Revistas by Yaneth Vasquez
Papers by Yaneth Vasquez
International Symposium on Oilfield Chemistry, 2003
Chemosphere, 2016
Biochemical passive treatment represents a promising option for the remediation of acid mine drai... more Biochemical passive treatment represents a promising option for the remediation of acid mine drainage. This study determined the effect of three hydraulic retention times (1, 2, and 4 days) on changes in system efficiency, reactive mixture, and microbial activity in bioreactors under upward flow conditions. Bioreactors were sacrificed in the weeks 8, 17 and 36, and the reactive mixture was sampled at the bottom, middle, and top layers. Physicochemical analyses were performed on reactive mixture post-treatment and correlated with sulfate-reducing bacteria and cellulolytic and dehydrogenase activity. All hydraulic retention times were efficient at increasing pH and alkalinity and removing sulfate (>60%) and metals (85-99% for Fe(2+) and 70-100% for Zn(2+)), except for Mn(2+). The longest hydraulic retention time (4 days) increased residual sulfides, deteriorated the quality of treated effluent and negatively impacted sulfate-reducing bacteria. Shortest hydraulic retention time (1 day) washed out biomass and increased input of dissolved oxygen in the reactors, leading to higher redox potential and decreasing metal removal efficiency. Concentrations of iron, zinc and metal sulfides were high in the bottom layer, especially with 2 day of hydraulic retention time. Sulfate-reducing bacteria, cellulolytic and dehydrogenase activity were higher in the middle layer at 4 days of hydraulic retention time. Hydraulic retention time had a strong influence on overall performance of passive reactors.
Environmental Earth Sciences, 2016
Revista Internacional De Contaminacion Ambiental, Aug 1, 2013
Revista Internacional de Contaminacion Ambiental
The concentrations of major (Fe and Al), minor (Na, K, Ca, Mg, Mn and Zn) and trace (Cr, Cu, Pb a... more The concentrations of major (Fe and Al), minor (Na, K, Ca, Mg, Mn and Zn) and trace (Cr, Cu, Pb and Cd) elements were determined in samples of bottom sediments of the Caura, Apure and Orinoco rivers in order to verify the existence of geogenic or anthropogenic abundance of several elements in these sediments. The samples were subjected to acid digestion with aqua regia and then analyzed by atomic absorption spectrometry. The sediment samples of the Caura River showed the lowest values of minor and trace elements probably due to the presence of clays and hydroxides that have a low cation exchange capacity (kaolinite and gibbsite) and the low pH values showed by the Caura River. The sediment samples of the Apure and Orinoco rivers showed high concentrations of major, minor and trace elements probably due to the presence of minerals such as Fe-oxyhydroxides and clays produced by an intermediate weathering stage, which have the capacity to occlude and adsorb minor and trace elements. Th...
Water, Air, & Soil Pollution, 2015
ABSTRACT This paper identifies the effects of red mud spills on several lagoons of the Orinoco Ri... more ABSTRACT This paper identifies the effects of red mud spills on several lagoons of the Orinoco River located surrounding the red mud deposits. Chemical and mineralogical analyses of sediments indicate that the geochemical signature of red mud is evident in Los Caribes and Guadita lagoons, with elevated concentrations of Fe, Al, and Na and the presence of goethite and hematite as the major mineral phases. Water quality analyses indicate that these lagoons have elevated values of dissolved oxygen, pH, conductivity, and dissolved Ca, Na, Ni, and Al. Also, elevated concentrations of Ca, Mg, and Mn in sediments suggest the precipitation of calcite, brucite a Mn-oxyhydroxides due to high pH values. Although Los Cardonales lagoon also showed evidence of redmud deposition, the enrichment of Mn, Zn, Ni, and Cd in sediments from this lagoon could be associated with wastewaters coming from landfills. The absence of vascular plants and the low abundance of fish communities in several lagoons can be related with the high pH values and the elevated concentrations of dissolved Al. The high concentrations of Fe and Mn in sediments of these lagoons can have adverse effects on benthic organisms, according to International Guidelines. Even though this lagunar system is impacted by red mud spills, hyperalkaline conditions (pH>13) were not found in superficial waters. Thus, dissolved trace element concentrations (Fe, Zn, Mn, Cr, Cu, Cd, and Pb) in waters were not high, mainly due to trace elements are immobilized by sorption or coprecipitation at circum-neutral pH.
Antarctic Science, 2015
ABSTRACT Comprehensive geochemical analyses (bulk parameters, major and trace elements, organic m... more ABSTRACT Comprehensive geochemical analyses (bulk parameters, major and trace elements, organic matter, mineralogy and particle analysis) were carried out on sediments from seven lakes on Fildes Peninsula, King George Island. The resulting compositional dataset was subjected to principal component analysis and cluster analysis. The results showed that four different lacustrine sedimentary environments can be distinguished: i) lakes 1 and 2 with relatively high values of secondary aluminous clay minerals, ii) lake 4 with anthropogenic enrichment of Co, Cu and Zn, iii) lake 7 with relatively high values of Ba and P and a high zeolite content, and iv) all the other studied lakes. Our results indicate moderate chemical weathering in all lacustrine sediments and that the distance to the glacial ice margin is one of the most important factors influencing the chemical weathering in the area. Furthermore, depositional processes have little influence on the geochemistry of the investigated elements and that local bedrock is the main source of sediments in the lakes on Fildes Peninsula.
Marine Pollution Bulletin, 2013
The oyster Crassostrea rhizophorae is a bivalve abundant in Venezuelan estuaries and consumed by ... more The oyster Crassostrea rhizophorae is a bivalve abundant in Venezuelan estuaries and consumed by local populations. No known values have been reported on trace metals in oysters from the central Venezuelan coast. We report the concentrations of Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V and Zn in the soft parts of C. rhizophorae, which were collected bimonthly between March 2008 and March 2009, at two sampling areas from the Central Venezuelan Coast: Buche estuary and Mochima estuary. Our results show that for each metal there is a similar temporal variation pattern. The concentrations of the heavy metals reported in this work are useful as reliable baselines and can be used for comparison in future environment studies. Concentrations in C. rhizophorae from the Buche estuary can be interpreted to be high on a global scale for Cd, Cu, Ni and Mn, indicating atypically raised bioavailabilities.
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Revistas by Yaneth Vasquez
Papers by Yaneth Vasquez