Papers by William W S Senior
The content of Fe, Mn, Cu, Cr, Ni, Zn, Cd and Pb in muscle tis- sues of fish and crustaceans from... more The content of Fe, Mn, Cu, Cr, Ni, Zn, Cd and Pb in muscle tis- sues 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 sedi- ments were also determined in
Coastal and Deep Ocean Pollution, 2019
Aquatic chemistry has become a rewarding and substantial area of research that is attracting many... more Aquatic chemistry has become a rewarding and substantial area of research that is attracting many scientists. Its literature has changed from a compilation of composition tables to studies of chemical
reactions that take place within aquatic environments. Given that the rivers deliver to the world’s oceans most of their dissolved and particulate components, the interactions of these two sets of
waters determine the vitality of our coastal waters. This chapter not only provides an introduction to the dynamics of aquatic chemicals, but also identifies materials that endanger marine and fluvial resources. The information presented here will be of great value to environmental scientists dedicated to maintaining renewable hydrosphere resources. As the size of the world population will increase in the near future and the uses of materials and energy show parallel increases, rivers and oceans should be considered as a resource to accept some of society’s waste. The capacity of these waters and the sediments to accommodate the waste must be evaluated continuously. The information presented in this chapter is based on the review and evaluation of scientific publications and technical reports
from various sources.
Brazilian Journal of Oceanography, 2017
The carbon regeneration in the water column of
the Cariaco Basin (Venezuela) was investigated
usi... more The carbon regeneration in the water column of
the Cariaco Basin (Venezuela) was investigated
using a regression model of total alkalinity (TA)
and the concentration of total inorganic carbon
(TCO2). Primary productivity (PP) was determined
from the inorganic carbon fraction assimilated
by phytoplankton and the variation of the 22 and
23°C isotherm was used as an indicator of coastal
upwelling. The results indicate that CO2
levels were lowest (1962 µmol/kg) at the surface and increased
to 2451 µmol/kg below the oxic-anoxic redox
interface. The vertical regeneration distribution of
carbon was dominated (82%) by organic carbon
originating from the soft tissue of photosynthetic
organisms, whereas 18% originated from the
dissolution of biogenic calcite. The regeneration
of organic carbon was highest in the surface layer
in agreement with the primary productivity values.
However, at the oxic-anoxic interface a second more
intense maximum was detected (70-80%), generated
by chemotrophic respiration of organic material
by microorganisms. The percentages in the anoxic
layers were lower than in the oxic zone because
aerobic decomposition occurs more rapidly than
anaerobic respiration of organic material because
more labile fractions of organic carbon have already
been mineralized in the upper layers.
Brazilian Journal of Oceanography · March 2017, 2017
The carbon regeneration in the water column of
the Cariaco Basin (Venezuela) was investigated
usi... more The carbon regeneration in the water column of
the Cariaco Basin (Venezuela) was investigated
using a regression model of total alkalinity (TA)
and the concentration of total inorganic carbon
(TCO2). Primary productivity (PP) was determined
from the inorganic carbon fraction assimilated
by phytoplankton and the variation of the 22 and
23°C isotherm was used as an indicator of coastal
upwelling. The results indicate that CO2
levels were lowest (1962 µmol/kg) at the surface and increased
to 2451 µmol/kg below the oxic-anoxic redox
interface. The vertical regeneration distribution of
carbon was dominated (82%) by organic carbon
originating from the soft tissue of photosynthetic
organisms, whereas 18% originated from the
dissolution of biogenic calcite. The regeneration
of organic carbon was highest in the surface layer
in agreement with the primary productivity values.
However, at the oxic-anoxic interface a second more
intense maximum was detected (70-80%), generated
by chemotrophic respiration of organic material
by microorganisms. The percentages in the anoxic
layers were rlower than in the oxic zone because
aerobic decomposition occurs more rapidly than
anaerobic respiration of organic material because
more labile fractions of organic carbon have already
been mineralized in the upper layers.
Copper Essential and Noxious to Aquatic Organisms, 2019
Aquatic chemistry has become a rewarding and substantial area of research that is attracting many... more Aquatic chemistry has become a rewarding and substantial area of research that is attracting many
scientists. Its literature has changed from a compilation of composition tables to studies of chemical
reactions that take place within aquatic environments. Given that the rivers deliver to the world’s
oceans most of their dissolved and particulate components, the interactions of these two sets of
waters determine the vitality of our coastal waters. This chapter not only provides an introduction
to the dynamics of aquatic chemicals, but also identifies materials that endanger marine and fluvial
resources. The information presented here will be of great value to environmental scientists dedicated
to maintaining renewable hydrosphere resources. As the size of the world population will increase in
the near future and the uses of materials and energy show parallel increases, rivers and oceans should
be considered as a resource to accept some of society’s waste. The capacity of these waters and the
sediments to accommodate the waste must be evaluated continuously. The information presented
in this chapter is based on the review and evaluation of scientific publications and technical reports
from various sources.
