 rats with the control ones, remarkable Al accumulation could be observed in serum (4.8/2.7 - 16.3 vs 0.4/0.2 - 1.2 mmol/l, P50.001), bone (3.33/1.78 - 4.85 vs 1.00/0.48 - 1.59 mmol/ g, P50.001), kidney (2.33/0.96 - 3.15 vs 0.52/0.22 - 2.07 mmol/g, P50.001), spleen (2.22/0.70 - 4.19 vs 0.27/ 0.11 - 0.36 mmol/g, P50.001) and liver (0.60/0.42 - 0.91 vs 0.24/0.14 - 0.78 mmol/g, P50.01) while brain Al content was not significantly increased. Aluminum levels were raised in the TAl-1 group only in serum (2.8/1.3 - 10.4 mmol/ g, P50.001), bone (1.85/1.00 - 3.41 mmol/g, P50.001) and kidney (1.74/0.96 - 2.07 mmol/g, P50.01). Bone Al concentration increased in a dose-dependent manner (TAl-2 vs TAl-1, P50.001). The results demonstrate different tissue Al accumulation in rats chronically exposed to Al citrate, irrespective of their intact renal function.

Aluminium accumulation in chronic renal failure affects erythropoiesis

Summary: Aluminium (Al) toxicity has been associated with anaemia in exposed patients with chronic renal failure (CRF). the present study was undertaken to determine whether the ingestion of Al citrate was able to affect erythropoiesis in rats with normal or impaired renal function. the renal insufficiency was induced by surgical procedures and control rats were sham operated. Twenty‐four rats were allocated to four groups of six rats each: (A) Sham; (B) Sham+Al; (C) CRF; and (D) CRF+Al. the groups B and D received daily doses of Al citrate (0.5 μmol/g bodyweight) and the groups A and C, deionized water, via the intragastric route. At the end of the experimental period (15 weeks) cultures of late erythroid progenitor cells (CFU‐E) stimulated with erythropoietin were performed and haematological parameters determined. the liver, kidney, brain, bone and serum Al amounts were quantified. the results are expressed as median and interquartile range. the CFU‐E growth was found inhibited in B and D groups (A: 100; B: 74/54‐83; C: 86/54‐98; D: 46/39‐53 %). the haematocrit values were significantly diminished in rats with renal insufficiency when compared to controls (A: 42/40‐43; B: 45/42‐46; C: 37/32‐40 and D: 37/24‐39 %). Serum Al accumulation was observed in B and D groups receiving Al (A: 8/5‐12; B: 36/36‐44; C: 5/5‐6; D: 45/26‐132 μg Al/l). No differences among groups were found in the liver and kidney Al contents, but uraemic state favoured Al accumulation in brain (A: 6/5.0‐9.0; B: 4/3.8‐4.3; C: 2/1.0‐3.0; D: 15/12.0‐21.0 μg Al/g tissue) and bone (A: 29/27‐31; B: 30/29‐39; C: 42/33‐48; D: 68/56‐79 μg Al/g tissue). We suggest that the heavy accumulation of Al in the bone compartment may result in a protracted endogenous exposure of bone marrow cells, affecting the erythropoiesis in vivo.

A simplified approach to the determination of N-nitroso glyphosate in technical glyphosate using HPLC with post-derivatization and colorimetric detection

A simple and sensitive HPLC post-derivatization method with colorimetric detection has been developed for the determination of N-nitroso glyphosate in samples of technical glyphosate. Separation of the analyte was accomplished using an anionic exchange resin (2.50mmx4.00mm i.d., 15mum particle size, functional group: quaternary ammonium salt) with Na(2)SO(4) 0.0075M (pH 11.5) (flow rate: 1.0mLmin(-1)) as mobile phase. After separation, the eluate was derivatized with a colorimetric reagent containing sulfanilamide 0.3% (w/v), [N-(1-naphtil)ethilendiamine] 0.03% (w/v) and HCl 4.5M in a thermostatized bath at 95 degrees C. Detection was performed at 546nm. All stages of the analytical procedure were optimized taking into account the concept of analytical minimalism: less operation times and costs; lower sample, reagents and energy consumption and minimal waste. The limit of detection (k=3) calculated for 10 blank replicates was 0.04mgL(-1) (0.8mgkg(-1)) in the solid sample which is lower than the maximum tolerable accepted by the Food and Agriculture Organization of the United Nations.