Enhancing in situ bioremediation with pneumatic fracturing

A major technical obstacle affecting the application of in situ bioremediation is the effective distribution of nutrients to the subsurface media. Pneumatic fracturing can increase the permeability of subsurface formations through the injection of high pressure air to create horizontal fracture planes, thus enhancing macro-scale mass-transfer processes. Pneumatic fracturing technology was demonstrated at two field sites at Tinker Air Force Base, Oklahoma City, Oklahoma. Tests were performed to increase the permeability for more effective bioventing, and evaluated the potential to increase permeability and recovery of free product in low permeability soils consisting of fine grain silts, clays, and sedimentary rock. Pneumatic fracturing significantly improved formation permeability by enhancing secondary permeability and by promoting removal of excess soil moisture from the unsaturated zone. Postfracture airflows were 500% to 1,700% higher than prefracture airflows for specific fractured intervals in the formation. This corresponds to an average prefracturing permeability of 0.017 Darcy, increasing to an average of 0.32 Darcy after fracturing. Pneumatic fracturing also increased free-product recovery rates of number 2 fuel from an average of 587 L (155 gal) per month before fracturing to 1,647 L (435 gal) per month after fracturing

Reactive diffusive transport of heavy metals in Lake Coeur d'Alene sediments

Lake Coeur d'Alene Basin, Idaho sediments have been heavily enriched with toxic metals, including Cd, Cu, Pb, and Zn, serving as a toxic, mutagenic and carcinogenic source of contaminants. Our focus is to develop a biotic/abiotic diffusive reactive transport model to evaluate the fate, transport, exposure and effects of zinc, lead, and copper in Lake Coeur d'Alene benthic sediments. The model is structured as a multicomponent reactive transport to simulate spatial and temporal distributions of metals in the benthic sediments and their effect on microbial consortia including multiple trophic groups and microbial populations in the benthic sediments. The 1-D inorganic diffusive transport model is coupled to a microbially-mediated redox reaction network which integrates syntrophic consortium biotransformation dynamics accounting for product and metal toxicity inhibition under a diffusive transport regime. The model simulates the mobilization of heavy metals initially sorbed onto hydrous ferric oxides through microbial reductive dissolution of Fe(III) minerals under redox disequilibrium conditions with simultaneous biogenic sulfide production, forming soluble metal (bi)sulfide complexes and insoluble metal sulfide minerals, and the effects of these metals on benthic microbial communities via accounting of dose, where dose is expressed in a novel fashion as a structural variable in the population dynamics of the microbial consortia

Reshaping pedagogies for a plurilingual agenda.

The realisation of plurilingualism requires a more open and inclusive approach to language teaching and one which takes account of various factors involved in working with learners who have a background in the target language and culture. This article seeks to identify these factors within the context of a set of broader principles for second language teaching and thereby to provide a basis for the development of flexible, personalised pedagogies. The theoretical model presented emerges from interviews carried out with former student teachers of Arabic, Mandarin, Panjabi and Urdu currently working in London schools as well as from the development of an innovative initial teacher education course at Goldsmiths, University of London, introduced to cater for the needs of teachers of these languages

Teaching Bioeconomics

Bioeconomics is a relatively young field that uses an expanded microeconomics to examine animal behavior, human behavior, and animal and human social institutions. A voluminous literature is rapidly accumulating. There are as yet no standard textbooks, but there are several excellent books and/or articles that can be used in combination with videos and other aids to make a course that students will enjoy and that teachers can use to advance the frontiers of scholarship in economics and biology. Copyright Springer 2005altruism, conflict, cooperation, evolution, game theory, institutions, rationality,