EQUILIBRIUM, 2018
En esta investigación se determinaron las fracciones P-adsorbida o lábil (F1), P-autigénica (F2),... more En esta investigación se determinaron las fracciones P-adsorbida o lábil (F1), P-autigénica (F2), P-asociada a óxidos (F3), P-detrítica (F4) y P-orgánica (F5), y la biodisponibilidad del fósforo en los sedimentos del Golfo de Paria, Venezuela. La concentración de fósforo total (PT) osciló entre 3,93-4,97 μmol P/g, y se encuentra principalmente en forma detrítica y orgánica. Se evidencian diferentes mecanismos de transporte y mecanismos posdepositacionales de partículas de composición química variable, que inducen a un gradiente decreciente en las concentraciones de las fracciones con respecto al fósforo total: P-detrítico (47,02% - 56,95%) > P-orgánico > (38,87% - 50,74%) > (1,14% - 2,28%) >P-autigénico P-asociados a óxidos (0,25% - 0,62%). Las fuentes principales del fósforo detrítico y orgánico, están asociadas a la apatita litogénica terrestre proveniente de material erosionado de los cinturones orogénicos de las Cordilleras de los Andes, de la Costa, Escudo Guayanés y de los Llanos venezolanos y colombianos. La materia orgánica compuesta de árboles (C3) y gramíneas (C4) provenientes de las sabanas que es transportada por el río Orinoco hasta su Delta y de allí redistribuido hacia el Golfo de Paria. Porcentaje de fósforo entre 0,50 % - 2,64 %, es fácilmente biodisponible para la biota, entre 39,12% y 51,36 % es potencialmente y entre 48,17 % - 58,43 es refractario.
Ríos en riesgo en Venezuela. Vol. 2, 2018
El río Manzanares tiene una relación histórica con la ciudad de Cumaná, ya sea por su papel ecoló... more El río Manzanares tiene una relación histórica con la ciudad de Cumaná, ya sea por su papel ecológico, cultural y económico pero también por los impactos ambientales que han afectado negativamente el estado de conservación de este hidrosistema. Se efectuó una actualización de la información sobre el estado de conservación del río Manzanares y su tributarios con base en la revisión de artículos científicos e informes variados. Se referenciaron las diferentes fuentes de contaminación y las magnitudes de variables ambientales, calidad de aguas y la biodiversidad acuática. Los reportes indican una problemática ambiental antigua y compleja a lo largo de toda la cuenca y por la acción combinada de diferentes perturbaciones. En el tramo final del río y su desembocadura es marcada la transformación y derivación del cauce, así como la transformación total de sus riberas naturales por áreas urbanas e industriales, que además generan residuos sólidos y efluentes que son vertidos al río. Los diferentes centros urbanos en las márgenes del río drenan aguas servidas y desechos sólidos directamente al mismo, pero también lo hacen las áreas de producción agrícola e industrial, que emplean fertilizantes e insecticidas que por escorrentía se incorporan a los afluentes, afectando la calidad del agua y las biotas acuáticas. La deforestación en la cuenca alta y la minería de gravas contribuyen al proceso de sedimentación de los cauces.
Los registros históricos sobre este ecosistema fluvial, denotan una pérdida importante de la biodiversidad, principalmente de moluscos, crustáceos y peces, pero también un incremento en la abundancia de especies tolerantes y la presencia de especies introducidas. No se evidencia un manejo adecuado de los efluentes, pero tampoco la aplicación de programas dirigidos a la conservación y restauración de los recursos hidrobiológicos.
Zootecnia Trop., 34 (2): 143-153., 2016
Se realizó un estudio preliminar sobre el contenido
de cadmio (Cd), plomo (Pb), mercurio (Hg) y
a... more Se realizó un estudio preliminar sobre el contenido
de cadmio (Cd), plomo (Pb), mercurio (Hg) y
arsénico (As) en muestras de fi letes de pescado
congelado de elevado consumo en El Ecuador
como, corvina (Cynoscion phoxocephalus), dorado
(Coryphaena hippurus), tilapia (Oreochromis
niloticus) y atún (Thunnus obesus); adquiridos en
diversos supermercados de la ciudad de Machala,
Provincia El Oro. Los resultados preliminares
muestran la contaminación de estos productos por
As, Pb y Hg, superando las Normas Internacionales
establecidas para el consumo humano. En todas
las muestras examinadas los valores de Cd
fueron inferiores al límite de detección del método
(0,0042 mg. kg-1). La correlación signifi cativa entre
el contenido de Hg, Pb y As en las muestras de
músculo de pescado evaluadas, puede sugerir
que estos contaminantes tienen un origen común
ya que las elevadas concentraciones de As, Pb y
Hg son consecuencia de las aguas domésticas e
industriales vertidas sin tratamiento alguno en la
zona costera así como, la escorrentía proveniente
de las zonas de cultivos y al aporte atmosférico.
