RESUMENSe analizó por Espectrofotometría de Absorcion Atomica de llama el contenido de Fe, Mn, Cu, Cr, Ni, Zn, Cd y Pb en tejidos musculares de peces y crustáceos de la laguna de Unare, estado Anzoátegui, Venezuela. Adicionalmente, se determinaron los niveles en el material en suspension del agua y en el sedimento para detectar posibles impactos en el ecosistema. En el agua, las concentraciones medias de metales fueron bajos (0,104-0,53 µmol/L Fe; 0,004-0,06 µmol/L Mn; 0,002-0,028 µmol/L Zn; 0,004-0,012 µmol/L Cr; no detectado-0,011 µmol/L Ni y no detectado-0,001 µmol/L Cd). En el sedimento se evidencia intervención antropogénica con valores medios que decrecen Mn (516,37)>Zn (127,49)>Ni (52,41)>Cr (51,69)>Cu (41,13)>Pb (29)>Cd (1,51 µg/g) y que superan los niveles establecidos para sedimentos no contaminados. En los tejidos de los organismos se detectó la presencia de metales tóxicos como el plomo y cadmio que superan los 0,16 y 0,04 µg/g, respectivamente, al igual que el zinc que alcanza niveles elevados que sobrepasan 17 µg/g en la mayoría de las especies. Las pruebas estadísticas de ANOVA (P<0,05) indican discrepancias en las concentraciones metales en los tejidos por los diferentes géneros y especies, al igual que en los valores de los individuos de la misma especie (Cathorops spixii) que habitan dentro y fuera de la laguna. Los niveles son mayores en los habitantes del interior de la laguna evidenciando fenóme-nos de bioacumulación. La investigación confirman un progresivo deterioro ambiental de la laguna y de las especies ícticas de este ecosistema que son comercializadas por las poblaciones aledañas a la laguna, las cuales sustentan su economía de su explotación pesquera.Palabras clave: Peces, tejidos, metales, laguna costera, degradación. ABSTRACTThe content of Fe, Mn, Cu, Cr, Ni, Zn, Cd and Pb in muscle tissues of fish and crustaceans from the Unare lagoon (Laguna de Unare) in the state of Anzoátegui, Venezuela, was analyzed by flame Atomic Absorption Spectrometry. The levels of these metals present in suspended material of the water and in sediments were also determined in order to detect possible impact on the ecosystem. The mean concentrations in the water were low ( ), all of which are greater than established levels for uncontaminated sediments. Toxic metals were detected in the examined organisms, such as lead and cadmium with levels above 0.16 and 0.04 µg/g, respectively, and zinc with levels greater than 17 µg/g in the majority of the species. ANOVA statistical tests (P < 0.05) show discrepancies in the concentrations or the metals in the tissues of the different genera and species, as well as in the values for individuals of the same species (Cathorops spixii) which live inside and outside of the lagoon. The levels are higher in those which live within the lagoon, 73Recibido: 02 /
Se estudiaron las concentraciones de metales pesados Co, Cr, Pb y Zn en la fracción biodisponible en sedimentos superficiales de la región marino-costera de la ciudad de Cumaná, Venezuela, durante los periodos de sequía y de lluvia, en 17 estaciones de muestreo distribuidas a lo largo de la costa. Se encontraron diferencias significativas entre los dos periodos de muestreo para cromo y plomo, los cuales registraron sus máximas concentraciones durante la temporada de lluvia. Para el resto de los metales estudiados se encontró un comportamiento similar en ambas épocas. Se observaron diferencias significativas para cromo y plomo, detectándose un mayor enriquecimiento de este último hacia la zona de alta influencia del río.Palabras clave: disponibilidad; metales pesados; sedimentos; zona costera. AbstractThe concentrations of heavy metals Co, Cr, Pb and Zn in the bioavailable fraction in surface sediments of marinecoastal region of the city of Cumana, Venezuela, were studied during periods of drought and rain, in 17 sampling stations located along the shoreline. Significant differences between the two periods of sampling were detected for chromium and lead concentrations, reaching the highest values during the rainy season. For the rest of the metals studied a similar behavior was found for both periods. Likewise, significant differences were observed for chromium and lead, showing a greater enrichment of the latter in the area of high river influence.
This paper reports the geochemical characteristics and environmental conditions of Cuchivero river sediments in Venezuela, depending on particle size, organic matter, organic carbon, nitrogen and total phosphorus, carbonates and heavy metals. The granulometry was typified by a predominance of sands with low organic matter (0.52 to 0.87%), organic carbon (0.06 to 0.09%) and carbonates content (0.54 to 2.61%) as well as high values of total nitrogen (602-985 mg / kg). The poor correlation between nitrogen, phosphorus and organic matter, suggests presence of nitrogen and total phosphorus of allochthonous origin and no Redfield organic matter. The average heavy metals in mg/kg, showed a descending concentration gradient, Fe (410)> Mn (63.14)> Zn (9.01)> Ni (3.38)> (2.21Cu)> Cr (2.09)> Co (1.13)> Cd (0.21) > Pb (0.07) mg / kg, with an association to the sands and carbonates, suggesting lithogenic origin. From the environmental point of view, there is no evidence of anthropogenic impact, as reflected by levels of organic matter and heavy metals which are below of the permissible values.
The hydrochemical, physical-chemical, and biological dynamics were studied in the eastern waters of the gulf ofCariaco, where wind and precipitation patterns govern these processes to a significant degree. Average monthly values forboth surface and bottom waters were respectively as follows: temperature: 25.69 °C each; salinity: 35.41 and 35.75 units;density anomaly (ó-t): 23.43 and 23.84 kg/m3; oxygen concentration: 184.49 and 178.38 mmol/kg; pH: 7.98 and 7.94;nitrates: 3.18 and 4.22 μmol/L; nitrites: 0.45 and 0.60 μmol/L; ammonium: 1.25 and 1.39 μmol/L; total nitrogen: 25.28 and26.31 μmol/L. Phosphate concentrations between surface and bottom waters varied between 0.60 and 0.79 μmol/L, whereasthose of total phosphorus ranged from 2 to 170 μmol/L. Surface and bottom chlorophyll a concentrations ranged from 5.19to 4.33 mg/m3, respectively. ANOVA (P<0.05) did not reveal any significant variation between the values studied, but it didshow differences between the values for different months. Decomposition of organic matter was detected, as typified by bothoxygen utilization greater than 50 mmol/kg and denitrification (N*), which increased ammonium concentration and reducedthe pH during periods of upwelling relaxation. There was an imbalance between the maxima of chlorophyll a and those ofnutrients, which evidenced that phosphorus could be an inhibitor of phytoplankton production, especially during upwellingletup, when Readfield ratio increases from N:P = 16:1 up to N:P = 24:1.
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