Química

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https://hdl.handle.net/10669/281

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Examinando Química por Autor "Acuña González, Jenaro"

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  • Miniatura
    Ítem
    Metals in coastal mollusks of Costa Rica
    (2015-12) Vargas Zamora, José A.; Acuña González, Jenaro; Gómez Ramírez, Eddy; Molina Delgado, Johan
    The input of contaminants to coastal ecosystems is a global problem on the rise. Data on metal pollution from tropical sites is often lacking and pilot surveys are urgently needed to provide a general framework to estimate the relative impact of these and other pollutants. The objective of this study was to make accessible data on trace metals collected during pilot surveys (2000-2006) at four coastal embayments of Costa Rica. Concentrations of Fe, Pb, Zn, Mn, and Ni were determined by Flame Atomic Absorption Spectrometry (FAAS) and Graphite Furnace Atomic Absorption Spectrometry (GFAAS), in tissues of the rock snail Acanthais brevidentata, the infaunal bivalves Anadara tuberculosa and Tagelus affinis from three Pacific shorelines (Culebra Bay, Gulf of Nicoya, and Golfito Bay) and in the clam Polymesoda arctata from the Caribbean coast (Moín Bay). In addition, Sn, Cd and Cu were evaluated in tissues of T. affinis. A group of specimens of T. affinis was depurated for 72 hours in filtered seawater from the collection site. Concentrations varied between and within sites and also between parts of the same organisms. Maximum concentrations (μg/g dry weight) were: Fe 2 230 (P. arctata-tissues, Moín Bay), Pb 195 (P. arctata-tissues, Moín Bay), Zn 961 (A. brevidentata-tissues, Golfito Bay), Mn 921(P. arctata-tissues, Moín Bay), and Ni 10.5 (A. tuberculosa-shells, Golfito Bay). Minimum concentrations (μg/g dry weight) were: Fe 5.36 (P. arctata-tissues, Moín Bay), Pb < 0.20 (P. arctata-foot, Moín Bay), Zn 2.75 (P. arctata-shell, Moín Bay), Mn 5.5(A. tuberculosa-foot, Gulf of Nicoya) and Ni 0.83 (A. tuberculosa-foot, Golfito Bay). Tissues of non-depurated T. affinis had maximum-minimum concentrations (μg/g dry weight) of Sn (3.74-2.73), Cd (0.69-0.43) and Cu (21.6-14.8). The concentrations (except for Pb and Mn) were within values reported in recent literature. The relatively high concentration of Pb was probably related to the use during sampling of leaded fuel in small boat operation at the site, while no evident cause was found for the high Mn values. Depuration was partially effective in lowering the metal burden in T. affinis. Data gathered during the pilot survey are indicative of relatively clean conditions of Culebra Bay, while the other three sites have important concentrations of certain contaminants, including metals. In spite of the fact that this data was collected more than a decade ago, it remains as the most recent available on trace metals from coastal mollusks of Costa Rica.
  • Miniatura
    Ítem
    Parámetros físico-químicos en aguas costeras de la Isla del Coco, Costa Rica (2001-2007)
    (2008-11-17) Acuña González, Jenaro; García Céspedes, Jairo; Gómez Ramírez, Eddy; Vargas Zamora, José A.; Cortés Núñez, Jorge
    Four cruises to Isla del Coco (Cocos Island), Costa Rica, were carried out in order to gather oceanographic data related to surface temperature, salinity, dissolved oxygen concentration, Secchi disk depth, nutrient concentra tions (nitrate, nitrite, phosphate, and silicate), chlorophyll-a, and suspended materials. Surface temperatures, salinities and dissolved oxygen concentrations were high, in the range of 26.5 to 29.7ºC, 27 to 32 psu, and 102.0 to 127.5% saturation, respectively. Phosphate was always present in the water samples, within the typical range of 0.10 to 0.53 µmol/L; the other nutrients were not detectable in some samples. Chlorophyll-a concentrations were in the range of 0.02 to 0.42 mg/m3 which revealed the influence of oceanic and coastal waters, with the higher phytoplanktonic pigment concentrations near the coast, and suspended materials from 1.08 to 17.91 mg/L.
  • Miniatura
    Ítem
    Reconnaissance of selected PPCP compounds in Costa Rican surface waters
    (2011-10-15) Spongberg, Alison L.; Witter, Jason D.; Acuña González, Jenaro; Vargas Zamora, José A.; Murillo Castro, Manuel María; Umaña Villalobos, Gerardo; Gómez Ramírez, Eddy; Pérez Rojas, Greivin
    Eighty-six water samples were collected in early 2009 from Costa Rican surface water and coastal locations for the analysis of 34 pharmaceutical and personal care product compounds (PPCPs). Sampling sites included areas receiving treated and untreated wastewaters, and urban and rural runoff. PPCPs were analyzed using a combination of solid phase extraction and liquid chromatography tandem mass spectrometry. The five most frequently detected compounds were doxycycline (77%), sulfadimethoxine (43%), salicylic acid (41%), triclosan (34%) and caffeine (29%). Caffeine had the maximum concentration of 1.1 mg L 1 , possibly due to coffee bean production facilities upstream. Other compounds found in high concentrations include: doxycycline (74 mg L 1 ), ibuprofen (37 mg L 1 ), gemfibrozil (17 mg L 1 ), acetominophen (13 mg L 1 ) and ketoprofen (10 mg L 1 ). The wastewater effluent collected from an oxidation pond had similar detection and concentrations of compounds compared to other studies reported in the literature. Waters receiving runoff from a nearby hospital showed higher concentrations than other areas for many PPCPs. Both caffeine and carbamazepine were found in low frequency compared to other studies, likely due to enhanced degradation and low usage, respectively. Overall concentrations of PPCPs in surface waters of Costa Rica are inline with currently reported occurrence data from around the world, with the exception of doxycycline