Se determinan las concentraciones de metales pesados en los moluscos bivalvos Anadara similis y A... more Se determinan las concentraciones de metales pesados en los moluscos bivalvos Anadara similis y A. tuberculosa. Los ejemplares fueron recolectados a 2 km de la desembocadura del Estero Huaylá, Provincia El Oro, Ecuador, en noviembre 2013. En el laboratorio se les determinaron la longitud y peso para cada una de las especies,
estableciéndose dos intervalos de tallas para A. similis y cuatro para A. tuberculosa. La carne de los organismos fue extraída, lavada y secada en un horno a 60 °C durante 72 h, para posteriormente digerirla con una mezcla de HNO3 y HClO4 en proporción 3:1. Las concentraciones de 4 metales: plomo, arsénico, mercurio y cadmio, fueron determinadas mediante espectrofotometría de absorción atómica. Los valores promedio obtenidos en A. similis (mg/kg), fueron: Pb (8,51 ± 0,34); As (1,42 ± 0,06); Hg (618,7 ± 355,32); Cd (1,21 ± 0,23) mg/kg; mientras que para A. tuberculosa fueron: Pb (7,52 ± 0,46); As (1,55 ± 0,14); Hg (364,38 ± 91,39); Cd (1,68 ± 0,28) mg/kg. Las concentraciones registradas de Pb, As, Cd y Hg en ambas especies de moluscos superan los límites máximos permisibles por las Normas Internacionales. Las tallas
más pequeñas (3-4 cm) de A. tuberculosa posee la capacidad de bioacumular mayor cantidad de Pb, Hg y Cd, mientras A. similis mostró su mayor concentración de Pb en su talla más pequeña (4-5 cm).
The concentration of heavy metals in the bivalve mollusks Anadara similis and A. tuberculosa was ... more The concentration of heavy metals in the bivalve mollusks Anadara similis and A. tuberculosa was determined. The samples were collected at 2 km from the mouth of Estero Huaylá, El Oro Province, Ecuador, in November 2013. In the laboratory, the length and weight of the specimens were determined, establishing two size ranges for A. similis and 4 for A.tuberculosa. The meat was extracted from the shells, washed and dried in an oven at 60 °C for 72 h, and subsequently digested with a mixture of HNO3 and HClO4 in a ratio 3:1. The concentration of four metals: lead, arsenic, mercury and cadmium, were determined by Atomic Absorption Spetrophotometry. The average values obtained in A. similis (mg/kg) were: Pb (8.51 ± 0.34); As (1.42 ± 0.06); Hg (618.7 ± 355.32); Cd (1.21 ± 0.23); and for A. tuberculosa: Pb (7.52 ± 0.46); As (1.55 ± 0.14); Hg (364.38 ± 91.39) and Cd (1.68 ± 0.28). The recorded concentrations of Pb, As, Cd and Hg in both species of mollusks exceed the maximum permissible international limits for human consumption. The smaller sizes (3-4 cm) of A. tuberculosa have the capacity to bioaccumulate a greater amount of Pb, Cd and Hg; while the smaller sizes (4-5 cm) of A. similis showed the highest concentration of Pb.
Aquaculture, 1995
... 136 (1995) 257276 Growth of the tropical scallop, Euvola (Pecten) ziczac, in bottom and suspe... more ... 136 (1995) 257276 Growth of the tropical scallop, Euvola (Pecten) ziczac, in bottom and suspended culture in the Golfo de Cariaco, Venezuela Anibal Velez a, Luis Freites a ... 1B). The cages in suspension were attached to a long line located at approximately 300 m from shore. ...
The carbon regeneration in the water column of the Cariaco Basin (Venezuela) was investigated usi... more The carbon regeneration in the water column of the Cariaco Basin (Venezuela) was investigated using a regression model of total alkalinity (TA) and the concentration of total inorganic carbon (TCO 2). Primary productivity (PP) was determined from the inorganic carbon fraction assimilated by phytoplankton and the variation of the 22 and 23°C isotherm was used as an indicator of coastal upwelling. The results indicate that CO 2 levels were lowest (1962 µmol/kg) at the surface and increased to 2451 µmol/kg below the oxic-anoxic redox interface. The vertical regeneration distribution of carbon was dominated (82%) by organic carbon originating from the soft tissue of photosynthetic organisms, whereas 18% originated from the dissolution of biogenic calcite. The regeneration of organic carbon was highest in the surface layer in agreement with the primary productivity values. However, at the oxic-anoxic interface a second more intense maximum was detected (70-80%), generated by chemotrophic respiration of organic material by microorganisms. The percentages in the anoxic layers were lower than in the oxic zone because aerobic decomposition occurs more rapidly than anaerobic respiration of organic material because more labile fractions of organic carbon have already been mineralized in the upper layers. Descriptors
The total concentration and the chemical forms of heavy metals were determined in
superficial sed... more The total concentration and the chemical forms of heavy metals were determined in
superficial sediments of the Cuchivero river, Venezuela, using sequential extraction and
atomic absorption spectrophotometry with flame. Pollution indices were used to study the
distribution, pollution and environmental risk in the sediments. Total values ranged from,
394-457 mgkg-1 Fe, 46,87-74,82 Mn, 6,45-11,92 Zn, 1,70-5,75 Ni, 0,39-3,7 Cu, 1,25-3,63
Cr, 0,37-1,82 Co, 0,10-0,30 Cd y <Ld-0,20 mgkg-1 Pb. The metals were found to be
strongly associated with the residual fraction minerals (70 to 90%), carbonates and iron
oxihidroxides. Manganese and cadmium were associated mostly exchangeable fraction
(60-70%). The indices indicate that the source of metals is mainly bedrock; no metal
enrichment and contamination exist. The risk of environmental disruption is low for Fe
and Co, high for Zn and Ni, medium for Cu and Cr, and very high for Mn, Cd and Pb.
