Seafloor geological impacts associated with drilling disturbance

This study describes the sedimentological composition and morphology of the sea bottom in an area located at 902 m depth in the Campos Basin of Brazil, and compares characteristics before and after drilling activity for oil exploration. The results show no significant sedimentological variation in the area affected by drilling. The most noticeable effects were observed during the second (MD(2)) of three cruises, in terms of change to grain size distribution, total organic carbon and clay mineral composition around the Eagle well. This impact occurred over the seabed in a direction that corresponds to the near-bottom circulation pattern, predominantly northward. In the third cruise (MD3), 12 months after drilling, some recovery was observed. Side-scan sonar imaging was used to explore the extent of the area affected by drilling, and sedimentological samples from it confirmed the effects of drilling. (C) 2008 Elsevier Ltd. All rights reserved.

Results from a 15-year study on hydrocarbon concentrations in water and sediment from Admiralty Bay, King George Island, Antarctica

Admiralty Bay on the King George Island hosts the Brazilian, Polish and Peruvian research stations as well as the American and Ecuadorian field stations. Human activities in this region require the use of fossil fuels as an energy source, thereby placing the region at risk of hydrocarbon contamination. Hydrocarbon monitoring was conducted on water and sediment samples from the bay over 15 years. Fluorescence spectroscopy was used for the analysis of total polycyclic aromatic hydrocarbons (PAHs) in seawater samples and gas chromatography with flame ionization and/or mass spectrometric detection was used to analyse individual n-alkanes and PAHs in sediment samples. The results revealed that most sites contaminated by these Compounds are around the Brazilian and Polish research stations due to the intense human activities, mainly during the summer. Moreover, the sediments revealed the presence of hydrocarbons from different sources, suggesting a mixture of the direct input of oil or derivatives and derived from hydrocarbon combustion. A decrease in PAH concentrations occurred following improvement of the sewage treatment facilities at the Brazilian research station, indicating that the contribution from human waste may be significant.

Tank experiments with borehole self-potential data

Despite their importance in the evaluation of petroleum and gas reservoirs, measurements of self-potential data under borehole conditions (well-logging) have found only minor applications in aquifer and waste-site characterization. This can be attributed to lower signals from the diffusion fronts in near-surface environments because measurements are made long after the drilling of the well, when concentration fronts are already disappearing. Proportionally higher signals arise from streaming potentials that prevent using simple interpretation models that assume signals from diffusion only. Our laboratory experiments found that dual-source self-potential signals can be described by a simple linear model, and that contributions (from diffusion and streaming potentials) can be isolated by slightly perturbing the borehole conditions. Perturbations are applied either by changing the concentration of the borehole-filling solution or its column height. Parameters useful for formation evaluation can be estimated from data measured during perturbations, namely, pore water resistivity, pressure drop across the borehole wall, and electrokinetic coupling parameter. These are important parameters to assess, respectively, water quality, aquifer lateral continuity, and interfacial properties of permeable formations.

Taxonomic sufficiency of polychaete taxocenes for estuary monitoring

The polychaetes assemblage structure was used in order to investigate taxonomic sufficiency in a heavily polluted tropical bay. Species abundance was aggregated into progressively higher taxa matrices (genus, family, order) and was analyzed using univariate and multivariate techniques. Polychaetes distribution in Guanabara Bay (GB) was in accordance with a pollution gradient, probably ruled by the organic enrichment, consequent effects of hypoxia and altered redox conditions coupled with prevailing patterns of circulation. Within the sectors of GB, an increasing gradient in species richness and occurrence was observed, ranging from the azoic and impoverished stations in the inner sector to a well-structured community in terms of species composition and abundance inhabiting the outer sector. Multivariate statistical analysis showed similar results when species were aggregated into genera and families, while greater difference occurred at coarser taxonomic identification (order). The literature about taxonomic sufficiency has demonstrated that faunal patterns at different taxonomic levels tend to become similar with increased pollution. In GB, an analysis carried out solely at family level is perfectly adequate to describe the environmental gradient, considered a useful tool for a quick environmental assessment. (C) 2011 Elsevier Ltd. All rights reserved.

Goal-directed fluid management based on pulse pressure variation monitoring during high-risk surgery: a pilot randomized controlled trial

Abstract Introduction Several studies have shown that maximizing stroke volume (or increasing it until a plateau is reached) by volume loading during high-risk surgery may improve post-operative outcome. This goal could be achieved simply by minimizing the variation in arterial pulse pressure (ΔPP) induced by mechanical ventilation. We tested this hypothesis in a prospective, randomized, single-centre study. The primary endpoint was the length of postoperative stay in hospital. Methods Thirty-three patients undergoing high-risk surgery were randomized either to a control group (group C, n = 16) or to an intervention group (group I, n = 17). In group I, ΔPP was continuously monitored during surgery by a multiparameter bedside monitor and minimized to 10% or less by volume loading. Results Both groups were comparable in terms of demographic data, American Society of Anesthesiology score, type, and duration of surgery. During surgery, group I received more fluid than group C (4,618 ± 1,557 versus 1,694 ± 705 ml (mean ± SD), P < 0.0001), and ΔPP decreased from 22 ± 75 to 9 ± 1% (P < 0.05) in group I. The median duration of postoperative stay in hospital (7 versus 17 days, P < 0.01) was lower in group I than in group C. The number of postoperative complications per patient (1.4 ± 2.1 versus 3.9 ± 2.8, P < 0.05), as well as the median duration of mechanical ventilation (1 versus 5 days, P < 0.05) and stay in the intensive care unit (3 versus 9 days, P < 0.01) was also lower in group I. Conclusion Monitoring and minimizing ΔPP by volume loading during high-risk surgery improves postoperative outcome and decreases the length of stay in hospital. Trial registration NCT00479011

Questionnaire for monitoring auditory and language development in the first year of life

Purpose: To validate a monitoring questionnaire about hearing and language development applied by community health agents in the first year of life. Methods: Seventy six community health agents, previously trained on infant hearing health, administered a questionnaire to the families of 304 children with ages from 0 to 1 year. The questionnaire contains questions regarding hearing and language development and, for all age groups, the question “Does your child hear well?” was presented. The validity of the questionnaire was assessed by analyzing false positive and false negative rates of the identified children. A double-blind study was conducted so that all children assessed by the questionnaire were submitted to hearing evaluation performed by audiologists. Results: Four children (1.32%) were diagnosed with sensorineural hearing loss (two unilateral), and 69 (22.7%) with conductive hearing loss. The monitoring questionnaire showed specificity of 96% and sensitivity of 67%, with a false-negative rate of 33% for not identifying the unilateral hearing loss, and a false-positive rate of 4%. Conclusion: The questionnaire used has shown to be feasible and relevant to actions of the community health agents of the Family Health Strategy program, with high specificity and moderate sensitivity. The use of the validated instrument should be considered to complement Newborn Hearing Screening Programs, in order to identify late onset or acquired hearing loss.