Removal of Mercury from Polluted Waters by the Water Hyacinth (Eichhornia crassipes)

The uptake of mercury by water hyacinth (Eichhornia crassipes) was studied in an outdoor experiment for 25 days at different metal concentrations. the removal of mercury from the water and uptake by plants was very effective during the first hours and decreased rapidly thereafter. the uptake of mercury was directly proportional to the initial concentration in the water. the highest concentrations were found in plant roots. According to the results, water hyacinth could be used for treatment of mercurial waste waters.     

Results from a reference laboratory for prenatal diagnosis of sickle cell disorders in Cuba

A nationwide programme for the prevention of sickle cell (SS and SC) disorders was initiated in Cuba in 1983. Couples at risk were identified by screening pregnant women and the partners of those who carry an abnormal haemoglobin, followed by genetic counselling and the offer of prenatal diagnosis. Prenatal diagnosis was performed in one laboratory, which had carried out 1068 prenatal tests for Hb SS and SC disorders by the end of 1992. The centralization of the service has permitted rapid identification and resolution of problems.     

Sulfur toxicity and media capacity for H2S removal in biofilters packed with a natural or a commercial granular medium

Two types of media, a natural medium (wood chips) and a commercially engineered medium, were evaluated for sulfur inhibition and capacity for removal of hydrogen sulfide (H2S). Sulfate was added artificially (40, 65, and 100 mg of S/g of medium) to test its effect on removal efficiency and the media. A humidified gas stream of 50 ppm by volume H2S was passed through the media-packed columns, and effluent readings for H2S at the outlet were measured continuously. The overall H2S baseline removal efficiencies of the column packed with natural medium remained >95% over a 2-day period even with the accumulated sulfur species. Added sulfate at a concentration high enough to saturate the biofilter moisture phase did not appear to affect the H2S removal process efficiency. The results of additional experiments with a commercial granular medium also demonstrated that the accumulation of amounts of sulfate sufficient enough to saturate the moisture phase of the medium did not have a significant effect on H2S removal. When the pH of the biofilter medium was lowered to 4, H2S removal efficiency did drop to 36%. This work suggests that sulfate mass transfer through the moisture phase to the biofilm phase does not appear to inhibit H2S removal rates in biofilters. Thus, performance degradation for odor-removing biofilters or H2S breakthrough in field applications is probably caused by other consequences of high H2S loading, such as sulfur precipitation.     

Tolerance to trichlorophenols in microorganisms from a polluted and a pristine site of a river

The effect of 2,4,5- and 2,4,6-trichlorophenol on the microbiota from a polluted and a pristine site of a river was studied. Bacterial metabolic activity measurements by epifluorescence microscopy showed that the polluted site contained more metabolically active cells than the pristine site. Total culturable bacterial counts and tolerant bacterial counts from both sites were not affected by incubation (for up to 5 days) with 200 ppm of chlorophenols. However, the incubation with 500 ppm of 2,4,5-trichlorophenol prevented detection of total and tolerant bacterial counts in the pristine site, and inhibited tolerants in the polluted site. None of 250 bacterial colonies directly isolated from these samples was able to grow on chlorophenols. However, bacteria able to grow on 2,4,6-trichlorophenol, were obtained by enrichment of water and sediments samples.     

Dermal exposure to pesticides in greenhouses workers: discrimination and selection of variables for the design of monitoring programs

Dermal exposure to pesticides is one of the main sanitaryproblems which greenhouses workers face. With the dual aimsof establishing both the body part that receives the greatestexposure and the variable that has greatest influence on this exposure level, 22 pesticide application trials were performed. Trials were carried out in different greenhouse vegetable crops,using different pesticides and different spray diameters from the spray gun. In order to determine dermal exposure, the wholebody method was used. Pieces of the applicator suit were subject to an extraction procedure and their pesticide contentdetermined using GC-NPD analysis. Multivariate analysis were applied to the data obtained. Principal component analysis showed that all trials produced a high exposure level on lowerleft leg and lower right leg. Cluster analysis distinguished between three sample groups. The most and the least affectedparts were clearly distinguished. Discriminant analysis indicated that the thin drop size of the spray gun is responsible for both the differences between groups and the minimum or maximum exposure level measured on the applicatorsuit. Therefore, selecting the variables, lower legs and thindrop size, is considered fundamental in designing programs formonitoring pesticide exposure.     

Ecosystem-based adaptation to climate change: what role for policy-makers, society and scientists?

In developing countries where economies and livelihoods depend largely on ecosystem services, policies for adaptation to climate change should take into account the role of these services in increasing the resilience of society. This ecosystem-based approach to adaptation was the focus of an international workshop on “Adaptation to Climate Change: the role of Ecosystem Services” held in November 2008 in Costa Rica. This article presents the key messages from the workshop.     

Using Four Capitals to Assess Watershed Sustainability

The La Antigua watershed drains into the Gulf of Mexico and can be considered as one of the most important areas in Mexico because of its high productivity, history, and biodiversity, although poverty remains high in the area in spite of these positive attributes. In this study, we performed an integrated assessment of the watershed to recommend a better direction toward a sustainable management in which the four capitals (natural, human, social, and built) are balanced. We contrasted these four capitals in the municipalities of the upper, middle and lower watershed and found that natural capital (natural ecosystems and ecosystem services) was higher in the upper and middle watershed, while human and social capitals (literacy, health, education and income) were generally higher downstream. Overall, Human Development Index was negatively correlated with the percentage of natural ecosystems in the watershed, especially in the upper and lower watershed regions. Our results indicate that natural capital must be fully considered in projections for increasing human development, so that natural resources can be preserved and managed adequately while sustaining intergenerational well-being.     

The transition of a line plume to round plume

Environmental Fluid Mechanics - Buoyant turbulent plumes are often categorized by their geometry and described as either round plumes, issuing from a point source, or line/planar plumes, issuing...