The total concentration and the chemical forms of heavy metals were determined in superficial sed... more The total concentration and the chemical forms of heavy metals were determined in superficial sediments of the Cuchivero river, Venezuela, using sequential extraction and atomic absorption spectrophotometry with flame. Pollution indices were used to study the distribution, pollution and environmental risk in the sediments. Total values ranged from, 394-457 mg kg-1 Fe, 46,87-74,82 Mn, 6,45-11,92 Zn, 1,70-5,75 Ni, 0,39-3,7 Cu, 1,25-3,63 Cr, 0,37-1,82 Co, 0,10-0,30 Cd y <Ld-0,20 mgkg-1 Pb. The metals were found to be strongly associated with the residual fraction minerals (70 to 90%), carbonates and iron oxihidroxides. Manganese and cadmium were associated mostly exchangeable fraction (60-70%). The indices indicate that the source of metals is mainly bedrock; no metal enrichment and contamination exist. The risk of environmental disruption is low for Fe and Co, high for Zn and Ni, medium for Cu and Cr, and very high for Mn, Cd and Pb.
RESUMEN Se analizó por Espectrofotometría de Absorción Atómica de llama el contenido de Fe, Mn, C... more RESUMEN Se analizó por Espectrofotometría de Absorción Atómica 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 suspensión del agua y en el sedimento para detectar posibles impactos en el ecosistema. En el agua, las concentraciones medias de metales fueron ba-jos (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 evi-dencia intervención antropogénica con valores medios que de-crecen 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 es-tablecidos 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, res-pectivamente, al igual que el zinc que alcanza niveles eleva-dos que sobrepasan 17 µg/g en la mayoría de las especies. Las pruebas estadísticas de ANOVA (P<0,05) indican discre-pancias 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 progre-sivo deterioro ambiental de la laguna y de las especies ícticas de este ecosistema que son comercializadas por las poblacio-nes aledañas a la laguna, las cuales sustentan su economía de su explotación pesquera. ABSTRACT The 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 (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; undetectable-0.011 µmol/L Ni and undectable-0.001 µmol/L Cd). In the sediments, evidence was found of anthropogenic intervention with mean values in decreasing order of Mn (516.37) > Zn (127.49) > Ni (52.41) > Cr (51.69) > Cu (41.13) > Pb (29) > Cd (1.51 µg/g), all of which are greater than established levels for uncontami-nated 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, 73
RESUMEN Con el propósito de detectar alteraciones en el productivo eco-sistema de la Laguna de Ca... more RESUMEN Con el propósito de detectar alteraciones en el productivo eco-sistema de la Laguna de Castillero (Caicara del Orinoco, muni-cipio Cedeño del estado Bolívar, Venezuela), se presentan re-sultados de mediciones granulométricas y de las concentracio-nes de los metales pesados: Fe, Mn, Zn, Pb y Co realizadas en junio 2001 sobre los sedimentos superficiales y del tejido muscular de varias especies autóctonas de peces (Plasgiosium squamossimos, Pigocentrus cariba, Pheudoplastyloma fascia-tum, e Hypostomus spp realizadas en junio 2001. Utilizando téc-nica de espectrofotometría de absorción atómica con llama de aire acetileno, se determinó que, las concentraciones de meta-les más altas están representadas por manganeso, zinc y plo-mo. En la parte más interna de la laguna, el tipo de sedimento predominante es el lodo, constituyendo entre 30% y un 65% del material colectado por estación. Se encuentra, que esos niveles decrecen hacia la boca de la laguna, producto de la interacción de las corrientes de flujo/reflujo que lavan el sedimento y que se refleja en la mayor presencia de arena fina. El análisis estadísti-co de ANOVA muestra diferencias significativas entre las con-centraciones de los metales en las estaciones, tipificadas por la presencia de promedios discrepantes. Los niveles promedios para los sedimentos superficiales de la zona son los siguientes: Fe (3365,44 ± 261,61), Mn (132,17 ± 25,46), Zn (253,04 ± 86,48), Pb (17,02 ± 2,21) y Co (4,65 ± 0,76) µg/g. Similarmente, en el tejido muscular de los peces se cuantificaron las siguien-tes concentraciones: Fe entre (31,26 ± 0,06) y (68,36 ± 0,05); Mn entre (2,02 ± 0,05) y (4,16 ± 0,03); Zn entre (19,09 ± 0,01) y (28,89 ± 0,01); Pb entre (0,38 ± 0,01) y (0,47 ± 0,03) µg/g. El análisis refleja una notable asociación entre los altos valores de concentraciones de metales y el tipo de sedimento, con un gra-diente creciente hacia el sedimento tipo lodo. Se encuentran va-lores elevados en la concentración de Pb y Zn, hecho atribuido al estrés que ejercen las actividades antropogénicas circundan-tes sobre la Laguna de Castillero. Se concluye que, en base al diagnóstico realizado, el ecosistema de la laguna se encuentra en evidente estado de deterioro con implicaciones que