Fate of petroleum hydrocarbons in bioturbated pristine sediments from Caleta Valdés (Patagonia Argentina): An ex situ bioassay.

Petroleum can pollute pristine shorelines as a consequence of accidental spills or chronic leaks. In this study, the fate of petroleum hydrocarbons in soft pristine sediment of Caleta Valdés (Argentina) subject to ex situ simulated oil pollution was assessed. Sedimentary columns were exposed to medium and high concentrations of Escalante Crude Oil (ECO) and incubated in the laboratory during 30 days. Levels of aliphatic hydrocarbons at different depths of the sedimentary column were determined by gas chromatography. Oil penetration was limited to the first three centimetres in both treatments, and under this depth, hydrocarbons were clearly biogenic (terrestrial plants) as in the whole sedimentary column of the control assay. Bioturbation by macrobenthic infauna was strongly impacted by oil pollution which resulted in reduced sediment oxygenation and low burial of petroleum hydrocarbons. This may partly explain the limited hydrocarbon biodegradation observed, as indicated by the relatively high values of the ratios nC17/pristane, nC18/phytane, and total resolved aliphatic hydrocarbons/unresolved complex mixture. Correspondingly, at the end of the experiment the most probable number of hydrocarbon-degrading bacteria reached ~ 103 MPN g-1 dry weight. These values were lower than those found in chronically polluted coastal sediments, reflecting a low activity level of the oil-degrading community. The results highlight the low attenuation capacities of Caleta Valdés pristine sediments to recover its original characteristics in a short time period if an oil spill occurs. In this work, we present a novel and integrative tool to evaluate the fate of petroleum hydrocarbons and their potential damage on pristine sediments.

Ceguera infantil en Chile: estudio de escuelas de ciegos / Child blindness in Chile: study of blind schools

Se examinaron 318 niños registrados en las escuelas para ciegos en Chile. Usando las definiciones de la Organización Mundial de la Salud (OMS), 267 tenían severa pérdida visual o ceguera. Los problemas retinales fueron la causa en 47,6 por ciento; enfermedades del nervio óptico en 12,7 por ciento, todo el ojo en 10,9 por ciento, catarata en 9 por ciento y glaucoma en 7,5 por ciento. La pérdida severa de visión fue atribuída a factores hereditarios en 29,6 por ciento, factores intrauterinos en 8,2 por ciento, factores perinatales en 22,5 por ciento y factores que se desarrollan en la niñez en 11,2 por ciento. La etiología no pudo ser determinada en 28,5 por ciento de los niños, que incluye un 15,7 por ciento con anormalidades del desarrollo. La retinopatía del prematuro (ROP), aporta 17,6 por ciento de todos los niños con severa pérdida visual. Análisis por edad sugiere que la ROP se está haciendo cada vez más importante. Se estima que 47 por ciento de los niños con severa limitación visual en Chile tienen ceguera evitable. Los hallazgos son discutidos para posible formulación de estrategias de control

The determination of 17-ketosteroids and ketogenic steroids in urine

A method is described for the extraction and estimation of 17-ketosteroids and 17-ketogenic steroids in human urine suitable for use in the moderately well equipped hospital laboratory. Data obtained from normal persons of both African and European descent is presented together with examples from two clinical conditions in the diagnosis of which these assays are invaluable

Adrenal cortical activity in the tropics

Evidence is presented from both the literature and personal observation supporting the thesis that adrenal cortical activity in the tropics is `abnormal' by existing standards. The current programme, designed to investigate the influence of the dominant variables (racial factors and environmental conditions), is outlined, with discussion of some preliminary trends (AU)

Urinary 17-ketosteroids and ketogenic steroids in a mixed Jamaican population

The mean daily 17-ketosteroid excretion for a group of coloured Jamaicans was not found to be significantly different from that of Europeans living under the same conditions. Mean 17-ketogenic steroid excretion was significantly lower in the Jamaicans (Summary)