Ultrastructural changes in the gill epithelium of the crab Chasmagnathus granulatus (Decapoda: Grapsidae) in diluted and concentrated seawater

Chasmagnathus granulatus Dana, 1851 is an intertidal estuarine crab that experiences acute salinity changes ranging from <1‰ to full-strength seawater and even hypersaline waters in tide pools concentrated by evaporation. Ultrastructural changes induced by salinity in the posterior gills were examined in crabs collected from the Rio de la Plata estuary Argentina during March 1999. The posterior gills of C. granulatus are involved both in ion uptake and ion secretion depending on the acclimation medium. These organs are mostly lined with a thick tissue, which presents the characteristics of a typical salt-transporting epithelium. Electron microscopy analysis of gill tissue from crabs acclimated to dilute, full, and concentrated seawater (12‰, 34‰, and 45‰ salinity) showed significant development of basolateral membrane interdigitations, with numerous mitochondria and conspicuous apical membrane infoldings. Morphometrical analysis indicated that the subcuticular space delimited by the infolding of the apical membrane was significantly increased in the gills of high-salinity acclimated crabs. Septate junctions, which are thought to define the paracellular permeability, were significantly shorter in high-salinity acclimated crabs, suggesting a possible role of the paracellular pathway in salt secretion.     

The recovery of schools from earthquake effects: Lessons from Mexico City

Much work has been done to prepare schools and institutions for the immediate effects of earthquakes and other disasters. This paper looks at the preparation needed for medium to long term recovery from the physical and psychological effects of earthquakes. Colegio Madrid, a school of 3,000 students that suffered major damage in the September 1985 Mexico City earthquake serves as the focus of this study. The experiences and actions of faculty, staff, students and parents at this school provide lessons for not only schools, but all institutions and communities which may face the prospect of reconstructing themselves following a disaster.     

Hexavalent Chromium Sorption by Modified Cellulose Macro and Nanofibers Obtained from Eucalyptus Residues

Journal of Polymers and the Environment - Exposure to potentially toxic metallic elements (PTME) released in watercourses by industries results in irreversible damage to living beings or even...     

A three-component model of phytoplankton size class for the Atlantic Ocean

A three-component model was developed which calculates the fractional contributions of three phytoplankton size classes (micro-, nano- and picoplankton) to the overall chlorophyll-a concentration in the Atlantic Ocean. The model is an extension of the Sathyendranath et al. (2001) approach, based on the assumption that small cells dominate at low chlorophyll-a concentrations and large cells at high chlorophyll-a concentrations. Diagnostic pigments were used to infer cell size using an established technique adapted to account for small picoeukaroytes in ultra-oligotrophic environments. Atlantic Meridional Transect (AMT) pigment data taken between 1997 and 2004 were split into two datasets; 1935 measurements were used to parameterise the model, and a further 241 surface measurements, spatially and temporally matched to chlorophyll-a derived from SeaWiFS satellite data, were set aside to validate the model. Comparison with an independent global pigment dataset (256 measurements) also supports the broader-scale application of the model. The effect of optical depth on the model parameters was also investigated and explicitly incorporated into the model. It is envisaged that future applications would include validating multi-plankton biogeochemical models and improving primary-production estimates by accounting for community composition.     

Evolution rates and PCB content of surface films that develop on impervious urban surfaces

Surface films on impervious surfaces mediate the fate of organic contaminants in urban areas. Using sheltered 3-mm diameter glass beads as a surrogate impervious urban surface, studies in downtown Toronto showed that surface films developed at a consistent rate of 1.6–2.6 nm day⁻¹. Linear film growth was observed up to and including the last day of three studies of 89-, 273-, and 84-day duration. Total PCB content (sum of 15 PCB congeners) also increased linearly, at a similar rate as the surface film. A complementary study using unsheltered beads showed that up to 80% of film mass and PCB content were removed by film wash-off during rain events. The film growth rate on beads exposed at a rural site, 200 km northeast of Toronto, was 12–20 times lower with PCB burdens that were 7–22 times lower compared to Toronto. Based on these findings, it is estimated that approximately 56–226 g of PCBs are captured by a 70 nm thick film covering just the horizontal surface area of Toronto. This is a substantial quantity of PCB that is available for rapid surface–air exchange and wash-off.     

Multibiomarker approach in fish to assess the impact of pollution in a large Brazilian river, Paraiba do Sul

This article examines the advantages of the use of biomarkers as environmental indicators by applying it to Paraiba do Sul watershed, one of the most important Brazilian water bodies, which is in a critical environmental situation. We use a multibiomarker approach in fish as an integrated strategy to assess the impact of pollution. It comprehends a general biomarker of fish health, the condition factor (CF), and specific biomarkers of contaminant exposure such as metallothionein (MT), acetylcholinesterase (AChE) activity and biliary polycyclic aromatic hydrocarbons (PAH) metabolites. Our results revealed different effects in the fish from diverse locations with varying degrees of pollution. Furthermore, fish located just upstream of the water-treatment plant of the metropolitan area of Rio de Janeiro has shown to be affected by metals. This study indicates the usefulness of integrating a set of biomarkers to define the effects of anthropogenic inputs in aquatic bodies under complex polluted situations.     

Integration of Solid Oxide Fuel Cell in a sugar-ethanol factory: analysis of the efficiency and the environmental profile of the products

The effect of the integration of Solid Oxide Fuel Cell (SOFC) technology in a sugar-ethanol factory on the environmental profile/footprint of the products (sugar, ethanol, electricity) is evaluated. The sugarcane is the primary feedstock and sugar, ethanol and electricity are the main products of the system, where the functional unit is defined as 9.86 ton/h of sugar, 2.195 ton/h of hydrated ethanol (96% w/w) and 847 kWh of electricity. A detailed set of material and energy inputs and outputs was obtained from a local factory and was completed using simulation data by Aspen Plus^®.The environmental impacts (greenhouse gases and air pollution), exergy efficiency and a renewability parameter have been considered as indicators for the comparative assessment with conventional sugar, ethanol and electricity production technologies. The results show that the use of a SOFC technology involves a reduction of greenhouse gas emissions (52-55%) and non-renewable resources (60-64%) when compared with the conventional integrated sugar and ethanol plant. The higher renewability index (0.93) and exergy efficiency (38%) are noticed for the Solid Oxide Fuel Cell technology integrated in the sugar-ethanol factory than conventional sugar-ethanol plant.