podrían afectar a las especies que habitan en ella y a su vez, las activi-dades económicas de las poblaciones que explotan los recur-sos bióticos de ese cuerpo de agua. ABSTRACT To detected alterations in the productive ecosystem of the Castillero Lagoon (Caicara of the Orinoco, Cedeño Municipality , Bolivar State, Venezuela), results are presented for granu-lometric measurements and heavy metals concentrations: Fe, Mn, Zn, Pb and Co made in June 2001 on superface sediments and of the muscular tissue of several native species of fish (Plasgiosium squamossimos, Pigocentrus cariba, Pheudo-plastyloma fasciatum, and Hypostomus spp. By using atomic absorption spectrophotometry with an air-acetylene flame, it was determined that the highest concentrations of metals are represented by manganese, zinc and lead. It was determined that the highest concentrations of metals are represented by manganese, zinc and lead. In the most internal part in the lagoon the type of predominant sediments is the mud, constituting among 30% and 65% of the material collected by station. Is that those levels fall toward the mouth of the lagoon, product of
RESUMEN: Esta investigación tuvo como objetivo, evaluar algunos parámetros geoquímicos de los sed... more RESUMEN: Esta investigación tuvo como objetivo, evaluar algunos parámetros geoquímicos de los sedimentos superficiales de la laguna costera La Restinga, ubicada en la Isla de Margarita, estado Nueva Esparta, Venezuela. Utilizando metodología clásica para estudios geoquímicos, se analizó la composición granulométrica y textura del sedimento, porcentaje de carbono orgánico y materia orgánica total, así como, carbonato de calcio. Adicionalmente, se determinaron las concentraciones de nitrógeno total, fósforo total e hidrocarburos alifáticos. Los resultados mostraron que en la laguna La Restinga predominó la textura sedimentaria arenosa, por encima de la areno-limosa y areno-arcillosa. Los porcentajes de carbono orgánico total, materia orgánica total y carbonato de calcio variaron respectivamente de la siguiente manera: 1,70-25,53%, 2,93-44,01% y 11,10-82,10%. Se determinaron concentraciones de 282,10-1571,80 mg kg -1 en nitrógeno total, 419,50-2033,70 mg kg -1 en fósforo total y 5,64-63,18 mg kg -1 para hidrocarburos alifáticos. La materia orgánica total en la laguna La Restinga se distribuyó en función de las partículas finas del sedimento y la presencia de manglares, a su vez el carbonato de calcio, estuvo asociado principalmente a los aportes de organismos con concha calcárea. Los bajos valores de la relación NT/PT (menores a 5), sugieren limitación del nitrógeno en el ecosistema, y un enriquecimiento natural o antrópico de fósforo en el sedimento. Los niveles de los hidrocarburos alifáticos determinados, no son considerados como niveles contaminantes de acuerdo a lo establecido por CARIPOL (1980), salvo en el extremo oriental del cuerpo principal de la laguna. De acuerdo a lo planteado en este estudio, se puede inferir que la laguna La Restinga presenta síntomas de degradación, producto de la intervención del hombre en el ecosistema.
Uploads
Papers by William W S Senior
reactions that take place within aquatic environments. Given that the rivers deliver to the world’s oceans most of their dissolved and particulate components, the interactions of these two sets of
waters determine the vitality of our coastal waters. This chapter not only provides an introduction to the dynamics of aquatic chemicals, but also identifies materials that endanger marine and fluvial resources. The information presented here will be of great value to environmental scientists dedicated to maintaining renewable hydrosphere resources. As the size of the world population will increase in the near future and the uses of materials and energy show parallel increases, rivers and oceans should be considered as a resource to accept some of society’s waste. The capacity of these waters and the sediments to accommodate the waste must be evaluated continuously. The information presented in this chapter is based on the review and evaluation of scientific publications and technical reports
from various sources.
the Cariaco Basin (Venezuela) was investigated
using a regression model of total alkalinity (TA)
and the concentration of total inorganic carbon
(TCO2). Primary productivity (PP) was determined
from the inorganic carbon fraction assimilated
by phytoplankton and the variation of the 22 and
23°C isotherm was used as an indicator of coastal
upwelling. The results indicate that CO2
levels were lowest (1962 µmol/kg) at the surface and increased
to 2451 µmol/kg below the oxic-anoxic redox
interface. The vertical regeneration distribution of
carbon was dominated (82%) by organic carbon
originating from the soft tissue of photosynthetic
organisms, whereas 18% originated from the
dissolution of biogenic calcite. The regeneration
of organic carbon was highest in the surface layer
in agreement with the primary productivity values.
However, at the oxic-anoxic interface a second more
intense maximum was detected (70-80%), generated
by chemotrophic respiration of organic material
by microorganisms. The percentages in the anoxic
layers were lower than in the oxic zone because
aerobic decomposition occurs more rapidly than
anaerobic respiration of organic material because
more labile fractions of organic carbon have already
been mineralized in the upper layers.
the Cariaco Basin (Venezuela) was investigated
using a regression model of total alkalinity (TA)
and the concentration of total inorganic carbon
(TCO2). Primary productivity (PP) was determined
from the inorganic carbon fraction assimilated
by phytoplankton and the variation of the 22 and
23°C isotherm was used as an indicator of coastal
upwelling. The results indicate that CO2
levels were lowest (1962 µmol/kg) at the surface and increased
to 2451 µmol/kg below the oxic-anoxic redox
interface. The vertical regeneration distribution of
carbon was dominated (82%) by organic carbon
originating from the soft tissue of photosynthetic
organisms, whereas 18% originated from the
dissolution of biogenic calcite. The regeneration
of organic carbon was highest in the surface layer
in agreement with the primary productivity values.
However, at the oxic-anoxic interface a second more
intense maximum was detected (70-80%), generated
by chemotrophic respiration of organic material
by microorganisms. The percentages in the anoxic
layers were rlower than in the oxic zone because
aerobic decomposition occurs more rapidly than
anaerobic respiration of organic material because
more labile fractions of organic carbon have already
been mineralized in the upper layers.
scientists. Its literature has changed from a compilation of composition tables to studies of chemical
reactions that take place within aquatic environments. Given that the rivers deliver to the world’s
oceans most of their dissolved and particulate components, the interactions of these two sets of
waters determine the vitality of our coastal waters. This chapter not only provides an introduction
to the dynamics of aquatic chemicals, but also identifies materials that endanger marine and fluvial
resources. The information presented here will be of great value to environmental scientists dedicated
to maintaining renewable hydrosphere resources. As the size of the world population will increase in
the near future and the uses of materials and energy show parallel increases, rivers and oceans should
be considered as a resource to accept some of society’s waste. The capacity of these waters and the
sediments to accommodate the waste must be evaluated continuously. The information presented
in this chapter is based on the review and evaluation of scientific publications and technical reports
from various sources.
Los registros históricos sobre este ecosistema fluvial, denotan una pérdida importante de la biodiversidad, principalmente de moluscos, crustáceos y peces, pero también un incremento en la abundancia de especies tolerantes y la presencia de especies introducidas. No se evidencia un manejo adecuado de los efluentes, pero tampoco la aplicación de programas dirigidos a la conservación y restauración de los recursos hidrobiológicos.
de cadmio (Cd), plomo (Pb), mercurio (Hg) y
arsénico (As) en muestras de fi letes de pescado
congelado de elevado consumo en El Ecuador
como, corvina (Cynoscion phoxocephalus), dorado
(Coryphaena hippurus), tilapia (Oreochromis
niloticus) y atún (Thunnus obesus); adquiridos en
diversos supermercados de la ciudad de Machala,
Provincia El Oro. Los resultados preliminares
muestran la contaminación de estos productos por
As, Pb y Hg, superando las Normas Internacionales
establecidas para el consumo humano. En todas
las muestras examinadas los valores de Cd
fueron inferiores al límite de detección del método
(0,0042 mg. kg-1). La correlación signifi cativa entre
el contenido de Hg, Pb y As en las muestras de
músculo de pescado evaluadas, puede sugerir
que estos contaminantes tienen un origen común
ya que las elevadas concentraciones de As, Pb y
Hg son consecuencia de las aguas domésticas e
industriales vertidas sin tratamiento alguno en la
zona costera así como, la escorrentía proveniente
de las zonas de cultivos y al aporte atmosférico.
estableciéndose dos intervalos de tallas para A. similis y cuatro para A. tuberculosa. La carne de los organismos fue extraída, lavada y secada en un horno a 60 °C durante 72 h, para posteriormente digerirla con una mezcla de HNO3 y HClO4 en proporción 3:1. Las concentraciones de 4 metales: plomo, arsénico, mercurio y cadmio, fueron determinadas mediante espectrofotometría de absorción atómica. Los valores promedio obtenidos en A. similis (mg/kg), fueron: Pb (8,51 ± 0,34); As (1,42 ± 0,06); Hg (618,7 ± 355,32); Cd (1,21 ± 0,23) mg/kg; mientras que para A. tuberculosa fueron: Pb (7,52 ± 0,46); As (1,55 ± 0,14); Hg (364,38 ± 91,39); Cd (1,68 ± 0,28) mg/kg. Las concentraciones registradas de Pb, As, Cd y Hg en ambas especies de moluscos superan los límites máximos permisibles por las Normas Internacionales. Las tallas
más pequeñas (3-4 cm) de A. tuberculosa posee la capacidad de bioacumular mayor cantidad de Pb, Hg y Cd, mientras A. similis mostró su mayor concentración de Pb en su talla más pequeña (4-5 cm).
superficial sediments of the Cuchivero river, Venezuela, using sequential extraction and
atomic absorption spectrophotometry with flame. Pollution indices were used to study the
distribution, pollution and environmental risk in the sediments. Total values ranged from,
394-457 mgkg-1 Fe, 46,87-74,82 Mn, 6,45-11,92 Zn, 1,70-5,75 Ni, 0,39-3,7 Cu, 1,25-3,63
Cr, 0,37-1,82 Co, 0,10-0,30 Cd y <Ld-0,20 mgkg-1 Pb. The metals were found to be
strongly associated with the residual fraction minerals (70 to 90%), carbonates and iron
oxihidroxides. Manganese and cadmium were associated mostly exchangeable fraction
(60-70%). The indices indicate that the source of metals is mainly bedrock; no metal
enrichment and contamination exist. The risk of environmental disruption is low for Fe
and Co, high for Zn and Ni, medium for Cu and Cr, and very high for Mn, Cd and Pb.
reactions that take place within aquatic environments. Given that the rivers deliver to the world’s oceans most of their dissolved and particulate components, the interactions of these two sets of
waters determine the vitality of our coastal waters. This chapter not only provides an introduction to the dynamics of aquatic chemicals, but also identifies materials that endanger marine and fluvial resources. The information presented here will be of great value to environmental scientists dedicated to maintaining renewable hydrosphere resources. As the size of the world population will increase in the near future and the uses of materials and energy show parallel increases, rivers and oceans should be considered as a resource to accept some of society’s waste. The capacity of these waters and the sediments to accommodate the waste must be evaluated continuously. The information presented in this chapter is based on the review and evaluation of scientific publications and technical reports
from various sources.
the Cariaco Basin (Venezuela) was investigated
using a regression model of total alkalinity (TA)
and the concentration of total inorganic carbon
(TCO2). Primary productivity (PP) was determined
from the inorganic carbon fraction assimilated
by phytoplankton and the variation of the 22 and
23°C isotherm was used as an indicator of coastal
upwelling. The results indicate that CO2
levels were lowest (1962 µmol/kg) at the surface and increased
to 2451 µmol/kg below the oxic-anoxic redox
interface. The vertical regeneration distribution of
carbon was dominated (82%) by organic carbon
originating from the soft tissue of photosynthetic
organisms, whereas 18% originated from the
dissolution of biogenic calcite. The regeneration
of organic carbon was highest in the surface layer
in agreement with the primary productivity values.
However, at the oxic-anoxic interface a second more
intense maximum was detected (70-80%), generated
by chemotrophic respiration of organic material
by microorganisms. The percentages in the anoxic
layers were lower than in the oxic zone because
aerobic decomposition occurs more rapidly than
anaerobic respiration of organic material because
more labile fractions of organic carbon have already
been mineralized in the upper layers.
the Cariaco Basin (Venezuela) was investigated
using a regression model of total alkalinity (TA)
and the concentration of total inorganic carbon
(TCO2). Primary productivity (PP) was determined
from the inorganic carbon fraction assimilated
by phytoplankton and the variation of the 22 and
23°C isotherm was used as an indicator of coastal
upwelling. The results indicate that CO2
levels were lowest (1962 µmol/kg) at the surface and increased
to 2451 µmol/kg below the oxic-anoxic redox
interface. The vertical regeneration distribution of
carbon was dominated (82%) by organic carbon
originating from the soft tissue of photosynthetic
organisms, whereas 18% originated from the
dissolution of biogenic calcite. The regeneration
of organic carbon was highest in the surface layer
in agreement with the primary productivity values.
However, at the oxic-anoxic interface a second more
intense maximum was detected (70-80%), generated
by chemotrophic respiration of organic material
by microorganisms. The percentages in the anoxic
layers were rlower than in the oxic zone because
aerobic decomposition occurs more rapidly than
anaerobic respiration of organic material because
more labile fractions of organic carbon have already
been mineralized in the upper layers.
scientists. Its literature has changed from a compilation of composition tables to studies of chemical
reactions that take place within aquatic environments. Given that the rivers deliver to the world’s
oceans most of their dissolved and particulate components, the interactions of these two sets of
waters determine the vitality of our coastal waters. This chapter not only provides an introduction
to the dynamics of aquatic chemicals, but also identifies materials that endanger marine and fluvial
resources. The information presented here will be of great value to environmental scientists dedicated
to maintaining renewable hydrosphere resources. As the size of the world population will increase in
the near future and the uses of materials and energy show parallel increases, rivers and oceans should
be considered as a resource to accept some of society’s waste. The capacity of these waters and the
sediments to accommodate the waste must be evaluated continuously. The information presented
in this chapter is based on the review and evaluation of scientific publications and technical reports
from various sources.
Los registros históricos sobre este ecosistema fluvial, denotan una pérdida importante de la biodiversidad, principalmente de moluscos, crustáceos y peces, pero también un incremento en la abundancia de especies tolerantes y la presencia de especies introducidas. No se evidencia un manejo adecuado de los efluentes, pero tampoco la aplicación de programas dirigidos a la conservación y restauración de los recursos hidrobiológicos.
de cadmio (Cd), plomo (Pb), mercurio (Hg) y
arsénico (As) en muestras de fi letes de pescado
congelado de elevado consumo en El Ecuador
como, corvina (Cynoscion phoxocephalus), dorado
(Coryphaena hippurus), tilapia (Oreochromis
niloticus) y atún (Thunnus obesus); adquiridos en
diversos supermercados de la ciudad de Machala,
Provincia El Oro. Los resultados preliminares
muestran la contaminación de estos productos por
As, Pb y Hg, superando las Normas Internacionales
establecidas para el consumo humano. En todas
las muestras examinadas los valores de Cd
fueron inferiores al límite de detección del método
(0,0042 mg. kg-1). La correlación signifi cativa entre
el contenido de Hg, Pb y As en las muestras de
músculo de pescado evaluadas, puede sugerir
que estos contaminantes tienen un origen común
ya que las elevadas concentraciones de As, Pb y
Hg son consecuencia de las aguas domésticas e
industriales vertidas sin tratamiento alguno en la
zona costera así como, la escorrentía proveniente
de las zonas de cultivos y al aporte atmosférico.
estableciéndose dos intervalos de tallas para A. similis y cuatro para A. tuberculosa. La carne de los organismos fue extraída, lavada y secada en un horno a 60 °C durante 72 h, para posteriormente digerirla con una mezcla de HNO3 y HClO4 en proporción 3:1. Las concentraciones de 4 metales: plomo, arsénico, mercurio y cadmio, fueron determinadas mediante espectrofotometría de absorción atómica. Los valores promedio obtenidos en A. similis (mg/kg), fueron: Pb (8,51 ± 0,34); As (1,42 ± 0,06); Hg (618,7 ± 355,32); Cd (1,21 ± 0,23) mg/kg; mientras que para A. tuberculosa fueron: Pb (7,52 ± 0,46); As (1,55 ± 0,14); Hg (364,38 ± 91,39); Cd (1,68 ± 0,28) mg/kg. Las concentraciones registradas de Pb, As, Cd y Hg en ambas especies de moluscos superan los límites máximos permisibles por las Normas Internacionales. Las tallas
más pequeñas (3-4 cm) de A. tuberculosa posee la capacidad de bioacumular mayor cantidad de Pb, Hg y Cd, mientras A. similis mostró su mayor concentración de Pb en su talla más pequeña (4-5 cm).
superficial sediments of the Cuchivero river, Venezuela, using sequential extraction and
atomic absorption spectrophotometry with flame. Pollution indices were used to study the
distribution, pollution and environmental risk in the sediments. Total values ranged from,
394-457 mgkg-1 Fe, 46,87-74,82 Mn, 6,45-11,92 Zn, 1,70-5,75 Ni, 0,39-3,7 Cu, 1,25-3,63
Cr, 0,37-1,82 Co, 0,10-0,30 Cd y <Ld-0,20 mgkg-1 Pb. The metals were found to be
strongly associated with the residual fraction minerals (70 to 90%), carbonates and iron
oxihidroxides. Manganese and cadmium were associated mostly exchangeable fraction
(60-70%). The indices indicate that the source of metals is mainly bedrock; no metal
enrichment and contamination exist. The risk of environmental disruption is low for Fe
and Co, high for Zn and Ni, medium for Cu and Cr, and very high for Mn, Cd and Pb.
actividad humana. Mas específicamente, esto está ocurriendo a lo largo de la costa, una
estrecha pero altamente productiva zona de transición que conecta la tierra con el océano, y
que consiste de múltiples ambientes diferenciados tales como los bosques marinos y las
dunas, las playas y orillas rocosas, las ciénagas, manglares y zonas cubiertas por las
mareas.
Pero los impactos humanos no se limitan a las zonas costeras, así como las actividades que
los causan. Desde las zonas costeras hasta bien tierra adentro, el estilo de vida de un
número creciente de personas y las industrias que nos sustentan afecta los ambientes
costeros y marinos desde el borde del mar hasta el océano profundo.
A través del mundo el crecimiento de población y de consumo y el crecimiento concomitante
de la actividad comercial, industrial y recreacional, continúan promoviendo el cambio y
degradación ambiental. Las causas específicas del cambio son complejas y entretejidas,
pero podemos identificar diversas amplias categorías de la actividad humana que debido a
su gran intensidad y penetración se han convertido en las fuerzas que dirigen la alteración
global del océano.
adscrito a la Universidad de Oriente, Núcleo de Sucre, ha emprendido una serie de observaciones
sobre la calidad de las aguas del río Manzanares. Esto se ha traducido en el desarrollo de siete (7)
tesis, entre Maestría y Licenciatura y unos ocho reportes técnicos, donde se evalúa las condiciones
de deterioro de las aguas de tan importante ecosistema. Estos trabajos han puesto en evidencia el
deterioro progresivo que ha venido sufriendo el río y encienden la alarma sobre la necesidad
imperiosa de tomar medidas urgentes, con la finalidad de detener el deterioro de este curso de
agua, y tratar de recuperar lo que se pueda, lo que en épocas anteriores fue orgullo del pueblo
sucrense, particularmente de las poblaciones ubicadas en sus riberas.